1964 c10 230 I6 Stumble

[Gofaster]

Hi,
I need the community's advice regarding the 230 I6 in my 1964 c10. It idles great and runs well with the choke out, but stumbles/bogs and sometimes dies under acceleration at low speeds with the choke in. The firing order, float level, air/fuel mixture, and fuel delivery are all good. Vacuum leaks are nonexistent. I've checked the timing as well, and all seems to well. I'm thinking it might be the jets? Sorry for the long post but I felt I should eliminate redundant replies by listing what I've already checked. What could be the cause of these problems?

[Backpayne]

What carb are you running?

[Gofaster]

Originally Posted by Backpayne

What carb are you running?

I'm running a rochester 1 barrel

[Backpayne]

I had similar issues as you while running the 1bbl Rochester. After switching to a Weber 32/36 life has been SO much better. I haven't had to worry at all.

[TJ's Chevy]

X2. I went from a rochester one barrel to an edebrock 4 barrel. No stumble now! haha

[Gofaster]

Sounds like its better to just ditch the rochester in favor of something better. Thanks for imparting your wisdom to a confused gearhead.

[oem4me]

Super common problem. First thing to check for is a healthy stream of gas in the carb throat on acceleration. Get a flashlight, hit the throttle and look for the stream. If you don't see it, accelerator pump is bad or passages are clogged. This would account for falling flat off the line.

[vince1]

Mine would spit back through the oil bath air cleaner and take a few seconds to clear. What I thought was a carb problem healed itself with the junk yard HEI and plug wire installation.

[vince1]

I had previously put in a carb kit. Super cheap at Napa.

[63ChevC10]

Originally Posted by vince1

Mine would spit back through the oil bath air cleaner and take a few seconds to clear. What I thought was a carb problem healed itself with the junk yard HEI and plug wire installation.

YES!! I can't emphasize the improvement the HEI did on my truck enough! I have a 63 with the 230 (or 250) Rochester 1 barrel. I was about to ditch the engine because it was so bad. The HEI cured all of it!

[TJ's Chevy]

FWIW, I just got done installing a pertronix igniter on my 305 V6 GMC. Made a nice little improvement. Idles smoother and pulls smoother. Neat thing is, you can order a pertronix under 292 Inline 6 Chevy and it will bolt right up to a 305E!

[geezer#99]

Originally Posted by Gofaster

Hi,
I need the community's advice regarding the 230 I6 in my 1964 c10. It idles great and runs well with the choke out, but stumbles/bogs and sometimes dies under acceleration at low speeds with the choke in. The firing order, float level, air/fuel mixture, and fuel delivery are all good. Vacuum leaks are nonexistent. I've checked the timing as well, and all seems to well. I'm thinking it might be the jets? Sorry for the long post but I felt I should eliminate redundant replies by listing what I've already checked. What could be the cause of these problems?

Timing good!!
Are you sure?
What's your initial timing?
Is your heat riser working?

[68gmsee]

As mentioned above- check the timing. Easiest thing to check.

Also, make sure you don't have any vacuum leaks. My mono had a gasket leak at the base and also the mid carb gasket was loose. To check this one you have to turn the carb upside down and make sure the two large bolts holding the top and bottom are tight.

Check points adjustment and insure the vacuum advance moves freely and is not leaking are things to check. I now have a vacuum pump but you can check the vacuum advance with mouth suction to see if it moves and holds vacuum.

One more thing you can dtry is to move the vacuum advance to manifold vacuum at the base of the carb below the butterfly valve to see if it helps.

[cadillac_al]

When points go bad you have to "feed your fire" with more choke. A lot of carbs got rebuilt due to bad points. My money is on worn out points and condenser.

[Gofaster]

Originally Posted by geezer#99

Timing good!!
Are you sure?
What's your initial timing?
Is your heat riser working?

My timing is 5 degrees advanced, and my heat riser is stock, and appears to be working.

[Gofaster]

The points and condenser are new, and check out ok on a Sun dwell/tach. The jetting also seems to be proficient. What are probable causes outside the carburetor?

[TJ's Chevy]

You could try more timing, like 8 degrees or even 10.

[geezer#99]

Originally Posted by Gofaster

My timing is 5 degrees advanced, and my heat riser is stock, and appears to be working.

Wow!!
Only 5 degrees at your elevation.
Wake that puppy up with way more timing!
Try 14 to start.

[Gofaster]

I advanced the timing to 10 degrees and that helped the truck run better, but the stumble lives on.

[storm9c1]

Based on everything else you have done and said, the next thing I'd do is disconnect and plug off the vacuum advance. Take it for a spin. If stumble is still there, the only thing left is the carb.

I still agree with others though, I'm done with points and dwell. I change everything over to electronic ignition of some sort. I even ditch points on old lawnmowers and outboards and swap in Kohler electronic units. Best thing since sliced bread... The new points and condenser kits are junk for just about every application these days. The quality isn't there like it used to be. I learned that lesson the hardest with outboards... try limping back to the launch on one cylinder on a moving river... That's what finally did me in.