drsleep

PLEASE HELP, I have an 81 vette with a holley 850 car runs fine no vacuum leaks or misses but when turning off car it continues to spit and sputter and it just doesnt have the get up it should. I have advanced the timing with no change, should I retard the timing or what can I do I GOT OUTRUN BY A TRUCK !!!!!!! NEED help

Also any suggestions on increasing HP without a complete rebuild
THANKS !!!!!!! :cuss

munday

continuing to run is prolly from a overly rich condition...getting beat by a truck is because yours like mine used to be is slow...my truck (01 silverado) would smoke my old engine....think about it..300+ horses vs. 190

drsleep

how did you increase your HP to 300 + ?

munday

my silverado was 320 horse from the factory. it's a 2001 with the 5.3 liter, they are 330 horse now from the factory.

Pauld

If you want more horse power, then get yourself some higher compression heads, performer intake, new carb (non computer) and some mild cams. That will make you around 300 horses. This is what I will eventually do for my '81 if I ever get around to it :D

Kevin Mason

Except that 330 horses is pushing a much heavier, less aerdynamic chunks of metal around. There's lot more to performance than horsepower. That's why a barge (which has more raw power than a Top Fueler) is neither fast nor quick.

For that matter, a VW Beetle with 190 horsepower is an insanely quick car. It doesn't weigh much and doesn't have many traction issues.

So I am not convinced that you are getting all you could out of your engine. Start by looking at your timing.

Vetterodder

An 850 Holley is awfully large for a street 350 unless it has some extensive mods, including gearing. Run-on is often caused by a high idle speed, which in turn is often needed due to some other problem. What is your idle rpm in neutral? What other mods does the engine have?

Jasonty

I agree, an 850 is too large for a stock L81... I have a 650 on my 383... I found a calculator somewhere once that showed what CFM carb I would need with my setup... It showed a 625CFM for a 383... Bigger isn't always better. ;) As for performance, I feel your pain. The stock 81's aren't very fast. Quick, but not fast. I'm not sure how much horsepower I have, but I'm assuming it's somewhere around 350-360. I run 0-60 in 5.3-5.5 with 2.87 gears in the rear. If you're seriously wanting to speed that thing up, go get yourself a 383 stroker kit, and find yourself a set of good flowing heads. It's a very good start. The L81 has too low of compression to do anything with, and the stock heads, well, suck.

drsleep

OK I see that my carb is to big the only mod is that is not computerized otherwise stock, if I lean it down will that help my problem ? I am idling about 1200 in park I know it is a little high but I have been trying to tune in the timing.

Thanks for you input :thumbs: