305e Holley 500 swap question
 

Hello,

I was able to get the info about the carb type and adapter needed for the swap, but there is some basic info that I'm missing. I'm normally an all stock guy, so I'm a but stumped with modifications :eek:
http://6066gmcguy.com/holley.html


1. Do I put the mr. gasket adapter on top of the original spacer or do I remove the original spacer?
https://6066gmcclub.com/attachment.p...1&d=1557417129

2. Linkage: I don't see an easy way to get the original throttle linkage to fit. Is there an adapter I need for the carb or different linkage?
https://6066gmcclub.com/attachment.p...1&d=1557417158

thank you
Jerr

Re: 305e Holley 500 swap question
 

remove the factory spacer and studs, your current accel rod should fit on the bigger hole just fine you may needs to unthread it for more legnth

Re: 305e Holley 500 swap question
 

awesome.... that sounds simple.... thank you!


jerr

Re: 305e Holley 500 swap question
 

Now if you bought a Holley with a manual choke you will find the cable isn't long enough with the new carburetor. On the right side of your column there is a block off plug in the dash for something not installed, I moved the choke cable assembly from the left side to that side and had enough length.

Re: 305e Holley 500 swap question
 

On my 68 the choke cable was actually long enough without requiring to move the cable to the right side of the cluster.

Re: 305e Holley 500 swap question
 

Because I had a '60, I had to create this linkage. Works perfect.

Re: 305e Holley 500 swap question
 

what's the number for that spring bracket? I don't know what it's called.

Re: 305e Holley 500 swap question
 

yes... I have manual choke. I have to buy a new cable so I hope it comes long and I can trim it down.

i found the adjustable end of the throttle rod and it seems like it will work well.

truck stated really well with new carb. I assume I'll have to do some tuning to get it to be drivable, and I need to hook up the vacuum advance to the carb as well.

Re: 305e Holley 500 swap question
 

Jerrspud,

Others might disagree (and probably will), I have found that my 305e engine runs a little rich with the stock Holley 500 (which does help the engine start easier), but I have not taken the time to play around with it. Because the choke on the 500 also moves the throttle on the other side of the carburetor, it is difficult to pull out the replacement choke and longer cable (from NAPA) that I am using. This is made easier by pushing down on the throttle pedal. But converting to the 500 is well worth the effort and makes the engine run much better at higher RPMs.

JRMunn

Re: 305e Holley 500 swap question
 

You're right the 305 V6 may run rich with the Holley 500 but it's an easy fix by just installing leaner jets.:upyes:

Re: 305e Holley 500 swap question
 

https://6066gmcclub.com/attachment.p...9&d=1557493862
I found the number

https://www.holley.com/products/fuel...age/parts/9678
THROTTLE RETURN SPRING KIT
Fits Holley
PART# 9678

Re: 305e Holley 500 swap question
 

did you do that? how many numbers you go down?

Also does everyone just bolt it on and forget it, or do you modify the intake at all so it flows better?

Re: 305e Holley 500 swap question
 

Personally I would make the everything (adapter and manifold) opening the same side as the carburetor throttle bores. I would also radius the lower edge of the manifold as it make the turn toward the runners. This is what I am planning on doing when I get around to do it (to many chores getting in my way).

Re: 305e Holley 500 swap question
 

Yes when I had the 305 in my 68 I opened up the intake at the base to match the larger throttle bore of the Holley 500:thumbsup:

Re: 305e Holley 500 swap question
 

Any idea of what headers to use with a 400sbc in my 60 gmc? Huggers headers? It has rams horn oem manifolds and straight spark plugs. Thanks, Joe.
https://uploads.tapatalk-cdn.com/201...ecaa8dcba2.jpg

Sent from my SM-T560NU using Tapatalk

Re: 305e Holley 500 swap question
 

this is the V6/V12 section of the site. :thumbsup:

Re: 305e Holley 500 swap question
 

So what would happen if I left it? I really don't like the idea of destroying the manifold because one day I may want to put the original carb back one. Would it just be less efficient or have running problems?

