13b manifold on a 12a?
 

my dad has a much of 13b parts laying around, and intake manifold is one of them. is there anyway to mate the manifold with the 12a? is it even worth it? i like the idea of fuel injection, although, if its only gaining me a couple hp, its not worth the trouble im imagining. anyone have any info?

edit: its a fc 13b, not gsl-se

Since the 12A is shorter then the 13B, the manifold can't fit. You could make a custom lower section, to mate the 12A to the upper manifold of the FC, much like "the Hitman" has done on his custom 3 rotor engine. The basic problem there was the same as yours: the engine was shorter then a 20B, so a custom lower section was made to mate with the upper section of a 20B maifold and plenum. Not to sure if it's worth the effort, but well, that's up to you to decide. I think it would be the only way to connect the two parts. If you really want EFI, you could go aftermarket. If it's just because you have the 13B parts available, I really would think about it twice...

it was just a thought. then i would have to get the ecu and all that shit wouldnt i? it would probably get a big pain in the ass and money that could be spent else-where

You can use a Dellorto 12a lower intake manifold from your favorite company Racing Beat :-) , it will bolt up the upper half of a 84-85 13B intake.

Could be, but he said "FC, not GSL-SE", so he doesn't have a 84-85 upper half, does he? It should bolt up to the 86+ upper half, and that might be a bit more difficult... (not sure though)

How about a 4 port 13B to a 4 port 12a?

~T.J.

No, the engine is still shorter, regardless of port setup. Either one will take more work than its worth.

Even if you got the manifold for free, sell it and buy a 12A one.

not sure if it matters, but i have a manifold adapter to run any 12a manifold on a 6 port 13b.....

the part i'm not too keep on is that there is nothing to separate the intake runners between the outer ports.

but since i'm running a 6 port 13b with a holley manifold, and a 650 double pumper (can you say "big flames"?- i knew you could) tha's not split either, i guess there is no real reason this adapter wouldn't work, but for now it's a conversation peice on my work bench.

you can get adapter plates that bolt between the manifold and block, well we can in oz anyway.

but the problem I can see with using 13B mani on a 12A, dont the 13B EFI motors use the two primatu injectors mounted in the centre plate of the engine? if so you would need injector bosses welded onto the standard manifold, then an adapter plate, not a very neat setup when its finished.

or you fabricate a lower mani section to suit the 12A onto the 13B upper as suggested.

That's true again... Kinda think it ain't worth the effort.

The 12A rotors are 70mm thick, and the 13B rotors are 80mm thick. That means the rotor housing for a 13B is 10mm thicker. X 2 rotors = 20mm. Sandwich the engine together and that is why the 13B is 20mm longer than the 12A.

I have heard of people using 12A manifolds on a 13B by oblonging the bolt holes and I think porting the exhaust in the manifold.

"Engine"= 12A. I know the difference.