380SE 116.xxx engine timing chain questions.

[Clemson88]

A few months ago I changed the plastic guides to metal backed guides. It was a preventive action. At that time I check the chain stretch by rolling then engine clockwise until the timing mark on the right cam lined up exactly. I found the mark on the left cam just a degree or two past it's reference mark. The crank balancer showed about seven degrees past the zero mark.

I ordered a new timing chain from phil along with a tensioner and some oil rail parts for the cams. Yesterday my son and I rolled the chain on with no problem.

I have not replaced the tensioner yet. I rolled the engine around once and got the timing mark on the right cam zeroed. The left cam mark looked the same as before and the crank balancer marks were exactly the same as they were with the old chain, seven degrees past zero.

Please give me your opinion on what the problem may be.

[nulu]

Cam gears are worn, crank gears worn, ,heads maybe cut?

[Clemson88]

I really don't want tear into the pan and change that crank gear. That would call for a new oil pump chain too. I guess I need to start looking into cam gears and hope for the best. Any chance the cam gears could fix this?

[Frank Reiner]

Rather than worrying about worn parts (provided the gear teeth are not severely hook shaped), suggest that you simply correct the cam timing.

Step one: verify the accuracy of the TDC mark on the dampner; i.e., check TDC of #1 piston vs. the mark.

Step two: use offset cam-to-gear keys to advance the cams by the amount of error which you observed as described above. The keys are supplied by MB for this purpose.

Advancing the cam timing by about 5 degrees vis-a-vis stock will provide a noticeable lower RPM torque boost.

[Clemson88]

Frank, would I need to setup a dial guage on a valve to check the TDC mark on the balancer or would bringing the piston to the top be accurate enough? I don't have the instrument to do the valve thing.

[whunter]

Originally Posted by Clemson88

A few months ago I changed the plastic guides to metal backed guides. It was a preventive action. At that time I check the chain stretch by rolling then engine clockwise until the timing mark on the right cam lined up exactly. I found the mark on the left cam just a degree or two past it's reference mark. The crank balancer showed about seven degrees past the zero mark.

I ordered a new timing chain from phil along with a tensioner and some oil rail parts for the cams. Yesterday my son and I rolled the chain on with no problem.

I have not replaced the tensioner yet. I rolled the engine around once and got the timing mark on the right cam zeroed. The left cam mark looked the same as before and the crank balancer marks were exactly the same as they were with the old chain, seven degrees past zero.

Please give me your opinion on what the problem may be.

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