Need ignition upgrade help/advice.
 

I'm looking to do some mild ignition upgrades to the 351 in my GMC 5000. Mainly trying to get a hotter spark in hopes that it will improve power....

Does anyone know of a good hot 12V coil? I have a NAPA replacement in there now (cylindrical style) and would like to replace with the same style.

And has anyone upgraded to an electronic ignition module and did away with points/condenser? If so, was there a difference?

Re: Need ignition upgrade help/advice.
 

I put the pertronix flamethrower in mine and the first thing I noticed was easier cold starts. Starts better hot and the engine runs smoother. The pertronix is fairly cheap and an easy bolt in unit, only beware is they can die without warning....like all modules.

Other option would be to build the Buick v6 dizzy that's explained here:
www.6066gmcguy.com/hei.html

Another option is to get a dizzy from HEIDIZZY on Ebay. Currently I don't see any on there.

I ran stock points with a 45K pertronix coil and it didn't take long for that hot coil to fry those points.

Re: Need ignition upgrade help/advice.
 

Thanks TJ.

So it looks like if I want to go with a hotter coil, I will have to upgrade to electronic ignition or I'll burn my points.

Do you have a link to the ignition module?

Now I have to figure if it's worth doing the swap....

Re: Need ignition upgrade help/advice.
 

When there is a "normal "spark, the fuel ignites. The words "Hotter Spark" were invented by ignition parts manufacturers. You won't get anything out of a "Hotter Spark" except the same combustion.
If you mean a "hotter plug", that has nothing to do with "power", as you say you want.

A "hotter" plug is one that is of a higher heat range than another. Once you understand the heat range, you'll see why there's no such thing as a "hotter" plug.

The spark plug acts as a heat sink for the combustion chamber. The plug's heat range needs to be matched to the chamber temperature, not the general engine temperature.

Running a higher heat range plug accomplishes nothing positive, same as running a colder heat range plug.

I advise good timing with good fresh distributor components, wires, plugs, fuel filters, air filters, carb rebuild, tire pressure. In other words, a tune up. Best you can do to get "power". The max power is already built into the motor when running per factory specs. The motor has a max RPM, max torque.

You can get more speed thru the drivetrain gearing or more pulling power thru the drivetrain gearing, all the way to the tire size. Not the motor. Not the spark. If you want to redesign the internals of the motor, then you may get more power. But "more power" means different things to different people. Not sure what exactly is wrong with the performance of your motor or what you need more of. You must access the overall condition of the motor if you feel it is weak. Compression test first. Oil consumption thru exhaust. Exhaust system. Carburetor. Fuel pump, clogged fuel filters, clogged air filters, bad gas, bad clutch, brakes dragging, loads too heavy....all depending on exactly what you think is missing regarding "power".

You see the trouble others are having screwing around with ignition. The only thing HEI gives is no points wear, reliability and no adjustment. Not power. Points have served well for many years. I would run away from Pertronix. The only HEI to consider is the one explained on our pages under "performance upgrades".


Contact member WE7X Rod Johnson. He has the parts and instructions for the mod.

Re: Need ignition upgrade help/advice.
 

Some good things to consider and think about Ken.

I've been down this road once on here so I didn't want to sound like a broken record, but the back story is...

Is a 20,000 mile '61 GMC 5000 12ft flat bed, used to be a fire truck. Ever since I got it home there has been an issue with it being able to pull the hills or loads (even a 2400lbs tractor). It has a bad tendency to slow down on the slight hills and I have to drop a gear. That's from 35mph without being in overdrive.

I've done just about everything to the engine except pull the heads and oil pan. Compression is 120+/-, ignition has all been done, carb rebuilt a couple times ETC... Maybe someone messed with the jets?

So at this point it either is what it is for a 56yro truck, or there's something I'm still overlooking.

Re: Need ignition upgrade help/advice.
 

Fire trucks carry 1000 gal H20 @ 8.34= 8340 lbs. Yours may have had a larger tank than that!!! Maybe it's built special with heavy duty frame or something? 20K miles should run strong. Something big does seem to be wrong. Is it winding up OK? while climbing/hauling or is it bogging down? Ebrake stuck on? :headscratch: Something goofy like that could be happening. Two speed rear end? 5 speed trans? I'm no expert on hauling with big trucks but do you keep it wound to highish RPM using proper gear changes? Could it be you? or are you experienced?

It is made to haul and it should do a good job.

I would absolutely check all brake shoes and parts at each wheel if you have never looked.