Re: 305e Holley 500 swap question
 

I didn't make any changes to the manifold. Seemed like I needed to rebuild the original carburetor (again), so it was a good time to try the Holley 500. I just bolted it over the adapter. Truck runs fine (better), just a little rich. I have smaller jets, but haven't installed them yet. Except for choke, conversion on my '64 305E was easier than a rebuild. The truck starts easier, which is good for the starter and battery, runs rough until it warms up (probably an adjustment issue), then runs better and with more power - especially at the top end. My main concern is potential to over rev the engine while trying to keep up with freeway traffic, which I have mostly solved with taller tires and 3.54 rear end - and trying to keep in mind that these trucks were not designed to go or stop as fast as modern vehicles. One thing to watch out for is that a backfire can pop off the vacuum port plug at the rear of the carburetor. This causes truck to die at idle and run only at higher rpms.

JRMunn

Re: 305e Holley 500 swap question
 

When I did my swap, I just bolted the adapter on and installed the carburetor. made the linkage work, moved the choke to the right side and I was off. Truck starts easier, runs smoother and best of all the carb is jettable if need be. I went from 1 size smaller jet, back to stock as my mileage went down after going smaller.
+1 on the vacuum port plugs, seems most issues I have had with swap deal with the port plugs disintegrating and allowing air into process. If your mileage or performance takes a sudden dump check them first.

Re: 305e Holley 500 swap question
 

Don't think you'll have any problems at, for instance the Magnum Trapezoid base manifolds have a considerably larger opening than the WWC carbs throttle bores.

Re: 305e Holley 500 swap question
 

wow.. thanks guys... I appreciate the info!:signthankspin:

I got my 56 with a 4 barrel holley running again and once I get that one tuned, I'll have a better idea how to tune the truck and get the carb dialed in. I'm trying to get as much info as I can to help others as well because there isn't much info on the swap besides some the one page on this site.

Re: 305e Holley 500 swap question
 

so I'm making progress. I discovered a new problem. I have bubbles in my fuel line. I noticed that when I pulled the sight plug and there was no fuel coming out no matter how much I turned it out.

So my guess is the line to the sending unit is not sealed,but I'll check the whole system. Besides that major issue... she idles great. :thumbsup:

Re: 305e Holley 500 swap question
 

I had a similar problem with air getting in the line. When it happen I could not get the fuel pump to prime, once I did it would run. What I had found is the new fuel sending unit has a fitting solder to the line. Well it didn't look right but I thought it was just me. I turn out the fitting had back off of the line just enough during manufacturing it had allow air between the fitting and the line. I solder it back on in it proper position and the rest is history.

Here is the thread from FetchMeAPepsi
https://6066gmcclub.com/showthread.php?t=47321&page=58

Re: 305e Holley 500 swap question
 

If you have air in the line, you might have to prime it to the pump to get it flowing again. I tied a tube to my fuel funnel and then tied that into my steel line coming up from my undercarriage to my fuel filter. So it went funnel, tube, steel line under the truck, under cab fuel filter (pass side), fuel tank. Hold the funnel up high and fill it about 5 or six times so it fills the entire line, then take it loose and hook it back up to the pump. Prime the carb and boom, off you go.

If it's sat without gas for awhile the seals dry out and leak air. If you get them wet with gas again they usually seal right back up.


Edit: Haha, James beat me to it! He's a quick one!

Re: 305e Holley 500 swap question
 

On all my vehicles I usually start a folder with information I gather over time from forums or experience. Since we are talking about the Holley 2300 series of carburetor here is the number for the fitting that adapts the original fitting from the stock carb fuel line to the Holley. Fitting to fit Holley 2300 series carburetor for fuel, inverted flare to pipe, BQ248.

One other thing, on my hard to start Willys car after sitting for a long time, starting became really easy after I installed a check valve from Summit racing in the fuel line close to the carb, from then on it always started right away as the gas never had a chance to escape from the line. When the pump started it was always primed.

Re: 305e Holley 500 swap question
 

I thought about it for a couple of days and my theory was the sock was plugged. The pump is pulling so hard that air is getting in past the rubber lines. I pulled the sender and sure enough it was plugged up. I have it back in the tank and everything seems to be running well now. I can dive the truck again and it doesn't stall anymore. Much more junk came out then what is in this picture.
https://6066gmcclub.com/attachment.p...1&d=1558896665

So next I'll pull the tank and flush it. The prior owner said he "drained the tank", but I think I just pulled the gas out and never flushed the tank.

Re: 305e Holley 500 swap question
 

I believed that what is left of the fuel that had dried up in the tank. Hopefully it won't make your intake valves stick.

Re: 305e Holley 500 swap question
 

so some updates.

Truck as been running well, but lot's of black soot out of the exhaust on driveway.

