Headers

Torque Junkie · July 29, 2001

I'm taking 76BBSub's advice and going with the Dynomax Ceram-coat headers, but cannot find on summit racing.com any that will fit my truck. Maybe I'm overlooking it, but I wonder if they're even available...... they have them for 73-87 2wd (no 4x4), 66-72 4x4 (no 73+) and just about any combo of Suburban, Blazer and Jimmy, but no 73-87 4x4 *hmmm*

Something I wanna add.... www.jegs.com has CeramaCoat headers (1 part #) for 66-87 SB Chevy 2wd&4wd 1/2, 3/4 and 1 ton pickups?!?

Any ideas or suggestions?

Another question..... kinda off topic for this forum, but it is somewhat related to my post-- if the headers have 3" collectors, would it be 'excessive' to run dual 3" pipe back to a pair of Flowmaster 40's?

(Edited by Torque Junkie at 5:10 am on July 29, 2001)

July 30, 2001

If you are running a small-block, fairly stock, I would go no larger that 2.5 inch pipe. The big pipe will help only at very high rpm. Personally, I think 2 inch pipe will work best. The smaller tube makes better torgue down low.

76BBSub · July 30, 2001

summit.com doesn't have a bunch of stuff that Summit catalogs have, I don't know why. Your best bet is to call them and ask them to look up your application, that's what I had to do. I guess as we wait for e-commerce to become mainstream we'll have this kind of stuff happening.

As for pipe size, I have to agree with Friz, 3" is probably a little bit excessive for a small block. It will hurt your low-end a little bit. I think that 2-1/2" or 2-1/2" pipes to the mufflers would work better, and include a cross-over of some type before the mufflers. I have a simple H-pipe, but there are some pretty cool looking X-pipes available that are supposed to improve the balancing effect.

The reason for the slightly smaller pipes is to keep the velocity up in the pipes and help the scavenging effect of the headers. If you have room, use a longer reducer sold by Flowmaster to step from 3" to whichever pipe size you choose.

Good luck!!

Jeff

Torque Junkie · July 30, 2001

Ok, I didn't think about the low-end. I'll stick with 2.5" then. One thing to consider, too, is it does have a roller cam in it, so it should breathe *more* than stock.

As for the H-pipe, what is the main purpose for that? I'll take your advice and spend the extra ~? the shop would probably to fab. it... I'm just curious as to what benefit it has.

(Edited by Torque Junkie at 7:48 pm on July 30, 2001)

July 31, 2001

An "H" or "X" exhaust configuration balances the two exhaust pipes and makes for better scavaging. The "X" is better than the "H", but it is cheaper and still helps.

76BBSub · July 31, 2001

The effect that you'll feel is improved throttle response in the low and mid range with no loss on the big end, and it is also a little quieter inside the vehicle. Outside sounds a little mellower, but about the same volume, so if you have loud mufflers they'll still be loud, just not raspy.

The guy at the muffler shop didn't believe me when I told him that, and decided not to put one on my Sub, although I had asked for it. It was kind of loud driving it home, so I got underneath, no H-pipe. Took it back up there, made him put it on, and it really does make a difference. The next week I took the Corvette up there and had one added, it really made it sound nice. The mufflers I have are pretty loud and were pretty raspy until I got the H-pipe, much better now.

Jeff

Torque Junkie · August 1, 2001

Awesome! Thanks for the help guys...

I'm ordering the parts tonight along with my 4 - 165W KC's

LOHRTBT · August 2, 2001

I have 3" on my truck, when I had the 305, it killed it down low, but ran great up top. I think I am gonna lose the 3" with dual 2 chamber flowmasters. Probably go with 2.5 or 2 1/4 with some more mello muffs. Maybe get a set of B&B muffs or possibly a Gibson Muff.