06 Corvette. I did a cold compression check and all the cylinder were around 210 and 215. Seems high to me. I have PRC ported heads that I bought second hand. The guy said it was stock chamber size. Only thing I can think of why the compression is little high (other than a faulty gauge) is the heads might have been shaved a little?
Will this cause issues?

 

Did you open the throttle body all the way while pumping?

 

I did not.

 

Need your location, to figure out the atmospheric pressure to begin with.

If your at sea level with 14.7PSI as the atmospheric pressure, then motor is showing about a 14.2-1 compression rate if your gauge is correct.
If valve clearance is fine with the shaved heads ( and gauge checks out good), should make good power from the compression ratio, if you can find a high enough octane fuel to not run into detonation problems. Hence better be running E85 with this motor (or meth kit), since pump fuel octane rating of even 93 is not going to cut it/ecm will be pushing itself to the low octane table timing retard from the start as it gets engine knock from detonation problem with the fuel octane not high enough instead.

If the game plan is to run this motor on standard pump petrol only, then time to change out the head gaskets to thicker ones, to lower the compression ratio.

 

I'd worry about something else. Lots of factors play into those numbers. As long as they are close together, you're fine. Cam timing can have an influence on them also.

 

We are about 886ft above sea level.

 

All the cylinder are close in numbers. So the cam timing can make those numbers higher?

 

Absolutely. The camshaft controls when the intake valve closes on the compression stroke. From bottom dead center, as the piston comes up on the compression stroke, the camshaft closes the intake valve. If it closes it earlier, you will have higher cranking compression. Later, or course, will result in lower cranking compression.

If you want to understand it a little better, do some research into "dynamic compression ratio" or DCR. That takes into account intake valve timing and static compression ratio to arrive at your DCR. That's what makes cylinder pressure. Here's one of the many DCR calculators available on the web:

Jeep Strokers - Dynamic\Static Compression Ratio Calculator

 

Your atmospheric pressure is around 14.2psi, so using that, and motor pump up at 210PSI, then motor compression is about 14.7-1. ,
So need fuel at an octane rating of 110 or better to prevent detonation problems.
As for pump E85, only has an octane rating of 100-105, and still not high enough to prevent detonation problems in the cylinders.

 

Is this something that can be adjusted in the tune? Or does the cam have to be clocked to correct degree? Everything I read said setting the crankshaft and camshaft dot to dot on this cam was normal.

 

Only real issues has been misfire at idle but that didn't start until later on in the tuning and after replacing both 02 sensor cause one 02 connector got burnt. I think that issues just need to be adjusted in the tune. Before I replaced the 02 sensor the car kept going rich during a pull no matter how much fuel he pulled. Still have to have the guy come back to finish tune. Just trying to make sure everything is working right cause I don't want to pay for another section.

 

Back up a little and give us the history on this LS2. There's absolutely no way to ascertain the engine's static compression ratio by a compression test.

An engine with an absurdly high compression ratio will idle just fine on reg gas. It just won't take a load. The chances of your engine's compression ratio being the problem are slim and none.

 

I don't think its the issue either but if this high compression is going to be an issue later on I rather fix it now.
I bought this 06 C6 about a year ago with 91k on it. The last guy that drove it broke the output shaft. I didn't get to talk to the owner unfortunately. It already had a fast intake, CAI and long tubes with a crappy exhaust. It Drove fine once I fixed the transmission. Later on I bought btr stg2 cam and prc ported heads from a guy on FB. I installed ls3 injectors with spacers. Once the tuner got it to run we went out for a drive. After the second update my clutch line blew cause it was to close to the exhaust (my dumb fault) I fixed the clutch line and drove it again. During the second outing we could get it to run right. Kept going rich no matter what. I found one of the 02 sensors popped out of the clip that was keeping it away from the exhaust and melted the side of it exhaust but it didn't look like any wires were damaged. I replaced both 02 sensor with denso sensor. Thats when I started to get the misfires on all cylinders only at idle. I was told the crank sensor might Just need a relearn or misfire time adjusted. I did a smoke test (Might do it one more time) to make sure I didn't have a vaccum leak and that seemed good. Just tested the injectors, they are good. I had replaced the maf and map since cause I thought the maf was bad. Figure the map sensor wasn't to expensive so why not. Wished I would have measured the chamber on the heads before I installed them but didn't think anything of it for some reason.

 

I'm assuming your short block is stock. I don't think anyone would mill stock heads enough to increase the compression ratio enough to be untunable on pump gas. Milling that much would also give you piston to valve clearance issues. That, and the P/O told you the heads weren't milled.

When I did my heads/cam setup, I milled the heads and also used a thinner head gasket. So, CNC ported and milled heads, thinner head gaskets, mild cam, ported and rod modded intake manifold, and ported throttle body. It ran just fine on the stock tune at low throttle inputs. No, I didn't go WOT until it was tuned. The cam you're using is quite a bit bigger, so it would probably need some tuning to get it to run right. But if it's not running right at low throttle inputs, added compression from your head swap isn't the problem. Adding static compression smooths out cam issues anyway. Absolutely, you could be octane limited at WOT on your previous tune, but your tuner should be able to straighten that out. If you're limited to 91 octane, your tuner's job is tougher, but not impossible.

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So would you say don't worry about the high compression if its running ok or should I clock the cam?

 

What changes have you made since the last time your engine ran well? If you installed the cam dot to dot, I sincerely don't think you have a problem with cam timing. I would guess 99% of aftermarket cams used on the streets are installed dot to dot and not degreed in. Maybe if you had the engine on a stand and wanted to impress somebody or make a UTube video, you might degree one in. Some aftermarket cams close the intake valve sooner which will result in a higher cranking compression reading.

Disclaimer...to those of you who always degree in their cams, I admire you more than you'd ever know..

 

I had installed a new clutch line. New 02 sensor, New spark plugs, new map and maf sensor. Just had a p0230 come up last time I test drove it so I'm ordering new relay.

Yeah That's what I read during my research before installing the cam. Some said must the time with a cam like this it would only be a degree or so anyways. That dot to dot was fine.