80 intake on a 83
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From: EDMONTON ALBERTA
80 intake on a 83
Hi guys,
I was just wondering if anybody has put an 79-80 intake onto a 81-85 12a. I have an intake off an 80 that i have cleaned up and what not, but have noticed that it looks a little different from the 83 one i have just taken off the car. My main concern is that there is a rectangular port right below the primary intake ports on the 83 intake manifold. The 80 does not have this. What is the reason for this? The 80 12a block i have has this rectangular notch below the ports that lines up with the 83 intake but on the block it is just a notch, doesnt go in or lead anywhere. Really doesnt look like its used for anything. Especially since the intake does not have the port. However on my engine right now, 83, its all gunky and oily inside the notch and i cant tell if it goes any deeper into the block. Can i just make my gasket to block this off??
Any input is greatly appreciated.
Thanks
I was just wondering if anybody has put an 79-80 intake onto a 81-85 12a. I have an intake off an 80 that i have cleaned up and what not, but have noticed that it looks a little different from the 83 one i have just taken off the car. My main concern is that there is a rectangular port right below the primary intake ports on the 83 intake manifold. The 80 does not have this. What is the reason for this? The 80 12a block i have has this rectangular notch below the ports that lines up with the 83 intake but on the block it is just a notch, doesnt go in or lead anywhere. Really doesnt look like its used for anything. Especially since the intake does not have the port. However on my engine right now, 83, its all gunky and oily inside the notch and i cant tell if it goes any deeper into the block. Can i just make my gasket to block this off??
Any input is greatly appreciated.
Thanks
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Joined: Mar 2006
Posts: 35
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From: Liberty, MO
Bringing this back from the dead a little, but found this in the search and had another question.
I am going to put an '80 mani on a (I think) '81 block. From the info above, it sounds like I can just use the 79/80 gasket set and call it good? Right not the car has a Weber on it that I am probably taking off, and I assume it doesn't have the anti-backfire valve either.
Just want to make sure I get the right gasket for my application since they are different part numbers.
I am going to put an '80 mani on a (I think) '81 block. From the info above, it sounds like I can just use the 79/80 gasket set and call it good? Right not the car has a Weber on it that I am probably taking off, and I assume it doesn't have the anti-backfire valve either.
Just want to make sure I get the right gasket for my application since they are different part numbers.
'76-'80 engines used thermal reactors. The rotor housings on these engines had small ports communicating with the exhaust through the exhaust port sleeves and the thermal reactor through a hole down near the lower exhaust stud. The rectangular port below the primary intake ports on the intermediate plate, was unused. It's fine to use a '79-'80 manifold on these engines or any engine which has these rotor housings.
The '74-'75 and '81-'85 engines made use of the rectangular port below the intermediate intake ports. If you want to use a '79-'80 manifold, you can fill this port with devcon, quicksteel or any other steel putty (just make sure you clean the carbon and oil from the inside first). This is easiest if the engine is apart for a rebuild. I'm probably leaving some info out, but that's the basic idea.
The engine I'm building for my rotary MG Midget project will use some '76-'78 rotor housings and a '76 manifold which also does not cover the rectangular port below the intermediate ports. The intermediate plate is most likely from an '81-'85 12A; it's a tall port Y casting with a carbon filled rectangular port. The tall ports match the reversed runner '76 Cosmo manifold in which the primaries actually flow to the front and rear plates, and the secondaries are port matched (tall) which is is ok since the secondaries only open at high RPM anyway. Strange, but it supposedly gives up some throttle response for increased torque. The nice thing is the secondaries come on nice and quick. I've already tested it and had good results in this car with a light steel flywheel (primary throttle response was actually plenty quick), plus it's the only manifold that will fit comfortably without modding the car etc.
The '74-'75 and '81-'85 engines made use of the rectangular port below the intermediate intake ports. If you want to use a '79-'80 manifold, you can fill this port with devcon, quicksteel or any other steel putty (just make sure you clean the carbon and oil from the inside first). This is easiest if the engine is apart for a rebuild. I'm probably leaving some info out, but that's the basic idea.
The engine I'm building for my rotary MG Midget project will use some '76-'78 rotor housings and a '76 manifold which also does not cover the rectangular port below the intermediate ports. The intermediate plate is most likely from an '81-'85 12A; it's a tall port Y casting with a carbon filled rectangular port. The tall ports match the reversed runner '76 Cosmo manifold in which the primaries actually flow to the front and rear plates, and the secondaries are port matched (tall) which is is ok since the secondaries only open at high RPM anyway. Strange, but it supposedly gives up some throttle response for increased torque. The nice thing is the secondaries come on nice and quick. I've already tested it and had good results in this car with a light steel flywheel (primary throttle response was actually plenty quick), plus it's the only manifold that will fit comfortably without modding the car etc.