Boat heads

[JBC]

I found some heads on a 1985 318 boat motor with adjustable rockers. I couldn't read the casting number, does anyone know how these heads would perform. The motor also had a steel crank, the guy that had it said I could take it for free. I have a 340 block that I was thinking it might work for.

 

[Guitar Jones]

The rockers will work, the heads won't, valves too small. The crank may be fine but you need to check the back of it for the register size, number of bolts and the distance from the block to the face of the flange. Also if you plan on using it in front of a manual trans check to see if it's drilled for a pilot bushing.

 

[1wild&crazyguy]

if it's reverse rotation too, then the rear main seal won't hold it in.

dodgetkboy78 knows about these boat motors.

 

[daliant]

if it's reverse rotation too, then the rear main seal won't hold it in.

Yep if its a reverse rotation engine the serrations near the rear seal are cut in the wrong direction for auto use, it will leak like an old diesel. The heads wouldn't be of much use unless your building an engine for a truck or motorhome (low speed/high torque)the ports and valves are small, the springs are weak and the exhaust vavles have heavy rotators on them. The cam (if its reverse rotation) is worth a few bucks if its in usable shape, save the oil pump drive with it too.

 

[1wild&crazyguy]

Depends if they are the water heated cross over type, then they have blind exhaust ports [side note] and maybe closed chambers.

In that case..they would make a great performance 318 head.

 

[dodgetkboy78]

Considering the LM318 never had a special marine head.... How do we know that the heads wont work? They also never made a LM 318 with adj valves, so there is a possibility they were added, or someone moved up from a 273 block to a 318. reverse rotation motors are easily spotted by the dist drive on the cam, the gears are pointing the other direction. The seal will work OK, if you don't mind a few drips...... I used a rope seal when I went from LH to RH, and it weeps like an old diesel too so I guess there is not much winning. What makes a RH crank leak running LH is the oil grooves on the crank where the main seal rides are bass ackwards.

As far as block and heads, there is no diff with the marine acessory holes, or any other. The LM blocks were simply premium auto blocks.