timing and coils

[chilly1]

I am curious about the timing on my 1971 55 hp 557 hc. I read that the top cylinder is used for timing, but mine has the bottom cylinder at btc when the timing marks line up. Am I missing something? I am waiting on a borrowed timing light, so I haven't done that yet.

Also, I am looking for a coil. Is there anything under $110? I think I need one for sure. It works well for a few minutes, and then starts firing erradically. Cracks, as well. Part number 818076a2 I think.

Thanks,
Joe

 

[Frank Acampora]

Re: timing and coils

Some of those flywheels have timing marks 180 degrees apart. Since the crankpins are 180 degrees apart, when the top cylinder timing mark is on the pointer (that is 32 degrees before TDC), then the bottom cylinder will be 32 degrees before bottom dead center. The reason: A difference of .0015 in the setting of the points gaps will equal one degree difference in timing.

Thus: There are two timing marks, one for the top cylinder and one for the bottom cylinder so the points can be set to give equal timing on both cylinders.

Note that depending upon the year of the engine, timing would be set to either 32 or 30 degrees BTDC.

 

[chilly1]

Re: timing and coils

Mine only has the one stamped mark on the flywheel for the bottom cylinder. I can use a magic marker and find 180 but I was making sure top was the one to go by. Thanks!

Coils, anyone?