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will it be absolutely necessary to mill the heads?
#1173157
02/06/12 08:01 AM
02/06/12 08:01 AM
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Joined: Nov 2004
Posts: 340
Vitoria, Spain
Coke
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enthusiast
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OP
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Posts: 340
Vitoria, Spain
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Hello everybody,
I have a set of new MP 452 heads in the box(84cc chamber)for my 440 engine.
Using a comp calculator i would get a comp ratio of 9.30 with a .039" gasket.
Well, i sent a mail to Hughes for ordering one of their whisplash cams,and they said to me that 9.30 is too low for aluminium heads and i will need to mill the heads 0.50 or 0.60..
Also said that a .020 gasket is not an option for alu heads.
I,m not very happy about that idea...troubles with the intake fitment,valve clearances etc...
What is your opinion?
Thanks a lot in advance for any input.
Last edited by Coke; 02/13/12 03:11 PM.
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Re: will it be be absolutely necessary to mill the heads?
[Re: Coke]
#1173160
02/06/12 10:35 AM
02/06/12 10:35 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I'd have the heads' deck milled then set the heads on head gaskets on the block then mockup/set the intake and its' gasket on there & see how far the port/bolt hole alignment is off then another trip to the machine shop to have the heads' intake faces' milled. It's not easy but later on when done & frying the tires cause you got every sub system dead on or near dead on (depending on the system) you'll have forgotten about the time/effort/occaisional aggravation that it took to get you there
live every 24 hour block of time like it's your last day on earth
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Re: will it be be absolutely necessary to mill the heads?
[Re: dogdays]
#1173162
02/06/12 12:49 PM
02/06/12 12:49 PM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
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A gulag near you.
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Quote:
What planet are we on?
Someone help me out here...the only Mopar 452 heads with which I am familiar are cast iron stockers from the late '70s, usually 90 - 92 cc chambers.
I've never associated that number with aluminum heads.
If the refrigerator magnet sticks to them they are cast iron. In that case 9.30:1 is a very usable compression ratio for pump gas.
R.
EARTH ...
MP sells an NHRA stock legal head called the 452 , it's an Ebrock head with straight plugs and a freeze plug in the slab ended head. Since NHRA was allowing outer makes to use it in stock they finally allowed Mopar one also.
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Re: will it be be absolutely necessary to mill the heads?
[Re: JohnRR]
#1173163
02/06/12 02:31 PM
02/06/12 02:31 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
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Posts: 16,376
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Re: will it be be absolutely necessary to mill the heads?
[Re: dogdays]
#1173164
02/06/12 02:53 PM
02/06/12 02:53 PM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
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Posts: 75,326
A gulag near you.
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Quote:
Well, I'll be dogged!
R.
They have been out for a couple years now , but you have been away from the site ...
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Re: will it be be absolutely necessary to mill the heads?
[Re: JohnRR]
#1173168
02/06/12 08:58 PM
02/06/12 08:58 PM
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Joined: Feb 2005
Posts: 4,334
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
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Prospect, PA
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Quote:
Quote:
Well, I'll be dogged!
R.
They have been out for a couple years now , but you have been away from the site ...
Actually, over five years.
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Re: will it be be absolutely necessary to mill the heads?
[Re: BSB67]
#1173169
02/07/12 01:12 AM
02/07/12 01:12 AM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,326
A gulag near you.
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Quote:
Quote:
Quote:
Well, I'll be dogged!
R.
They have been out for a couple years now , but you have been away from the site ...
Actually, over five years.
I'm screwed either way , I was going to say they have been out for a number or years and then second guessed my self expecting a ... actually they came out last year ...
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Re: will it be be absolutely necessary to mill the heads?
[Re: JohnRR]
#1173170
02/07/12 07:33 AM
02/07/12 07:33 AM
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Joined: Feb 2005
Posts: 4,334
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,334
Prospect, PA
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Quote:
Quote:
Quote:
Quote:
Well, I'll be dogged!
R.
They have been out for a couple years now , but you have been away from the site ...
Actually, over five years.
I'm screwed either way , I was going to say they have been out for a number or years and then second guessed my self expecting a ... actually they came out last year ...
Yeah, I did not mean it as nit-picking. When I read yours, I said to myself, "I think its three years", then walked over to my files. Man, the time sure goes, but I belive your point was simply ,...they've been around for a while...., and they certainly have. 
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Re: will it be be absolutely necessary to mill the heads?
[Re: dogdays]
#1173171
02/07/12 07:52 AM
02/07/12 07:52 AM
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Joined: Nov 2004
Posts: 340
Vitoria, Spain
Coke
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enthusiast
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OP
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Posts: 340
Vitoria, Spain
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Thanks a lot for all the replies Dogdays, The pistons are flat ,stock style,TRW L2388,1.926" comp distance . The deck is not exactly the same in all the cyls,but they are between .068" wich is the one most closer to the surface and .074" that would be the most deeper in the hole. The Whiplash cam lift is .518". What i thought,or at least what i have read in some web page, is that the Alu heads subtract one pound from the compresion,but they compensate that loss of power in other ways. So if it is 9.30:1 would it go to 8.30:1? Here is a link to Youtube about a 66 Coronet wich is running a very similar set up,440 engine ,Whiplash cam and 452 heads.(The cast iron ones ?)The engine is from a motor-home,8.5 comp ratio and the owner seems to be very happy with it... http://www.youtube.com/watch?v=MjeCyVvg4Ss
Last edited by Coke; 02/11/12 09:00 AM.
