Took the weekend off of school to head home to Socal to finish a client's 2.8 short stroke motor.
Here are the specs. so you guys know what's up-
'77 930/02 case
2.2 crank, knife-edged, 2.2 rods (66mm stroke)
JE custom pistons, dome vol. ~48.7cc
3.2 95mm cylinders
modified 911SC heads. With twin plugs, volume=90cc (spec. for stock, single plug)
DC80 cams
I checked the deck height (using solder), got around 1.6mm with NO cylinder base gasket. Checked it again because I couldn't believe it. Yep, 1.6mm. Checked with a .25mm gasket and it goes up, as expected, to about 1.85mm. This is way too high. Not even mentioning its increased propensity to detonate, the compression falls from 10.65:1 to about 9.8-9.9:1. Dammit.
I really do not know why this is. The case spigot surfaces are perfect and the case has never been decked before. The only real possibilities are 1) the rods were resized improperly by Ollie's, or 2) JE made the pistons just a tad off.
So, now I see I have two options: 1) call JE and futz around with getting new pistons (?) or 2) machine the cylinders down at the spigot seat (not the head face) by .035" or so. Also I would machine the chain boxes the same amount.
Any input? Henry Schmidt?
Thanks for any help,
Scott