71 LT-1 Holley Problem
Thread Starter
Advanced
Joined: Mar 2018
Posts: 62
Likes: 5
71 LT-1 Holley Problem
Need help with 71 LT-1 carb problem. The car starts just fine and runs fine but after a while it starts stumbling when I take off from a stop (this has just started). I have to pump the accelerator to keep it from stalling. The carb has been gone thru twice. It is the original 780 Holley. Any suggestions?
Cruising
Joined: Aug 2016
Posts: 13
Likes: 1
The first thing I would check is the float level when the stumble occurs, but be VERY CAREFUL when you remove the screw on the float bowl, you DONOT want a fire! Second , I would suspect the fuel filter . Third , is the fuel pump losing pressure or volume to the carb, that requires an in line fuel pressure gauge. Fourth if you have a SOCK on the fuel pickup in the tank it might be very well be clogged with debris. Number four is probably the most hassle because you have use compressed air to blow back from the fuel pump inlet into the tank to clear any debris around the Sock Good Luck . Steve.
Thread Starter
Advanced
Joined: Mar 2018
Posts: 62
Likes: 5
Thanks Steve! I have done most of what you have suggested. The car runs just fine for 45 min or so. It seems to start after I run it at about 3500 rpm on a highway and then into city traffic. Like stopping at a light and then starting. The engine runs at normal temp 160 degrees. Once the car starts moving it runs like an LT-1 should. Steve
Cruising
Joined: Aug 2016
Posts: 13
Likes: 1
Well plan B. Do you have a heat isolator under the carb? Usually they are phenolic or a composit wood material, I'm leaning towards a fuel percolation problem in the float bowels or a incorrect Power Valve in the primary metering block.
Thread Starter
Advanced
Joined: Mar 2018
Posts: 62
Likes: 5
Yes, there is a heat isolator under the carb. I also think it is some kind of fuel problem. If it was a Power valve wouldn't it stumble or do the same thing all the time (car runs great for about 30 min)? When this happens I remove the air cleaner and can see fuel squirting into the venturi while operating the accelerator. This is why this has me baffled.
Cruising
Joined: Aug 2016
Posts: 13
Likes: 1
The accelerator pump draws fuel directly from the float bowl . It,s a totally separate circuit from the power valve, however they both share the same float bowel. I know its a hassle but I suspect you have a flaky power valve or a needle valve and seat that is binding in the float bowel. I think this plan C. Steve
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Burning Brakes
Joined: Sep 2018
Posts: 1,002
Likes: 410
Is your heat riser opening?
Mine was not and was forcing hot air under the carb causing it to boil the fuel out of the bowls percolating not allowing it to run through the jets or pv. IT would run fine for 30 min or so then would die... then would restart after cooling off.
Mine was not and was forcing hot air under the carb causing it to boil the fuel out of the bowls percolating not allowing it to run through the jets or pv. IT would run fine for 30 min or so then would die... then would restart after cooling off.
Dr. Detroit
Joined: Mar 2012
Posts: 10,095
Likes: 4,022
From: New Braunfels Texas
Is your heat riser opening?
Mine was not and was forcing hot air under the carb causing it to boil the fuel out of the bowls percolating not allowing it to run through the jets or pv. IT would run fine for 30 min or so then would die... then would restart after cooling off.
Mine was not and was forcing hot air under the carb causing it to boil the fuel out of the bowls percolating not allowing it to run through the jets or pv. IT would run fine for 30 min or so then would die... then would restart after cooling off.
Jebby