The Stovebolt Site Forums The Shop Area Engine Shop 60' 235 Won't accept the hammer

Okay, I rarely utilize forums for these kinds of problems, but this one has been biting me for almost 6 months now, its not a huge problem, but I would really like to resolve it

Bought a 1960 Chevrolet C30 Cab/chassis truck, I'm from Kansas, this truck was ordered by Kansas for hauling trees and was used until the early 90s. It came fully original, lots of paperwork, tag still on the carb, original emergency box with markers etc.
Engine and trans were seized up, sitting for approx 2 years. With some ATF/PB it free'd up the next day, really I probably could have just used a breaker bar it didnt take much to break it free. I put on plug wires, plugs, changed the fluids and it did manage to 'run' and 'drive'
Later found coolant in oil, probably why it sat. only ran a few times prior to finding the coolant.
removed head, replaced head gasket, during which rockers, spring and such looked and moved good, things looked pretty solid and clean, intake, exhuast gaskets, and did a carb rebuild, bought a new heat block under carb. after 2 tries I got everything to seal up. and I have good vacuum pressure 15-20 depending on idle. changed the oil again, no more coolant, all is well.
The 235 can run OK at idle, and run OK up to WOT, but it has to be a reasonably slow transition, or it will hesitate for a second and then start catching up. on a full idle-wot stomp it will either: A: stall, B: hesitate a lot and then catch up, or C: backfire through carb (rare)
I've seen a lot of trouble with the distributors, I did the usual fixes for the OG points dizzy, no change. I converted to a brand new HEI setup. all new plugs and wires again, no difference. Problem occurs no matter where timing is placed.
I looked into the fuel system. I got a brand new fuel pump, and put in brand new rubber in case of pinhole leaks, fuel tank was cleaned out, which really was pretty clean for vintage gas tanks IMO.
I've really dug into the accelerator pump on the carb, I put in a new one from the rebuild kit, it seemed a little too tight, I tried switching it back to the OG, no difference. everything else on the carb looks good, I blew it out with compressor. everything that should move freely is moving. doubled checked again for vacuum leaks even though pressure is good, couldnt find anything.
Tune wise, it seems happiest/fastest/smoothest with a lot of timing, fast idle, and mixture backed out a ways. anything outside of that combination it gets boggy or rough

You can drive the truck around fairly well. it cruises well, the power feels accurate. You can downshift without issues, have plenty of power. it just has a really hard time with the upshifts. I do have a higher gear ratio out back than OG but then, it has the issue while parked also. I'm not a stovebolt expert but it sure feels like I'm going to be by the time I get this thing running better.

Well im no expert either. In fact the more I poke around on here, the more I realize I dont know.. lol. Anyhow it sounds like its starving for fuel. Partially restricted fuel filter? pinched hose? something stupid??Or id go back to the carb if you can verify all else is up to par, Timing, Compression, Secondary ignition? Vacumm leaks are sometimes hard to find also. Spray some carb cleaner around carb, intake, vac hoses. Idles smooths and climbs..Bingo.

What carb are you running? Do you know for sure if it's sized for the 235?
I'm wondering if the vacuum advance is working.

With engine off, look down the throat of the carb as you work the throttle. You should see a small stream of fuel squirt out. If not the accelerator pump is not working and the engine is starving until the air stream can start drawing the fuel through the carb.

Sun Electric Co. had a slogan that they put on every piece of test equipment they built- - - - -"We Test, Not Guess!" Instead of shotgunning parts at the problem, how about trying to figure out what's going on by concentrating on making sure every system is functioning properly and is adjusted correctly? Bogging or backfiring on quick acceleration is frequently caused by either late ignition timing or an improper advance curve in the distributor. Have you plotted the advance curve on that "new" HEI? If it's one of the offshore clones of the GM distributor, there's no telling what the internal calibration is going to be. I buy those things, but I immediately scrap all the internal electronics and wiring and replace it with OEM-quality components. Then I use a delay-flash timing light to plot the advance curve, and adjust it as necessary.

