Power loss my 396 [Archive] - Chevelle Tech

: Power loss my 396


Ryankey
Apr 18th, 99, 11:56 AM
My 1969 396 seems to have lost some of its power... The engine only has about 2,500 miles on it and I'm running a Holley 750. It seems to have been losing power since I first bought it, which was about 1 year ago. The carburator looks very old, but seems to be in good shampe... What could account for this loss in power? Right now it has hardly any power in the top-end, and the low-end power is going down as well... Should I assume it is the carberator? And what are the most common reasons of power-loss in a new motor?? Thanks guys!!!

Oh, just out of curiousity I have an electric fuel pump mounted on the left inner wheel-well. I was told I should move it closer to the gas tank. Would that significantly add power, if any at all?

SCPAC
Apr 18th, 99, 12:50 PM
everyones definition of power loss is different. I would check points,dwell,timing,plugs,and also do a compression test. Check the basics before you start diggin' into the engine. Rebuild or replace the carb if everything else checks out.

Saleen306
Apr 20th, 99, 2:09 PM
it was capriito, and autoshop.

Patrick Schamun
Apr 20th, 99, 2:53 PM
Two things:

1. Electric fuel pumps are designed to push fuel, not pull it. Don't use both the mech. fuel pump and elect. The elect. pump can rupture the mech. pump and you can end up with a crankcase full of gas.
2. You can't tell what's going on inside the carb. by looking at the outside. If you are using the stock intake, you might consider a Edelbrock Q-Jet. I have one on my 69 and it works great. Or, have the Holley rebuilt by a Holly rebuilder. Don't just anybody rebuild it. There are a lot of builders in CHEVY HIGH PERFORMANCE magzine

Canrod
Apr 20th, 99, 4:29 PM
Read your plugs, if they are all blacks you're too rich so set your carb.

Steve S
Apr 23rd, 99, 11:28 AM
It has been my experience that if an engine runs smooth (no misses, no bogs, no backfires) that the problem lies with total iginition advance. Check the vacuum and mechanical advance.

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Steve Strasemeier (70SS)

Saleen306
Jun 10th, 99, 3:54 PM
I belive that a 396 comes stock with power loss...

Just my .02 cents.

J/K of course http://www.chevelles.com/forum/smile.gif

Sky