mercruiser mcm 120 torque specs

[dkeefe46]

I am rebuilding a mcm 120. Does anyone have the torque specs for this engine? I used the specs from a manual for a 2.5 liter chev [which I know is a different engine but was all I could find] mains 75 ft/lbs, rods 35 ft/lbs and I am now at the rocker arms. The book calls for either 20 or 25 ft/lbs and I am not sure about this. Any help would be greatly appreciated.

 

[Haut Medoc]

Re: mercruiser mcm 120 torque specs

IF it is a Chevy, it should be 3/4 turn down from zero lash .....JK

 

[Don S]

Re: mercruiser mcm 120 torque specs

How about a year? It may change somewhere.

 

[dkeefe46]

Re: mercruiser mcm 120 torque specs

How about a year? It may change somewhere.

as near as I can find out it is 79-82 serial # 5875114 also I forgot to mention the head bolts which I torqued to 85 ft/lbs.

 

[Don S]

Re: mercruiser mcm 120 torque specs

Here is a scan from Mercruiser service manual #3.
Rocker arms are NOT torqued on the 120's, so you might want to throw whatever manual you are using away and get the real thing. The OEM manual calls for 1 turn from Zero lash.

 

[Haut Medoc]

Re: mercruiser mcm 120 torque specs

I was looking at manual #2.....
So for your year it turns out that it is one turn from 'zero lash'.....
From the front of the engine the valves are:EIIEEIIE...
In the #1 TDC position, adjust #1-EI #2 -I #3-E #4-I
In the #4 position, #2-E #3-I #4-E....
Hope this helps.........JK

 

[dkeefe46]

Re: mercruiser mcm 120 torque specs

Here is a scan from Mercruiser service manual #3.
Rocker arms are NOT torqued on the 120's, so you might want to throw whatever manual you are using away and get the real thing. The OEM manual calls for 1 turn from Zero lash.

 

[dkeefe46]

Re: mercruiser mcm 120 torque specs

many thanks guys, just the info I needed