Where can I find GM OEM engine build specs. Specifically Compression Specs.

[Greg_E]

1997 GM 454 TBI engine supplied to Crusader 320 HP.

What I'm looking for is an official document stating what the min max compression readings and acceptable cylinder to cylinder variation can be for the engine to pass inspection and leave the factory. I know. GM doesn't make 454's anymore but there are remanufacturers out there that build them to those specs so it exist somewhere.

I already have the GM procedure for compression testing. That is not what I am looking for. If you go by that document you could have an engine with 150 psi in one cylinder and 105 psi in the other 7, and say it tested good.

I have been told what those numbers are by one of the remanufacturers. but unless you can prove you are the owner of a particular engine they will not give you the build sheet.

Next best thing would be some build sheets, so if anyone has some and is willing to share them with me it would be appreciated. You can block out any person information on the document. The build sheets wound have to be for that series engine. 1993 -1997??? Not sure on that so if anyone knows that info please post it.

Thanks for any help on this.

 

[Scott Danforth]

your manual (PCM (crusader and pleasurcraft), ilmor, indmar, volvo or mercruiser) has this information in detail. see the stickies

however if you have 150 in one cylinder and 105 in the other, you need to rebuild. it would not have passed a compression test, and the next thing to do is a leakdown test.

gust google Gen V (1991-1995) or Gen VI (1996-2000) BBC

for example, I just built my Gen VI motor, cranking compression across all 8 cylinders is coming in at 152-156psi.

your crusader 320hp is a stock block Gen VI L29 BBC. nothing special as it is the exact same block, heads, cam, pistons, etc found in a 1997 3/4 ton or 1 ton truck. your compression should be about 150 on all cylinders rebuild if less than 120

variation from low to high on a used motor is not to exceed 10%, new motor, not to exceed 5%. with your cylinders, your at 33%.

 

[alldodge]

I already have the GM procedure for compression testing. That is not what I am looking for. If you go by that document you could have an engine with 150 psi in one cylinder and 105 psi in the other 7, and say it tested good.

If you do a leak down test and it turns out to be a valve, then do a valve job and your good. If its rings, your in rebuild area

 

[Greg_E]

I don't have the manual because I don't own the boat. I need the information for court. That is why I need an official document stating the compression specs when an engine leaves the factory.
I had a difference of opinion with the boat owner as to what the compression should be, on an engine with 50 hours. He is refusing let me even do a proper compression test and is refusing to return my deposit and property that was on the boat. I will win the case but he is intent on making this difficult.

 

[alldodge]

Here is the manual for the motor and to the page showing 140 psi

http://162.144.28.33/lib/mercruiser/manuals/mercruiser16.html#/258

 

[Greg_E]

Thanks guys.

AllDodge: That is just what I needed The compression spec. for that particular engine in a manufacturers service document,
I think 140 was a typo. When I viewed the document is says 150 psi.

Scott: Here is the link to the service bulletin that I was referring to. It is basically a reprint of the GM document with a few things added.
http://www.boatfix.com/merc/bullet/97/97_25.pdf
The procedure is useful but the specs are so loose just about any engine that runs would pass. Certainly you would not use those specs. to determine the health of a nearly new reman.engine, but they make no distinction in that document.

 

[alldodge]

Yep 140 was typo

 

[Greg_E]

Scott.

"your crusader 320hp is a stock block Gen VI L29 BBC. nothing special as it is the exact same block, heads, cam, pistons, etc found in a 1997 3/4 ton or 1 ton truck. your compression should be about 150 on all cylinders rebuild if less than 120
variation from low to high on a used motor is not to exceed 10%, new motor, not to exceed 5%.
Do you have this information in a repair manual or other publication? If so can you pdf it and send it to me?
Forum posts won't fly in court. Send me an IM and I will send you my email address if you have it..

 

[Greg_E]

Scott,
Can you reply to my previous posts #6 and #8? I have tried to IM you twice but it does not show up in my sent folder.

 

[Scott Danforth]

Look in the factory manual for any of the marine motor manufacturers.

Also, you need to use the quote button, not a cut-n-paste to aler forum members

 

[Scott Danforth]

Your lawyer and you can look online at the manuals http://www.boatinfo.no

However you may need to actually purchase a GM upfitter manual to be used for legal reasons

 

[Greg_E]

Your lawyer and you can look online at the manuals http://www.boatinfo.no

However you may need to actually purchase a GM upfitter manual to be used for legal reasons

Thanks for the info. AllDodge had already given me a link to that site, but the repair manual just lists the compression spec of 150 psi. I was looking for that info as well as the + - spec.