Head gasket torque

[AnkorCraft79]

I have a 1979 Mercruiser 120 4cyl and my book says 130 ft/lbs for GMC motor and 90 ft/lbs for Mercruiser. I know the motor is a GM product so which one is it. I'm thinking the 90 lbs is correct? I had a leaking exhaust valve on #2 cyl. New exhaust valves and lapping all the others should do the trick. Is the adjustment like the old GM's, tight enough to run, 1/4 turn down after ticking starts to 1 full turn. Mark

 

[Alpheus]

Re: Head gasket torque

You said you have the book. Whats it say?

 

[zbnutcase]

Re: Head gasket torque

Head bolt torque 90-100 ft lbs. And yes valves adjust like every other Chev engine

 

[AnkorCraft79]

Re: Head gasket torque

To zbnutcase, THANK YOU! To Alpheus, why waste my time and yours with a reply like that? I can read but just wanted to be sure, never heard of the GMC motor. Mark

 

[ziggy]

Re: Head gasket torque

well, here's the way i read it.


from s/m #3, pp 6A-1. for all inline engines.

cyl. head torque...

93 ft. lbs.
retorque after frist 20 hours of operation....

that's what it says from reading it anyways..

 

[Don S]

Re: Head gasket torque

I have a 1979 Mercruiser 120 4cyl and my book says 130 ft/lbs for GMC motor and 90 ft/lbs for Mercruiser.

I would have to ask what "Book" you have. Obviously not the OEM Service manual for the Mercruiser 120 of 79. For one thing, Mercruiser does not refer to the 120 as a GMC motor. and no where in the OEM service manual does it say 130 ft/lbs for the head bolts.

 

[stonyloam]

Re: Head gasket torque

and no where in the OEM service manual does it say 130 ft/lbs for the head bolts.

The one 4 cyl engine of that vintage with head bolt torque values of 130 ft/lb would be the Mercruiser 470. That is defiantly not a GM engine. I think it might be time to get another "book".

 

[Alpheus]

Re: Head gasket torque

To Alpheus, why waste my time and yours with a reply like that? I can read but just wanted to be sure, never heard of the GMC motor. Mark

I wanted to know what your book said so I could compare it to what the OEM service manual says. I was going to give you the link to download the OEM service manual for free, but I guess I would be wasting our time...

 

[AnkorCraft79]

Re: Head gasket torque

Thanks to everyone for the information. I apologize for the sharp statement, I was not having a good day. I have the Seloc 1964-1991 Mercruiser manual. This is a very low budget build to teach my two boys (and myself) the basics of boat repair. Over 90% of my money goes toward collage so there is little left for projects. I was getting tired of hearing "IF YOU NEED TO ASK THE PRICE YOU SHOULD NOT BE IN BOATING".Did get it running and on the lake Sunday. 4 new exhaust valves that we installed and laped along with the intakes ourselves. New exhaust bellows, gaskets, therm, outdrive pump kit.Cleaned and painted everything. Now I'm looking at 140+ PSI across the board and 40 psi oil pressure at 3000 rpm. Best thing is they did most of the work, big smiles when that engine fired and ran smooth with no leaks.

 

[Don S]

Re: Head gasket torque

I have the Seloc 1964-1991 Mercruiser manual.

Well, that explains all the mistakes. That is an aftermarket manual, with lots of errors and omissions.

For future repairs, here are downloadable manuals for your engine and drive.

Drive = http://www.4shared.com/document/z_94xkbJ/Mercruiser_Service_Manual_4_19.htm

Engine = http://www.4shared.com/document/M35B2RL4/Service_Manual_03.html