The Stovebolt Site Forums The Shop Area Engine Shop One flange for Intake and Exhaust manifolds?

After receiving and fitting up the fenton headers that I purchased for my 228 with the intake manifold I'm feeling very uneasy with fitting them up correctly with their respective ports. I really don't like the original design using the clamps for both manifolds. And now with the fenton's, nothing seems to line up correctly, nor is there any way to reference their positions to match the gasket and the ports. I threw around the idea of fabricating up new clamps to help with the clamping force, but I'm still left with the accuracy of the alignment on the head.

Heres my new plan, and I'd really like some constructive feedback on this. I'd like to design a single flange and weld both manifolds to it. This would create a much more easy and accurate installation. I've checked out the clearance of adding say a 3/8" flange and there isn't anything hindering that. The real issues I see with doing this are welding the manifolds to mild steel, and the heat sinking that will occur from the exhaust to the intake.

I'm in a good position to give this a try. I'm a welding and fabrication student at our local community college. I have a decent amount of hours in all the processes and a few certifications under belt. My instructors are CWI's with decades of experience welding and fabricating in all areas of the industry and I have access to all the equipment, including a Lincoln tourchmate 4800 that I've recently learned how to operate correctly. I'm confident I can create a quality flange that will measure up accurately and meet the demands. I'm also sure that I'll have the correct guidance and tools to do the job. So I guess there isn't much holding me back from trying it. My fear is I have to scrap the manifolds or waste my valuable time pursuing this. My goal is to create a quality product that will perform and last the life of the truck as well as accomplish something different that will put my skills to the test.

I'll keep this thread up to date on my findings and progress if I decide this is worth working on.

Take care everyone,
Matt

Go ahead and try- - - -it will add to your portfolio of experience that can only come from attempting the impossible. Sometimes you succeed- - - -sort of. Where did you find a Fenton-style header that's actually dimensioned for a GMC head? They're extremely scarce, and the ones made for a Chevy don't fit at all.
Jerry

Matt,

Since you're in a welding class you may already know this but there is a stick electrode made by Harris called "Super Missile Weld" that will weld any ferrous metal to itself or to any other ferrous metal. It makes a beautiful bead and, unlike "Ni rod", is very easy to use.

I've used it to repair broken cast iron items and to weld stainless steel to mild steel. It's some pretty amazing stuff. I'm told it's kept locked up in welding shops because its bead quality makes anyone look like a skilled welder so they all want to use it, but it is expensive.

I got the headers from chevsofthe40s. They're listed as fitting the 228, 248 and 270 heads. Mine is a 270 head on a 228 block. The ears with the holes for the studs on each end of the manifolds are the only part that aligns up. The other ends barely even touch the studs/botls.

Good luck- - - -you're going to need it!
Jerry

Pictures are worth a thousand words.

you are going to have to do a lot of work to get it all to fit even in the original configuration. As far as I know the molds are very old and aren't reproducing them very well. I had to really trim, file, grind all the parts to get them to work. Actually pretty much anything I have bought for the truck required a lot of fabrication. I just consider it part of the fun.

Instead of welding them to the adaptor, why not index them to it using locating pins. Use longer bolts and custom hold downs, then let the locating pins hold the manifolds in place. The problem I see with the whole welding process is heat expansion. That much cast iron is going to move around after welding from heat of the exhaust and something will give way.

Maybe you could bolt the manifolds to the adaptor from the back side with recessed bolts, them bolt the whole assembly to the head with factory mounts. Or, see about a oversized water jet cut flange so you can bolt around the edges.

I just don't see weld as a very good option when then are other ways of getting there.

You could do it the way it's been done for decades- - - - -bolt the manifolds together and mill the manifold/head mating surfaces for a correct fit. At the machine shop where I ran the connecting rod reconditioning department, we had a big belt sander (16" wide and 48" long) that we used to surface manifolds and other parts that needed to have a flat mounting surface. Either option would beat ruining an expensive part with an attempt at doing the impossible.

You could also choose to use an original equipment manifold instead of a piece of rough-cast junk from China.
Jerry

I understand everyone's concerns with the welding the manifolds. It's a last ditch effort to make this all work. This is why I'm asking so I don't junk these manifolds. You guys have the experience to help me avoid that. I appreciate the feedback.


Joe,
I really like this idea! I could use countersunk bolts on the backside to attach the manifolds to the flange. Theres enough surface area on the intake to do this. My concern is that on the headers, theres only one ear per runner to mount to. Do you guys think that would be enough clamping force to avoid leaks?