Question
Fleet Mechanic
Joined: Nov 2002
Posts: 1,643
Likes: 69
You an do it cold or warm. I do mine cold. The biggest help to me is to compare cyl-to-cyl and track the numbers over the life of the engine so you can diagnose where a problem is.
On my home-built gage I see numbers for a fully prepared racing engine in the 3 - 8% range. On a stock fresh engine it is not uncommon for those numbers to range in the 20 - 25% range.
On my home-built gage I see numbers for a fully prepared racing engine in the 3 - 8% range. On a stock fresh engine it is not uncommon for those numbers to range in the 20 - 25% range.
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New User
Joined: Oct 2014
Posts: 20
Likes: 0
I just rebuilt this engine and I was getting 25 psi in most cylinders dry. However I just poured a little oil down the spark plug hole and got a reading of 5psi. Does this sound right? Which one is more accurate? and should there be any concern?
Fleet Mechanic
Joined: Nov 2002
Posts: 1,643
Likes: 69
Don't use oil. If you are using the stock ring pack with un-gapped ends, stock head bolts, bored / honed without a block plate, and a typical machine shop valve job I would expect around 25% as previously mentioned.
Fleet Mechanic
Joined: May 2017
Posts: 1,295
Likes: 29
From: Southern CA
Just like to add a little more information to leak down test question. What would be a good psi reading for a fresh 300 rebuild with big valve 240 head, new hyper aluminum pistons, end gaped moly ring pack, machine shop performance 3 angle valve job, honed without block plate?
Cargo Master
Joined: Jul 2015
Posts: 2,063
Likes: 137
From: tucson
Originally Posted by The Frenchtown Flyer;
If you are using the stock ring pack with un-gapped ends, .
adjusted it if needed.
john
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