World Products 427 Short Block Compression Ratio

[Mean 69]

Thinking of buying the 427 short block assembly from World Products. They have two different version, one with a dome piston, the other with a dished piston. The dished unit allegedly makes about 9.5:1 compression with their 220 Motown heads.

What about the bigger piston piece? I have 67 cc chambers on the Brodix heads that will go on the motor. Does anyone know how high the compression will be with the dome pistons? I fear too high for a pump gas/race gas mix, but can't seem to find the specific numbers.

Gracias,
Mark

[68protouring454]

entered some numbers in compression ratio calc, got dome size from worlds website, they offer a 10 cc dome and a -20cc dish, using your 67 cc heads, the 10 cc dome would be 14.1074-1, too much, the -20 cc dish would come in at 10.0465-1,still alittle light i would be 10.75-1 or higher
tony at afr says to push 11-1 out of cast block, alum head motors, and he lives in the land of 91 octane too
jake

[Mean 69]

That's what I thought, thanks dude. Too damn high, for certain.

Hmmmm.

[68protouring454]

mark use the -20 cc and have heads milled down some to bump up to 10-5-1 or higher depending on how much can be taken off before piston to valve clearance , take as much as possible to get to 11-1 or so
jake

[ProdigyCustoms]

There are plenty of 5cc valve relief pistons around to be able to run right at 11 to 1. Without doing your math I know my 404 is 10.6 to 1 at 70CCs.

I can hook you up with a discount on World stuff. let me know when you are ready to buy. The discount ain't a bunch, but it is a discount none the less.

[Mean 69]

Thanks a million Frank (and Jake!!!), but it is starting to look like the path of least resistance, and cost, and most importantly time! is to go with a Dart based 406. Might not be as sexy for bench racing as a 427, but I just want a solid reliable motor, as soon as possible so I can whip the poopy out of my car (Willow Springs 9/22? doubt it, but maybe?). Like yesterday. I can get a block locally tomorrow, pistons are readily available off the shelf, rods and cranks too, so the only element left to take me hostage is a machine shop. And we all know "that" won't happen....

Mark

[68protouring454]

mark sounds great, frank i was just going by using what came with in thw world short block, as you say, a new piston would be the way to go, but why look at a shortblock you have to change pistons in?? right, goodluck mark
jake