has anyone here ever filled the exhaust crossover p***ages in their cylinder heads? and if so,what did you use? an oldtime drag racer i know says they used to melt down ***mins diesel pistons and pour'em in,but i don't have access to a foundry or high heat source. it would take a ridiculous amount of J.B.Weld to fill these (394 Oldsmobile) heads,but maybe there's some kind of plumber's putty that will withstand high heat without costing a fortune?
Similar set up on Pontiacs... I usually make a thin block off plate that sandwiches between the intake and the heads. (cut out the small piece of the intake gasket that covers the crossover, and replace it with 18ga sheet metal, leaving the rest of the gasket intact.) On another note, the intake crossover is a good thing on a street motor. What is your application? -Abone.
Are you talking about the goofy little diversion port that forks off the exhaust p***age on some cylinder heads? I've seen these before--I think on a set of '57 Fuelie heads, if I'm not mistaken. It's like a direct feed of exhaust gas to the heat riser p***ages in the intake manifold, correct? When I was contemplating this, I was thinking some sort of epoxy that engine builders use to build up areas in cylinder heads would work. Or, as stated earlier, molten aluminum poured in. Ask a machine shop what they would recommend. -Brad
This has been a subject discussed a lot of times on an Oldsmobile site I go to occasionally. The consensus there is to use old pistons or an alloy (ZA-12?) that can be purchased for that purpose which has a little lower melting point . The pistons can be melted down in a large iron pot over a good torch flame. You don't need industrial ovens or special equipment. For Oldsmobiles you can buy a plug for that purpose but people that have used them say they never stay tight and you get rattles after a while. I haven't done this so I can't say either way, just thought I would comment to help out. Here is a link to one of them http://realoldspower.com/phpBB2/viewtopic.php?t=8674&highlight=crossover
For flathead Fords they used "shim stock" Sheet metal used to shim bearings and such. Cut it to size with a 90 deg. flange on one end to use as a handle. You'd loosen the intake bolts and work it in between the gasket and the block. The oldtimers did it to get a raspier exhaust note from the pipes. When the constable gave you a ticket for noise, loosen the bolts and pull the shim stock back out. When you got back home from the inspection...reverse the procedure. I seem to remember some high performance intake gaskets (probably Chevrolet) that came with optional stamped sheet metal block off plates for this purpose.
Old street racer's trick-We used to stuff them with little wads of aluminum foil.Keep packing them in,using a wooden dowel.Also block the manifold side with sheet copper shims. I wonder if portland cement could be used,like the old 'blok-Roc' filler,of years ago. I know when flathead blocks,are filled with molten aluminum,they pre-heat the whole block,in an oven,to keep expansion from cracking it.Sparky
I blocked it off on my S2D motor thinking I wanted to prevent the intake charge from being heated. Does it serve a purpose other than warming the engine up quicker?
Your heat p***ages are probably bigger than the 455 Buick's are. The Buicks have a couple of approx. 1" plus diameter holes in each head. I machined a couple of 1" plugs from hot-rolled that matched the length of the holes. Hot-rolled chosen because it usually machines quite rough. Sorta like frozen peanut ****er, more tearing away than cutting. You can use a slightly damaged carbide bit to roughen them up even more. The plugs are a sloppy fit in the head holes . . . which is good, you don't want a nice machinist type fit. In fact, a couple of hacksawed off pieces of round stock would do it. Clean the plugs and head holes with lacquer thinner or acetone. Mix up a batch of JB Weld - good for 600 degrees F. - and coat both plugs and holes. Put the plugs in place, wipe off the excess JB with a paper towel, set the head at an angle so the plugs are horizontally oriented and let cure overnight. Last time I looked at these was at about 30,000 miles and no probs.
Devcon won't take the temperatures directly in an exhaust port. There may be a better product for high temps.
Plugging the gaping hole isn't enough to gain any real benefit. The heat riser feeds from to holes into the middle exhaust ports. This merges the exhaust ports and diminishes scavenging. Fill 'em with old pistons. If you have your heads dis***embled you can see the holes near the valves. This is where to pour the alum. Bolt a block-off plate on the intake side. Pouring in from the other way might find you filling your intake ports with aluminum. I fill all my Pontiacs. I'll post a pic Sunday of a set of heads I have on the bench all filled and ready to go. Torch and a cast iron pot works great. You can find a pot for $15 at a housewares store. Use a formed piece of sheetmetal for a 'funnel' of sorts.
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