Speedmaster CNC chamber cc's

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dart_68

dart_68

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I have a set of the CNC'd Speedmaster heads. I cc'd the chamber and came up with 75 cc's. Seems a bit big but I'm sure of my measurement. Anyone else cc'd their heads yet?
 
There's a few threads about it. Just put Speedmaster heads in the search box
 
dart_68 said:
I have a set of the CNC'd Speedmaster heads. I cc'd the chamber and came up with 75 cc's. Seems a bit big but I'm sure of my measurement. Anyone else cc'd their heads yet?
Click to expand...

I CC'd mine last week. I got 65cc in multiple chambers.

edit: I also CC'd a pair of intake ports after I got the heads back together, 188cc.
 
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Please specify if you guys checked a CNC chamber or an as-cast chamber. The CNC ports have been delivered both ways, according to other threads. I think bare CNC version was an untouched as-cast chamber and the assembled CNC version had the chamber CNC cut as well. So the sizes may be different.
 
Bobzilla said:
Please specify if you guys checked a CNC chamber or an as-cast chamber. The CNC ports have been delivered both ways, according to other threads. I think bare CNC version was an untouched as-cast chamber and the assembled CNC version had the chamber CNC cut as well. So the sizes may be different.
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Sorry, I covered all that when I posted in the AM inspection thread and didn't think to post it all again.

The numbers for the as cast head are probably accurate.

The assembled CNC heads all come with no chamber work, and are list as 68cc. That's inaccurate. I measured them and They have the same 65cc chamber as the unported heads. The runner volume is accurate at 188cc as measured.

The bare CNC heads come with a CNC chamber, there's only one person I know of for sure that has those, and he hasn't posted any data.
 
I will try to get mine roughly measured this weekend. Mine came as fully assembled CNC ports but they do also have CNC chambers as well.
D02FAF57-553F-4FB9-8C4B-830B9171E736.jpeg
 
First thing I’d do if I had some SM SB Mopar heads that checked at 75cc...... is double check my work.

I don’t see how you could get another 10cc out of those chambers without radically altering the shape.

If they were indeed 75cc...... I’d send them back....... unless of course you wanted them to be 75cc.

Since it would appear that the cnc’d chambers did come on some assembled heads....... I wonder how SM decides which heads get it, and which don’t.
 
Bobzilla said:
Please specify if you guys checked a CNC chamber or an as-cast chamber. The CNC ports have been delivered both ways, according to other threads. I think bare CNC version was an untouched as-cast chamber and the assembled CNC version had the chamber CNC cut as well. So the sizes may be different.
Click to expand...
My heads are the CNC ports but the chambers look cast. I'll check again today.
 
Bobzilla said:
I will try to get mine roughly measured this weekend. Mine came as fully assembled CNC ports but they do also have CNC chambers as well.
View attachment 1715509076
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That's interesting. They don't show those heads on their site. The only way they offer them, going back to BF as far as I can tell, is as an empty head.

Can you post the part number that was on your invoice/head?
 
Here's what I have for P/N and description

Cast Bare - 281.1654
Cast Hyd FT - 281.2146
Cast Hyd Roller - 281.2149

CNC Hyd FT - 281.2148
CNC Hyd Roller - 281.2151

CNC Bare w/ CNC chamber - 281.1656
 
The boxes and the invoice for mine have them matching, with part number PCE281.2151. I did order them for hydraulic roller application. In reality, I would have preferred them without the chamber work, since they leave a sharp edge between the valves.

Maybe since they had so many orders they started sending these out to fill those orders. I did order later than others. I think I placed mine late Monday, toward the end of the sale.
 
dart_68 said:
I have a set of the CNC'd Speedmaster heads. I cc'd the chamber and came up with 75 cc's. Seems a bit big but I'm sure of my measurement. Anyone else cc'd their heads yet?
Click to expand...
Update:

I cc'd my chambers again and got 68 cc's. The chamber is CNC as well as the ports. I found out why I got 75 cc's on when I did it the first time. The fluid I was using was leaking past the exhaust valve. WTF! For the 2nd time I sealed the valve seat with vasoline and got the 68 cc's for CNC's chamber.
 
I saw one close up pic of the CNC chambered version....... I didn’t care for what was left of the valve job after the CNC work was done.

The seats in the one I was looking at needed some attention IMO.
 
dart_68 said:
Update:

I cc'd my chambers again and got 68 cc's. The chamber is CNC as well as the ports. I found out why I got 75 cc's on when I did it the first time. The fluid I was using was leaking past the exhaust valve. WTF! For the 2nd time I sealed the valve seat with vasoline and got the 68 cc's for CNC's chamber.
Click to expand...
What is the country of origin for Speedmaster products?
 
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