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The 410 stroker saga continues

2K views 24 replies 16 participants last post by  jerpro9 
#1 ·
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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#2 ·
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...
 
#4 ·
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.
 
#6 ·
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
 
#10 ·
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.
 
#13 ·
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.
 
#15 ·
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.
 
#16 ·
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.
 
#21 ·
A stock 1970 4v had 11-1 compression from the factory!!
Compression Ratio (max.)
11.0:1 4V 70

10.7:1 4V 71

9.0:1 CJ 71

11.7:1 Boss 71

9.0:1 4V/CJ 72

9.2:1 “R” code 72
I bet gas had a lot higher octane rating back then as well.
 
#22 ·
Hmmm...
I remember some ol' fart telling you in chat detonation could cause head gasket problems AND bearing problems...

"My motor isn't detonating" :D

Open chamber heads are less prone to detonation.

Remember this! Anything over 10.5/1 C.R. is too much for pump gasoline!
 
#23 ·
Crate motors are fine, as long as you make no assumptions about them. Fer instance
  • don't assume that any of the work done on a crate motor is quality; verify everything yourself.
  • if the crate motor comes with heads, don't assume that the valves are any good, unless you know for sure that they are one-piece units
I would say that having an engine built by a knowledgable shop is a far better way to go, but both methods have their own set of problems.

Witness the fact that I STILL don't have an engine. Had I gone with another crate I'd have had the engine months ago.
 
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