Been reading your past posts. BBV6 mentioned 5 deg BTDC, you said 10. I think 5 means 5. If it won't run there, find out why, don't use 10.
Snazzypig questioned your jets, gasket arrangement, vacuum, etc. I think you need a new stock carb. I think you have tinkered it into a mish mosh. Start over, do it right, don't screw with Mother Nature. These motors are not made to customize and tweek around on. They are designed by engineers who perfected it already. It ain't no SBC. Leave the jets alone. Assemble carb carefully, ALL NEW parts, setting level and drop as necessary. You are only 450 ft above sea level unless you are on some big mountain. So that should not be the problem.

I am not slamming you, just cutting to the chase. Hope you understand. Don't want to blog it to death, want to fix it. Making sure you are out of the past box and into brainstorming. You have added many new parts. Double check your work and your points gap. Tune it all TO SPEC, not someone's BS ideas. You can play with timing a little. It's not what it sounds like, it's what it runs like. I think you may have said it "pops" at 5 deg? Make sure that is Before TDC and not after. If it backfires at spec then it's vacuum leak....big time. Even an exhaust leak will do that. Analyze some more and see what you get. Please state if it's a carb backfire (pop) or a tail pipe backfire....at 5 BTDC. We'll get there...me, Snazzy, BBV6, TJ and anyone else who can try.

Re: Need ignition upgrade help/advice.
 

Jake, did you ever get a chance to put those new intake gaskets on? Lightly buff the surfaces? Also did you reseal the valley pan?

351 power specs are: 180 hp @ 3400 and 312 pound ft @ 1800-2000 gross

351E power specs are: 220 hp @ 4000 and 320 pound ft @ 1600 gross

So not a Ton of power to begin with but plenty of torque to haul that thing at a decent speed. Specs are 4-6 degrees advanced so if you had to add an extra 5 degrees advance just to make it run decently I have to wonder if the timing jumped? The chains on these are not very tight so that could be a possibility. I haven't read of it happening yet, but there's always a first time.
Vacuum leak already mentioned.....check all gaskets and hoses.
When you did the carb rebuild did you check to see if the throttle shafts in the carb were all worn out? Vacuum leak through there will cause backfiring and power loss.

Re: Need ignition upgrade help/advice.
 

Thank you Ken! Reading through that widdled everything down that I've been thinking about.

Let's see... this was a tanker truck so I'm sure it had at least 2000gal tank on it, I would figure. Has the boxed frame with the ladder-work on the inside.
Seems to wind up okay when you are on flat ground, sometimes a little hesitation at first.
Sometimes when winding up going up a hill or pulling a hill, I can keep putting my foot into it and there is no RPM/power change, then when getting close to the floor it will start to pick up some..

Negetory on the E-brake, no problems there.

Yep, 2 speed rear, 5 speed main, and a 3 speed brownie for OD. I keep the rear in HI now that I have the brownie. When pulling hills I keep my foot into it, not over speed the engine but to keep the momentum in order to change gears. If it's flat, 2nd, 3rd, 4th, 5th then OD. Hill or hauling, starting with the Brownie in Direct (2nd)... 2ndD, 3rdD, 3rdOD, 4thD, 5thD, 4thOD, 5thOD. The gap between 3-4 is pretty significant and I have a working 4th.

Front brakes have been done, rears I haven't but they don't drag... should still check 'em.

Sounds good, I'll have to set the timing back to 5 and see what happens.

As for the carb, if I can find another that would be great, if not, I'll have to see about ordering another kit and 2 new jets, because I messed with these ones...

Exhaust pop at 5. And that was before I did manifold gaskets and a few other things this year. Need to check that again.

YES! Less write up and more progress. I have to haul tractors to a show next weekend with it so with any luck I can delve into it before hand and give you-all an update.




Yep, that I did TJ. Beginning of the year took care of everything...

Throttle shafts are good and tight.

Timing chain has been on my mind for a while now. I did the whole metal rod in #1 cylinder at TDC thing, distributor was where it should be, of course that might not tell me if the chain is off.

Re: Need ignition upgrade help/advice.
 

Greetings fellow members!

I agree with TJ. Although rare, timing chain "jumps" have been known to happen, and when they do, the engine runs really crappy, and you have to advance the ignition timing to even get the engine to start and run. I know. I had a '70 Buick Le Sabre in which the timing chain "jumped" causing the problems that I just described. If the chain has "jumped" and you have no (or known) vacuum leaks, you will have a very low vacuum reading on your vacuum guage indicating "late valve timing," and as I previously said, your engine will run really lousy and have no power.

Re: Need ignition upgrade help/advice.
 

