How it runs

Tiny
DIESEL ADDICT24
  • MEMBER
  • 1976 CHEVROLET TRUCK
  • 5,000 MILES
As soon as I hit the gas it lugs until it gets to a certain point then it starts running fine. What could it be?
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Monday, April 29th, 2013 AT 9:01 AM

10 Replies

Tiny
HMAC300
  • EXPERT
Check your ignition stuff first like timing etc. Then check the carb sounds like your accelerator pump is shot which would mean time for an overhaul on the carb. Lot of alcohol in todays fuel so it wears carbs out. Especially older ones. If this truck has been modified though then this is not really the correct diagnosis.
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Monday, April 29th, 2013 AT 9:44 AM
Tiny
DIESEL ADDICT24
  • MEMBER
It's got a 383 stroker in it. All the plugs and wires are new plus a new coil, cap, and rotor in the distributor and its timed. So would it be the carb then?
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Monday, April 29th, 2013 AT 9:52 AM
Tiny
HMAC300
  • EXPERT
It still could be but it might work with adjusting the accelerator pump more but it also depends on what cam I sin the thing to to big a cam will cause that an d what size carb is on it. 750 cfm carb is optimum size for that engine
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Monday, April 29th, 2013 AT 9:58 AM
Tiny
DIESEL ADDICT24
  • MEMBER
It's got a carter competition series carb I'm not sure how big the cam is though. The motor is like brand new but the carb came off the 400 I pulled out of the truck would that make a difference?
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Monday, April 29th, 2013 AT 10:38 AM
Tiny
HMAC300
  • EXPERT
Carter went out of business many years ago but the competition series were three different types afb avs and hell ican't remember the name of it lol. It hasd a bakelight bowl an dloked very similar to a Rochester 4 barrel it was 850 and 1000 cfms. If it's the 100 it's way to big. It cold still be an overhaul as well though
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Monday, April 29th, 2013 AT 10:46 AM
Tiny
DIESEL ADDICT24
  • MEMBER
Sorry I didn't list it all the first time. It an afb 9755s which according to there web sight is a 750cfm
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Monday, April 29th, 2013 AT 10:56 AM
Tiny
HMAC300
  • EXPERT
Well you need to know what your timing is you may have to bump the timing up to 12 degrees initial then go from there due to spark knock. Check the stuff out on line for your carb they maybe tell you how to adjust acc pump, metering rods, etc. Your rods may be to small as well. When you modify these motors you just can't throw stuff on it and expect it to run right it takes tinkering here and there to perform.
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Monday, April 29th, 2013 AT 11:02 AM
Tiny
DIESEL ADDICT24
  • MEMBER
I have it set at 11 degrees advanced at idle it ran fine a week ago I also switched from 85 octane to to an 88 octane. But I've ran through that tank and have 85 back in it.
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Monday, April 29th, 2013 AT 11:27 AM
Tiny
HMAC300
  • EXPERT
I can't fix it for you I have given you everything I can think of
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Monday, April 29th, 2013 AT 12:00 PM
Tiny
DIESEL ADDICT24
  • MEMBER
I know thanks for your help it was much appreciated. I just rebuilt the carb and it runs like a bat out of hell again. The carb was really dirty. Thanks again.
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Monday, April 29th, 2013 AT 4:59 PM

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