Head and compression questions???

[396_WAYS_TO_SPIT]

Ok I am getting ready to build my friends 454. His pistons are speedpro forged l2399f30.
Here is what they state
100.9cc heads- 10.23-1 compression
106.9cc heads- 9.71-1 compression
109.4cc heads- 9.52-1 compression
116.9cc heads- 8.98-1 compression
119.0cc heads- 8.84-1 compression
The problem is that his heads cc'd at 119cc's. That compression is too low unless he is going to run a blower which he isnt. How much can we shave off the heads to raise the compression without running into piston to valve clearance? Or should we look for different heads? We dont want to change pistons because his motor is already balanced and the pistons are full floaters.We want to be around 9.5-10-1 compression. Any info would be appreciated.
396

[Nucking futs]

There is a chart on river rat life in the tech info that tells you.I would think that if you got a used set of closed chamber heads that would get you where you want to be.If you shave off the material from the head you will run into piston to valve issues.I think its like 0.010=1 cc but im not sure on that.

[Fiat48]

Closed chamber (109cc) would get you there.
You could angle mill the heads and get down to 110 cc roughly. But I don't advise that as it's permanent for the head. And your piston valve clearance will go down according to what you mill off the head.
Better way would be to change pistons. Get lighter pistons than you have now and it will just be a little overbalanced. That way you don't have to rebalance. And you don't mess up the heads.
But first you must find out how Speed pro is rating that compression chart by knowing:
How thick a head gasket are they figuring?
What deck clearance?
What bore size of head gasket?
These are all variables. You may be really at 8.25 to 1 with your deck, available head gasket.
Head milling chart: http://home.isoa.net/~mharrisj/mill.html

[396_WAYS_TO_SPIT]

The block is "zero" decked.
Speedpro states "All comperssion ratios are calculated using a standard uncut block dimension,and a gasket thickness of .0385"

[Fiat48]

The piston weighs 679 grams, has a dome height of .095 and that cc's to 13.8 cc's.
at 0 deck height with a 119cc head = 9.25 to 1 IF YOU CAN FIND A GASKET THAT IS 4.280 BORE ROUND AND .0385 THICK.
Using the typical Fel pro available of 4.370 bore, the compression drops to 9.22 to 1.
So that's where you are at.
Specs courtesy of my 1986 Speed pro book.

[396_WAYS_TO_SPIT]

Originally posted by Fiat48
The piston weighs 679 grams, has a dome height of .095 and that cc's to 13.8 cc's.
at 0 deck height with a 119cc head = 9.25 to 1 IF YOU CAN FIND A GASKET THAT IS 4.280 BORE ROUND AND .0385 THICK.
Using the typical Fel pro available of 4.370 bore, the compression drops to 9.22 to 1.
So that's where you are at.
Specs courtesy of my 1986 Speed pro book.
So what you are saying is that since we "zero" decked the block we are ok with out compression.
Nice;)
396

[396_WAYS_TO_SPIT]

hey Fiat48, Im going to throw another scenario at you;)
this is "My" motor.
454.30 over
L2349F30 in a "zero" decked block and 100cc heads. Where would that put me?
396

[Fiat48]

Originally posted by 396_WAYS_TO_SPIT
hey Fiat48, Im going to throw another scenario at you;)
this is "My" motor.
454.30 over
L2349F30 in a "zero" decked block and 100cc heads. Where would that put me?
396
Detonation without racing gas is where it will put you.:p
658 grms
.221 dome
dome cc 29.4
12.76 to 1 with typical Felpro 4.370 bore gasket.

[396_WAYS_TO_SPIT]

my speed pro book states that the pistons have a .210 dome. Why is your numbers different?
My book states this.
100.9cc head-11.89
106.9cc head-11.18
109.4cc head-10.91
116.9cc head-10.19
119.0cc head-10.01
396
I am going to be runnig av gas;)

[Fiat48]

My book is showing the bigger the bore size, the smaller the dome volume:
L2349F = 30.6 cc and .265 dome
L2349 F 30 = 29.4 and .221 dome
L2349 F 60 = 27.9 and .210 dome
some pistons that way..some not. Example:
L2307 F = 50 cc dome and .580 dome
.030,.060,.100 all show same.
also matches what my 1998 book lists.
12.76 is correct with 100cc head, 0 deck, 29.4 cc dome and 4.370 bore .039 head gasket.
I think the reason the L2349 dome size changes with bore size is that it is a "replacement" piston for an LS-6 and has been accepted by NHRA in the stock classes. So the dome is smaller on the bigger bore piston to keep compression ratio the same as the smaller bore piston.

[396_WAYS_TO_SPIT]

Originally posted by Fiat48
Closed chamber (109cc) would get you there.
You could angle mill the heads and get down to 110 cc roughly. But I don't advise that as it's permanent for the head. And your piston valve clearance will go down according to what you mill off the head.
Better way would be to change pistons. Get lighter pistons than you have now and it will just be a little overbalanced. That way you don't have to rebalance. And you don't mess up the heads.
But first you must find out how Speed pro is rating that compression chart by knowing:
How thick a head gasket are they figuring?
What deck clearance?
What bore size of head gasket?
These are all variables. You may be really at 8.25 to 1 with your deck, available head gasket.
Head milling chart: http://home.isoa.net/~mharrisj/mill.html
(Refering to the 2399f pistons)
Ok If we went to a closed chamber head wouldnt we run into problems with open chamber pistons. Piston to valve and piston to head clearance. i was looking at a set of 110cc heads.
396

[Fiat48]

We determined with 0 deck you are already at 9.25 or close. You wanted 9.5. Isn't that close enough? If not, mill the heads.
1/4 point not worth the fight to get it.
Yes, closed chamber heads and these small dome open pistons would no doubt conflict.

[396_WAYS_TO_SPIT]

Ok thats whats I was looking for. I am thinking that we are running what we have.This is my buddy motor i am building for him;) thanks for the help Fiat48
396