omc V4 bearing differances

[orca]

G,day<br />I have stripped a couple of V4 OMC motors and have noticed a couple of differances in the motors.<br />The older motor is an 85HP 1979. The wrist pin bearings are loose needles. The wrist pin is tight in the piston. However with the other motor which is a 1986 90HP the wrist pin is tight on the conrod and loose on the piston. <br />Also the Big end bearings are loose in the cage on the older motor but helds in a race on the newer motor.<br />The con rod numbers on both motors is the same, 321712. Both have oil holes drilled at the wrist pin.<br />My question is, why the differances and are the pistons, rods etc transferable between motors?<br />Thanks in advance

 

[Dhadley]

Re: omc V4 bearing differances

OMC went back and forth on loose and caged bearings. It had as much to do with vendors as anything. The strength of the loose and caged rod bearings is the same but assembly time is less, obviously, with the caged rod bearings.<br /><br />At one point they believed the cageless wrist pin bearing (full compliment bearing) was stronger than the caged bearing. In stock recreational motors at factory rpm, there was no advantage, or disadvantage to either other than assembly time.<br /><br />However, in higher-rpm-than-stock applications we have found the caged wrist pin bearing to be better. Any crossflow motor running above 6500 (or so) I would use only the caged wp bearing.<br /><br />All recreational V4 crossflow rods from 1974 & newer & V6 cf from 1976 & newer are the same. There are several castings with at least 11 different versions. Most of the differences are un-noticable and make no difference in the way the motor runs. The 60* rods are the same as these crossflow rods too.

 

[orca]

Re: omc V4 bearing differances

Thanks Dhadley. Thats just what I needed to know