Did not get feedback on my post re: Backfire. Carb? Exhaust? or a pop somewhere? May or may not be a clue there. Hard start would be a clue. Slow or fast starter turning could be a clue. Hope you didn't put on a custom 3" Dia. air cleaner or some such item? Did we mentioned fuel pump, fuel filter clog, line clog, tank clog or gas cap not venting? Run without cap.

He said all cylinders have 120 psi. Jump timing would probably lower the psi. Compression would be uneven or low.

Low mileage, seems unlikely chain is stretched that much.

I think he will recon the situation as time allows. If it runs on flat land at 50MPH and slows on hills. Gravity may be acting on gas flow or debris flow somewhere. Bad fuel pumps always show up under load/hills.

Re: Need ignition upgrade help/advice.
 

My reply should be coming guys (replyed last night), when I quote a post it says it has to go to the moderator first for some reason....

George, I haven't checked it with a gauge, but I think my vacuum is okay. I have the Hydro-vac booster for the brakes and the large vacuum reserve tank. Booster was rebuilt and brakes work nice. When my foot is on the brake and I first start the truck from sitting, the pedal goes up about 1/2"-1" so it must be pulling a good vac.

Re: Need ignition upgrade help/advice.
 

Quick update on the truck...

Adjusted the timing back to 5deg. Cleaned and set points to .020 according to shop manual.

Hauled everything to and from the show this weekend. Truck ran a bit better but is still lacking power.

Once I start reaching an incline and put my foot into it, the first 1/3 or so of pedal travel makes a difference. After that if I stomp it to the boards there is no RPM change, no power change, doesn't seem to fire much harder.

Any ideas? I'm going to change my fuel filter again. Is there secondaries in these WW carburetors? If so maybe they aren't kicking in? Maybe the vacuum piston in the carb isn't working?

Re: Need ignition upgrade help/advice.
 

Sounds like fuel starvation somewhere.....I would pull the sending unit out of the tank and see if there's a bunch of crap built up on it....then check the tank. After that I would disconnect and blow out all fuel lines. There could be some blockage in the main jet of the carb still. I had a pesky arctic cat quad with a rather odd carb design do that to me....first 3rd of the throttle was fine....floor it and no change except you could hear it bog. Turns out there was a bit of crap stuck in the main jet "tube" where the fuel flows after the jet. Issue is different issues can cause the same symptoms. If you are sure you have a clean fuel system and good carb...then there's still something else lacking.

Edit: Check fuel filter or filters for any signs....excess crap built up...or really any crap at all.

Re: Need ignition upgrade help/advice.
 

I have been hauling 1500 gal of water every 4 days with my '65 5000 6X6 (also ex fire, has about 40K miles).

Going up a slight incline I make about 20 MPH. Decent incline (4% to 6%) 15 mph is tops. It seems to pull hardest at about 1600 RPM where, as you say, after the first 1/3 or 1/2 of the pedal travel, there is no more power to be had. If you wind it up to 2500 or 3K RPM, then it is more "responsive", for lack of better term.

My truck scales in just shy of 14K empty for a total GVW of 26K loaded. No matter what you do to the little 351, it's not going to light the world on fire. It will get you there no problem, but it might take awhile.

JFYI, on the 30% grade that I have to pull, I have to drop to 2nd gear in low range. At 2500 RPM, the speedo needle doesn't even come off the stop...

Re: Need ignition upgrade help/advice.
 

Will do TJ. I won't get to the truck for another week or so due to work here, but when I do, updates to follow.

'72, I know this thing won't be a rocket sled on rails I just thought that it should have a bit more pep than what it has now. Maybe the 351's is running good and it's all in my head...

Anyways, here's a street view of a road in town. I'm not up to par on % grades so I don't know what it would be... Pics kinda small but it's a pretty fair hill.

Pulling a load of 4 garden tractors, about 2600 lbs, I dropped the brownie back into direct and the main down to 4th pulling the hill at about 20-25mph. So it sounds like that would be about average for what my truck is.


Attachment 6648

Re: Need ignition upgrade help/advice.
 

Any idea what your empty weight is?

Re: Need ignition upgrade help/advice.
 

I'm guessing 7500-8000.

When the guy hauled it up here from NC, he went over the scales and it was about 6500 just cab and chassis.

GVW is same as yours 26,000.

Re: Need ignition upgrade help/advice.
 

Reviving this thread since I've done some more work to the '61 and had some questions.

I recently installed a like new take off Stromberg WW carburetor that was removed in the 60's. It was rebuilt with a new kit, correct size .057 main jets and #67 power by-pass jet for the 351.

