"Papa Smurf" - 1966 GMC 1500 Custom

[LordNatedawg]

Tires and alignment complete. I went with Hercules TerraTrac CH4. A nice highway tire that is very affordable. The PO had 245/75/R16, but I switched over to LT235/85/R16. A taller and thinner tire should help with MPG and it greatly reduces steering effort. Running 40psi in all 4 tires for now. I can switch that to 60psi front, 80psi rear if it ever gets a heavy load.

As for alignment specs, I was surprised to find that the Hunter alignment machine at work had factory specs for a 66 GMC 4x2. Modest positive camber, about 2.5* caster, and a pretty insane amount of positive toe. It wanted 0.18*, but I left it at 0.15*. Just a word of advice: if you bring your truck somewhere for an alignment, make sure to give the tech coffee and donuts. Camber shims are no fun to mess with. The tech will be grateful and will ensure that your alignment is dead on, not just "good enough". Talking from experience here. Lol.

And of course, my posts would no be mine if they didn't end with a new problem. My blinker fuse keeps blowing at random. I haven't found any way to get it to blow reliably; I don't know what's causing it. One minute they work, but the next time I go to turn them on I suddenly have nothing. For now I'm going to do a "fix" by installing a breaker instead of a fuse. That way I can get blinkers back when I'm on the road. Also saves me money. I've already put 3 fuses in it this week.

[LordNatedawg]

I'm still trying to track down the source of my blinker fuse issue. I've inspected all the wiring that I installed and can't find any dead shorts or worn through insulation. The only wiring I haven't inspected is within the steering column itself. But without a consistent fuse blow, it's hard to say what the issue is. Sometimes it blows when I'm sitting stationary, sometimes it happens as soon as I try to use the blinkers, sometimes it happens when I'm turning. Some drives it doesn't happen at all.

I added a few grounds to my battery and engine. It won't solve the issue I'm having, but it will help with overall electrical efficiency. I already had the main ground from battery to engine. I added battery to chassis and frame, engine to body, engine to frame. I also added one from hood to chassis.

I've been enjoying my truck and discovering new problems with it. I expected new problems to arise once I actually started using it. On top of my blinker issue I have discovered that my coolant reservoir is too small. Kind of expected that. I'm running my truck hotter than some classics, as well as running a lower pressure radiator cap; there is going to be quite a bit of expansion. Not a huge issue, but should be addressed. I also found a loose u-joint in my driveshaft. That will need immediate attention. No fun having a u-joint explode at 65mph. Ask me how I know...

All that being said. I am still very much enjoying my truck. It isn't registered yet so I can't take it to work yet. But I have been using it for grocery runs or quick errands down the street. That will have to cease until I can fix the u-joint though.

[LordNatedawg]

Sort of an update and a warning of what is to come. I'm excited for this one.

First. I haven't had much time to work on Papa Smurf. So the u-joint is still shot and my blinkers aren't fixed. However, I think I found where my blinker issue lies. While moving my truck in the driveway I happened to bump the connector for my steering column and my blinker relay suddenly started clicking. That tells me I have a short in that connector. Poor pin fitment, bent pins, or similar. I need to pull the connector apart and take a gander.

Second. While doing some spring cleaning in the backyard shed, I found an old Rochester carburetor. My dad says it came off his 74 GMC and "never quite ran right". It was not the original carb for that truck though. The markings suggested that it originally came off of a 1977 Ch*vy.

Anyways. I sent that carb away to Sean Murphy Induction for a Stage 1 rebuild. That should be done in about 15 weeks. Continuing on, I decided that I want to pair that carb with a computer.

I'm a mechanic on modern vehicles, so I understand computer controlled fuel injection fairly well (I am far from an expert though). A friend of mine showed me how to control the AFR of my carb with an oxygen sensor. A product called the Carb Cheater allows the carburetor to self adjust to a set AFR based on readings from an oxygen sensor by inducing a controlled vacuum leak. I am oversimplifying it a lot. It does so much more. And the best part is that install is easy and non-invasive. It will not ruin your carb if the system were to die. This product is similar to a feedback carburetor, but updated with superior modern technology. This product is also on a 15 week wait time.

