BBC HEADS # 3946074 Winters foundary

[6.50camaro]

Hey y'll , stopped by the local machine shop today . The owner got a pair of these heads in for some work . He is not familiar with BBC performance heads . Do these have any great value as being rare or to a numbers matching guy . Casting number 3946074 dated 9. 8. 72 . Any info on these would be helpful . Dan

[Ericnova]

1972 date puts them as over-the-counter sales as either a pair of heads or on a crate performance replacement engine....so not going to have a big value like a 1968-70 dated pair that could have come on a factory installed deal like an L89 option 396, 427, 454 or the ZL-1 Camaro 427 deal.

[6.50camaro]

Thanks ericnova , I am assuming that is the date code (9. 8. 72) it is cast on the intake runner on the underside or deck side of the head . My buddy doesn't want to work on them if the were of great value . They look like a nice set of unmolested heads ,no port work, stripped threads , welding repairs only had a 3 angle vj and the intake guides were lined and reduced to 11/32 with some kind of threaded guide liner which have given up the ghost. . He needs to put new guides on the intakes and maybe just put liners in the exhaust . Dan

[6.50camaro]

Any tips on changing guide in these heads? Do any of them go thru the coolant passage like on the iron big block heads? Dan

[Sparksalot]

The guides are integral to the head casting. There is no separate part to replace. There are many ways to repair them. Liners (the mentioned threaded version is one type) are commonly used.

[maxracesoftware]

new Topic SpeedTalk Link to :
BBC 3946074 OpenChamber RoundPortExhaust Flow Numbers + Pics + Info
viewtopic.php?f=1&t=65545

[mag2555]

The guides are replaceable, but there a pain since they can only be driven in and out in one direction.

It's much better especially in terms preserving the valve job and not sink the valves to install guide liners and run 11/32" stem valves.

Even the factory 3/8" stem valves where known to snap off there heads, so don't chance it for the sake of 250 bucks in new valves!

[1980RS]

They are good heads. My deceased race friend had them on a 520 Pat Musi BBC and he made 680hp with a flat tappet cam and 11:1 compression. When it was 13:1 the engine made 730hp. I am sure whoever Pat had do the heads had a little to do with it.