It's a 23-133A. The only noticeable difference is the throttle plate has 2 small vacuum holes that run up into the vacuum port on the backside. The port on my truck is plugged so I'd assume those holes don't make a difference once I plugged the port.

The truck seems to hold a bit better on hills and accelerates up a hill a bit better.

My very rough estimated MPG is about 4.7+/-. Sound about right for a 351?

I was thinking of trying a set of .056 jets just for kicks since it almost seems like it might be running a bit rich.
For curiosity I swapped in the .055's that came out of the WW and it was struggling starting out so I think the 56's may starve it also.

Any thoughts appreciated. I should probably just run it, but I'm a bit finicky when it comes to this stuff.

Re: Need ignition upgrade help/advice.
 

My experience with these motors, especially the 478 in my Massey 1100 tractor, are that most of them are under-fueled. Now that we have the percentage of alcohol in fuels we have another problem different from the fuel these motors were designed to use. When pulling garden tractors on alcohol we had to increase jet sizes a lot to get the power from alcohol. The same is true here now; the alcohol in the fuel has a negative effect. More has to be put into the motor to get the power back. 'Back in the day', 1970's, when I worked at Meyer Motors GMC/Allis Chalmers dealership we would have complaints about these motors. We would drill out the main jets about .010" size increase and power would come up, run cooler, and mileage would actually increase because the driver did not have to have his 'foot in it' so much. When the weather conditions were right we would have motors 'backside' pistons, burning them. After repairing the damage we increased jet sizes and the problem never happened again. I suspect the industry's push for fuel mileage caused some of this leaning out from the factory to happen. For my Massey with the 478 (hence my name) I had several drilled jet sizes I tried until I got what I wanted. There is also an enrichment piston in the carb that drops dowm as engine vacuum decreases, opening an enrichment jet to give the motor more fuel. My 478 would drop more RPM than I wanted it to in a herd pull before the enrichment came in so I stretched the spring on the rod for the enrichment valve until I got it to come in at less RPM drop. When it let the RPM drop too far, when it came in the power boost would cause the tractor to spin out. I also throw away the timing light and 'power' time motors, moving the distributor and trying it until I get the proper performance. We also do that with out street/race motors then mark the distributor base so we know where to set it. I also find that the standard ignition system with a MSD 6 or MSD 6al and the associated MSD coil added will help tremendously. These units give five spark pulses per plug until they reach 3,000 RPM at which time they give one. Much better than Pertronix. The MSD 6al is different from the MSD 6 in that the 6al has chips that can be plugged into the side that limit the high end RPM the motor is allowed to reach. Made the motor run much better. I think the 5 sparks per plug help these motors light the fuel more efficiently in the large bore size they have. Believe me, you do not want to get shocked by one of these units! Big no-no! Just my experience here. Others may be different, but it has always worked for me on these motors.

Re: Need ignition upgrade help/advice.
 

I see Ken has mentioned exhaust.....
Back in the early 70's, I took my 63 GMC with 305 V6 to Midas Muffler and had a dual exhaust setup installed. Don't know if your big 5000 has the same single exhaust like all the 305's did coming from the factory that way.
That being said, I went from a steady 11 mpg to over 13 with dual exhaust and nothing else- nothing crazy- just two inch pipe through some low back-pressure type "turbo" mufflers that do not make a bunch of noise like some do today, and I noticed a BIG difference in how the engine performed, and it absolutely was better on the hills. The engine just breathes so much better. It was the best $80 I ever spent (back then). In my own situation, I had the mufflers installed outside the frame rail and dumped the exhaust out the sides at a 45 degree angle in front of the rear wheels/tires. Sounded great too! With a 20 percent jump in fuel "economy", I was impressed with this change.
Something ELSE to consider......FWIW,
JimJ AZ :thumbsup:

Re: Need ignition upgrade help/advice.
 

I can give that a whirl. The jets that were in the original carburetor I messed with some and opened up last year. Probably to around .057+/-, and it made a noticeable difference when I did that. Compared to those modified jets, with the new 57's I have to keep my foot into it a lot more and as you said, I'm cooking through gas. For the few flat stretches of road here in NE just touching the throttle keeps it at 45, but most of the time I'm laying into it keeping it at speed or climbing hills.

Power piston I'm not sure if it's working. I'm matted it a few times and there is no noticeable difference that the plunger has hit the valve. Might not be coming down... or heck, who knows... might not be moving up. But I know my vacuum is good since the truck is hydro-vac brakes.

Thought about the ignition upgrade just wasn't sure what to get. I'll take a look into the MSD's!




