455 C heads vs Ga heads?

[BryanDRussell]

Is it worth the $700~800 to go from a set of stock Ga heads to a set of street ported C heads? Or should I just have the Ga heads street ported for $175.

Also are roller rockers worth the extra $400 and can they be installed at a later date after the heads are back on the car?

The engine is a 455 with a mild cam, troker intake and performer carb, headers, hei and I am guessing at 10:1. Bought the car from an estate, so I don't really know what is in the motor.

Thanks for the help.

Bryan

[Sgt Art]

I replaced a set of G heads with a set of C's and never felt any difference. I guess if they were used in conjunction with a high compression engine that they were designed for, you'd see greater performance. However, as a daily driver which seldom went over 65 - 70 MPH, it wasn't worth the money. I think I paid about $200 for the heads and another $400 having hard inserts added, bronze guides and the springs shimmed etc. It really wasn't worth it.

[BryanDRussell]

That was what I was wondering, what about the roller and porting of a set of g heads. I pulled the heads off to replace a leaking gasket and wondered about doing any additional work while they are off.

I was thinking the money might be better spent on a 4 speed auto tranny, or upgraded four wheel disc brakes.

Thanks

[Sgt Art]

Are the pistons flat tops or dished? If dished, they are low compression, probably somewhere in the 8.5:1 ratio. If they're flat tops you may indeed have a high comp engine. However, the Ga heads were for 1972 W30 engines ( Ga '72 455 80 409100 W-30's, manual 442's used big valves see Olds FAQ site) and all comp ratios were down to 8.5:1 by then.

No question that HP is made in the cylinder heads, but I guess it all depends on what you want to do. The O/D auto will improve your gas mileage and the 700R have a low 1st gear. However, the cost is about double a good TH350 or even Th400 - which one do you have now? It's your decision, but like I said before, I didn't see all that much improvement with the C castings. I have to wonder what porting would really do for you. I think most of those tricks are worthwhile for racing where a tenth of a second makes a difference. But, for everyday driving, you'll be happier with a smooth idle, good acceleration (better than probably 90 % of what's on the road these days) and decent MPG. Have fun.

[rocketraider]

Save your money and use the Ga's. They already have induction hardened seats and flow almost as good as C's. A street port job will open things up nicely.

If you get a set of roller rockers that don't require any machine work to install, you can put them on later. Otherwise do them when the heads are off. Seems like Harland Sharp or Milodon had them once upon a time, but last time I looked was about ten years ago.

You'll have to have an adapter to put a 700 behind your 455. A 200-4R will bolt right up but may not live long behind the combination you have. Get an 85-87 core and have it built past GN specs, and it might live a while. Otherwise I'd stick with a TH400.

[Guest Blownolds]

Best place to keep up with what's going on in the world of Oldsmobile performance is realoldspower.com

[bwalat]

In my case, I got lucky, as my '68 Delta 455 came with C heads. I had EVERYTHING replaced, but stayed with a stock valvetrain, except for stiffer double springs to match the cam. I had hardened seats put in, which was moot because I had several bad seats anyway.