351W commpression pondering
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
351W commpression pondering
I know I had mentioned this in a previous thread but thought I would pitch it. From what I remember the manual says the compression of the 5.8 should be within 75% of each other. I ran a compression test (rented a tool from a parts store), I measured all the cylinders and they were all about 70PSI. Something doesn't seem right. Probably user error
. Anyways I appreciate any input yall wanna pitch. Also the reason for the compression test was I think I was having excessive blowby it was drinking about a qt of oil for every 100 miles, via the PCV, its just one thing I wanna rule out. Thanks guys!
. Anyways I appreciate any input yall wanna pitch. Also the reason for the compression test was I think I was having excessive blowby it was drinking about a qt of oil for every 100 miles, via the PCV, its just one thing I wanna rule out. Thanks guys!
Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
The spec is actually 85 percent
You do not need all the plugs out, or to crack the throttle
It does make it easier though
Problem becomes if you crank it over too many times, you get a false higher reading
That problem is made worse with all the plugs out and the throttle cracked
Do it either way you want
You do not need all the plugs out, or to crack the throttle
It does make it easier though
Problem becomes if you crank it over too many times, you get a false higher reading
That problem is made worse with all the plugs out and the throttle cracked
Do it either way you want
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
The spec is actually 85 percent
You do not need all the plugs out, or to crack the throttle
It does make it easier though
Problem becomes if you crank it over too many times, you get a false higher reading
That problem is made worse with all the plugs out and the throttle cracked
Do it either way you want
You do not need all the plugs out, or to crack the throttle
It does make it easier though
Problem becomes if you crank it over too many times, you get a false higher reading
That problem is made worse with all the plugs out and the throttle cracked
Do it either way you want
Ford Motor Company disagrees with you.
Lead Driver
Joined: Sep 2002
Posts: 9,539
Likes: 2,030
From: North Texas
The 351W were rated around 8.8:1 static as I recall. On my 9:1 engines I look for 160-170psi.
Consider another test kit as I am not sure how well that would even operate at 70psi/hole.
Consider another test kit as I am not sure how well that would even operate at 70psi/hole.
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Tuned
Joined: Apr 2023
Posts: 468
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From: Near SLC Utah
That is what I was thinking on doing, the engine had really good power, no problem getting up to speed. The only time I had it bog on me was on a 10 degree slope going 50 in 5th.
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Logistics Pro
Joined: Aug 2014
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I did a compression test on a motor that had the upper intake off, lower had tape over the ports, and got 10-20lbs compression.
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Tuned
Joined: Apr 2023
Posts: 468
Likes: 67
From: Near SLC Utah
I ran the test with WOT, I am gonna try another compression kit, I have a friend who has one, maybe I can bribe him 
. I don't know where I could get a leakdown test kit, I imagine I could rent one from somewhere, but after this other tester I am kinda weary. Thanks guys I appreciate the input.
. I don't know where I could get a leakdown test kit, I imagine I could rent one from somewhere, but after this other tester I am kinda weary. Thanks guys I appreciate the input.
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