545 Comp Ratio Questions

In prepping for a 93 octane street 545 build I'm trying to find a shelf piston that will give me as close to a 11:1 comp ratio as possible. I understand that I can call Diamond and have whatever pistons I want made but I just don't think that its necessary for this build. I always have the option of mixing the 93 with E-85 or high octane but id rather not have that be a requirement.

1977 Lincoln 460 Block ( I don't believe the deck height has been altered)
Lunati 4.5 Stroke Crank
SCAT 6.7" Steel Rods
New SCJ Heads (advertised as 72cc comb chamber but I haven't measured them yet)
Felpro 1018 .041 Head Gaskets
Custom ground cam from a vendor here
6500 Max RPM
Ignition and timing might end up computer controlled if I go with EFI.  

The Icon IC861 22cc dish has caught my attention. From what I can find it doesn't seem like anyone makes a shelf dish piston with a SCJ intake valve layout between the 22cc that Icon offers and the 36-38cc that Icon and a plethora of others offer.  

If my math is correct and I use the 22cc dish Icon at .020 in the hole my comp ratio should be approx 11.2:1 and the quench would be about .060. Please correct me it my math is wrong. My other option would be to use a bigger dish piston and deck the block to 10.30.

Here are my questions for the guru's.
On a later 460 block (like my 77) the deck height was supposedly 10.32", how often do you find this # to be true?
How many cc's of dish can I add to the Icon 22cc dish pistons if needed? When I talked to UEM they said the 22cc dish crown was .232" thick and they recommended not going thinner than .200" in a NA application.

Thanks Guys

Justin

Whats the Application?

That Cam? Specs?

4200 Lb Street Car, TKO600 Trans

No cam specs yet, cam will be tailored to the final engine combination

At that weight with a manual trans, running pump gas I'd stay closer to 10:1 to be safe.

In other words spend the Little bit extra on reverse domes with the proper -CC and get your quench tight to about .045.

Don't allow slightly lower shelf piston cost to influence you to put together a poor combination.

You also need to get the deck height measured to get the proper quench, don't assume the dimensions old blocks are all over the place

+1 go for the tighter quench and proper dish volume . No more than 10.7 -1 if you only have 91 octane. 11 REQUIRES 93 octane to be safe. Buy the right part instead of reworking a cheap part to fit.

I don't have a problem with ordering custom pistons, if that's what It takes to maximize the combo that I want to build then that's what will happen. A couple of hundred dollars extra is nothing in the grand scheme of an engine build.

I know quench is important that's why I specifically asked about it.

As far as the fuel goes we have 93 octane at most stations here in MI , in fact some have 94 octane and I also have an ethanol plant less than a mile from my house. I've seriously thought about upping the compression and going with E-85 but that brings with it its own set quirks.

Justin

Compression certainly makes torque which =s HP too.

If you have E85 avaliable it’s definetly a good option if you want to run some compression but maximizing for E85 means pump gas is no longer an option

Your calculations, and your assumptions are correct.

The difference between 10.0:1 and 11.0:1 will not be noticed in a street application...unless the cam requires it.

Hey Mark

Is there a 28cc-33cc reverse dome for an SCJ head available from your resources?

Justin