I have a question ,can i use blue open chamber heads on a black block ,i would like to use closed chamber blue or black unleaded heads eventualy when i can afford it. I know there isent a lot of difference but haveing not done it before i thought i would ask first.Thanks chris.
Last edited by landau37; 10-15-2005 at 19:29.
Reason: spelling
Yes the heads are interchangeable as the blue/black blocks are essentially the same. You have to take into account the chamber cc differences when calculating the compression ratios. ie closed chambers on a 351 with factory/flattop pistions will give around 10.5:1
I have a question ,can i use blue open chamber heads on a black block ,i would like to use closed chamber blue or black unleaded heads eventualy when i can afford it. I know there isent a lot of difference but haveing not done it before i thought i would ask first.Thanks chris.
As above, the heads are interchangeable. But, black heads aren't "unleaded", the seats are the same as earlier ones. Also, there are actually 3 different heads. The 351 open chamber, and 2 different size 302 heads, roughly 54 and 65 cc (opens are 76). The 54s are a bit small for a 351, unless you are on gas.....
Yes the heads are interchangeable as the blue/black blocks are essentially the same. You have to take into account the chamber cc differences when calculating the compression ratios. ie closed chambers on a 351 with factory/flattop pistions will give around 10.5:1
Thanks mate as far as i can tell its a standard motor .How can i tell 54 from 65 cc 302 heads?
I've heard about the different CC sized open and close chamber heads. I'm yet to see a factory closed chamber thats under 60cc though.
As a comparison 4V closed chamber heads are normaly 61-63cc, the chamber looks bigger than any 302C heads ive seen so id say 302 CC heads would be more like 55-60cc's. That said valve recess form valve seat wear will effect this figure allot.
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I've heard about the different CC sized open and close chamber heads. I'm yet to see a factory closed chamber thats under 60cc though.
Me too. I have heard a lot talk about 58cc, but the few sets i have measured were bang on 60cc, but once they are skiimed, 58cc is definatly a reality.
yup. All the factory 302cc heads I've cc'd were 60->64cc. There's a pair of genuine 240,000k old 302cc heads sitting in a mates garage off his 302 that was in his XB coupe. I can guarantee they won't be under 60cc.
With machining you can get them there but you can do anything with machining and know how.
Yep, 100%. I haven't got all the spec's any more, but I think it was XY and XA that had the 54s fitted. Probably not many around anymore though...
On a side note, the chamber sizes are basically the same as the 4Vs ( makes sense too...). Three different sizes on them as well. Open chamber, and 2 closed chamber sizes, with the 54s going on the HO engines.
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