IronMaidens2.0

Can someone tell me were to get a set of shorty headers that work with stock exhaust flange. I found a bunch that have the collectors with them but I want to use stock bolt up flange

Dynra Rockets

A frequently asked question. McJacks or OEM 81-82/L98 C4 are about your only choice. No performance gain over stock manifolds. Unless you absolutely must keep your OEM flange for some reason there are far better performance choices for headers. Here is a thread from last month...

https://www.corvetteforum.com/forums...n-an-81-a.html

Bikespace

Would a 2.5" collector work for you, or do you need the 2"? There are a number of cheap, Chinese cast repros out there at Summit, Jegs, and elsewhere. I'll probably try a pair on my '80 at some point. I have a very short section of 2" pipe before the rest of the exhaust is 2.5" starting at the turns. I'd replace that at the same time, and have an exhaust shop do the welds. I could get O2 sensor bungs at the same time.

terry82

so are the 1982 tru 1984 factory headers the same as the later model headers?same flange bolt up ,same head bolt up?i want to get a new set of headers and do what you did .

Dynra Rockets

OEM 81-82 have the tubes up high
OEM 84-91 have the tubes down low.

If you have an automatic you can use either. If you have a stock manual with Z bar then you cannot use the C4 on the drivers side as it interferes with the Z bar.

I have a 81-82 on the drivers side and a 84-91 on the passenger side. (my original plan was to use C4 but then when installing I discovered the Z-bar foul, so had to source a 81/82 for the drivers side)

I personally would not recommend going the OEM route unless you already have some laying around and do not need more than 300 hp. Aftermarket headers are far superior and do not require any reconditioning such as tube spreading, welding the AIR holes shut or rust removal.

terry82

I have less than 300 hp . I have the automatic .yes I could go aftermarket but I don't want to change the exhaust pipes.If I take out the tubes inside the factory headers close up the holes ,they would be better than what I have.the info that you have told me is helpful thankyou.

leadfoot4

Check the 'Speedway Motors' catalog (the street/muscle car one, not the race one), and look up "rams horn manifolds"............

Dynra Rockets

Those all have flat flanges that require some sort of "reducer" adapter to connect to the exhaust. Sounds like these guys are looking for a manifold that has the flare donut built in so they can use their existing stock exhaust as-is without cutting or welding.

Reducer:


flare donut built in:

jb78L-82

Speedway has what you want in a 2.5 inch ram horn that will fit a stock exhaust system:

http://www.speedwaymotors.com/Corvet...fold,9133.html

I would not bother with McJacks or the 81-82 tubular manifolds, not worth the effort for the return in power. I had McJacks for 10 years and yes better than the 2 inch ram horn but I wonder about the 2.5 inch ramhorns???????????....

Dynra Rockets

The only thing that is different for mounting is the length of the bolts. If possible try to source a set with bolts included. Also note that the 87.5-91 C4 are raised D port style, they will work fine though.

tfuno

I agree with jb78L-82. I am in the process of getting my 77 smog legal in CA. I bought a set of the OEM 81-82 exhaust with AIR. I was going to do some minor clean up on the ports. The OEM quality control is not all that and to clean them up was a huge time investment so I am going to go with the Speedway RamHorn for $59. I'll drill them out to accept the AIR and the ceracoat them.

Advantage will be less heat and much easier to port the ramhorn. You can shape the ports because there is more material to work with.

Just my 2 cents

terry82

that is a great price .let us know how they turn out.

carbster09

I have MacJacks on my BB. They offer awesome quality and they fit! As for the no performance gain I call BS. My BB with long tube 4-1s dyno'ed at 511hp. With MacJacks she only lost 15hp and pulled 496hp! I did not perform a pull through the cast iron manifolds, but I highly doubt they would put out the same.

IronMaidens2.0

the pic of bottom ones are those the macjack ones ?

jb78L-82

Oh don't get me wrong...I loved my McJacks and do think that they add power especially on modded motors but for a stock type engine with OEM type HP considering the price, I would go with ported 2.5 inch Speedway ramhorns....

I used my McJacks on the rebuilt/upgraded (2014) 355 L-82 (450 Gross HP with Roller cam and AFR heads)) up to this year and the McJacks were great but I switched this year to 1 7/8 inch LTH and the difference is noticeable in the 3,500-6,000 RPM range with the LTH...you can feel the engine pull harder than with the 1 5/8 inch Shorty McJacks.....

Dynra Rockets

The bottom pic is the OEM C4 manifolds cermaic coated by McJacks.

These are the McJacks manifolds referenced above:

http://www.vetteheaders.com/c3-corvette-headers/

R

terry82

Mcjacks headers would be the way to go but ,,,that is pricey.

tfuno

I spoke with a rep from mcjacks a few years ago. They buy old oem exhausts and clean them up. They clean up welds and imperfections then ceramic coat them. Very nice work. Interesting point, they claim these are not smog legal in CA. However I found out that since they have the original one part number, these are considered oem and therefore are legal in CA.

Shark Racer

Hedman has a series of long tube headers that are CA legal - with and without AIR tubes. AIR tubes are only required for cars that came with them originally (typically CA L48, L82 and I *think* high altitude cars but am not sure on that one).

You'll need to do a little bit of welding work to fit the exhaust up to the stock system, but it's definitely an option if long tubes are on your list.