I still have the factory setup on this one (seems like factory up until the Y). 2-1/2" pipe out of the manifolds, Y's under the drivers side and then runs 3" pipe about 6ft back into a muffler. So it might not be a bad idea to put dual exhausts on it with pipes straight back. Seems like it breaths pretty well with what it has but it might not be enough.


Thanks guys, I'll start with modifying the old pair of jets in the next week or so and I'll report back.

Re: Need ignition upgrade help/advice.
 

For the timing, I rotate the distributor both ways, retard and advance with the motor idling. I rotate it retard until the motor sounds like it is starting to labor, then rotate it advance until the motor starts to 'flutter'. I back it away from the flutter setting until it just starts to run smooth and does not kick back at the starter when cranking which is a good place to start finer tuning as you drive it. Listen for pinging and do not set it so that persists more than a bit off the idle on acceleration if you hear it at all. Gasoline nowadays with the added alcohol will tolerate more advance without pinging. I bet you will find the motor freeing up a good bit from the cookie cutter factory timing light setting. When you are happy with it you can then put a light on it if you wish so you know where the setting is you like the best.
The 478 in my Massey 1100 seems happiest when the jet sizes cause just a bit of black smoke when under light load. Under really heavy load at night I get a 4" cone of blue fire out the exhaust stacks with a circular shock ring showing just at the top of the pipes. You will never see that on a truck because the tractor has vertical headers and short collector pipes; the longer truck exhaust system will burn it up before it gets to the end of the system. Because it is happy this way, the MSD system keeps the plugs cleaned up much better than the stock system. With the MSD you also can open up plug gap to around .050" or a bit more to create even better ignition of the fuel charge. For a truck you probably will not want to set it that rich because the truck motor is not running at 50 to 60% + of the rated HP or more all of the time.

Re: Need ignition upgrade help/advice.
 

Be absolutely 100% sure there are no vacuum leaks. At carb, manifold, fittings, tubing, hoses, gaskets and etc. That would cause BIG power loss.
It will seem like carburetor or ignition problems. It's a sneaking symptom.

I repeat, these hot coils and trick ignitions do not do anything for a normal everyday motor. I just sounds cool to say "I have a super blaster, lightning carbonite spark, lightsaber, deathstar coil."....but a guy with a Napa stock coil still blows your doors off.

Re: Need ignition upgrade help/advice.
 

I am sorry AZKen, but I totally but respectfully disagree with your comment that 'trick' ignitions do not make a difference on stock motors. I have had the experience of the difference too many times on stock as well as race motors to agree with what you are saying. I am 72 now so I have worked on and owned many, many motors in my time, and have tried many things. Engineering facts come into play. The wider plug gap these ignitions allow one to use gives better lighting of the fuel charge. Multiple sparks like the MSD uses keep lighting more charge as the swirl in the cylinder passes the mix past the plug. Yes, we are talking milliseconds here, but it adds up. As compression comes up with the piston approaching TDC it takes more voltage to get the spark to jump the plug gap, so systems with stronger spark will keep working dependably with the beneficial wider plug gap. Have you ever tried a system like the MSD and drawn a truly objective conclusion based on facts and observations? I do not think you would say what you are if you had given them a really good, objective try. A stock system consistently blowing my doors off does not hold well for me with well over a thousand passes down the drag strip, setting and still holding the record number of class wins at Osceola drag strip and hours upon hours behind the Massey 478 and other motors in the field. The enhanced systems give much better long-term dependability at a higher level of performance than the stock system. On the strip, track, or hours in the field it is long term dependability one needs. The MSD system gives reliable spark even if system voltage drops a bit or goes higher due to some system malfunction you may not be immediately aware of, or may happen for only a short time. A tenth of a second, even a few thousandths of a second lost due to that on the strip and you go home. I have won and lost races by .001 second. Again I want to say I am not trying to put you down, just that I cannot agree from experience. This is an example of the freedom of speech we have in the good old USA that grants us both the freedom to have an opinion and express it respectfully even if we walk away still disagreeing. Many times both people learn something!

Re: Need ignition upgrade help/advice.
 

As most do, you are mixing drag strip/race motors with everyday motors. Spark is one factor on high compression, high RPM motors. You are in love with an idea that has no basis on a GMC truck motor. He is not looking for .001 second, he is trying to get up a hill. With a 3400-4000 max RPM motor. With all due respect to your experience, MSD style, multi spark, hot coil suggestions, for this fellow, are bad advice and a waste of money.
HEI is a good upgrade as well as a good coil. All of these will probably last longer and start better in cold weather. They may help with fouling, but fouling has a root cause. They won't get a big truck up a hill faster.
Just to let you know, you are not talking to a young kid, I'm 71 3/4. I do respect your opinion and will leave it to the poster and the other members to help decide the best troubleshoot approach. I think some are thinking the motor, with whatever mileage it has, is giving all it has. The weight, grade of hill, gearing= maxed out.
The "extra" spark issue is not supported by others on the internet.

