9 to 1 Piston for EQ 62cc Head

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wishihadahemi

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putting together a Hobby Stock 360 using EQ 62 cc heads. need the Magnum style double quench dish piston with enough positive volume (more than 20 cc's) to get 9 to 1.
It's .040 over, zero deck, .039 FelPro Gasket.
Probably a custom piston ??

Last night at PJ (33).JPG
 
So I assume it HAS to be 9.1?
You can get 20.5 pistons all day but you'll have 9.29
Thicker head gaskets might be cheaper..lol

What pistons you're running now?
Does HAVE to be Magnum style double Q pistons?
You're having to follow specific rules?
 
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mullinax95 said:
So I assume it HAS to be 9.1?
You can get 20.5 pistons all day but you'll have 9.29
Thicker head gaskets might be cheaper..lol

What pistons you're running now?
Does HAVE to be Magnum style double Q pistons?
You're having to follow specific rules?
Click to expand...
first time trying to use EQ heads, best power is made by close to zero deck......or using .039 gasket, i would use .028 mr gskt as before on my other engines with X and J heads with KB 232 Step Dish Pistons.
David Crower from Crower Cams (RIP) told me years ago that engines that keep carbon cleaned off the quench area made more power. Theory is more than .040 over the quench part of the piston and the fuel will not be reacted ...... Smokey Yunick
 
wishihadahemi said:
first time trying to use EQ heads, best power is made by close to zero deck......or using .039 gasket, i would use .028 mr gskt as before on my other engines with X and J heads with KB 232 Step Dish Pistons.
David Crower from Crower Cams (RIP) told me years ago that engines that keep carbon cleaned off the quench area made more power. Theory is more than .040 over the quench part of the piston and the fuel will not be reacted ...... Smokey Yunick
Click to expand...
part number of .040 over size with +20.5 dish?
 
I think you'll be looking at custom pistons.

You'l need 24 cc dish volume.
 
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This KB232 piston that you mention, I read it as 18cc volume And a "Elevated Quench Dome .050 tall". If this is to be an option "closed chamber" design heads may not fit!
 
With stock deck heights, you would mill the KB232 quench pad down to around .012" high to get that pad to deck height, leaving around 0.5 cc in the pad. But then your SCR will still be around 9.3....

I am coming up with similar numbers to the above....20.5 cc's. It looks like you need right at 2.5-3 cc's more to get down to 9:1. I bet you have at least 1 cc of that in the crevice above the top ring. I would just mill some from the dish and around the lip not under the quench area; .015" or so and you should have 2 more cc's gone. Or see if you can hog our some from the chambers.
 
I didn't explain that right , i have used the 232 pistons for the X and J heads in the past , they have the bump for the open chamber/ dead ..... wasted space that the step takes care of and forces the mixture over to the combustion chamber to be reacted .
I'm wanting to switch to the EQ Double Quench Head for more efficient chambers and better port runners, but need to keep 9 to 1 and hold that tight quench for efficient burn.
so i guess i need a heck of a dish to get back to 9 to 1 , sounds like 600.00 custom pistons ??
 
I think we understand what you have. No you don't need a lot more dish to get down to 9:1.

My post #8 was to explain how to modify the KB232's for use with the 62 cc heads to have the quench that you want and how much to take out of the chamber area to get to 9:1. The elevated pad can be used as is or machined as needed. At .050" tall, it isn't actually tall enough to give you quench with the open chamber heads, unless you have milled the head or decked the block. With stock LA deck and unmilled X or J heads, and a .039" head gasket, that pad will give a quench gap of maybe .090 to .100".

BTW.... IS you block decked at all? Is it an LA block or Magnum block? That changes the equation; I've been assuming an LA block.

I like your car!
 
nm9stheham said:
I think we understand what you have. No you don't need a lot more dish to get down to 9:1.

My post #8 was to explain how to modify the KB232's for use with the 62 cc heads to have the quench that you want and how much to take out of the chamber area to get to 9:1. The elevated pad can be used as is or machined as needed. At .050" tall, it isn't actually tall enough to give you quench with the open chamber heads, unless you have milled the head or decked the block. With stock LA deck and unmilled X or J heads, and a .039" head gasket, that pad will give a quench gap of maybe .090 to .100".

BTW.... IS you block decked at all? Is it an LA block or Magnum block? That changes the equation; I've been assuming an LA block.

