489" chevelle Gotta love a tunnel-ram BBC

[O4L]

That is odd.
I have ported many sbc heads and the 2.02 valve in non ported head is not worth the bother.. you will actually be down on power.
Valve is too shrouded.
My old 186 casting double humps with 1.94-1.50 would out flow the RPM heads and the runner was not enlarged much still came in at 158CC
My 305 HO heads with 1.84-1.50 valves come in at 170cc runners and flow very well for what they are.
Flow aside shape is very important especially the chamber. Lot of power in the chamber especially if you rev it past the 6000 rpm mark. Or if you stuck large valves in it.

That's my experience with the 2.02 heads also.

I used to run a factory stock dirt track car with a small block 400 bored .060 over with 10:1 flatops, .194 double hump heads, factory intake and a Q-jet.

An old gearhead loaned me a set of 2.02 heads he had polished to try out. Those heads cost me nearly 1000 rpms on the top end.

 

[swampratt]

Yep ..Buddy had some 487X heads on his mild 350" it had a 268H cam and RPM intake timing dialed in and the carb was a 750 it was dialed in also.
5500rpm first to second and then second to third was 5000 rpm shift point.

Now he wanted more power the 487X head had 1.94-1.50 valves.
I told him get some 601 casting 305 HO heads and bring them to me.
He got some from marks machine shop .. mark told him they are stock and need larger valves as they only had 1.84-1.50 valves.

I said leave the stock valves in there and bring them to me.
I ported them and opened the 53.5cc chambers to 58cc and he stuck them on.
Huge power gains!!! No traction available where before he was hard pressed to spin the wheels.

Shift points came up also 6500 first to second and 6000 rpm second to third.

I stuck 1.94-1.50 valves in some 601 heads and unshrouded to 60cc accommodate the larger 1.94.
This was a different build with 292H cam.. it was petered out at 7000 rpm.
HHHMMM I had a personal 350 with 280H that would go 7200rpm for the sweet spot. and this 292H is nosing over at 7000.

I tuned and tuned and 3 days later I pulled the heads off my buddies nova.
I noticed some fuel wash near the spark plug on the intake side.
I kicked the chamber out right there and the chamber got 2cc larger. Now 62cc.

Stuck them back on and was rewarded greatly. this thing will pull hard past 7500rpm now.
I told him shift it at 7400-7500rpm.

It ran 11.94 in the 1/4. on 7-11 91 octane gas no power adders except your right foot. 305 heads on a 350 with old school cam tunnel-ram and ford 9"
Here is that car I built the entire thing for my buddy of course I made him be right there getting dirty and learn a thing or 2.


http://www.dragtimes.com/Chevrolet-Nova-Timeslip-14820.html

Click link to see picture and see all the specs. 1978 nova