Re: Need ignition upgrade help/advice.
 

Hey I'm 71 too. I guess we're not out to pasture yet! Lots of experience being shared by Ken and Massey478 and many others here on this forum. I just appreciate learning and gleaning what I can, and sifting it out to apply to my individual needs. I always appreciate others taking the time to share their knowledge and wisdom. Thanks to you both and many others who contribute to our knowledge of these great old trucks!!

Re: Need ignition upgrade help/advice.
 

Sifting is a good word. That's what we all have to do when reading anything on the internet. This forum is on the internet.

Re: Need ignition upgrade help/advice.
 

AZKen, I am also referring to stock motors in my advice and not mixing the two. You do not have to spend the high dollars for the new MSD system. There are good used ones on Ebay. Read the Bosch fuel manual about the alcohol blend fuel. It states that the alcohol in the fuel attracts some water which, when present in the fuel charge, causes the mix to be harder for the ignition system to ignite, so enhanced ignition systems are a good idea. After sitting long enough I have had the blend fuel phase-separate. This is really ugly to the point you have to drain it and throw it away. Putting some of the drained fuel in a glass jar, one will actually see two layers of liquid! Also a factor in this is that many of the vintage trucks folks on here own are not driven regularly so the alcohol blend fuel draws even more moisture, too often to the point it rusts the bejeebers out of the fuel tank and corrodes the carburetors, giving even worse problems. Also, now we have computer control on all of the modern motors. It automatically controls spark advance and fuel rate to optimum conditions with knock sensors and exhaust mixture monitoring. For this reason we do not notice the difference caused by the alcohol blends. We do however have to make modifications to the older non-computerized systems on our V-6 and other older stock motors motors to give them the best performance we can in the absence of computer monitoring and control. This is one of the reasons why the enhanced multi-spark system helps. I have not put the MSD system on any stock motor that it did not immediately make a noticeable difference in idle quality, starting ease, and better performance. This is not bad advice and it definitely for me has not been a waste of money. Also you mention vacuum leaks causing power loss. They affect idle quality, not top end, foot on the floor performance. This is because intake manifold vacuum is at its maximum at idle when the carb throttle plates are closed, a condition when the vacuum leak would be most noticed by evidence of choppy idle. When you have the throttle plates fully open under full power, the vacuum in the intake drops to a very low reading. Because of this fact, the effect of a vacuum leak is minimized at full throttle because the manifold vacuum is not there to make it as much of a factor if at all as well as the air volume going into the motor makes the vacuum leak a very small percentage of the total flow. The vacuum leak would have to be large enough the motor probably would not idle at all to affect full throttle performance in a really noticeable way. I am not pointing this next comment following at you, AZKen, but as for things being supported or not supported on the internet, many times I do not get involved in the discussions and advice I see being given because it truly scares me to see what some post as solid advice. It makes me think "Wow, if some poor guy takes that advice as gospel and does it, bad things may happen!" Internet information is like all things in life, some good and some way off the mark. One has to carefully digest the information and try things on his own equipment in his own environment and way to see what works best for him. I have never seen one of these V-6 motors that bringing the timing forward as I advised and enriching the fuel and enhancing the spark system did not help in a noticeable way. I do agree the HEI system is a very good system but there are ones like MSD that surpass it, in my experience even on stock motors. Ignition point quality seems to be lower now than years ago. Stock systems charge/discharge the coil with the action of the points, putting a high voltage/amperage load through them, diminishing their life. All they do with the MSD system is trigger the system so the load is very low leading to longer point life. I had another brand of electronic ignition, single spark, on my Massey 478 before putting on the MSD. I immediately saw a difference, and still do. As with modern cars, and even back years ago, lessons learned in competition like the drag strips and oval track racing were applied to stock motors to enhance their performance. A lot of work was done at the strip by factory engineers like the Ramchargers for Dodge who used lessons they learned at the strip in testing to apply to their stock motor designs. I certainly bow to them and their likes for their engineering knowledge which I recognize is above and beyond my engineering training, which is in mechanical engineering. My training applies a good bit, but not to the level of factory engineers who work with it on motors as a life work. I take what people like them do and report and learn from it for my own enhancement, going forward to apply it in my way in my environment with more trust in them than what is found many times on internet. That is what I am dong here. All of this methodology I am recommending applied back in the 70's when I worked on these V-6 motors for a living, and now, even more so with the new alcohol fuels and worn motor components. Thanks, AZKen, for your comments and I always welcome good, open, respectful discussion.

