Hey guys. I have a custom intake/exhaust setup for my Model A engine that I need to re-engineer. The guy that made them was well meaning but not an especially good welder and his idea for where the intake mates to the exhaust doesn’t work. So I am gonna cut the flanges off and rethink it. Is there any reason the intake and exhaust manifolds must be separate parts? I think the easiest route would be just to weld it all to a common flange.
It adds heat to the intake manifold. Depending on what want to do will dictate which way to go. Intakes with heat have a better driveability in winter months but some designs can cause vapor lock in the summer in an enclosed engine compartment. Cool makes more hp.
Does the intake have vacuum leaks the way it bolts to the exhaust flange or is it blocking the port flow into the head? You can do it either way. It just depends on how you want to do it and how much you want to take apart for disassembly. Most stock straight-6 engines you have to remove the intake and exhaust manifolds together.
I haven’t attempted to run it but there is no way to fully tighten the hardware to join the manifolds the way he has it set up. There are also some flow issues to deal with as he made it up out of pipe and didn’t trim the ends where they intersect. I figured it wouldn’t hurt to make it all one piece but wanted to be sure!
When you do the modifications, could you flip the intake to be a downdraft style? it looks like the current design the flanges would work to do this? Downdraft would look cool on there. But that may also create more work with linkages, fuel delivery, etc. For tightening the fasteners, you might look into reduced head bolts, or making a custom bent wrench. Custom wrench have been done many times as needed over the years. There is usually a solution somewhere, just need to figure out what is needed to make it happen.
No way to tell what’s underneath all of that wrapping could be ugly enough that you’ll want to start from scratch. Either why not make a downdraft intake and get the whole intake up away from the exhaust.
I wanted to stick with updraft carbs because… well, mostly just because. I like em. As for the fasteners- I was going to modify the bolts to clear, but the threads pulled out on the flange very easily even on the ones I could get in & turn. The holes on the intake flanges are drilled way too close to the pipe, so close that on 2 of them you can’t get a bolt in them because the head hits the pipe. An allen wrench would work to tighten them if the bolts fit in the first place haha.
Yeah, just redo it. If there is enough material in the flange, you can try slotting the holes outward and welding in studs. It's not just the sealing but the threads or studs have to be anchored in deep enough to carry the weight of the intake and carbs as they vibrate hanging out off the side of the block. A support rod or two at the carb base back to the block somewhere would be good too.
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