I bought a 13 : 1 Compression bottom end with High dollar forged everything (JE domes, Oliver rods, Callies crank)...It was this comp ratio with 118cc heads. My question is can I run 840 rect heads (107cc) on this engine safely?? If so what would my compression be?? What size head gasket to make work?

This would save me at least $1500.00 (new Iron heads...Merlin/Dart)
How much actual power would I lose?
(YES, ITS A PULLING TRUCK...AND IT'S GONNA HIT 7500 RPM REGULARLY)

Thanks guys,

A.....

I bought a 13 : 1 Compression bottom end with High dollar forged everything (JE domes, Oliver rods, Callies crank)...It was this comp ratio with 118cc heads. My question is can I run 840 rect heads (107cc) on this engine safely?? If so what would my compression be?? What size head gasket to make work?

This would save me at least $1500.00 (new Iron heads...Merlin/Dart)
How much actual power would I lose?
(YES, ITS A PULLING TRUCK...AND IT'S GONNA HIT 7500 RPM REGULARLY)

Thanks guys,

A.....


With all the investment in parts I suggest that the engine be dummied up and clay put on the pistons to verify clearance. I know that combustion chamber shapes make a big difference on Big blocks and what type piston will work, the pistons can be notched some or the dome shaved on certain combinations.

Steve

Steve

I bought a 13 : 1 Compression bottom end with High dollar forged everything (JE domes, Oliver rods, Callies crank)...It was this comp ratio with 118cc heads. My question is can I run 840 rect heads (107cc) on this engine safely?? If so what would my compression be?? What size head gasket to make work?

This would save me at least $1500.00 (new Iron heads...Merlin/Dart)
How much actual power would I lose?
(YES, ITS A PULLING TRUCK...AND IT'S GONNA HIT 7500 RPM REGULARLY)

Thanks guys,

A.....
=
No

Please DISregard my e-mail Mr. Lewis...

Thanks,

A.......

Mike,

What will he be at??

16.5 to 1 CR. w/ 107 cc heads on top of a 13 to 1 CR. engine w/ 118 cc heads now...

pdq67

840's are closed chamber.

I dont think your 13.1 dome will clear a closed chamber head!

Mike, (I.e., Wolfplace that is!!)...

Again!!

"What will he be at??

16.5 to 1 CR. w/ 107 cc heads on top of a 13 to 1 CR. engine w/ 118 cc heads now..."

And I'm talking if the pistons fit the chamber to keep it simple here!!!!

pdq67

Mike, (I.e., Wolfplace that is!!)...

Again!!

"What will he be at??

16.5 to 1 CR. w/ 107 cc heads on top of a 13 to 1 CR. engine w/ 118 cc heads now..."

And I'm talking if the pistons fit the chamber to keep it simple here!!!!

pdq67
=
Hi Paul,
It is 14.91, not 14.1,,
I edited this, I missed the nine when I replied earlier from the shop, I was busy,,

But it is academic as the pistons are not going to fit the chamber as I answered earlier, ;)

For the heck of it Paul ,heres a KB piston that gets 13-1 w/118cc head and the page has a CR calculator .
http://kb-silvolite.com/forged.php?action=details&P_id=352
Seems to give a 14.990 c/r w/107cc's -that seems right.

A piston dome designed for an open chamber matched with a bath tub closed chamber?Clearance issues would need to be addressed big time.Not sure on the static CR..but open chamber tin heads should flow better and stave off detonation.

Ironhead and Mike are why I followed up on this!!

pdq67

Hey dieseleater, by any chance is that shortblock a 509"??

470......stock stroke.

Ironhead and Mike are why I followed up on this!!

pdq67

Witch Mike are you referring to?

Gimmie a break.........

All of youse guys!!!!!!!!!!!!!

He, He!!

I just figured that stepping down from 118 to 107 would up his CR drastically is why I brought it up and I use this site..............

http://www.campbellenterprises.com/Race%20math%20calculators.htm

to figure CR, but I have NO idea about piston dome sizes.

One thing about it tho, is that if he want's to step up to E85, he can run that CR. if he can buy the stuff locally like we can here in the midwest!

I've field-tripped through two new Ethanol Plants too!!

pdq67

I didn't mean to sound like a dumba$$ with that question......I just thought maybe there was a little trick that someone had tried somewhere...Kinda like running rectangle intake on oval heads......I thought that just maybe with a thick head gasket and some tender handy work it would be possible...

Cause I know NOBODY WANTS TO SHELL OUT 1500 BUCKS FOR HEADS IF HE DOESN'T HAVE TO!!!!!

I would not loosen up quench at all!

I'd tighten it up to the min. of what I figure is .035" and go!!

You really need to set your CR, to what you want w/ a tight quench!!

pdq67