428 Compression Reading

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Oct 21, 2004 | 09:53 AM

Purely Ford

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From: East Bend, Carolina, U.S

428 Compression Reading

While checking compression to isolate a problem with my 428 I was getting around 152 - 158 psi readings. Just out of curiosity, what have any of you guys gotten for readings from compression tests you have performed on your 428s.

I found a weak cylinder while testing. Number 7 cylinder has about 60 psi, so I am going to have to break it down.

Oct 21, 2004 | 11:05 AM

Mike G

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From: Littleton, CO

Don't have a 428, but the numbers sound on the top end of reasonable for an FE.

--Mike

Oct 21, 2004 | 11:17 AM

Purely Ford

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From: East Bend, Carolina, U.S

Thanks! Just wanted to know how the other cylinders compare to what is normal.

Oct 21, 2004 | 11:37 AM

Mike G

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From: Littleton, CO

Shoot a little oil into that cylinder and see if it comes up closer to the rest.

--Mike

Oct 21, 2004 | 01:20 PM

Purely Ford

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From: East Bend, Carolina, U.S

I already used the oil trick and it didn't change the compression on that cylinder. The piston is most likely damaged (hole burned through). The engine ran lean on a long trip on the highway awhile back in the summer because of a vacuum leak. Slowing down getting off of the highway I noticed a miss (not a single woman, lol) at idle and then after shutting the engine down I could hear the vacuum leak under the dash. The climate control had seperated and allowed plenty of raw air into the engine.

This engine doesn't have much mileage since it was rebuilt in 1994. Maybe 20-22 thousand miles, so it has plenty of life left in it before it needs another complete rebuild. Once I tear into it I may decide to replace all pistons and maybe do a few more updates like maybe a different camshaft.