Gm BBC Heads 396 question

[day2demon]

I picked up an untouched 4-bolt 396 block today that came with a pair of oval-port heads, GM castings 3964290 and 3917215.
From what I understand, one of these castings was a later service replacement installed around 1974. Both heads now appear to have the same valve sizes (2.190"/1.880"). Originally they differed in valve sizing, but that seems to have been corrected at some point.
Am I correct in thinking that, as they sit now, these two castings are effectively the same in terms of functionality?

[cheveslakr]

You're good, the two heads both have the same combustion chamber. I would guess the only difference is the 290 head has the side bung for the temp sensor, the 215 won't. If you have a choice, put the 290 head on the driver's side.

[big gear head]

Both heads are similar. They both look the same externally. There might be very slight differences in the port volume or shape, but not enough that you would notice. Combustion chambers will be the same. The 215 would be a '68 head and the 290 was used in '70.

[WILMASBOYL78]

Both of these heads were produced with smaller valve sizes from the plant...so, if you have 2.19/1.88 valves, they have been worked on. Many folks refer to the 290 as a 'semi-open chamber' because it has a little relief on one side of the chamber.

The other factors to consider will be the type of pistons, CR and cam choice. Of course all of this also needs to be considered in relationship to the car, trans and rear gears.

For a stock style build I doubt you will notice and difference...except for maybe the spark plug size...the 290 should use the smaller 5/8 tapered seat setup.

-wilma

[67SS4spd]

I’m running the 290’s on my 396.

[big gear head]

I have a single 215 head for sale for $50 if you want to have a matching pair on your 396. You would have to have the machine work done to transfer the valves and other parts from your 290 head. The head is listed in the parts for sale area.