Many Chevrolets were never split. The rear got a cast elbow or pipe jammed into a drilled hole, interference fit, hole coming straight down then brazed. The inside was sand blasted an fit with steel metal to block the back 1/2.
I never saw that, jimmy six. Wow. We cut the manifold, brazed the ends shut and brazed on something for the second pipe which usually was , GASP, flex. 1950 era. Ben
Cast has to be done by heating it then welding it then slow cooled. I believe it has to be stick welded too.Find a welder with experience. Also split 4-2 if you can,sounds cool.
Scoop nailed the process. I did a few back in the sixties, yeah I’m old, I think you can still buy a header if you want one. Reds I believe and I’ve seen old headman at swap meets.
I welded up a crack and low place on a Ford 8n banger manifold with my wire welder. So far it has held up. Didn't do anything special to it, just took my time, let it cool slowly, then ground it down. Took about three tries to get the flange built up enough to grind it level enough a gasket would seal it. Your results may vary....
The heat riser on a Ford 6 makes it one tough sumbitch to split isolated 3 & 3 .... most of them just had a piece of pipe welded in resulting in a sound like dragging a wet dishrag over a linoleum floor.
The process as it was described to me. Pre heat the manifold with a your torch, once it's warmed up gas weld it up an inch at a time, then use your ball peen hammer to smack the welds to "relieve tension". Throw it in a bucket of sand or oil soak when done to let it cool as slow as possible.
My friend who does this sort of thing puts the part on the Barbecue to heat them up, weld, and then back on to slow cool as the fire dies out.
Lots of great information here. On cool days with windows up might there be any danger of Monoxide buildup, I know that is a loaded question, guess what I am really asking if the welds are likely to hold.... Steve
Back in 1962 an old hot rodder helped me split the manifold on my 53 Chevy 4 and 2. This car would rattle the windows in the business's on our small town main street. If I remember right we braised everything. Nothing ever broke so we must have done a good job.
Propane grill on high,20 minutes ,wire weld what ever you are using for a block off plate ,back on grill for 20, then weld on new flange for rear pipe, back to grill for 20 still on high,then lower heat 30 minutes,then close all vents and shut off heat let sit till cold ,peen with hammer or needle scaler . Good to go. Done a few late model 4 cylinder junk this way . No returns in the past 5 years
I'm not a welder by any stretch. But, I have successfully welded exhaust manifolds. Long ago brazing was the choice. Works, but slow and acetylene is expensive. Starting in the 80s I switched to nickle rod. Seems to work best on DC, straight polarity. It will do cast to cast, cast to steel or steel to steel. So extending a manifold with normal pipe is possible. IME the shape of the manifold will dictate whether preheat or controlled cooling is needed. A plain log shape seems to be OK without any special treatment, but lots of curves and crooks will need some preheat. Grill, Propane weed burner, wood fire, all work along with the stuff used to soak up oil spills from the shop floor (or kitty litter) for controlled cooling.
Not a split, but put a 1963 389 Pontiac engine in a 57 Safari wagon. Had to clearance the left manifold to clear the power steering box. Ground out the manifold into the exhaust passage and shaped a piece of steel to fit. Heated up the manifold with a torch and brazed the steel plate to the cast iron manifold. Worked perfect for 5 years that I had the car.
In the 60’s my dad did his with his Lincoln, I didn’t see the process of cutting it up and that, I was the “holder” as he put the pieces on the engine and I held them in place as he tacked them. He pulled them off and welded them up. I recall the welds had a shiny look against the cast iron. I assume nickel rod? Maybe certainium? After it was tacked he laid it on the welding table and heated it all up with the torch and welded it as soon as he sat the torch down. Turned it over, heated again and welded. It work for a few years till he put in a 283. I sure can remember the sound of it.
My go to rod was Certanium 702. I did a Buick manifold in the mid 70s and it's still on the car today. It welds like welding mild steel.
My dad was good good with a stick welder. Funny thing was when I got a MM35 he had a hell of a time trying to get the hang of it, he’d get the arc going, push into it. Ya, ya know what happened. But he could watch me weld and tell me and guide me (using the Mig) on what to do with the puddle.