440 Exhaust Manifold Dilemma

[ZippyZoo]

Before I completely disassembled the Challenger for restoration, I had slight exhaust leaks at both manifold/head pipe joints. Since the car is apart, I took the exhaust manifolds (RH#2899879 / LH#2951865) to a well rated machine shop to clean up/true up the outlet flanges. (I know I have to "true up" the head pipe flange faces, too.) I was expecting the machinist to remove a couple hundredths or so. Instead the faces now have a "front to rear" taper. The front of each outlet flange is about 0.330" thinner than the rear of the flange at the bolt holes.
I can only think of three options on my end:

1. Have new head pipes custom made with the flange at the correct angle when I put the exhaust system back on.
2. Have a machine shop taper two 1/2" exhaust flanges to match the manifold taper and install them between the manifolds and the existing head pipes to get close to square again.
3. Buy replacement manifolds - a significant expense I hadn't planned for.

What to do? Suggestions? Thanks.

 

[413]

That flange is so thin it will not hold up. The pipes are heavy. That machinist has destroyed your manifolds. This is totally unacceptable!

I choose option #4) You should seek compensation from them for replacement manifolds, AND get you bill refunded.

1969 and older right side has the bolt holes moved, pipe mods needed now.

This photo is how the flange should look.

 

[moparlee]

Option #4 as 413 said. They F'd Up a simple machining job.

 

[DetMatt1]

Agreed!

 

[ZippyZoo]

Thanks 413 and DetMatt1.
That's the same unfortunate conclusion I keep coming back to.
I see Year One has the "B" body '68-'69 new repop manifolds on sale for $600 and free shipping. They are technically the wrong part numbers, (#2806900/2843992) but everything looks like they should work. Manifolds on eBay seem excessive.
Anybody have decent 440 HP exhaust manifolds available for a more digestible cost (plus shipping to 80127 Denver CO)? This is a definite driver build! Numbers matching went out the window years ago!

 

[cuda dan]

I two sets. Have a extra set that came off of a 70 383 RT Challenger. They were removed around 1978 or so.
Need to figure out which set was for my 70 Cuda go I can keep my original set.
I could use a set for a 340 if you had some to trade?
I usually don't sell anything but I've seen the prices!
I'm in Oregon if that helps at all.

 

[ZippyZoo]

Thanks for the kind offer, Cuda Dan. Unfortunately, I just purchased a used set of the Year One reproductions off Craigslist. I would have preferred yours though........oh, well!

 

[aussiemark]

Check the position of the heat riser flap centre pivot (axle) I checked some of mine and while the manifolds look the same the flap pivots are 90 degrees different on some which may cause problems you can see the extra boss in the last photo the hole for the pivot is drilled into that instead. You could plug the holes and redrill it if need be.

 

[Avalanche]

Are the year one manifolds cast as original or are they steel?

 

[ZippyZoo]

Avalanche - I purchased them out of town and have not received them yet. They appear to be cast. Here's a link to the Year One ($600 with free shipping) site plus a shot of the as purchased used manifolds off Craigslist.
1966-74 A B E-Body Exhaust Manifold Set

Aussiemark: thanks. I am aware of the different heat riser location. I have the plugged manifold crossover valley pan so I will "disable" the heat riser anyway. As you can see on the picture, the heat riser counterweight is missing. I'll keep an eye out at swap meets for one........

 

[413]

That missing counter weight is the same on a LP log manifold 1966-1969. Makes it much easier to find.

I’d sell those manifolds and get the proper 1970 manifolds for the car. Not that hard to find. But to each his own.

You have to change the pipes to use these, why do it?

 

[Avalanche]

The reason I ask if they are cast is year one states ceramic coated with cast iron appearance .
It would be great to hear about the quality when you do receive them.
Thanks.