I pulled the 73 jets and installed 72. I also put in some clean plugs to keep track of how they look. I can't imagine one size down is enough... but I'll just drive it an see. Long term plan is to install an O2 gauge, but this will tell me something for now at least.
https://6066gmcclub.com/attachment.p...1&d=1561571341

Anyone running a 2" tach? they are either cheap garbage or really expensive... nothing in between.

:thumbsup:

Re: 305e Holley 500 swap question
 

Just a thought, the black soot could also be from the oil.
Put some miles on it and see if the black soot in the tailpipe goes away.
Have you been tracking your gas mileage? This will also show an improvement if it was too much fuel. Should also perform better to.

Re: 305e Holley 500 swap question
 

Put an HEI in as well if you don't already have one to help burn the fuel. I'm running a 500 cfm eddy 4 barrel on my 305E. Opened up a magnum intake. It's way more than the engine needs, but ready for the future 401 or 478 I may find.

Re: 305e Holley 500 swap question
 

Hello. Power Valve question.

Everything is working fine, still very rich on idle. Silly me... I finally adjusted the idle screws in and vacuum when up so I'm on the right track. I probably turned them in almost a full turn to get the best vacuum. I read the specs on the stock carb and the power valve is a 5. My Vacuum is 17-19 so I'm assuming I need a much larger power valve then a five. Anyone put a higher number in?

and if I do put in a higher number... I would dump more fuel at acceleration right?

specs
https://www.holley.com/products/fuel...b0e_ENCG868neA
:signthankspin:

Re: 305e Holley 500 swap question
 

I did not change the power valve but I did use lower number jets. I believe I used 68"s.

Re: 305e Holley 500 swap question
 

Running rich at idle is usually the float is too high. Adjust the float level until it barely come out the sight hole on the right side of the bowl. If you do not have the instruction be sure to download the instruction from the web site.

Power valve is just fine like it is. It only open when the vacuum drop to 5" of vacuum, it is for fuel enrichment during full throttle operation. Changing it to a higher number will not help your acceleration, it could make your engine run worst by making it run too rich too soon.

If you have acceleration issue will need to make changes on your discharge nozzle (stock is a 28). When you snap open the throttle and it backfire through the carb you need a larger nozzle, I would go to a 35 and see if the would help. If it bog down then accelerate OK the you need to go to a smaller nozzle, maybe a 24. You can go up or down from there to get the best response. There is a couple of other adjustments that can help fine tune it if needed. Here a link for some of the different sizes:
https://www.summitracing.com/search/...charge-nozzles
Also I would stay with the same style of nozzle.

Once the above is working right the recheck the idle speed and idle mixture.

Keep us posted on the progress good or bad so we can get the engine running great.

Re: 305e Holley 500 swap question
 

Yeah... I was kinda thinking to leave it alone. It's definitely got more then enough fuel now, and I don't need to dump more in with a higher number Power Valve. I have 70 mains in it right now, and it's still a a little rich. I can see white some when I rev the motor from idle. The rich idle is much better since I turned in the idle screws. I even had to turn down the idle speed a bit so that's another sign I'm on the right path turning down the idle mixture.
:signthankspin:

Float level is fine. This is a 500CFM carb on a motor that doesn't need that much fuel. So I'm trying to get it dialed in to match the motor a well as possible. :thumbsup:

Re: 305e Holley 500 swap question
 

@TJ, what are these things in your fuel system?

Re: 305e Holley 500 swap question
 

Fuel pressure regulator.

Re: 305e Holley 500 swap question
 

I have a super-low mileage blue '67 K15 with the 305E that I bought earlier this year (it had been parked for >20 years). After replacing brakes and working on the fuel system, I replaced the Stromberg WW with a Holley 4412S 2BBL, but kept the mechanical fuel pump (for now).
The engine runs well, but doesn't idle consistently. I'm not sure I have vacuum connected everywhere correctly. The Stromberg WW had just one vacuum port, but the Holley has 3 vacuum ports - one on the throttle body (power brake or PCV vacuum port according to Holley pdf), the timed spark vacuum port on the choke side that was capped from the factory, and the full manifold vacuum port on the front, under the fuel inlet. I tee'd the single vacuum line from the distributor to the power brake/pcv port on the throttle body, and to the full manifold vacuum port, while leaving the timed spark port on the left side capped.
Something just doesn't seem right - the engine will either idle really high, like 1800-2000 rpm, or drop down to a more standard 700 rpm. I also struggled with the carb return spring - the one from the Stromberg was too stiff and pulls the throttle back into no-man's land when you let off the accelerator where the engine dies. Removing that spring allows the carb's built-in return spring to pull the accelerator back normally, but I know some sort of spring is supposed to be added.
I drove it on city streets today for the first time and it died on me, after stopping to put 15 gallons of gas in. It was seemingly for lack of fuel. The see-through fuel filter I added below the fuel pump was empty, even after just filling up the tank. So, I had it towed home and I'm not sure where to go next. The fuel filter is full of gas now that it's home (off the wrecker), but it just seems out of sorts.
Do I have the vacuum lines connect properly, or should I investigate something else first?
Thanks!
Am I better

