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OMC 3.8 distributor

R

rosbullterrier

Member
Just overhauling distributor in final engine rebuild -
I'm thrown by the advance weights appearing to be clamped stationary by a plastic collar.
My manual does not mention this. Is this correct? Why should it be so?
the two tags say:
6269951
prestolite
IBM 7014 4 N
and:
MARINE
SAE - J1171
 
looks like there's room there for them to move.
28.png
 
I have dismantled the mechanism completely. The rectangular plastic collar with slots either side which the pegs through the weights protrude prevents any movement of the weights.
The plastic collar is held rigid on the shaft.
Both weights are completely unseized and free to move up and down on their pivots by a few thou.
 
Marine gasser ignition timing, advance curve and TA (total advance) are too important to risk not having correct.
I'd recommend that you take the distributor to a shop who owns an "Old School" Sun, or other, Distributor Machine (and one who has a Technician capable of operating it), and have it correctly set up.
This is done dynamically, rate of spring tension, etc, will all be adjusted, and will be very close to Dead-On when done!
You will need to provide the correct OEM curve for them. DO NOT use an automotive curve!

NOTE: Is this by chance one of the odd firing angle gm v-6 engines????? (I don't know enough as to which models used this.)
Seems that there are one or two of these smaller GM V-6's that DO NOT fire in equal divisions of crank angles.
IOW, there is a division that is not separated by an equal 120* of crank rotation (60* of distributor angle).
If so, this distributor is "Index" sensitive when re-installing.

BTW, the cam weights would have moved in order to have given your engine any Ignition Advance.
It would not have worked otherwise..... and you would have had ZERO power!
Likewise if this is index sensitive.

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I think the odd firing V6 you refer to would be an early to mid 60's Buick 3.8...These engines can be identified by a distributor placement at the front of the engine...I'm not even sure if these were ever used by OMC.
 
I see that this was posted on iBoats also. Seems as though he was able to get the cam/weights free.

I still maintain that this should be checked on a machine since the curve and limit are so important.
One spring that is not meeting the OEM value, or not installed correctly, or not in it's original position, could throw off the curve.

I'd recommend at the very least, check the curve and limit once this is re-installed.
The balancer will need to be marked off, and you'll want to use a timing light in "Standard" mode, IMO.

No offense to the OP...., but of all the items for a DIY'r to mess with, this is NOT one of them!

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Chief, we can discuss and recommend this until the cows come home....... some will never quite understand the true importance of Ignition Timing......., not until their own engine suffurs Detonation damage!
Or, for years they never knew that their engine was not performing at it's potential due to incorrect ignition advance on the low side! (usually, no signs of damage)

Our perfectly running marine engines may be only a few degrees away from Detonating..... which means that only a few degrees in the wrong direction can place us in harms way of Detonation!
One degree error at the distributor = two degrees error at the crankshaft!
It's just something that we don't dare screw around with.

It can range from mild damage.................................................... to more severe damage.
(examples only)
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