604 Leak Down

[talclipse]

What do most of you consider to be the service limit when doing a leak down on a crate?

I bought a used motor and I'm not sure how much life it has in it before it will need freshened. Thanks for any help.

[brad hibbard]

everybody likes to see it 6% or less but that is rare in a used crate engine
1 thing that will make a difference is---when did this engine run last?
if possible---start the engine and let it get to operating temperature and then let it cool down until the next day
this will clear any build up that might give you a bad leak test

we always remove the rocker arms headers and carb
all cylinders leak something and knowing where the leak is, can help you determine the power loss

we have had engines in the low to mid 20's that make nearly the power of an engine under 10%
we recently had an engine with high 20's and the customer could not wait for a rebuild--
I told him we would dyno it and MAYBE it really isn't all that bad---
But the dyno confirmed that high 20's is too much---it was down 30 peak HP and was really ugly on torque through the middle rpm range

hope that helps -
Brad

https://www.race-1.com

[talclipse]

Thanks Brad.