[JD]

BillK, Awhile back you said that you can fill in the exhaust passage from the exhaust port to the intake(in the heads). Can you just melt pistons with a propane torch to do this? And how many pistons would it take? And I guess the aluminum would stay cool enough not to move around? I know this may just be a small improvement, but I have more time than money. Any opinions appreciated.

[Dave Birdwell]

I'm not sure exactly what the context of the previous conversation was, but the most common way of blocking the crossover passage to the intake is by using a plate supplied with good intake gaskets, it is a steel shim stock plate that goes over the gasket hole to block the passage off.
I don't think you could get a piston hot enough to melt with a propane torch, and if you tried an acetylene torch, you could end up catching the aluminum on fire. Don't try this at home, kiddies!!

[JD]

Dave, I'm more concerned about smoothing out the exhaust port for better flow. I was hoping to be able to fill the hole in the two center exhaust ports and polish it like the ports on each end of the head. It may be overkill, but I had a little time on my hands and figured what the heck. I thought about welding it with cast iron rods, but was afraid it might crack. Also, while were on the head subject, I have 76cc heads and my CR right now is 8.9 to 1. Does anyone know about how much to mill the heads to get 9.5 to 1? This is assuming I go with .020 head gaskets to keep quench at .040 Thanks for any input...JD

[Dave Birdwell]

I would say that if filling in that transfer slot made that much more power, everyone would be doing it. I've never heard of anyone trying it! Food for thought...if you block the passage off at the gasket, once the port gets full of exhaust, it shouldn't affect the flow anyway. I doubt if you'd see 5-10 horsepower on the dyno with that passage filled in.
To gain .6 in CR, you'd have to lose about 6 CC's from the chamber....quite a bit of milling, I would think. Better to go with a pair of Edelbrock RPM heads with 70 CC chambers.

[Joe Harrison]

I think you have way to much time on your hands. Save some money and the time and do it the right way as mentioned above. If you start messing with one off mods your gona have problems. What would hold that aluminum plug in even if you could melt some down and plug it it up. The exhaust gets pretty hot and I bet you would have aluminum all over the top of your valves because if your able to melt (smelt) it at home your combustion chamber should be able to do the same thing for you, only spredding it all over inside your engines cylinder walls ect. I think ( I hope) Bill was talking about pluging it at the intake and head with an aluminum plate. Take the extra time you have to make some extra money and save up, I know not an easy thing, but I think you will be better off and will have spent less in the long run.

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cruiser4@home.com

[JD]

Thanks Dave, Joe and Bill. I guess I won't attack that project. Was just thinking about it. I might go with these heads and mill them as much as possible, then next year go with aftermarket heads and EFI. This is a side project so I'm not in a hurry. It's going in a 68 convertible, with a 350 turbo w/373's. Don't know whats in it now, it drives fine, just does'nt have the umph I'd like it to. Again, thanks allot. Any suggestions appreciated.