Hi! iam rebuilding my 13b gsl-se engine and as you guys this is a 6port but i want to convert to a 4 port. but while looking for the front,middle & rear housing i was told that i can use those part from a 12a engine. so i ask can this be done.iam not using any turbo but what will be a good combination using a holly 650,RB exhaust,light flyweel,act cluth,electric fans maybe an msd or a direct fire ignition. this car will be my daily drive.i dont want a rocket anyway i dont have the cash for all that but i want something that move faster than stock.thank you in advance.

 

yes, this could be done, i have actually seen it done before, a a 13bt had 12a housings, with rotors of of an 88 turbo, heard the12a housings are stronger as well(not positive that they r stronger,but i heard they were) ,....... later

jonathan

 

Ok I really doubt you saw 12a housings ..it wouldnt be a 13b ..

It HAD to been 12A PLATES,Yes you can do this..and in my opinion..its 100 times better than a 6 port.

 

Yeah, sure man. 13B housing, 12A plates, 13B eccentric shaft, gears, rotors, etc...

~T.J.

 

Yeah, I think he's talking about the side and center housings. It gets confusing when people don't specify ROTOR housings, or SIDE housings. Anyway, I've heard that it can be done. Converting to a 4-port is a great idea, street-port the heck out of it and run a carb, and then there are no electronics to mess with. That 650 Holley MAY be too big, though. It would probably work on a bridge-port, but then it would be a lousy daily driver. Just my 2 cents. -WG

 

thanks guys this is very helpful

 

Wait a sec...
So I can just buy a 12a and use the front/rear and middle housings to go 4 port? ANd use the 13b rotor housings for the rotors? No special modifications?

Simple as that? Can it really be that easy?

 

Yeah...Basically. As long as you have the other stuff to build it, like the eccentric shaft and rotors and crap .

~T.J.

 

Sweet. I've got a set of S5 rotors and flywheel for the build up. Be a hell of a lot nicer with the 4 port instead of the 6port BS.

Would adversely effect the ECU, electronics or, vacume to run it as a 4 port NA rather than the regular 6 port?

Hmm... looks like I'm gonna be picking up a motor when I get some cash!

 

One possible problem which occurs to me is that the water seal grooves are on the side housings rather than the rotor housings on the later 13Bs. So you would have to use the right rotor housings in that respect. And naturally, the 12A ports are going to be smaller, so some porting work would be in order.

 

The 12a's have the water seal grooves in the Rotor housing or Center housings?

And the porting is not a problem

 

The 12As have the water seal groove in the rotor housing, SOME of the 13Bs have the groove in the rotor housings, but not all. That's why I say it's important to be aware of the difference, so you use the right 13B rotor housings. And I would definitely go with a carb setup over the stock FI. That's half the beauty of going to a 4-port, being rid of the damned electronics. Then all the motor needs to run is a crankcase vent and a tank purge line. Makes it sooooo much simpler to tune and troubleshoot. Just my opinion, though.

 

Use 84-85 rotor housings. 86 and newer moved the water seal. At least, thats what I was told.

~T.J.

 

This is all new too me... all this time i was thinking i was going to have to find a 4port 13b.

What e-shaft and rotors do you need to have? Which years are best? This is amazaing!

 

we can team up on the engine, ive got an old 12a lying around here with good side and front housings!

i didnt realize u could do this either!
might one day get my hands on some 13 rotor, housing, eshaft and sump and get myslef a 13b

 

more questions!

im asuming u have to use a 12a dizzy on this if ur making it carb?

and...
what intake manifold would u use?? were the older 13b's 4 port?

this has just brought a whole new dimension to what i could do to my car.

 

This is very interesting. When you say you would need the right e-shaft and rotors, the stock 13b rotors won't work I take it? If not, then what are the "right" e-shaft and rotors?

 

Correct me if im wrong, but the rx4, and pickup were both 13b 4-ports. I want to think it was in something else to, but im not sure.

 

i did had a cosmo and it was 13b iam not sure about the rx-4 but i think it was.

 

yes

 

The RX4, RX5 (Cosmo), and REPUs all came with 4-port 13Bs. You need to use a 4-port 13B manifold and carb from any of them, as well as a '81 or newer 12A distributor. -WG

 

How hard are those to come by?

 

there was one on ebay in kanssas about a week ago. but they are fairly rare. If you look hard enough you can find one though.