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As some of you may know, I need new heads.
So as part of the process of getting new heads, I decided to have my old heads cc to make sure I staying the 10.5:1 compression range with the new ones.

My current heads: 67 cc closed chamber.
All the heads I have evaluated to date.....63 or 61 cc chambers....that won't be to good I thought.

So on a whim I decided to investigate what my total compression really is....keep in mind it is suppose to be 10.5:1.

So I call up Speedomotovie who built my kit, they don't know.
So I call up Ross Racing you custom machined my pistons, they don't know unless I have a number.
So I call uo my machine shop and get the number.
Call back up ross, give them the number, and they pull the work order.

Ok.....Custom pistons.....etc etc....specs.....built for 10.5:1.....with a 78cc head.

A 78 CC head!!!!!!.....that's a 4v open head....I have 4v closed heads...and told the stoker manufacturer that I have 4v closed heads...but somehow they built it for open heads.

My current total compression 11.56:1

Ugh.

So now I am faced with a choice. Purchase a set of 4v closed with an even smaller combustion chamber (63cc) and ahve my nice pistons further modyfied to lower the compression, meaning I will also need the whole thing re-balanced, or go to 4v open heads and actually maintian my 10.5:1 compression which is what I wanted.

4v open heads are historically less pricey, but I have heard that they cost lotsa torque in the low end. Will this still be true since I have a piston designed for 10.5 with their chamber or will I get similiar performance from a 4v open with 10.5 as I would with a 4v closed with 10.5?
 

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Wow, what a situation you've got. I am sorry you are having to experience all fo this real time.
Not to take the wind out of your sails, but your escapade is really making me lean towards procuring a crate motor when my engine dies...
 

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Discussion Starter #3
This could have just have easily happened with a crate motor ;)

Well...some crate motors....didn't Kent buy a crate motor?
 

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Perhaps you can find a set of OC heads at a good price. With those heads, the extra cubes and a cam spec'd with the right events for your application, you'll build a ton of power.
 

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I'd bet the CHI heads are sounding pretty good right about now.

What a major dilema. It sure sounds like you'll lose a lot of bottom end with the open heads.
 

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If i were yu I would go with the open chamber heads with all those cubes torque shouldnt be a problem. I dont know what your budget is but i was just reading about some blue thunder cleavland style heads there expensive but man would they be sweet looking in there
 

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Ive seen several sets of 351CJ heads on egay recently.......


Open chambered heads would almost be necessary on a 400ci stroker running on pump gas (unless you bought dished pistons.!!)
 

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Discussion Starter #9
This pistons were supposed to be customed made to get me to 10.5 with closed chamber heads :( I paid almost $700 for them :(
 

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I know what you mean. I was shooting for 10.5:1 on my fastback. I got a killer deal on the heads I'm currently running, and I did the calcs and up to a 11.75:1 compression.
 

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Closed chambe Cleveland heads CAN run over 11:1 compression. It is the design that makes them efficient. Mind you, I wouldnt want to go OVER 11:1, but it has been done. Boss 351's ran that way from the factory for crying out loud. I would zero deck the block, run your calculations, and see where you are. Then I would open the chamber up/modify pistons as needed to get to between 10.5:1 and 11:1.
 

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If i remember correctly 7DMACH1 is running a fairly radical cam, would be bleeding of some of that compression. 11.50-1 with a mild cam, it is gonna be hard to control pinging on pump gas. Might be why your head gaskets went...
 

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Too bad you're way over there on the ECoast.
I have a set of OC 4V Clevelands on the shelf.
Haven't been following this too close -- assume Cleveland's what you need.
They're ugly and rusty, but I'd give 'em to ya.
Seattle's a long way away...
PM me if you're interested.
 

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i would complain to ross if it was me, if you ordered for closed and they made it for open. for 700 bucks they should be making what you want. my .02, thats probably the whole reason all this happened or atleast a big part of it i would think.
 
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