Author Topic: Off idle stumble and stall, going to rebuild but what else?  (Read 1771 times)

Offline dkraven

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Off idle stumble and stall, going to rebuild but what else?
« on: August 30, 2023, 01:59:32 AM »
Put some of this in a different thread. I’m going to list what I have, what I did, and what I’m going to do. My main question is how much to throw at the problem at once? Not a huge fan of taking apart the carb multiple times if I can help it.

I have a 17057213 on a 350 SBC in a 1977 Sierra Grande. Initial timing at 12 btdc, haven’t addressed full timing yet.

Rebuilt the carb using an Oreilly kit that Cliff told me in a prev thread is likely part of the problem. The kit was basic and I didn’t replace the float, rods, or jets. I used carb cleaner and flushed everything out with compressed air but didn’t stick wires in any holes. Also replaced my distributor cap and rotor, which is good, but added new weights and springs which Cliff explained probably added to the problems.

So here’s my plan. Get Cliff’s rebuild kit, probably the HP one so I have all the pieces. Rebuild the carb again. Put back the factory weights and springs in the distributor. Put it all on the truck and set up the carb according to basic tuning principles.

The off idle stumble I have is pretty serious. It often just dies unless I hammer on the throttle. Usually the best way to go is to let it get some momentum while in drive with no throttle and then to hit the gas.  I’m wondering if while I have the carburetor taken apart if I should fiddle with jet size? I understand the basic principle of the stumble is a lean condition and I’m chasing down the cause of it. I’m not sure how much to throw at that particular issue.

Offline quadrajam

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Re: Off idle stumble and stall, going to rebuild but what else?
« Reply #1 on: August 30, 2023, 07:43:38 AM »
Likely accelerator pump cup failure for a stumble that bad.

QJ

Offline dkraven

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Re: Off idle stumble and stall, going to rebuild but what else?
« Reply #2 on: August 30, 2023, 07:50:44 AM »
Yeah, thinking back to the rebuild, it was a struggle to get the cup on the pump using the plastic cone tool that came with it, and I reached a point of “this is good enough”. No, apparently it wasn’t!

Offline von

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Re: Off idle stumble and stall, going to rebuild but what else?
« Reply #3 on: August 31, 2023, 02:29:08 AM »
Put vaseline on the white cone thing and the seal will slide right on.

Offline Cliff Ruggles

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Re: Off idle stumble and stall, going to rebuild but what else?
« Reply #4 on: September 01, 2023, 03:49:04 AM »
Save the Vaseline for your next romantic adventure and buy one of my rebuild kits with a USA made complete accl pump assembly with a lifetime warranty on it. 

All those "blue" seals in the rebuild kits currently being sold are coming from the same source and aren't worth two squirts of duck poop.

I test all of them, below is a pic of three seals, a black one from a NAPA kit for early Pontiac carbs, a blue one from a Walker kit (Walker supplies nearly all the kits these days no matter what box it comes in) and my USA made seal on the right. 

They were soaked in 93 octane fuel with 10 percent ethanol for about 3 hours. Which seal do you want in your carb?......