4.7 compression #s ??

[jonny rotten]

Looking for the compression on a 1991 4.7 mercuiser. Does it differ from year to year? Whats the lowest it can be and still be considered healthy?

 

[Don S]

Re: 4.7 compression #s ??

Assuming you meant the 4.3 Chevy V6, this Merc service bulletin should cover your questions.

 

[jonny rotten]

Re: 4.7 compression #s ??

Seller states its a 4.7 aprox 290 hp. does that motor exist???

 

[Don S]

Re: 4.7 compression #s ??

Wed can't give you specs on anything if you can't tell us what it is.
If the sellers doesn't know what it is, it's time to worry, because you know it has had little if any maintenance or preventive maintenance. Either V8 or V6, the compression specs are the same. It came from GM, not Mercruiser.

 

[jonny rotten]

Re: 4.7 compression #s ??

Hes an older guy.Has the marina work on everything and has papers to prove it.After speaking to him I could see how he may not know.But still need compression numbers,the link didnt work.If v6 abd v8 are the same im covered either way.Do you know what the #s are?

 

[r.j.dawg]

Re: 4.7 compression #s ??

I'm thinking you may mean "5.7". That may make more sense. Is it a V8 or V6? How about posting an engine serial number. Sure would make things a lot easier.

 

[Don S]

Re: 4.7 compression #s ??

Just click on the thumbnail picture in my link above. It's a .pdf file (Adobe Acrobat) file. Once you download it, just click on it and it will open automatically.