Re: Need ignition upgrade help/advice.
 

Alright guys lets take it easy here!! I re-opened this thread for questions regarding my GMC 5000, not for a who's right contest...

I've put a lot of hard work into this rig and would like to just get it to run right.

As time allows in between work I'll pick though everyone's recent comments, do so some trials on the engine and see what happens. Fist things first will be the carburetor jets and vacuum leaks. Although the booster works well, I know some of the other vacuum hoses need to be replaced. Very good chance there might be a leak.

Once I get those squared away I'll let you-all know what happens!

Re: Need ignition upgrade help/advice.
 

Chill Jr. Member. you got plenty of help. You are welcome.

Re: Need ignition upgrade help/advice.
 

5Tractor guy and AZKen, my apology if my presentations of engineering facts and experiences seemed to be a battle of who is right and who is wrong. It was not intended to come across that way! It was to be presented as a discussion of engineering facts and sharing my hard earned experiences and with work on our tractor dyno with the Massey 1100 with the 478 for the edification of others here that have not had those opportunities. For the doubters about the MSD system, google "Benefits of an MSD ignition system" and read the testimonials and factory information. My son and I too adamantly ignored these systems on other's cars in years past, thinking we were as good as them with our Mopar orange box and stock or later the Excel Super Coil. After finally trying an MSD system we were amazed at the difference. A friend of ours followed suit with the same result on his strip/mostly street car. It will be of interest of those here to see that MSD systems actually do transfer down to stock motor use because of their ability to do the multiple 5 spark discharge (Hence the name "MSD") to enhance fuel mixture ignition up to 3,000 RPM which is the range in which most stock motors operate. Our car we race but drive on the street mostly is not a full race car. It is of all things a 1968 four door Dodge Monaco 440 CI with the 1960's era long ram two four barrel manifolds with chassis enhancements we know work on the strip but leave it street driveable with no problem. No performance stickers in the windows, etc. like lots of guys do. We look at all of the stickers and say "Right, how much of that stuff is really on your car and how much is to supposedly intimidate others?!". We believe in keeping a low profile and not ballyhooing what we have on the car, only things we have proven work. The MSD tremendously helped street performance, no more fouled plugs, better fuel mileage. I do not care about mileage anyway if the vehicle is doing what I want, but the improvement was still there! SAE (Society of Automotive Engineers) journals detail how our 'friends' at EPA have caused gasoline refiners to make new gasolines with a long chain molecule instead of the older circular molecule structure our carbureted V-6 motors were designed to run on. They went to the long chain molecules because of vapor emissions when filling the tank for instance. The long chain molecular structure does not vaporize as fast as the older ring molecular structure, resulting in fewer vapors. This also means it does not vaporize in carbureted systems as fast as the older fuels did, making it harder to light and therefore decreasing fuel mileage and performance. Then you have the added 10% alcohol that makes it even worse as I have explained. Now they are trying to mandate 15% alcohol! The problem will become even worse! These problems do not come into play in the computer controlled fuel injection systems virtually all newer engines have currently. Those reasons are why we have to give our older motors all of the advantages we can given the changed fuel situations we now have to deal with.

Re: Need ignition upgrade help/advice.
 

The fuel mandates are very frustrating. The blended gasoline and diesel actually do not help the emissions to the environment at all. I buy the alcohol free 'boat fuel' we are fortunate enough to have at some stations like Country Mark here. It is 91 octane and more expensive but it goes in every older fuel system we have on combines, tractors and trucks not designed for the blend fuel, especially those that sit for periods of time between use. It is worth it not to have the corrosion problems blend fuel causes. The bean oil blend diesel is also very destructive to fuel systems not designed for it since it too is very corrosive with constituents removed that lubricated pumps and injectors to the point for older engines we have to put in additives to provide that lubrication or the older systems will be destroyed. Every time people like us try to present facts and figures for government meetings reviewing the mandates and showing how they are pointless we are ignored by big government and big money interests that want to keep their profits rolling in. The diversion of farm products to the fuel mandates has significantly increased what you pay for food. Another boondoggle is the removal of zinc from engine oils. We have to add STP or ZDDP type zinc bearing additives for our flat tappet motors or we will grind off the cam lobes and lifter bottoms will be cupped out. EPA is a government organization on a rampage with totally unreasonable and unneeded regulation. There is no good oversee of them, forcing them to prove the benefit of a ruling before they implement it. As is too often the case, we average Joes are the losers. Next they will mandate catalytic convertors for volcanoes!! LOL!! The Earth takes care of herself. Their favorite ploy is to present a problem, make us feel guilty for it to the point we allow them to run with it and make us pay for it, feeling good we helped in some way. I have to say "common sense" is not so common anymore! I wish everyone a great day and best of good times with your trucks.

