 Compression ratio..shaved head m42
1995 Ti, m42 overheated and I rebuilt the top end. while the head was off I sent it to the machine shop and it was pretty twisty. the shop took off .020" to clean it up and give me a little extra bump in compression ratio.
my question is, how do I calculate the approximate new compression ratio? stock replacement headgasket, .020" off a virgin head.. I'm thinking it may have been a decent bump after all.
I was running 89 octane before the radiator blew out and overheated the car and the car ran well on that. Since the shave and new hg it has been not so good, I did use a can of Seafoam and it didn't smoke much at all tho.. It just seemed sluggish and ran out of breath it seemed.
So for the hell of it, I pumped in 93 tonight and it runs great now.. pulls smoothly and pretty hard all the way to redline. I'm guessing that the car has been running pretty lean on the 89 since the headswap.
well I guess its premium from now on, unless the sluggishness comes back again.
CLIFFS*** How to determine new CR on m42 head shaved .020" | 
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