781 Oval ports

[406jeep]

How much can be had from these in a 468? Will 2.25 valves be OK in them? How much port work needs to be done to make any power? Just looking for a street/strip motor for my 56 Chev. and can get a good one cheap! How much will stock rods take, cast crank?

[DOTracer]

I've run 781's for a few years now. The current combination is basically all new and untuned. It's a .030 over 454 with 13 to 1 compression. The heads have 2.25/1.88 valves, bowl blend, 3 angle valve job, short turn radius gently contoured, and the intake port opening matched to the intake manifold. The ports and chambers are stock with no porting other than a little opening on the chamber in one spot to clear the piston domes.

Solid roller with 262/272 @ .050, .697 lift, Vic jr intake, 850 Holley. Car weighs 3550 lbs w/driver, th400, 8" ATI, 4.10 gear, 275/60 M/T drag radial, full exhaust out the back. Initial runs were 10.27 @ 129.85 mph off the trailer with a 1.43 60' footbrakeing at 2000 rpm.

I can't say exactly how much power this is making, but my best guess would be in the 650-675 range at the crank.

Decent heads and they perform well, but I've got almost $1500 invested in mine. For right at $2k you can have a set of Brodix Race Rite ovals. From what I've seen, they look like a really good option to rebuilding stock iron heads.

[85Iroc]

Stock crank and rods will take quite a bit of abuse. 600+ hp

Truck rods are better than car.

Chuck

[Pat M]

I used a set of 781 oval ports that I did myself. I put the 2.19s an 1.88 in them. I had a machine shop cut the heads for the bigger valves an then did all the rest of the work myself.

I pocket ported the heads, matched the ports an gave them a good 3 angle valve job. My motor was a 12-1 460 in a 3400lb car an it ran a best of 10.29@ 129mph.

I figure it was making a good 600HP. I used the stock truck rods with good ARP bolts. I would try to find a steel crank if possible. Esp if your going to push it very hard.

I had about $550 in my heads when I got done but if you have to spend $1000+ I would also look at the Brodix RR heads. They flow more out of the box than a ported set of 781s plus you will drop 75lbs off the nose of the car.

[Mike Stark]

I just stuck a set of 781's on a 396. Heads were bowl ported with 2.19 valves. The motor is 60 over with 10:1 and a decent hyd. flat tappet. It makes a little over 500 HP on pump gas. The 781's flow just over 300 with a 2.19 and a bowl port.

[406jeep]

Mike, what would you charge to do my heads just like the 396? New larger valves, springs to match a flat tappet solid, bowl port, good valve job.

[Mike Stark]

As long as the guides are good your looking at around $450 to $500 or so for all of the work and parts.

[406jeep]

Mike, that sounds good, let me get some other projects out of the way and I'll get back with you. Might build this to take a small hit of nitrous just for giggles. Probably need to go good rods and crank. Does anyone know if the TRW- Speed Pro pistons would be up to this? (forged)

[85Iroc]

to my knowledge, the Speed-Pro/TRW pistons are some of the toughest out there. The only drawback is they're a little heavier but I think durability wise, they're as good as something like a JE and probably better than SRP.

Chuck