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Discussion Starter #1
What size ports would this head have?
1 7/8 or 1 3/4
They are not the original heads that came on my
70XR7. Note the bump next to the 4. these must be the open chamber 4v heads.

Thanks,
richard
 

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Discussion Starter #2
When I got home from work, I look in the old yellow book and it said:

All 4v heads have the same ports and valves. BUT the 70 - 71
versions have the smaller quench combustion chamber which are good for 1.5 points more compression than the larger open-chamber heads.

fair enough.
 

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Bowl,
Cleveland header gaskets come in two varieties -- 2V or 4V. The only thing you have to worry about is that big number 4 on the head which says that it is a 4V, or big port head. All of the header manufacturers (and gasket makers) know the difference! 2V gaskets will not work on 4V heads since the outer edge of the port isn't even covered by a 2V gasket! Those 4V intake and exhaust ports are HUGE!

As I have posted a couple of days ago, not all 'bump-4' heads are open chamber! I had assumed so until last weekend when I saw two sets of *4 closed chamber (high compression) heads. You know what they say about when you assume... ;)

Now, can anyone tell me what in the heck the bump is for? :confused:

1973 and 74 4V Cleveland heads have the smaller 2V valves but still have the 4V port sizing. That little tidbit isn't in any book that I know of. Trust me on this one. I have two 73 351C-4Vs and my buddy has the two 73 351C-4V Mustangs! We found out the hard way!

Milo
 
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