PRH
Well-Known Member
Maybe you are!!
Rebuild older factory heads or buy bare promaxx heads
- Thread starter Dan the man
- Start date
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Not a very good one. lol
I'd have to be dealing a lot of "something" to afford those! 
Just looked up my receipt.. bought an assembled set of SBM 171's 04/21/21 and the price was $1437. Same set today is $1692. Inflation hitting everything.
Dan the man
Well-Known Member
It sure is. If I was to run a open chamber head, can I still run the pistons at zero deck height
I had similar questions (not zero deck) and have received varying responses. I will not know for sure until I get the new heads mocked up on the block.
Dan the man
Well-Known Member
How much have you spent on the cylinder heads that you are running now?I'd have to be dealing a lot of "something" to afford those!
Dan the man
Well-Known Member
I think that I'll still run them at zero deck height as that not only helps the compression ratio but flame travel too
Rat Bastid
Dunamis Metron
If you are going to run the open chamber head, then it needs to come out of the deck. If that means doing that will make the compression too high then use a dished piston.
Lets say the depth of the chamber is .060 although most are .100 unless they’ve been milled. And you run a zero deck. That’s .100 clearance PLUS the gasket. Even if you had an .017 gasket, which I think Cometic makes, you are still at zero effective quench.
I’m not a big quench guy, because all that started with GM heads having a garbage plug location. But, I don’t think being .100 away from the head is anywhere near ideal either.
That means using the numbers above, you’d stick the piston out of the deck .060 and use an .039 gasket. That’s .039 away from the head. Set your compression ratio with the size of the dish or maybe even a flat top depending on chamber size and stroke.
On my end, part of the initial cost of the entire car, lol! They're stock 675 318 head with a .010 cut and a more performance oriented valve job than stock. But I'm starting on a set of iron heads that quoted for around an $800 to $900 outlay, but we're going to have to see what inflation is going to do for that. That's not including my time for what little home port work I plan on doing. There's quite a bit of machine work and parts for that, though.
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Sir Henry Ricardo figured out what quench was and how it worked back in 1919. Here's a summary from Wikipedia but its best to actually read his work
"In 1919 Ricardo was studying the phenomena affecting the combustion within the petrol engine and the diesel engine. He realised that turbulence within the combustion chamber increased flame speed, and that he could achieve this by offsetting the cylinder head. He also realised that making the chamber as compact as possible would reduce the distance that the flame had to travel and would reduce the likelihood of detonation. He later developed the induction swirl chamber, which was an attempt to achieve orderly air motion in a diesel engine, the swirl being initiated by inclined ports and accentuated by forcing the air into a small cylindrical volume. Finally he developed the compression swirl chamber for diesel engines. This design embodied intense swirl with a reasonable rate of pressure rise and good fuel consumption.[10]"
The whole point of quench is to direct the unburnt mixture into the advancing flame front and improve the burn so as to increase the pressure rise in the cylinder.
MOPAROFFICIAL
Oogliboogli
Look at 7.3 International / Ford Pistons.. that's a Ricardo bowl design.
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