Shim Headgasket help?

[andy30thz]

To increase my quench and compression I took a chance and installed a set of 0.016 thick copper gaskets on our project Lincoln's 460. (stock is 0.041 thick)
I installed them on a nondecked bock and freshly milled D3VE heads with four coats of Copper Coat sealer. Unfortunately they leak.... Not too bad, but I can see a bubble or two between the block and head on the driver side at idle.
The oil looks OK and I'm not loosing any noticeable amount of coolant....so I'm not sure what to do.

I did two compression tests. The first was with the throttle closed and got 175-180psi on all cylinders. The second test was WOT and they all read 190-195psi. Although, I don't think a compression test can always spot head gasket leakage? The coolant does smell a little like exhaust.

What is the best way to tell if the cylinders are leaking? I'm not as concerned if it is just leaking coolant externally, but if is leaking cylinder pressure....that's not good.

I'm thinking about a block sealer kind of deal....but I don't want really want to go down that road. I threw some aluma seal (after reading that the Mopar guys do that with their steel shim gaskets) in it when we first put it together, but I didn't follow the instructions and added it after the thermostat opened, instead of when cold, thinking it would get mixed better...... I have no idea if that makes a difference?

If you've got any helpfull hints to send my way, that would be great!
If I have to install traditional gaskets, its no big deal. I need to get it done before Power Tour and the clock is ticking!

[Beagle]

I'm having a tough time visualizing the bubble - do you have any pics? More importantly... does it run any better?

[andy30thz]

Nope, no pics of the bubble. It is right at the seam, head to block mating surface, front driverside, cylinder #5 just under the header.

I'm more concerned if the cylinders are leaking...... It has a good compression reading. I guess I need to do a leak down test

I didn't really beat on it, just dipped into the throttle a couple of times. The first time it felt pretty strong, but at the end of the ride it did seem to have a part throttle bog. It was really hard to tell, we didn't drive it more than three miles.

[DanStokes]

My experience with Copper Coat has been excellent - it was the only thing we could get to seal up a Peugeot Diesel head gasket. Dumb question, but did you retorque the heads after they were warm? It was critical on the Peugeot. With your compression readings I'm guessing you're OK but the leakdown test would be a good plan for sure.

Good Luck
Dan

[andy30thz]

Yeah, it was putting pressure back into the cooling system.....no good.

I blew it back a part and am putting composition head gaskets in it now.

Sucks cause the cooper gaskets were damn expensive and would have fixed my quench distance problems.....
Oh well, It was worth a shot.

[Beagle]

well carp, I was wondering if it would help it. I think you can reuse them - we used to with little two strokes because we were too broke to buy new ones. Paint them with copper paint and away we would go.

The sad thing for this is that I think you might want to deck it just to make sure the surface was flat, smooth and square and by then, you've solved your quench problems as well, making them not really necessary. Sorry to hear it Andy.

[andy30thz]

Exactly! If I decked the block to where is was truely square and flat, might as well cut it to zero deck and run composition gaskets.

It was worth a shot! It was just one part of fixing my lame build; increase the compression/quench with thin gaskets, 0.045 milled home ported heads for compression and flow, advance the cam 4* for more low end.
I guess just having two out of three ain't bad......

This car is too heavy to do much anyway, so its not a huge loss. I need to stop messing with it for power and just make it more reliable for cruising!