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Hello,
I just found out that I have 2 different heads on my engine. One head has a casting number of 3964291 and the other is 3919840. They are both rectangle port heads but one is 107cc and the other is 109cc according to what I found on the net. The engine runs great but should I be concerned? Thanks
Which side are the 107's on?
The 107's are on the 1,3,5,7, side.
How about milling the 109 side down so that their 107.
problem will only exist if you are concerned with high performance balance. most stockers are so far out of stoiciometry that a 2pnt. difference is nothing to worry about. if you have ever ground heads you will know that 2 cc"s is not hard to get out of shape with.
I agree ... just don't like things that aren't right. Also, 109's are on the rich side.
I would tend to think that no factory BBC head is balanced as far as flow goes.
Flow to the #1,5,8,4 intake runner/cylinder is better than flow to the #3,7,6,2 on each head (think I got that right :rolleyes: ).
Even though it is not right, it probably will not make much of a difference if it was correct.(regarding the 2 different heads..cc wise)
Removing 2cc's out of a combustion chamber would not be that hard, and maybe even better cause the removal might better the flow around the valve (shrouded valve).
[ December 04, 2002, 05:02 PM: Message edited by: MikeF ]
I would imagine many of the castings are the same, just minor flow-characteristic changes, no?
I say this because Holley has created many different models of carbs, but based off only "X" amount of castings.
Just food for thought! Don't you think? :D