Re: Need ignition upgrade help/advice.
 

Greetings Massey!

You might want to check out Royal Purple's line of Synthetic oils, as they contain ZDDP. Now, I realize that synthetic oils are more expensive than crude base oils, but given the benefit of the ZDDP already in the oil, and the extended life of synthetic oils over crude base oils, the synthetic oil more than pays for itself in the long run by reducing engine wear and repair costs. Visit Royal Purple at; http://www.royalpurpleconsumer.com/r...ment-articles/. You can contact them with any questions you may have about their products, and they will promptly answer those questions via e-mail. I have recently started using Royal Purple in my car, and I am extremely pleased with their product, since it is my opinion that it is far superior to Mobil1 or Amsoil. :thumbsup:

Re: Need ignition upgrade help/advice.
 

GEORGE & MASSEY, NAPA sells Royal Purple in up to 20w50. They possibly can order you either SAE30 OR SAE 40 as well. I run either 20w50 or SAE 30 in my older vehicles.

Re: Need ignition upgrade help/advice.
 

Regarding massey478's great explanation of the fuel boondoggle, it is probably the most costly fraud ever perpetrated on the American people and the entire world by our government. They promised it would benefit farmers by increasing corn prices, but it has mainly benefitted the pockets of politicians and big agriculture. I have heard figures in the billions of dollars it has cost the rest of us by forcing us to use the current nasty fuel blends and pay higher food prices.
To get back to 5Tractorguy's problem, I would say that today's so called gasoline does have an effect on his engine performance as well as all of ours.

Re: Need ignition upgrade help/advice.
 

My two cents worth on ignition and oil. MSD is a great improvement over other ignition systems. A lot of times it will take away some of the cold blooded symptoms on Motors. Last week at the shop I do my work at MSD was installed on a 62hp tractor on the Dino and went to 76hp and ran smoother at all speeds. On the oil recommendation I run Chevron Delo 10W 30 in my V6s. I have driven and owned diesel semis for over 45yrs and close to 5 million miles. I believe something when I see it with my own eyes. The last truck I had ran 987000 miles before it was traded off with no oil use and the same oil pressure as day one. That was with Delo 400LE 15-40 and 20000 mile changes. Just my experiences your mileage may vary. Dave

Re: Need ignition upgrade help/advice.
 

Thank you, George, Lewis, snazzypig, and Quigley for your good responses! I will check out the oil recommendations. Good to see someone is putting zinc back in them. Quigley, the HP increase due to MSD is what we saw on the Massey 1100 with the 478 in it. Our problem is our M&W Gear dyno is a 540 RPM unit so it does not go as high for HP rating as the 1,000 RPM models. My son has an Massey 1155 with the 540 Perkins V-8 diesel in with a modified fuel system. He pushed the dyno above 200 HP with it and cracked the dyno pump rear housing. That took some welding and machining to repair! So, we now do not push it above its highest rating. I cannot tell you, therefore, how much actual HP the 478 gained with the MSD. I can say it reached the 200 HP dyno maximum HP capability at a much lower RPM on the PTO than before the installation of the MSD, which is a sure indicator of higher HP output. When we put the MSD on our Monaco, cammed, and a friend of ours did the same with a cammed 440 motor in a 1965 Coronet, it almost sounded like we changed cams due to how much the idle smoothed out. Running it out proved no cam change, but an increase in street drive-ability and better acceleration was noted.

Re: Need ignition upgrade help/advice.
 

Wow! , this post has been hijacked from the original poster.

Re: Need ignition upgrade help/advice.
 

Original post is about upgrading ignition is it not? Oil was a add on. Dave

Re: Need ignition upgrade help/advice.
 

You can find a lot on the internet regarding Royal Purple vs. Amsoil. This is a good one: http://www.kc-synthetic-oil.com/AMSO...al-purple.html. I think the author hits the nail on the head when he says "There are a few topics you should never bring up at your family holiday party. Those topics are religion, politics, and what motor oil you should use. A lot of emotion gets tied up in a man's choice of motor oil."

I've been using nothing but Amsoil since 1974. Their Z-ROD oil is formulated with high ZDDP to protect flat-tappet cams. See https://www.amsoil.com/shop/by-produ...?code=ZRTQT-EA