Kiwi-85IROC

G'day...I'm a kiwi who doesn't have all the selection you guys have in the States, so I'm going to import a set of headers.
We dont have to run Cat converters or smog gear here, so the headers/engine will just be free flow.

What I would like is some info on this: Is there a set of headers that I can import that will fit straight onto my 85 305 IROC without any alteration other than finishing the exhausts. Also are shorty headers worth it or do I need to go for the full length ones?

They will be matched up to a SUM-G5000 Summit cam set which I'll get at the same time.This seems to be the one to get. lookin at the posts re cams for a 305.

Duration: 268 intake/278 exhaust
Duration at .050 in. cam lift: 204 intake/214 exhaust
Gross valve lift: .420 in. intake/.442 exhaust
Lobe separation: 112 degrees

Cheers and merry xmas in advance

Wayne

Mark A Shields

Long tubes wouldn't be the best with that setup, and make hinder you slightly, not sure though.

I'd get some Hooker shorties.

rx7speed

why would long tubes hinder?

nice to hear of you guys down there working on the thirdgen

I know lots of you guys seem to take to the rotary though

Mark A Shields

maybe not hinder, but it won't help at all over shorties on a 305 is my understanding from what others on here have said.

Kiwi-85IROC

I forgot to ask what diameter?

five7kid

iTrader: (14)

The Hooker shorties with no A.I.R. would seem to be the trick. Summit p/n HOK-2460, with 1-5/8" primaries. Then finish the exhaust, like you say. Either have a y-pipe fabricated, or run dual pipes to the factory cat location, then "y" them together with a single 3" to the muffler, or you could run dual pipes back to the muffler.

When you don't have emissions to worry about, routing and ground clearance are the only concerns you have left. Long tubes complicate both of those, and the performance gains over the above shorties would be minimal at best.

Kiwi-85IROC

RGR that five7kid, great answer mate....You guys are soo lucky in the States with all those speed shops .

rx7speed

depends on what size the piping is


long tubes generaly are a lot larger as far as diam of the pipng that could be why they are not as good


but shorties are not the most efficient at flow either from what it looks like.... very unequal primaries and if they are equal there are some sharp bends in there


if you could find some long tubes that have good clearance and are not using huge primaries you would be better off for a low to mid rpm powerband use...

rx7speed

yeah but most shops don't want to touch any exhuast before the cat because it is against fed law to change anything unless they are tested and proven not to increase smog

and getting rid of a cat is big taboo here for shops also something like a $20,000 fine to tamper with stuff like that


but if you know ppl or the shop just doesn't care or you have a car that is old enough... then they might do it