My Edelbrock runs just fine. But my goal is to have a truck that is more powerful and more fuel efficient. I think a computer controlled Rochester is the way to go. When the carb and computer arrive I will install both at the same time, but I won't turn on the computer until I have verified that the carb is tuned perfectly. That way I know I'm getting the most out of the system. The computer is an enhancement, not a band-aid. The carb needs to be in good working order first. That means a solid tune with the proper settings.

And just to finish off, my truck is finally registered. No smog required in Nevada for any vehicle older than 1967 which means I can get normal license plates.

it's gonna be a long 15 weeks waiting for my new toys to arrive. In the meantime I still have plenty of work left to do on my truck. Stay tuned!

[Prowbar]

The carb cheater is a great idea. From a guy on YouTube called Thunderhead289 for anyone wondering.

But I think that with a little knowledge about carb tuning and a wideband O2 sensor you can come a long way, without the need for a carb cheater.

[LordNatedawg]

Originally Posted by Prowbar

To view some links or images in this forum your post count must be 1 or greater. You currently have 0 posts. Maybe you should introduce yourself with a new topic?

The carb cheater is a great idea. From a guy on YouTube called Thunderhead289 for anyone wondering.

But I think that with a little knowledge about carb tuning and a wideband O2 sensor you can come a long way, without the need for a carb cheater.

You're right. A little practice is all it takes to get a carb tuned right. But the cheater is still useful even after a perfect tune is achieved. As mentioned before, it cannot replace a solid tune. It can only enhance.

In other news. I think I fixed my blinker issue. Touching the connector actually had nothing to do with the problem. My finger was just touching the wire for the flasher unit and providing it with a path to ground. However, inside the connector was a pin that was flattened. It was sliding under the female pin instead of inside of it. That can cause excessive current draw and heat. Time will tell if the issue is actually resolved. I was never able to get a reliable way to blow the fuse.

I also tried to fix my loose u-joint. I got the driveshaft removed and took some measurements, only to find that the u-joint is fine and my differential yoke is stretched. I don't have the tools to replace the yoke at home. I'll have to bring it to my shop on my day off. Should be a quick swap.

[LordNatedawg]

Merry Christmas! I hope you all are enjoying time with family this holiday season.

Papa Smurf is unfortunately down for the foreseeable future. Last night I attempted to drive it around the neighborhood to view Christmas lights with my family. I didn't even get down my street before it blew a blinker fuse, sprung a major fuel leak at the pump, and 3rd gear disappeared.

I can shift into 1, 2, 4, and reverse, but the detent for 3rd seems to be gone. I'm guessing there is an issue with the shift fork, or maybe the detent is full of crud. Either way the transmission needs to be looked at.

The fuel leak obviously needs to be addressed as well. A while ago I had a small leak, but I was able to fix it just by tightening a loose fitting. That same fitting is leaking again, but it is much worse.

As far as the blinker issue goes, I have exhausted every potential cause except the wiring in the steering column. I will have to pull the column out and disassemble it. The short has to be internal.

As always, this presents opportunities for upgrades. I like the heavy duty nature of my truck and I want to keep that theme going. Since the transmission might need a rebuild, maybe I look into swapping it for something else. My truck screams at 50mph and would benefit from having an additional gear just to bring down the RPMs at 55mph. One way to accomplish this is with a NV4500 transmission. A 5 speed manual with a granny first. These transmissions were used by The Big Three behind various big blocks or diesels. Not uncommon to find one in a 8.1L Chevy bucket truck. The ultimate dream would be to find one of those bucket trucks and take the whole powertrain. I would be converting my truck to EFI at that point, but it would provide me with all the towing and hauling power I could ever ask for.

Realistically, I need to open up my current transmission (NP435) and figure out what's happening.

