100M Timing

[MikeAH100M]

Anyone know the proper timing for the 100M with the modified advance curve? I was unable to initially find the timing mark on the drive shaft pulley so used the old "put a dowel in the first cylinder" routine. I then cleaned the pulley some more and found a small hole drilled in the pulley that had been filled with paint!!! Matching that to the TDC arrow on the timing cover was a challenge so I JB Welded a small arrow on the cover. Very crude and not concours but really helped my poor eyes. Picture enclosed.

 

[Sr_Pinguino]

Hi, according to the publication Austin Healey Special Equipment and Tuning Instructions, the initial static timing for the 100 with the engine modifications is 9 degrees BTDC. Also, the car should be road tested and the best timing arrived at by using a stopwatch to determine the best top gear acceleration. The tappets should be adjusted to .015 inches, but remember that this is with the thin head gasket, not the stock gasket.

 

[MikeAH100M]

Thanks. Very helpful. Do you know if there is any way to determine if the gasket is stock or thin without pulling the head?

 

[Sr_Pinguino]

I do not know if there is a way to tell if a 100 has the high compression cylinder head gasket. Someone with more technical knowledge than I have may know. My 100m had had a valve job before I bought it, and I didn't know which gasket was used, so I set its tappets to .015 inches. I had replaced the rocker shaft and bushings. I observed no problems with the way the engine ran.