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Moparman143

Donny
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Bolton Landing, New York
I am looking to build a 655 ci engine for my '70 duster, and i need to know the difference between "open" and "closed" heads to see if it's possible. If anyone knows the diff please let me know. The only reason i need to know is b/c if you look at Indy Heads rotating assemblies online their 655" setup comes at 16:1 comp. and i need it to go down to 10:1. And i can shrink the pistons too much. soo if you know, give me a holler. Thanks

P.S. i was looking at indy's big easy heads if u need to see more info on them.
 
i assume with a 655" engine its a large bore spacing engine. i wouldn't even think of using the Indy Heads. go to either a B1 or Predator Head. getting 10:1 or so is just a matter of piston & head gasket choise.
 
nah...this piston will do it.

Predatorheaddishpiston.jpg
 
As long as it sit a foot in the hole or the chamber is 150ccs, LOL
 
AdamR said:
As long as it sit a foot in the hole or the chamber is 150ccs, LOL
Click to expand...
:shock: :thumbup:

with the ROL .040" gasket it was a hair over 11:1cr. you can prolly get thicker ROL's and lower it about another .5-.75 cr.
 
out of a 655 though ? a 500 cube stroker ends up with 11:1 with a set of 68cc heads a .040" gasket and flat tops at zero deck. Add a 155 cubes, Thats a lot of volume to keep the squeeze down on.
 
yah your right. i just did the math again, and with the dished pistons it came to 11.787:1 on the 651cid engine. Those where with .040" gaskets. 10:1 will be kinda hard to achieve. but can be done i suspose. :thumbup:
 
I think at that point you would be better off with the high compression. With the big dish your not going to have any quench or detonation tolerance. With all the stroke needed to get in to the 650 cube range theres no way to get the piston to sit ran in the hole either.
 
Green, you will want to run at least 11.5 on that anyway. Giants dont run by the same rules...lol. It should be fun to find a set of heads that will work well, and more important, a camshaft to work with them. The -13s I dont think will work so well without a bunch of work, and the Predators dont have a great 4bbl intake.
 
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