Simply rolling a wheelbarrow full of new parts up to the car and swapping everything in sight would get a guy working for me fired before lunch on his first day on the job!
Jerry

What are the spark plugs telling you? You can read them like a book. The bog on acceleration can be caused by too rich or too lean condition while the secondary portion of the carburetor is doing the work. Idle mixture setting does add to the big picture while the throttle plate is open, but the impact is minor. The secondary jet's job is to provide the proper fuel delivery during acceleration. The accelerator pump adds a squirt of fuel to fill in the gap when transitioning from idle to full throttle to prevent lean out.
A warped carb will allow fuel to leak into the intake manifold and puddle up causing a bog situation.
The spark plugs will tell you if you are getting too much fuel, or if not enough.

Having said all of this, listen to HRL about checking every component before you dig into the carburetor. It is almost always "never the carburetor".
Even if it is the carburetor, you need to know that everything else is right so that you are not chasing 2 gremlins at the same time.
Carl

Factory Roch B is the carb, note that most of these replacements happened along the journey, not just for this problem. Just pointing out what has been done that could be related.

Can't find any issues with vacuum, it definitely does better with the advance on rather than taking the hose off and plugging it, as if its working, and the gauge says it has plenty of vacuum so I think that is out of the way.

I have not dug inside of the dist advance, I will look into that. perhaps the old advance was seized up and the new one has the wrong advance curve causing both setups to give the issue?

It feels like its lean condition, though I cannot find any problems in the line or with the pump, it has 5/16 line, I have used different filters/no filter, it has good flow to the carb.

Sometimes when starting the engine cold, it will fire up strong, and then bog down and stall after 5-15sec, feathering in some throttle or giving a couple pumps will get it going for good. once its warmed up it gets better, and will always start up strong once its been running.

The accelerator pump squirts well.

I agree with carb, really it was very clean and it wasn't any trouble during rebuild unlike many that are seized up in lots of places.

What do the plugs look like (he asked politely a second time)?
Is your manifold heat flapper valve free and operational with a good bimetallic spring?

LOL...This symptom is plaguing theses old trucks, like arthritis to old men....see my thread on 'Rochester B no idle after rebuild'.....Well after tinkering I got it to idle, but coughs,sputters & stalls upon acceleration..... Hot Rod Lincoln aka Jerry, as with others, have been very instrumental with advise....Jerry was gracious enough to speak with me directly....He is most knowledgeable, understanding & patient..... The biggest advise he gave was checking the basics.....vacuum, timing, ect. something that I know, but in the cobwebs of my dormant mind,but lost sight of....As time allows I will shift my focus to the basics....My truck as well, has a HEI distributor, was there when I bought it...the only modification....and I wonder why ??? . I have another truck with a 292 with the stock points distributor and it runs perfectly..... I don't have the technical ability to diagnose internal springs, weights, advance curves & what ever else is in there, but I can replace the distributor with the points and reset the timing.....and I'm good to go......A spare points & condenser in the glove box, never left me stranded....Good Luck.....

I can attest to having exactly the same symptoms that you describe, Cody Cthirty.
Interestingly, (like you) it's with an HEI, granted it "improved" with a mechanical dizzy. But still doesn't have the performance it should. But then I'm working with an unknown year "crate motor". So until I can sort out the year. This is as good as it'll get.
I guess what I'm saying here, is; take heed of Jerry's (Hotrod Lincoln) advice. I'm pretty sure he's on to something.

Good luck!

Chris

Been some time, problem has been resolved, choke spring was wearing out, it would move as if it was working but actually just a ways off enough to mess it up. and also found it would sometimes stick despite cleaning it wasnt bad enough to be obvious, just bad enough to screw it up. It would start off fine but as it warmed up and expanded it threw it off and left the choke far more open or closed than it needed to be and killing it. and then I would tune it up while hot and get it running fairly well, but then once it got cold and contracted it became a different ball game and run terrible. new spring and thorough cleaning of choke assembly has it working properly. I've been driving it now for about a week straight so I think its fixed. thanks all

Thanks for the update. 🛠