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Re: will it be be absolutely necessary to mill the heads?
[Re: Coke]
#1173172
02/07/12 09:49 AM
02/07/12 09:49 AM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
top fuel
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top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
Thanks a lot for all the replies
Dogdays,
The pistons are flat ,stock style,TRW L2388,0.75" comp distance .
The deck is not exactly the same in all the cyls,but they are between .068" wich is the one most closer to the surface and .074" that would be the most deeper in the hole.
The Whiplash cam lift is .518".
What i thought,or at least what i have read in some web page, is that the Alu heads subtract one pound from the compresion,but they compensate that loss of power in other ways.
So if it is 9.30:1 would it go to 8.30:1?
]
The guys here will correct me if I'm wrong, but I think it's not that aluminum lowers compression, but more like you can run more compression with aluminum than an iron head without detonation, all things being equal.
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Re: will it be be absolutely necessary to mill the heads?
[Re: bobs66440]
#1173173
02/07/12 10:29 AM
02/07/12 10:29 AM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,326
A gulag near you.
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Quote:
The guys here will correct me if I'm wrong, but I think it's not that aluminum lowers compression, but more like you can run more compression with aluminum than an iron head without detonation, all things being equal.
This is what everything points to .
Coke , with pistons that deep in the hole you'll have no issues with piston to valve interference. but you'll want to be careful with compression being too high without the benefit of quench because of how deep they are in the hole.
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Re: will it be be absolutely necessary to mill the heads?
[Re: JohnRR]
#1173174
02/09/12 07:28 AM
02/09/12 07:28 AM
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Joined: Nov 2004
Posts: 340
Vitoria, Spain
Coke
OP
enthusiast
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OP
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Joined: Nov 2004
Posts: 340
Vitoria, Spain
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Quote:
The guys here will correct me if I'm wrong, but I think it's not that aluminum lowers compression, but more like you can run more compression with aluminum than an iron head without detonation, all things being equal.
It seems that they dissperse the heat a lot faster than the iron,wich means that they would evite detonation on a 10:1 and upper CR,but i don,t know what would happen with the power on an engine with less than 10:1.
Quote:
Coke , with pistons that deep in the hole you'll have no issues with piston to valve interference. but you'll want to be careful with compression being too high without the benefit of quench because of how deep they are in the hole.
John,
Do you mean that the compression could damage the gasket triying to scape ?That is the explanation that i find,cause the quench is the flat part of the piston wich leves with the block surface,but this would be on a dish piston,six pack style for example.
However 9.3 or 9.5:1 CR wouldn,t be a trouble,would it?
Thanks both of you
Last edited by Coke; 02/09/12 07:50 AM.
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Re: will it be be absolutely necessary to mill the heads?
[Re: Coke]
#1173175
02/09/12 09:48 AM
02/09/12 09:48 AM
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Joined: Jan 2003
Posts: 75,326
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,326
A gulag near you.
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Quote:
Quote:
Coke , with pistons that deep in the hole you'll have no issues with piston to valve interference. but you'll want to be careful with compression being too high without the benefit of quench because of how deep they are in the hole.
John,
Do you mean that the compression could damage the gasket triying to scape ?That is the explanation that i find,cause the quench is the flat part of the piston wich leves with the block surface,but this would be on a dish piston,six pack style for example.
However 9.3 or 9.5:1 CR wouldn,t be a trouble,would it?
Thanks both of you
No the compression won't damage the gasket . Your compression ratio under 10 is fine as long as you don't run the lowest octane fuel available .
I'm not getting your question , your english is generally good but I'm a little confused by
the flat part of the piston wich leves with the block surface
is that supposed to read
the flat part of the piston which levels with the block surface ... meaning zero deck ?
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Re: will it be be absolutely necessary to mill the heads?
[Re: JohnRR]
#1173176
02/09/12 02:01 PM
02/09/12 02:01 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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I believe Hughes told you that because the aluminum head can run about 1 point higher in comp to be equal with and iron head. So if you run 10.5 with the 452 aluminum head its like 9.5 with the cast iron head. I can tell you we milled the Eddy heads on my sons 400 .040 to get 10.8 comp. It does not have good quench but runs fine on 92 or 92 pump and it has no fitting problems as we milled the intake side .040 also.
Sure you can run the comp at 9.5 but you will have a little better performance if you up the aluminum headed eng to 10.5. You will just loose a tad of power at 9.5. That said I run 10.6 in my aluminum headed 493 and it does have quench and runs great on 92 pump. Ron
Last edited by 383man; 02/09/12 02:02 PM.
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Provided he has the piston to head clearance. If it is a zero deck engine .020-.027 could be flirting with disaster.