[sdbob]

Just wanted to start something-ohboy. Got talking to another SD owner yesterday he stated he has heard some OEM Manifolds haven't cracked in use and others have. Does anybody have OEM maifolds that haven't cracked? Mine are cracked-39k.

[Baron Von Zeppelin]

My passenger side was all to he[[ and had substandard brazed repairs.
Driver side was fine - or gave all indications of being fine "on the car".
At high 70k's - low 80k's miles in 1989

[sdbob]

I had a set of 62 SD maniflods furnaced-brazed and they held up. I was thinking after market repos.

['ol Pinion head]

Have 3 pair of late '70 RAIV- 72 HO manifolds that haven't cracked, none are off high mile cars but I bet the 72 set has 100K miles on it. I've had several '69 & 70 RAIV pairs in my hands from GTO's I was working on that were not cracked either.

Back in the late 80's myself & an old friend sold several single cracked roundport manifolds to a fellow from San Antonio who picked them up for Paul Delfield. Paul was cutting them up to study them & make molds for his first repro roundport manifolds. I was told Paul ended up going with the '73-74 SD version, because it has the extra bolt holes on the ends. For cosmetic reasons I didn't need this style, but have a pair of the 2.45" outlet repro's to use on my '72 T/A

[74 SD455 Formula]

I am still running my originals and I have 48K mile's on the car. Brewster keeps telling me to get them off to preserve them before they crack.It's not a matter of if, but it's a matter of when they crack. He has told me to get the repop's from Ram Air Restoration's.He says they make the best one's out there.....

[njsteve]

My72 T/A had 114,000 on the original manifolds.

[Brewster]

Mine started to have a hair line fracture around 20k miles and its the passenger side that fails. Its an sd thing and maybe Jimmer isnt drive his car hard enough?

[x-bird2]

passenger side on mine was shot with multiple failed repairs on it, driver side wasn't as bad but had cracked at some point, repairs had held up but it had broken off bolt lugs.

[bird72]

I have a 72 HO that has a hairline crack in the crease between runners on the outside where it curves down a few inches away from head flange.... should I try to have fixed?

[bluebird455]

My 74 sd 455 has the original ones and so far no cracks, car has 54k miles. Now am thinking of removing them and getting some from Ram Air restorations.

[74SDformula]

When I got my Formula the drivers side manifold was in good shape but the passengers side manifold had some creative repair in the past.

[Baron Von Zeppelin]

Originally Posted by 74SDformula

When I got my Formula the drivers side manifold was in good shape but the passengers side manifold had some creative repair in the past.

They really almost fixed it - just a couple small spots popped through.
Crude, but it was working and holding.

Probably was heated up to orange then arc welded with a nickel rod.
It took some time to do all that and fitting up scrap pieces for bandages.

Passenger side is the weakest on all of the Roundport exh man's.
Ram IV manifolds seem to be tougher than HO and SD.

[Baron Von Zeppelin]

Originally Posted by bird72

I have a 72 HO that has a hairline crack in the crease between runners on the outside where it curves down a few inches away from head flange.... should I try to have fixed?

If you can find a highly reputable furnace welder that does the welding inside a furnace with mechanical arms - it can be done right. And finished out almost undetectable.

idunno how much they would charge and if it would be cost effective after shipping round trip.

also figure on having to get it resurfaced on the mounting flats

[poncho-mike]

There was a company on Statesville Avenue in Charlotte that repaired diesel blocks that welded cast. They repaired a set of 455HO exhaust manifolds for me when I was still living in Charlotte.

I have a set of 74 SD manifolds that have no cracks. I was lucky enough to pick up an original intake, carb, and exhaust manifolds from a guy who bought a 74 SD new and raced it. The manifolds were pulled off of the car when it was almost new and replaced with Hooker Headers.

Mike

[x-bird2]

Originally Posted by bluebird455

My 74 sd 455 has the original ones and so far no cracks, car has 54k miles. Now am thinking of removing them and getting some from Ram Air restorations.

If you run it often enough, that would be a good plan of action. center area of the manifolds just can't take the heat.