Thread: L67 engine block

Originally Posted by rolyat

Now has new fuel pump assembly and a known good ICM... same problem.

Is there an actual compression difference between a L36 with the L67 top end components? I know compression ratios are different, but what about the actual compression? Will it be higher? I really want to know if my car has an L36 lower end... I saw that a bolt was missing out of the transmission bell housing, which leads me to believe either the engine or trans was pulled at some time...

CC's are both 64 cc.

The only difference in the bottom end are the rods, pistons, pins, balancer, flexplate, and cam gear.

Originally Posted by Rico

A couple things to check IMO:

Catalytic convertor clogged?
DP 3"?
Compression ratio

I think you are on to something with the compression ratio. The L36 should be about 160psi and the L67/L32 should be much lower. Like the other guys said, have someone with tuning experience take a look at it if it appears to have the lower compression pistons.

You cannot check compression ratio short of boroscoping both types of blocks or CC'ing the pistons.

The cam gear in a N/A block is 1* advanced. Not exactly detectable.

Compression test values are quite a useless figure considering ring wear and valve/seat wear would negate any differences.

Originally Posted by rolyat

I have ZZP's MPS

No catalytic converter. I have headers with 3" dp.
I'll try checking the compression on it sometime. I'm also thinking about closing the gap on my plugs a little... maybe .045 or so. They are gaped at .053 right now. Maybe that will help...

Closing the gap isn't the best way to solve this.

Have a known good ICM you can swap in?

When I first top swapped my car wouldnt run KR free past 2 psi until I swapped out the ICM for another unit.