Hi guys, although im a new member to the site and I have been thread lurking here for years and have found alot of great information. Does anyone happen to know off the top of your head, what the dish volume of the stock L03 piston is in cc's? Thanks!

If you can find a good online compression ratio calculator, you can calculate it by reverse-figuring based on these facts:
True compression ratio: 8.8:1
True combustion chamber volume: 55cc
True piston-to-deck clearance 0.023"
True head gasket thickness: 0.018"
that's all I have.

Thanks for the reply.


Ok, so now im wondering if this is an L03 or not.

My pistons are down bore .032 at tdc (checked both sides) and my head gasket measures .045.

This motor was in an '80 z28 when I bought it so the throttle body was long gone. It did however, have the 187 casting heads and the "5.0 LgI" roller block. V0109BLB is stamped on the pad just behind the water pump on the passenger side on block.

Here is a pic of my piston. the dish is .050 deep.



Any insight would be greatly appriciated.

I've disassembl;ed dozens of these because of my career, but I only ever measured one. The 8.8:1 I gave you is for the one and only LO3 I ever checked, and it had the specs given. Your head gaskets are not original GM gaskets, but that doesn't mean much.
The relevant thing now is that if you use a steelshim gasket and a 55 cc head, you'll be right back at 8.7:1-8.9:1
You can flat-mill the Vortec 350 heads to 53cc, if you remove the intake valves before milling. The aftermarket offers a bunch of different 49-50 cc headswith 180cc intake ports and 2.02/1.60 valves. You can run these IF you limit your actual lift at the valve to 0.450", both intake and exhaust. That means either a custom-ground low-lift hydraulic roller cam, (COMP has a bunch of hyd. roller, 0.450"-lift lobes) or a "lift-rule" hydraulic flat-tappet (non-roller) cam. The rollers will still perform better.
Your other option is the TrickFlow 175cc heads they designed for 305s. They are claimed to come with 56cc chambers, but could be milled a bit.

Thanks, man.

I traded the 187's for a set of 601's, and im planning on milling them to around 50cc (i havent cc'd them yet) and porting them.