Valve seals

[Accelo]

I guessed at .008 for the deck clearance. Your closer to .045 deck clearance. Then add the gasket thickness and you are closer to .085 as the quench area.

I would use the thin steel gasket on the iron heads for sure.
Quench should never be less than .035-inches.
Standard head gaskets typically have a compressed thickness around .040-inches.
If the pistons were at deck height you would have a perfect quench with a composite gasket.

"The quench" effect causes turbulence in the combustion chamber as the piston comes up to TDC. "Good" quench reduces an engines tendency to ping. Also, the space is so small in cannot support combustion, this also reduces the tendency to ping.

Roughly over .060"-.080", the quench effect stops, that area is just another part of the combustion chamber.

I think you made a good choice. If you had all the numbers your compression would likely be in the 9:1 (nominal range).

BTW Effective dome volume for your motor would be the CC of the valve dimples in the pistons. This would be a negative number. Positive only if you have a piston dome.

Likely this is just too much information. Use the thin gasket and enjoy you new motor.
Cheers.

[68LAlonghorn]

Originally Posted by Accelo

I guessed at .008 for the deck clearance. Your closer to .045 deck clearance. Then add the gasket thickness and you are closer to .085 as the quench area.

I would use the thin steel gasket on the iron heads for sure.
Quench should never be less than .035-inches.
Standard head gaskets typically have a compressed thickness around .040-inches.
If the pistons were at deck height you would have a perfect quench with a composite gasket.

"The quench" effect causes turbulence in the combustion chamber as the piston comes up to TDC. "Good" quench reduces an engines tendency to ping. Also, the space is so small in cannot support combustion, this also reduces the tendency to ping.

Roughly over .060"-.080", the quench effect stops, that area is just another part of the combustion chamber.

I think you made a good choice. If you had all the numbers your compression would likely be in the 9:1 (nominal range).

BTW Effective dome volume for your motor would be the CC of the valve dimples in the pistons. This would be a negative number. Positive only if you have a piston dome.

Likely this is just too much information. Use the thin gasket and enjoy you new motor.
Cheers.

Thanks so much for the help with this Accelo. I'm using a digital caliper to measure the deck, maybe that is not the best way to do it? I also cleaned the pistons, which cleaned super easy with just a brush and some carb cleaner. Mechanic neighbor said the engine has definitely been rebuilt and estimated it has very few miles based on the look of the pistons, chambers.

[68LAlonghorn]

Some pics of how the pistons look after cleaning them a bit. The intake manifold area was basically that clean, not much dirt at all.

[68LAlonghorn]

Well, after some additional reading I've clearly measured the deck height incorrectly. I'll keep at it and come back after learning a bit more about all this.

Thanks again to all for the help and information.

[Carl Spangler]

The 'ring ridge' and wear at the top of the cylinders might need addressing depending on how you plan on using this engine. The engine is a candidate for a re-ring/hone at the very least. JMO, based on the photos.

[Caddylackn]

For measuring quench I would use a straight edge across the cylinder, then a feeler gauge. Measure where the corresponding flat area of the head would be. This is your quench area.

I would also use this time to find true TDC and mark your balancer accordingly with one of those aftermarket timing tape strips.

[Accelo]

There are many methods of measuring deck clearance. Some account for piston rock and a bunch of other variables. All you need is an approximation which your calipers provided. The feeler gauge and straight edge is also a good method without investing in tools you may never need again.
The heads are ordered so you have already made your decision. Not the time to look back. Confirming the timing mark is a good idea. No tools needed. You could use the old head and set a nut on top the piston as a stop. You can look up how it's done on YouTube. Sometimes the balancers well get mixed with an incorrect pointer. Some balancers are marked TDC in line with the shaft key and others are offset. No need to worry about any ridge as I doubt you are going to change out the rings. Nor would I recommend it. You mentioned little to no ridge and the motor has obvious been rebuild as it was bored .020 over. If it have many miles on it the pistons would not have cleaned up that nicely.

My though it you have done a great job for your first time.

[Steeveedee]

If you're going to use the thin steel gaskets, make absolutely certain that the block is flat. Get a known good straightedge and check it all with a feeler gauge on each bank. Every single bit of crud on the deck has to be gone. Otherwise, you may develop a leak- coolant or compression, depending. The heads are new, so ostensibly flat, but I'd check them as well.