I picked up a set of brand new hooker super comp headers part # 2225 off Craigslist yeaterday. I thought they were ceramic coated but they were just chromed. The guy said he bought em in the late 80s and they've been in his garage ever since. They had some minor surface rust in a couple places but nothing to bad. For half price of what they cost new I wasn't complaining.

The headers I had on the car were not massaged or dimpled, whoever put them on beat on em like a red headed stepchild. The part number stamped on em was 80608. I think that's a Hedman part number so I'm glad I found these because I was wanting to buy some Hedmans since I heard they have better ground clearance and I guess I'd have to beat on them to.

The hooker headers fit like a glove! Not a single issue! It could be the easiest header install I've ever done. The old ones fell right out and the new ones slid right in. The only thing I had to take off was the spark plugs on the drivers side and the zbar. I can't believe these headers are bigger and fit so much better than the smaller ones I took off. None of the plug wires are touching the headers where my old ones I had to beat quite a bit to get the #1 plug to quit burning off. I did have to bend the brake lines from the master cylinder to the frame rail slightly.

Now the bad....
The old headers hugged the transmission tunnel and lined up pretty close to the factory holes in the cross member, these are WAY off. They also are up against the metal plate on the floor. I hope they won't get hot enough on the metal plate that they'd mess up the fiberglass floor. The ground clearance is non existent. I measured 3.25 inches from the collector to the ground. Im gonna have my exhaust guy cut the flange off and put a band clamp instead to gain a little room. Are all these headers that far over where they are completely under the floor? It looks like the exhaust guy will have to make a pretty big bend to get it back in the transmission tunnel.

I didn't pay attention to how close the starter wires were to the headers and I cranked it up to see what it sounded like and fried all the wires.... it was bad enough that when I opened the hood the wires were on fire..... no big deal I can fix that easy enough. But man the sound was awesome! This car finally sounds like a beast! The factory 2 inch exhaust definetly wasn't letting the ls7 454 breathe.


New vs old

 

do you have motor mounts that are in good condition and are factory style. See the installation note concerning them.
184 - Factory-style big block frame stands and motor mounts must be used to ensure proper engine locations and header fit.

 

Yea the motor mounts are the oe rubber style. If anything I figured they'd be squished down.... I'd like to see how somebody with the hooker super comps with 3.5 inch collectors and 3 inch exhaust ran theirs.

 

I think a lot of people would recommend modifying the crossmember to bypass the holes.

 

Yea I've seen the cross members gkull built and the ones manufacturers make but the car is originally a l89 so I'd like to keep the saw off the car.

 

I had them on mine before I added turbos...and even before I made a custom crossmember where the pipes could go under it. You've got 3.5" collectors vs the 3" of the old ones..so that's some of the issue plus they have longer primaries whch puts them further back. I have Brodix heads with .600" raised ports so it brought them a little higher. In the picture, that right one looks angled down a lot..is that the final angle of them? May need to do some judicious use with a floorjack to get it up as much as possible.

Best thing to do is use some mandrel bent tubes and piece together as smooth as you can to get it through the crossmember. 3" will go through there. Don't let them "kink bend" that section or you'll choke everything you've gained.

The band clamps will help a lot...or a ball socket setup welded to them.

The 2-1/8"are pretty big for a 454..but it's got compression and it will want to rev.

JIM

 

I see what you mean by no ground clearance. They are hanging pretty low down. The band clamp idea may give you an added 1/2 inch of clearance, but that is a needed change.

kdf

 

Wow, those are close to the floor board. You may start a fire with those...
The ones you had on, do look like Hedman's which is what I have and they are specifically designed for C2/C3 Vette's and have good ground clearance.
The hp gain from going to a longer primary/collectors is negligable for street car.
I have an LS7 also and I have several inches of clearance and my floor boards get over 125* F +. And mine are ceramic coated.
I also run 3 " true dual exhaust. Would like to go to mandrel set up one day. That was not in the budget when I had this exhaust installed originally.
Go get your Hedman's coated and put em back on.

 

quite often the idiot welders just slap the header flange on. what if you cut them off and rotated the higher bolt points.

Other than the motor mounts. You can un shim the rear tranny mount for clearance.

I have the bubble wrap looking heat shields under my floor boards. My pipes used to get so hot out road racing that I melted the poly engine mounts.

I've worked on very expensive cars. Lots of these older cars had faulty break prone parts. So do you want a cross member that works or ar you a purist? Anything can be returned to OEM at a later date.

We installed 9 inch ford custom IRS rear ends in cars worth millions of dollars and we throw all the crap in a wooden storage box

 

I know on a street car the Hedmans are fine but I bought all the parts for a 12 bolt from toms so I plan on making this a strip car as well. I'd like it to run somewhere in the 10.99-11.50 range when it's all done.

I'm not so much a purist but I do appreciate the car for what it is. I really didn't want any kind of fancy car because I didn't wanna feel bad hacking it up but after I found the build sheet I would prefer to keep it as easily returned to original as possible. That's why I went with toms 12 bolt over saving alot of money and having a better solid axle rear end.

I'm gonna try and mess with it some today and see how much I can move them around and fix the starter wiring. I did a little searching on the forum and I'm wondering how much the body bushings could be affecting the fitment. I'm pretty sure they are original and maybe they're smushed and that's why it's touching the floors but fitting right everywhere else.

 

I think if you search the archives threads, many have found the same problem with the super competition under chassis headers. I know I did on my 69. Sold them as I knew they would never work on my car.

 

Yea I'd done some reading and that's why I was so suprised the hooker fit so well everywhere but the floor.

I have no problem with the Hedmans other than that's what I had before and they had to have some major dents on the drivers side to clear the steering box and the #1 plug. When I got the car the #1 plug was burned in half even after the PO dented it in and I had to beat on it more and put a plug sock on it. So I'm not sure what the answer is....

 

Hey Mike, as you know all the C3 's frames are the same from year to year, with slight variations here and there, as we all know , just like the bodies. LOL.

Dmoroso put a BB in his 81 and he used the BB Hedman Corvette headers. His fit just about perfect. I do not think he had to ding any of the tubes.
He also had GM style Iron heads with original exhaust port locations.
I on the other hand have raised exh ports (.350 ") I think over factory and that caused mine to require me discipline my #3 tube for the steering box. No other fitament problems with the other 7 tubes.
Hedman has made some improvements over the years for better clearance. Not sure how old your Hedman's are. But that could be the issue.