Engine Hesitation Under Load
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Joined: May 2013
Posts: 9
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From: Kent NY
Engine Hesitation Under Load
I have a 74 Corvette. I have been working on it for 3 years now. Full engine rebuild using one of the Trick Flow top end kits. Included heads, camshaft, double-roller timing chain (the list goes on). I upgraded to an HEI distributor as well from Summit. Im running an Edelbrock AVS thunder series carb on a performer series intake. When the car is put under load in acceleration from a standstill the car tends to bog down or hesitate as if it is missing. I am positive that the timing is correct so i dont believe that that is an issue. I am thinking that upgrading to MSD spark wires could solve the issue. Does anyone know any possible causes for this hesitation?
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Either the timing is still wrong on the low side, the vacuum can is not hooked up or correct for the distributor, or the carb is not giving sufficient fuel from the accelerator pump. You also could have a vacuum leak somewhere.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The vacuum advance can (on the dist) has nothing to do with a WOT bog. At WOT, engine vacuum is very low...especially at low rpms. But, for best idle quality and running engine cooler at idle, that dist can should be hooked to a 'manifold' vacuum source--either from the manifold directly or from a 'manifold' port on the carb. Most carbs have both manifold and ported vacuum connections on them.
A low rpm, WOT bog can be due to:
- too little fuel (accelerator pump in carb is not doing its job);
- too much fuel (accel pump set in wrong position);
- carb secondaries not opening or not opening fully;
- timing is set to "stock" settings, rather than for 'performance'.
There are probably other possible causes, but those are the most common reasons for the problem you are describing.
A low rpm, WOT bog can be due to:
- too little fuel (accelerator pump in carb is not doing its job);
- too much fuel (accel pump set in wrong position);
- carb secondaries not opening or not opening fully;
- timing is set to "stock" settings, rather than for 'performance'.
There are probably other possible causes, but those are the most common reasons for the problem you are describing.
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Thread Starter
Navigator
Joined: May 2013
Posts: 9
Likes: 0
From: Kent NY
The vacuum advance can (on the dist) has nothing to do with a WOT bog. At WOT, engine vacuum is very low...especially at low rpms. But, for best idle quality and running engine cooler at idle, that dist can should be hooked to a 'manifold' vacuum source--either from the manifold directly or from a 'manifold' port on the carb. Most carbs have both manifold and ported vacuum connections on them.
A low rpm, WOT bog can be due to:
- too little fuel (accelerator pump in carb is not doing its job);
- too much fuel (accel pump set in wrong position);
- carb secondaries not opening or not opening fully;
- timing is set to "stock" settings, rather than for 'performance'.
There are probably other possible causes, but those are the most common reasons for the problem you are describing.
A low rpm, WOT bog can be due to:
- too little fuel (accelerator pump in carb is not doing its job);
- too much fuel (accel pump set in wrong position);
- carb secondaries not opening or not opening fully;
- timing is set to "stock" settings, rather than for 'performance'.
There are probably other possible causes, but those are the most common reasons for the problem you are describing.