pros about a 79 manifold
#1
pros about a 79 manifold
i bought a 79 intake manny at the yard today it is noticably shorter intake runners and the middle ports are alot smaller than 84 85 but it looks easier to port than the 84 i think i paid 15 for it i got the oil cooler and tower as well. i was just wondering if there were any power improvements with the manny id assume a little more top end power.
#4
gregs brings up a interesting topic i think, i am new to the rotary thing but from what i have learned is that the 84 85 had better compression then the earlier wouldnt that account for better something i know higher compression piston motors make more power rx7carl has flow tested the after 79 manifolds and he was dissapointed with the flow differences in each runner to me the runners look egual to one another outside with outside and inside with inside i mean i just find it a little odd that tha horsepower didnt change with the years also since didnt the 82 have a lighter flywheel i just dont think those numbers are very accurate but maybe im bringing up an old thing.
#7
Airflow is my life
Compression ratio remained constant in the 1st gens. The early cars had lighter FW's, but heavier rotors, so that cancels out. As far as the manifold, the 79-80 has a much better plenum and less bumps and crap to interfere with the airflow. The runners arent smaller, its decieving. Look down into the 84-85 and look how the runners neck down.
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#12
Whack 'em and stack 'em
Join Date: Mar 2003
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Originally Posted by Rx7carl
Too ghetto. I take a piece of angle aluminum and bolt it to the bottom of the manifold to block that port.
Also- an unrelated but related question- Can I use one of the vacuum ports on the manifold for a pcv valve/breather on the oil filler neck? Reason I ask is if I use my stock 85 manifold base plate/shield- I don't believe the vacuum holes match with the manifold.
#15
Whack 'em and stack 'em
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Yup- that's been ported. I was thinking about port matching the 79 manifold that I have and use it with the sterling/carl carb on my stock 12A, but really don't know if it's worth it or not.
I've done a few searches on here before and came up with mixed results (port matching and porting intakes).
How's your intake project coming along, Carl?
I've done a few searches on here before and came up with mixed results (port matching and porting intakes).
How's your intake project coming along, Carl?
#17
Lapping = Fapping
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You should see the engine it came off of. It's a streetported Pineapple Racing engine.
It looks like they used some Devcon in the EGR port. It's got 3B rear, R5 intermediate and Y front casings with '76-ish rotor housings and '83-'85 rotating assembly.
It looks like they used some Devcon in the EGR port. It's got 3B rear, R5 intermediate and Y front casings with '76-ish rotor housings and '83-'85 rotating assembly.
Last edited by Jeff20B; 09-28-04 at 02:29 PM.
#20
Airflow is my life
To keep the coolant from heating the manifold. I think it was a boat anchor. Oh and that porting MAY be ok for a SP. I havent tested SP's for flow yet.
Yup, primaries are the 2 center ports.
Yup, primaries are the 2 center ports.
#21
Lapping = Fapping
iTrader: (13)
It was a racing engine that had a Racing Beat old style black air cleaner assembly. Somebody left it out in the rain and water simply would collect at the concave part at the center of the lid. Then it would drip down the long stud and into the carb. The carb butterflies and everything below them was ruined due to water damage. The side plates were so bad that the metal could be scraped away with a fingernail after the rust coating was removed. At least the carbon apex seals may be reusable, as well as the rotor housings. I haven't dug deep enough yet to know.
#23
Airflow is my life
Its not a secret subject. It comes up once in a while. Most people just dont wanna hassel with it. Sure you can. Some guys epoxy quarters over the holes. I use 20mm freeze plugs. 2 engines and only one small seep.
#24
is it worth it for a daily driven 7? also should the egr port be blocked off? because i scored a race car with a atkins motor and this motor had a piece of aluminum welded and smoothed to block the egr port would it be benificial to block the coolant holes as well?