Question about compression & serial number

[alamantia]

1987 Wellcraft 222 Elite with a 260/350 Mercruiser

The Serial number (unless I am reading it wrong) is either 6489983 or 8489983 (I am unsure about the first diget) never the less I cant find either number anywhere online, it doesnt sound correct. Is either number a valid number?

The block casting number is 4088548 which is a 1986-87 one piece rear main with either a 2 bolt or 4 bolt main.

The guy I bought it from says it is the original engine. It has the 4 bolt perimiter valve covers.

I found the manual for the engine and it says that the comprtession is 9.0:1 and it says the compression pressure is 150psi

I did a compression test on the engine and all cylinders were between 175-180psi

So what is the 150psi in the manual? Is that a minimum pressure?

 

[Bondo]

Re: Question about compression & serial number

The Serial number (unless I am reading it wrong) is either 6489983 or 8489983 (I am unsure about the first diget) never the less I cant find either number anywhere online, it doesnt sound correct. Is either number a valid number?

Ayuh,.... I think all the Merc numbers start with a Letter, before that vintage....

Was the motor, "Just run" when tested,..??

 

[achris]

Re: Question about compression & serial number

That serial number (6489983) comes up as a 200hp Mercury outboard, so that's not right and the other number is not valid.

Compressions all between 175 and 180 is excellent. Nothing wrong with that engine. The 150psi in the book is a minimum pressure, so you're good on that score too...

Chris.....

 

[Don S]

Re: Question about compression & serial number

The number is actually B489983 which is a 1987 260 V8. The compression numbers are tyical for a good engine, minimum is 100.

I see 175 to 180 on newer Vortec engines, but not on the older ones like you have. My guess is your gauge is off a little. The fact that they are all the same or close to it means everything is probably fine.