Pulled the heads-pics, Back-up race engine needs work Options

[groot]

As some of you know, #1 and #2 cylinders of my back-up race engine are pretty low on compression (110 and 115 psi) compared to #3 and #4 (145 and 150 psi). I squirted a bit of oil in the cylinders and the compression only gained a few psi.

So, I have a little break in the racing and I decided to pull the heads and do whatever valve work is required. Here are some pics.

Looks like the intake valves hit the pistons a little bit, maybe on a over-rev during a downshift.

Cyl #1 and #2

[Thorshammer]

Kevin,

Good pics.

Starting with the pistons, I agree with Brett, reassemble using no head gasket and set the deck height at .038-.040. Your number 1-2 cylinder are closer on the deck clearance than the 3-4. you can see this from the clean (no carbon) ring around the top of the piston and the 1-2 head is also cleaner.

If you don't have a dingle ball hone, buy one their cheap. just make sure you don't hone the thing very long and don't hone it flat, meaning stroke the hone in and out ( no sexual connotations here) so you achieve a 45 degree crosshatch pattern and do throw some new rings in it. I would recommend a total seal top ring. Even though I know some people don't like them I have had good luck with 914's. Are these 93 mm pistons or 94mm pistons?

Without good accurate deck height the squish will compromised and the power will be reduced. As for the porting job, nothing you can do here, except a valve job.
Have the machinist do a small 30 degree back cut on the valve when he does you valve job and that should pick up the flow a touch. also the guides in your heads are TOO long. You need valve support but I think yours are a little too long. Don't think the machinist will be able to do anything about them. Check the guide for wear, and if you weigh the valve, keeper retainer valve spring, and tell me the seat pressure you are running, and what the valve spring pressure is at full lift. I can look at your valve springs. Brett may have some good springs it sounds like. Also remember,sometimes the case center is not in the center of the motor, causing the deck to be more on one side than the other. It happens. Otherwise, looks like a decent B motor.


Erik Madsen