I like your car!
Click to expand...
 
block is decked for zero at flat part of piston.
the piston i think i need is a
Sealed Power H405CP
, it has the double quench but the dish in the center is not enough.
my block is a 74 360

100_1839.JPG
 
I think if it is around 9.2:1 they will let u thru tech-until u start winning. those are 340 or 360 exhaust manifolds right? (not 318)
 
wishihadahemi said:
block is decked for zero at flat part of piston.
the piston i think i need is a
Sealed Power H405CP
, it has the double quench but the dish in the center is not enough.
my block is a 74 360

View attachment 1715132254
Click to expand...
Not going to achieve what you want. The block sounds like it is decked .012" (which is based on zero-decking to the flat top of the KB232, which is what I assume you mean), and you will end up with 9.2-9.3 SCR with the H405CP's and a .039" head gasket. AND, your quench gap will be a useless .082"; the H405CP's sit down in the hole a fair amount. A standard Felpro head gasket would get you pretty close to 9.0-9.1, with an even more useless quench gap.

You're better off starting with the KB232's if you really want a quench gap IMHO. I haven't worked out the exact numbers with that and a thicker head gasket.

And I would not worry overly much on having quench on both sides. You're gonna get benefit from one side just fine. Are you limited to something like 87 octane pump gas? 9:1 is not all that high.

Standing inside the engine compartment for motor work makes it so easy that it is like cheating LOL
 
ok, so the 405 has a different pin height, lowering the piston..... i didn't check all the numbers, thanks....but that's what i want is tight quench top and bottom with fuel mixture compressed only into the chamber. that's what is making these modern LS , Hemi,ect..... make power. "The keys are heads with quick-burn combustion chambers, optimal quench achieved with near-zero deck heights, an aggressive cam ground to Brandes’ specs, and careful carburetor and ignition tuning.Brandes explains, “I try to achieve around 0.040-inch quench. That’s about what a modern LS-series motor has. Spark-plug positioning in the chamber, slightly biased toward the exhaust valve, is also critical."Article i found in Hot Rod Magazine. ( my old Street Stock Barracuda W-2 360,was fast... my 2nd year wasn't that good, i just do Hobby Stocks with my Kids now)

95 Street Stock002.jpg
 
I've been running a Q of about .034,since 2001;over 100,000 street miles. Aluminum heads, and KB107s, stock rods and lotsa 7000 blasts,some 7200s, just for fun. I'm geared for 7000=65mph in First-overdrive.
Probably unlike you tho, I have little to no traction.
 
wishihadahemi said:
ok, so the 405 has a different pin height, lowering the piston..... i didn't check all the numbers, thanks....but that's what i want is tight quench top and bottom with fuel mixture compressed only into the chamber. that's what is making these modern LS , Hemi,ect..... make power. "The keys are heads with quick-burn combustion chambers, optimal quench achieved with near-zero deck heights, an aggressive cam ground to Brandes’ specs, and careful carburetor and ignition tuning.Brandes explains, “I try to achieve around 0.040-inch quench. That’s about what a modern LS-series motor has. Spark-plug positioning in the chamber, slightly biased toward the exhaust valve, is also critical."Article i found in Hot Rod Magazine. ( my old Street Stock Barracuda W-2 360,was fast... my 2nd year wasn't that good, i just do Hobby Stocks with my Kids now)

View attachment 1715132319
Click to expand...
Cool beans on the racing. I like it. Man, I gotta laugh at the 'modern LS' thing..... seriously, I read pretty much the same thing 45 years ago in Hot Rod and Car Craft.....except without the 'LS' in the articles. Built my 1st engine (a 351C) with TRW quench dome piston, that closed off one side of the open chamber 2 BBL Cleveland head. A bit over 10:1 when I hogged out the chambers a bit more. Good engine and no detonation issues as long as I kept the timing advance under control.

Seriously, you will get what you need from quench from one side. What is not well explained is that a big part of fighting detonation is just from using small chambers. That mention of 'quick burn' chambers is just from them being small; you get that right from the smaller chamber.

And in essence, with your block decked by .012" (as it sounds like it is), then the ledge all around the KB232 piston top is going to come up to right a zero deck... like you said. So with a .039" gasket, and milling off ALL of that pad, you are going to have 2x quench. Now you are back to that SCR issue. You 're gonna need to get about 4 cc's out of the chambers or the dish or both. 4 cc's is not a lot to mill out of that dish, maybe .030"..... Seems like you have what you need expect some machining.
 
Do they actually check compression in Louisiana? Not a knock on you but those Cajun's and Coonasses are some of the best cheaters I've ever seen.

Call Randy at RaceTec pistons... he'll build what you need at a friendly price.

Then call Mike Jones at Jones Cams. His oval track cams are dynamite and his computer program and can grinder will allow him to build a cam with a lot of area 'under the curve'. Don't be fooled... the numbers on his cam look very mild... but they'll make your engine pull like a freight train.

Off the shelf stuff is what the guy running 2nd uses...
 
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