TiViD

Im looking for just the flange off the intake manifold of a 12a. I was wondering if there are any companies that sell them? I tried mazdacomp because i heard they had them, but i checked out their website and couldnt find it anywhere. I'm hoping to find a steel one, because im not going to be able to weld on aluminum, and i dont want to have to pay a shop to do it.

The reason im trying to get ahold of this is becuase im going to be experimeting with using the set of 4 carbs from a Honda CBR600 F4 motorcycle. So if anyone knows where i could pick a flange up id really appreciate it.

Thanks.

Jeezus

iTrader: (4)

is this what you are talking about?

chedda_j

Ok, flanges arent going to be easy to come by if you want a steel one. Now what you could do is make one, if you have a intake manifold gasket i bet you could just take it to a shop and get them to make you one cheap, like 60 bucks. I know i could make one myself with a oxy fuel cutter and a milling machine but i dont know if you will have access to one. I was actually thinking of doing the same thing as you, the motorcylce carbs, but you forget that one intake draws more fuel that the other, if i remember correctly. So for that to work you would have to rejet two of them. A stock carb uses 450cfm i believe, so make sure those carbs can run 125 cfm a piece and be able to jet them for the fuel usuage.

What your trying to do works good on honda 4 cylinder motors, ive done one myself, but on a rotary i think many ppl here will agree that the sterling or stock carb is best. I think that most ppl upgrade to a edelbrock or holley for reliability or for more flow on ported motors. Other than that, stock is best IMO.

TiViD

well thats the whole manifold. Im just looking for a the flat piece on there, about .5 inch thick that bolts onto the block. Like I said, im going to weld piping on to allow the new carb to fit, provided i can get ahold of a flange.

heres a quick photoshop of what im looking for basically:


EDIT: You posted while i was makin the picture, but yeah, i had a holley for a while. It needs a rebuild now and I was just lookin to try something new. Your right, Most people probally would say sterling or nikki is best, but i bet alot of pelope havent tried what im trying either. I guess ill try it out and see how it goes

on a side note, what do you think the minimum thickness for the flange would be, I could cut it myself if i could get ahold of some real thick sheet metal.

chedda_j

lol you dont need sheet metal, a 10" wide piece of flat bar by 3/8 will be well enough for the product, if you want to make it 1/2 go right ahead but i think it will be over kill. When you make the runners, cut the intake mani ports slightly larger so that you can fit the runner inside the hole and then weld from the inside, ground, and flapper wheel untill really smooth. Strengthen the structure by welding along the back side of the runners with a mig or very small (3.2mm) 6010 GMAW rod, 50 amps. This will produce the smoothest flow. if this is too complicated, make sure the runners are slightly larger than the holes so that when you weld them on, you can just port them out to make them smooth. Not too smooth tho remember, have to worry about sticky fuel.

Lucky for you, you can just take welded straights or tubing and make small runners, make sure to make them long enough to allow for anodization, a curvature would work reasonably better. Long radius weld u's would work great, any plumbing store can sell you one for about 10 bucks a piece at the most.

chedda_j

When welding the intake runners to the plate, mechanically clamp to prevent warpage, if at all possible heat the entire plate with a rose bud or cutting torch, preheat, weld, post heat, and lay in sand. If you warp the intake flange then your fucked, unless you can machine the piece while the runners are welded on. Check for latitudinal warpage, horizontal, and verticle with a straight edge at the least. You might get away with it if you run a 1/4 inch Derlin spacer between the intake mani and gaskets.

blwfly

iTrader: (4)

couldnt u cut like 1/8 off the front of a stock manifold with some sorta metal cutting machine maybe a horizontal ban saw
then work off that

better to use a gasket trace and cut ur own flange

chedda_j

I think we already mentioned that he cant use aluminum becaues he doesnt have the welder, but, if you were to cut off 1/4 for a spacer that would work. But You gotta remember the fact that there is that little lip on the inside of the intake manifold to prevent "overlap" as trochoid said. You would have to work that in there too.

trochoid

iTrader: (6)

As REVHED pointed out, it's technically reversion, not overlap.

Personally, I would go with 7/16-1/2" mild steel for the flange, but I have a tendency to always over build for strength. Worked on to many rr cars and steel structures I guess.

TiViD

Thanks for all the input guys. My original plan was to take the flange off the stock intake manifold, but:
1. its aluminum, and
2. it would take forever to use a cutting wheel on it, just because of the odd shape.

I think ill end up just putting a piece of paper over the flange and running some charcoal over it or something to get an exact trace. Then ill give the paper to a machine shop and just ask them to make it out of steel, maybe like 3/8 thick. Then im gonna pick up some steel tubing and put it together, and just use some rubber couplers and tightening rings to connect to the carb.

Does anyone know the optimal length for the intake runners for a stockport 12a?

chedda_j

it is actually prolly a better idea to go thicker, less chance for warpage, which would be the worst problem about building an intake mani glange. If he could port the holes in the plate, weld, then cut the outer edge, it would creat atleast a little more stiffness to prevent wapage. Although if the runners are bent at all it would be a paint to try and cut the flange out after welding.