Danp76

Hi guys, I have G heads for my 455 olds. I have 2.000 intakes, and 1.685 exhaust valves. If I enlarge the intake to 2.072 will there be a risk of cracking? can it be done safely? I know most heads have the 1.625 smaller exhaust valve, but mine are measuring out as if they were Ga heads...Recommendations??

Danp76

Basically, can a Ga head accommodate a 2.072 intake valve?

joe_padavano

Well, considering that some of them came that way from the factory, I'll say "yes". Olds used the exact same castings for big and small valve applications. The only difference is the size of the machined valve seat.

By the way, if you're worried about cutting an additional 0.035" off the valve seats, consider the fact the people routinely machine much larger counterbores in these heads to install hardened valve seats, with no problems.

And yes, I'm aware that the GAs had induction hardened seats from the factory. Still not the same as real hardened inserts.

Danp76

Hi Joe, didn't the factory Ga heads with the 2.072 have the smaller exhaust valve of 1.625? and not the 1.685?...why didn't they use the larger exhaust valve when using the larger 2.072 intake?...

Danp76

I guess the Ga heads also have a unique valve angle, and valves are much more expensive for these heads as compared to the more common large-valve heads or standard G heads. It seems I have the "odd ball" G heads with the same specs as a Ga head.

507OLDS

Keep the exhaust valve small,and machine/install a 2.07" or 2.11" intake valve.

joe_padavano

The normal definition of "valve angle" is the angle of the valve stem relative to the centerline of the cylinder. All 1964-1990 Olds factory heads have the same valve angle. I believe you are referring to the valve SEAT angle. That's really just a function of how the castings are machined, nothing special about the casting itself.