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The lean mean donut machine
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I need to know what is the largest valve size that will fit in a 440 head, casting number 2780915. These are the closed chamber heads from 1967. I want to port these heads with much larger than stock 2.08/1.74 valves, in an effort to make well over 300cfm. This will be going on a 500 cu. in 440 stroker engine with all radical race type components, and is currently in the works.
 

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It seems like I recall being able to stuff 2.35 intakes and 1.81 exhaust into big block heads once, and the valves were just barely not touching.
 

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Well, standard "big valve" sizes would be 2.14/1.88, I have heard of people using 2.25 BBC intake valves, however. This will take a little bit of research, as I don't believe BBC valve lengths are the same. You might be able to fit a larger valve in, but i would become worried that they would be come shrouded by the bore. IIRC, I believe with 2.14/1.88, you will need a plunge cut made to the chamber for clearance and deshrouding.

If I may ask, is there a reason you want to go with the 915s? Don't get me wrong, those are (IMO) definitely the best regular production head to have. But 300 cfm is not generally within the abilities of your average home porter. To get 300 cfm out of any stock BBM head is going to take someone with a lot of knowledge and a flow bench, and if your paying to have these ported, your going to be at the cost of a set of new Edelbrocks in short order. The E-heads will flow mid-290s out of the box, with room to grow. Not to mention, if you want to run pump gas, with a 500 cid stroker you are going to have to use a piston with a pretty good sized dish in order to get under 9.5:1 (10:1 possibly with good quench) for iron heads. Not to mention, it seems strange to run a stock head on a stroker with "all radical race type components".
 
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