I am still waiting on my Rochester carb. I was told it should be shipped out within the next week or two. My Carb Cheater has already arrived. Neither of these are going to be of much use if my truck can't shift gears.

[Prowbar]

I feel your frustration...
Rebuild kits for NP435's are available if needed. As you said, could be as simple as a stuck detent.
NV4500's are the most common in Dodge trucks but need an adapter plate. Not sure if the GM unit just bolts up the the V6 bellhousing. In both cases the shifter moves back in the cab, very close to the bench seat.

[LordNatedawg]

Originally Posted by Prowbar

To view some links or images in this forum your post count must be 1 or greater. You currently have 0 posts. Maybe you should introduce yourself with a new topic?

I feel your frustration...
Rebuild kits for NP435's are available if needed. As you said, could be as simple as a stuck detent.
NV4500's are the most common in Dodge trucks but need an adapter plate. Not sure if the GM unit just bolts up the the V6 bellhousing. In both cases the shifter moves back in the cab, very close to the bench seat.

I have a SBC 350, so my trans options are nearly endless. The NV4500 did come with Dodge commonly, but they were also in quite a few GM trucks behind the small block, big block, and LS motors. GM trucks of all kind are much more common at my local wrecking yard than Dodge.

Regardless, after a bit of thought and research, I think a better option would be to utilize a TR4050. A more robust, smoother shifting version of the NV4500. My old NP435 will be stashed away for later use. I can mate it with my 351E and use them to restore a different vehicle back to factory original some day.

The TR4050 swap will not be cheap nor easy. But I'll let you all know how it goes. Just don't expect any updates on that any time soon. Gotta save a bit before I can afford that. In the meantime I'll try to tackle my fuel leak and blinker issues.

[LordNatedawg]

It seems that this thread was reverted to Dec 25. I'll try to catch it up to the best of my memory.

I received my rebuilt Q-jet a back in January. A stage 2 rebuild from Sean Murphy Induction. I have not had the chance to install it yet. I'm trying to track down various bits and pieces such as choke linkage and vacuum port adapters. It'll happen soon enough.

I fixed my fuel leak just by replacing the offending fitting. A few months have passed and the fuel leak has not come back.

Lastly. I have been driving my truck around the block on occasion to avoid flat spots in my tires and try to get my blinker fuse to blow. Since December, the fuse has not blown again. This issue is getting extremely frustrating. No patterns to it as of yet.

[LordNatedawg]

Got a few more updates to share.

I've slowly been gathering parts for my q-jet. I needed some things like the divorced choke linkage and some various fuel and vacuum fittings. I should have everything I need now. I plan on installing the carb around the same time I replace my motor mounts, so that I can use a lift plate when the carb is off to hold my engine up.

Speaking of motor mounts. I discovered that the P.O. of my truck used the wrong motor mount perches. There are several different styles that vary by engine, vehicle, year, etc. Whatever he used was a front mount perch. Obviously that won't work for a rear mount application (unless you booger weld it in place like he did). I ordered some 67-72 motor perches that should fit significantly better.

My blinker issue is still ongoing. I might have made progress with diagnosis. My blinker fuse popped while I wasn't even in the truck. It was idling in the driveway. I verified the blinkers worked prior to walking away. When I came back they no longer worked. I have yet to duplicate this incident, but it suggests that I have a very small short somewhere that is causing gradual heat buildup. The first thing I'm going to try is replacing my LEDs on the blinker circuit one by one. I want to make sure the circuitry in the switchbacks isn't the issue.

Lastly. I got tired of my coolant reservoir. It was only a quart sized reservoir and it always overfills before my truck reaches operating temps. I calculated that I would need approximately 3 quarts to allow for expansion and drawdown. Just to be safe I ordered a 1 gallon coolant reservoir and then proceeded to make a custom bracket for it. I used 1/8" flat steel and bent everything with a hammer and vice grips. It took 2 days to get everything bent, drilled, and painted. But it came out great and the reservoir is very sturdy. A total of 6ft of flat steel was used to make the bracket.