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1972 115 hp Mercury - timing belt

R

RGP

Regular Contributor
Serial # 3274177 115 hp blue band mercury.

flywheel has a three dots in a vertical row as a marker. Nothing else.

1. Should arrow on distributor pulley point at dot mark when correctly aligned?

2. sticker on motor reads max timing 23 deg, btdc. sticker on flywheel shroud, with degree markers shows max timing in a range of about 15 - 20 deg. What's that about? 23 deg. is beyond the reference "range" on the shroud (flywheel cover) sticker. Also, isn't a 5 degree "range" kind of sloppy?

3. There is no reference at all on any sticker anywhere on this motor indicating where the idle speed timing should be. What's that about?

I understand that max timing has to be dialed in with a timing light while running the engine under load.

Any information would be greatly appreciated.

Thanks.
 
Thanks for the input.

Distributor was swapped out by previous owner. It had shattered the rotor. Swap is the correct part. Story is motor ran perfect until the dist swap. Now it fails to make past half throttle under load. It stutters, picks up, slows down. Just plain erratic. First suspicion is the timing. Could be anything from reeds to seals to low compression etc., etc. But.....I thought I would start by verifying that the timing and synch and link is right.
 
Thanks again for your input.

Timing belt does line up flywheel dots and pulley arrow. If this is correct or not is anybodies guess.

I would really appreciate any reply to my first three questions. Yes a factory manual, specific to make, model and year would really help.
 
Very easy to time it with a light, and then you'll be safe instead of sorry. And, no, one can NOT rely on the factory timing adjustment, especially after changing the belt.

The way I do it is to remove the top carbs throttle linkage (one screw) so I can hold the throttle wide open (about 3 grand). One can then adjust the "max spark advance" without having to rev the snots out of it.

Jeff
 
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