Engine dies at full throttle
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5th Gear
Joined: Aug 2019
Posts: 5
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From: North Texas
Engine dies at full throttle
My first post. I need some input on this issue. 1971 Corvette, Blueprint 383 stroker 420hp, Brawler 650cfm carb (new carb 1 year), 700r4 trans. Recently had it tuned up with a new at cable added as it wasn't shifting properly. Testing at different acceleration speeds it worked fine until from a rolling speed of 5 mph I romp on it! It was pulling great up to about 60 and then dies completely. Put it in neutral and start it up while rolling, back in gear, with a little hesitation takes off again. A short while later I do it again and the same results. Drove back to the mechanic and explained what happened and he is thinking something electrical. I am thinking fuel. This is probably not enough information but....what do you think? All input welcome.
Is my vette stock?? HAHA
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whats your fuel pressure
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
7 psi should be more than enough. But if it's a clogged sock or filter or pump problem then the pressure likely drops off during use. Not part of your problem, a 650 cfm carb for a 383 may be a bit small. 750 would be better.
Melting Slicks
Joined: Jul 2006
Posts: 2,277
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From: Salmon Arm, BC
If you've got a gauge on the fuel line, set up your camera somehow.... focused on the gauge.....then go do your 0-60 MPH fun again and see if the pressure gets low. That should give you a direction to follow 
BTW....welcome to the forum!
BTW....welcome to the forum!
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Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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What are your float bowl levels set too? maybe get a little more fuel in there, maybe you are sucking them dry and they arent refilling fast enough?
Pro
Joined: Nov 2014
Posts: 728
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From: Smyrna, TN
I was thinking the small accelerator pump on the 650 might starve the 383 as it winds up...
I seem to remember some smaller Holleys having a stumble from idle to full throttle when you stomped it...
But if it is stumbling at full throttle while running at highway speeds. it could be fuel delivery problem or it could be the spark is not advancing...
OP says he is at idle and then stomps on it...Could try adjusting the accelerator pump on the 650 to see if that solves the problem...
I seem to remember some smaller Holleys having a stumble from idle to full throttle when you stomped it...
But if it is stumbling at full throttle while running at highway speeds. it could be fuel delivery problem or it could be the spark is not advancing...
OP says he is at idle and then stomps on it...Could try adjusting the accelerator pump on the 650 to see if that solves the problem...
Last edited by n2h2o2; Aug 6, 2023 at 09:36 AM. Reason: finished thought
Is my vette stock?? HAHA
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From: Im not allowed to tell you
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He gets all the way to 60 beforebit dies, accelerator pumps just provide an extra squirt to supplement the throttles going full open and not having enough fuel forbthat bigbgulp of air...it would bog or go very lean on transition if it was the pump.
Having an AFR gauge would help
Having an AFR gauge would help
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,108
Likes: 9,236
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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Is your tank vent clear? IF the vent is plugged and you take a huge pull on it, it cant get gas....try opening the gas cap and take it for a quick romp....I had a motorcycle waaaaay back that had a vent issue and it would die until I openned the gas cap