440 Compression/quench/cam questions

[T2R9]

Oh My!

Here is what I have. late 440 block, 30 over, Icon IC968 flat tops that are .022 above the deck. My original plan was to run a set of redone 452 iron heads. Compression with an .039 gasket and assuming 88cc's for the heads have me at 10.25 compression.
So I feel this is too high for iron heads so started looking at aluminum. A Stealth is 80cc's and Sidewinders are 84cc's. If I run a .051 gasket this gives me .029 for a quench area. Too little? Quench area on the 452's is.097 with .039 gaskets. Edlbrock has an 88cc open chamber.
Todd Marsh can assemble me a head to match the cam I choose and he is close by so there is that. They are angle plug heads but from what I have read not a big deal with manifolds.

This is a 74 Charger, Automatic 2300-2500 11" converter. 3.23 gears. HP exhaust manifolds. Performer intake with a 850 Thermoquard was the plan. I am looking for cruising drivability and need vacumme for AC and power brakes.

Cams. I was looking at the Crower 271HDP or the 267HDP. The 271 has very simular specs to the Voodoo 702 that I have in my 71 but that is a 4-speed with 3.55 gears, I like it. It has plenty of vacuume and a nice idle.
I called Crower and the tech was pushing the 277H over the above grinds. This is very much like the Summit 6400 and I have one of those on the shelf, but it seems small but would have a ton of touque.

I would be open to a gear change if needed but thoughts on if either the Crower 271HDP or 267HDP will work with the 3.23's?

Yeah I know I am all over the place but I can change most anything for this short block at this point in the build.

Thanks

 

[gkent]

I was facing a similar dilemma with the piston too far out of the hole. I went for SCE copper head gaskets. They aren't cheap but when you can't find anything thicker than .052 ... !!

Look through their catalog carefully. Find the thickness you need - I'd say minimum .062 for your application which will give you a nice, safe .040 quench. Get the correct bore size for your application and get the ones with the fire ring.

They are very helpful by email or phone but their products are only available through their supplier network - Summit, Jegs, etc.'

SCE Gaskets - Premium Engine Gaskets | Delivering Horsepower

 

[Don Frelier]

I agree 10.25 is high for iron heads and a mild cam.

But you need to measure what you have as it doesn't sound like you've done that.

 

[68-500]

Off the wall idea here. Set your 452 heads on the block. Scribe the bore of each cylinder, have chambers sized to the bore than you can run the head gasket of your choice.

 

[gkent]

Machining costs more than gaskets !!

 

[T2R9]

But you need to measure what you have as it doesn't sound like you've done that.

Point me in the right direction Don. The block was decked. Stock rods and crank. with a 2.067 piston compression height that puts my deck height at 10.688. That sounds like a lot was taken off.

 

[gtxrt]

i would say the block was cut .035.

 

[T2R9]

Sounds about right. Looking like pricey head gaskets and aluminum heads.

 

[gtxrt]

does the piston rock in the bore when out that far for a good ring seal ?

 

[T2R9]

I can move it slightly.

 

[33 IMP]

Quench is nice, but there are millions of bbm out there with no quench at all.
If aluminum heads are in the budget, I'd get either SCE or cometic gaskets that get you to 9 3/4-10 to one (leaning toward a lower number for smallish cam and pump premium).
But I don't see anything wrong with a big fat gasket and your 452s, and a 9.5 comp ratio. I'd run them first.... and then if I wasn't happy, THEN consider an aluminum head swap.
The solid copper SCE could probably be re-used.

 

[R413]

does the piston rock in the bore when out that far for a good ring seal ?

The top of the piston is loose in the bore anyway, the skirt is where you measure and set the clearance.

 

[gkent]

Something to note:

ALL pistons measurements are calculated using the factory deck height spec. So if a piston manufacturer says their piston is "supposed" to be .009 IN the hole and its .022 above the deck then some simple math tells you the deck was cut approximately .031. I say "approximately" because factory deck heights were all over the map - one of the reasons racers "blueprinted" their motors !!

Next, factory head gasket thickness ensured a few things, compression, quench, valve clearance AND port match to intakes - no fancy machining to get things to match!

So ideally you want a head gasket that will be equal to the original gasket thickness PLUS the difference from the factory deck height spec. That done you can safely assume ports will match and you can now use the various head specs (cc volumes) to determine what your compression will be with a given piston. Usually piston manufacturers supply this info - compression ratios for specific combustion chamber volumes. And usually they've already taken quench into account.

All that said, now is the time to chose your head gasket and go from there.

 

[68-500]

Machining costs more than gaskets !!

I did state it was outside the box thinking!

 

[gkent]

No, you said it was "off the wall"

 

[T2R9]

Thanks everyone. With a stock deck height it looks like the piston should sit .015 in the hole. My 452 heads have been surfaced so that is likely .010 there. I ordered a set of SCE head gaskets with a compression thickness of .093 that puts me within .002 of the stock deck height with a felpro .039 gasket. With that compression looks like about 9.53 with the 452 heads. So I will run them for now as imp33 suggested. And Thanks gkent for the very helpful info!

 

[gkent]

Was the factory gasket .039? For some reason I'm thinking it was a .019 steel shim. OR did the piston mfg state the compression with a .039 gasket?

 

[T2R9]

Was the factory gasket .039? For some reason I'm thinking it was a .019 steel shim. OR did the piston mfg state the compression with a .039 gasket?

I was going by the standard Felpro available today.

 

[Geoff 2]

The piston is loose in the bore on the engine stand & will have some movement. At operating temp, the piston has expanded & taken up the clearance.
I do not believe you will have a problem with 0.029" quench clearance as long as rpm is kept below 6000.

 

[BSB67]

Off the wall idea here. Set your 452 heads on the block. Scribe the bore of each cylinder, have chambers sized to the bore than you can run the head gasket of your choice.

I would consider this. You don’t need a machine shop. You could do this with some simple home tools.