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Measured head chamber volume & deck height
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Author:  72polara [ Wed Jan 03, 2007 7:36 pm ]
Post subject:  Measured head chamber volume & deck height
Just sort of an fyi/for giggles post. The answer to "what cc are /6 heads?" is definately "measure!!"

I cc'd the head off my '83 slant and came up with 60cc - it was at least pretty consistent across all 6 chambers.

The nasty part is the deck height: 6/32, or .1875". Run the numbers... that's like 7.5:1 from the factory. This thing must've been a dog when it was pulled, no wonder it's a low mileage motor... :)

Anybody else measured their head chamber volume and deck heigh off their slants? I've got a '73 engine I'll be tearing down in a month or so, I'll post those results whenever I get to em.
Author:  DusterIdiot [ Thu Jan 04, 2007 6:08 am ]
Post subject:  Pretty much everyone in the know...
Quote:
Anybody else measured their head chamber volume and deck height off their slants?
Pretty much anyone here that is rebuilding or pulling the head off for some refreshing and milling. Truck motors seem to have the higher chamber size(probably so they don't ping badly with low octane/heavy underpowered vehicle/stiff timing curve/emissions timing curve/etc...), the last head I had done was a 1963 head, it was 68 cc to begin with and I had to deck .080 off it to be able to use it on the '67 mill I was working on... I notice there is a little better "consistency" in the mid to late 70's car engine heads (ranges from 52-54cc)...


-D.Idiot
Author:  70valiant [ Thu Jan 04, 2007 2:09 pm ]
Post subject: 
I didn't cc my head before taking 0.100" off but I ended up wioth 39cc chambers afterward.
Author:  slantzilla [ Thu Jan 04, 2007 2:19 pm ]
Post subject: 
My '81 head has 56 cc chambers, my '76 head has 53 cc. '76 head was milled .040", the '81 .016".

I have seen pistons down anywhere from .125" to .200".

Consitency was not job 1 at Mopar. :shock:
Author:  Super6 [ Fri Jan 05, 2007 7:44 am ]
Post subject: 
My '87 head is 39 cc after milling .080", but the head has had at least one, and I believe more likely two cleanup (±.010") passes done to it in the past.

My piston-deck is -.165".
Author:  wicked/six [ Fri Jan 05, 2007 11:47 pm ]
Post subject: 
My 74 head has 55cc and the deck hieght is .194 at 30 over this is about 7.9 to 1 compression ratio. That just wont do for me so Ill have to shave .60 off the head and .60 off the block. should run good. :shrug:
Author:  65deuce [ Wed Jan 17, 2007 12:19 pm ]
Post subject: 
At what point do we need to move to aftermarket pushrods?
Author:  65deuce [ Wed Jan 17, 2007 12:20 pm ]
Post subject: 
At what point do we need to move to aftermarket pushrods?
Author:  Greg Ondayko [ Wed Jan 17, 2007 12:45 pm ]
Post subject: 
There is a few factors going into pushrod length.

1. Head milling

2. (for Solid Lifter Motors) Adjustable rocker arm screws

3. Cam

I have taken .100-.110 off a head and still be able to use stock push rods.

The aduuster screws can take up alot of this.

If you use a higher lift cam -usually the base circle is smalller to create more lift - meaning the pushrod / lifter will sit further down anyway.

If you take off .100 and use a stock cam - i will be close. Maybe shorter rods for you.

If you plant to use a bigger lift cam with a milled head then, the smaller base circle and adjuster screws will take up the length requirements.


Greg
Author:  72polara [ Fri Jan 19, 2007 8:59 am ]
Post subject: 
After taking a total of .110" off of my '83 /6 head, I now have 46cc combustion chambers. Deck height is still 6/32, so CR will be in the 8.7-8.8 range.

I haven't cc'ed the '73 head yet, but the pistons in the stock '73 mill are 5/32 into the block.

It's a good thing these engines are so meaty and can be milled like crazy.
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