Re: 305e Holley 500 swap question
 

The ported vacuum (timed spark vacuum port) on the choke side in the metering block does nothing on the 4412, the throttle plate base does not have the hole in to allow that to work. I had drill the hole in my throttle plate base and the gasket to allow this feature to work on the metering block. Depending on how old your 4412 is, the ported vacuum is either on the metering block or on the throttle plate base below the choke or both. If it is on the throttle plate base it should be functional. Back in the day (correct me if I'm wrong) all of the distributor vacuum cans went to manifold vacuum. So that third fitting (on the front of the throttle plate base) I believe is manifold vacuum, if that what you have that is where the distributor vacuum can gets connected to. With tighter emission it got moved to ported vacuum. If you chose to use ported vacuum you have to readjust the idle up and maybe advance the distributor timing a few degrees from specs.

As for the throttle return spring, buy any spring that will give enough pull to keep the throttle close and still allow full throttle. The one on the carburetor normally not enough to keep the throttle close once installed on the manifold.

On the subject of fuel, did the engine start after you got home? Have you check the fuel pressure with a gauge tee in? Did you check the fuel level in the fuel bowl after you been cranking for a few seconds (without pumping the throttle)?

Let us know what you figure out.

Re: 305e Holley 500 swap question
 

Yes, the truck started when I got it home, but after some more thought, I capped the PCV/Power Brake vacuum line on the throttle body side of the Holley carb, since the truck doesn't have power brakes or a PCV line. This means that the timed spark vacuum port under the choke is capped, as is the power brake/PCV vacuum. Doing this has helped it idle much better, but maybe the timed spark vacuum and the full manifold vacuum lines should both be connected via tee to the vacuum line from the distributor. I'll try that next.

I bought a collection of throttle return springs from O'Reilly's and installed one of the lighter springs, which seems to provide enough tension to return the throttle back closed. The fuel level in the bowl seems to be about right - it was right at the edge of the screw hole on the side, but I haven't measured it after cranking with no throttle. It is worth mentioning that the truck starts so much better when cold with the Holley vs the Stromberg - I rarely have to touch the choke, but it also hasn't been much below 50 degrees F, either.
The only issue now is the engine has a tendency to die when coming to a stop, such as approaching a stop sign or traffic light. It restarts easily, but something isn't right with fuel delivery. I'm wondering if the engine is being flooded since the Holley 4412 has the original jets in it and may be over-providing fuel to an engine such as the 305e. Once when it died at a light, I smelled gas, so that has me wondering. It's worth noting that when I put the clutch in to coast toward a light, if I give it some throttle, the engine won't die.
I haven't tested fuel pressure with a gauge and tee, since I don't own one, but perhaps that's worth buying for this issue, if after connecting the timed spark vacuum port with a tee doesn't improve the way it runs when coming to a stop.

Thanks for all your suggestions. The truck is coming along and while the manual steering takes some getting used to, as does the SM420 shifter, notably downshifting from 3rd to 2nd seems touchy and a bit hard to find 2nd consistently, it's going to be a great vehicle.

Re: 305e Holley 500 swap question
 

My direction to you is to start with backing down the jets - that carb is overkill on fuel metering when it comes to a 305. Did you check your power valve to see it's not ruptured? Holley's been known to blow their power valve if the engine back-fires thru the carb. What kind of exhaust system do you have? With any engine when you start feeding it more gas - you need to increase the air flow - usually this is done with increased cam lift/duration and timing adjusted to comsume the increased fuel - and then you need to be able to get rid of the increased volume of exhaust. My advice is to get a good flowing exhaust system before you do anything else. What goes in - must come out.