[Bill Meyer]

I need to put a set of RAIII exhaust manifolds on my '70 GTO. I've heard that there are two different reproductions avail.
One is supposed to be better for using 2 1/2" pipes with. Can anyone help with this ?
Also, I saw an offering for aluminum ones. How would they work on cast iron heads (#12)?
Would the only advantage be weight, or would they flow better?? Thanks, Bill

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GT37

[Bill Meyer]

I need to put a set of RAIII exhaust manifolds on my '70 GTO. I've heard that there are two different reproductions avail.
One is supposed to be better for using 2 1/2" pipes with. Can anyone help with this ?
Also, I saw an offering for aluminum ones. How would they work on cast iron heads (#12)?
Would the only advantage be weight, or would they flow better?? Thanks, Bill

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GT37

[Ccass]

There are 2 molds for these manifolds. 1 from Texas 1 from Ohio. The company in Ohio has always had a better "looking" manifold but I have never heard any complaints about either. I can't confirm, but I believe the Texas mold is not in production anymore. Many have used the mold from Ohio for 2 1/2" pipes and again no problems. Finally, the aluminum manifolds are from the mold in Texas. They were extremely touchy and we saw numberous ones come back with holes melted in the side. Proper timing on those is critical. Other than weight, I doubt if you could realize any better performance since they come from the same mold.

[This message has been edited by Ccass (edited 12-23-1999).]

[Eric Gardner]

Bill,

It has come to our attention that both companies are using basic 67 HO left hand manifold castings to build the 68-70 D ports (converting to the two bolt flange). Problem is that the basic casting is different. Most notably the collector portion is an inch farther to the rear of the car. Exhaust pipes can be built to compensate but the owner must know what he has.
All the reproduction manifolds used what they refer to as a beveled outlet (cone shaped). The originals were a ball shaped which made for a better seal to the exhaust pipe. The ball shape allows for some motion still maintaining the seal the V has no adjustment.

[Paul Delfeld]

Bill and all contributors--I can provide you with the most accurate info in response to Bill's questions and some of the statements that have been made.

Two entities make Pontiac repro castings. The Ohio company, Classic Reproductions in Greenville sells their product thru parts distributors. They have a very poor service record on these manifolds--frequent b/os. The Texas company, Ram Air Restoration Ent., sells directly to the user. Their tool is not "in active" as previously reported. As a matter of fact, they advised that they have a very strong inventory position on these and on round ports.

Both companies use the 67 design as their base casting. As far as one looking better than the other, I have noted that several contours on the OH product is not as accurate as the TX casting. The 67 design's collector is actually .375 further aft than the RAIII (not 1"). The adaptation that is made to the 67 castings to allow them to fit on the 68-72 A bodies (no adjustment needed for F or G bodies) is to re-clock the collector bolts so that adequate clearance can be attained between flange and A-frame bracket. Both companies can provide a good fit to your '70.

As for using 2.5" pipes, the Texas company, RARE, now has a version of this header with a 2.5" outlet. The stock outlet is 2.125". As for the flange cut, ball type cut provides no gain in functionality over straight cut bevel, due mainly to a very forgiving match between the pipe (soft material) and manifold (hard ductile iron).

[Jerry Brock]

I have 2 sets of the manifolds from RARE, 1 set with 2 1/4" outlets and 1 set with 2 1/2" outlets. They are a quality piece, and I have no problem with recommending them to anyone.

[bs78ta]

I have the repros from RARE also. I had them hogged out to 2.5". Quality product and the service is exceptional. I recommend them highly. Cut out the middle man and order direct.

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Butch

[77TA]

how much do the manifolds cost and what is the contact number. Also how do they compare performance wise to 4 tube headers !

[Jerry Brock]

The RamAir repop manifolds will not flow as well as good 4 tube headers, but will flow equal to, or better than most 3 tube headers.
Th phone number for Ram Air Restoration Ent.
is 1-800-421-8455(order line) or 1-972-720-1593 for tech or fax. They will work with you for your application, and will tell you if they don't have what you need.

[Rocky Rotella]

I will make one comment. I have a set of the hogged out RARE d-port manifolds on my 1976 455 4 speed Trans Am. They fit great and perform as well. They only problem I had was my LH manifold is of the 3-stud/flange and my clutch countershaft rests up against it. Also, on the same manifold, the outer stud was resting against the boxed area of the lower control arm. With a clutch adjustment and a little minor grinding, they fit perfect. No complaints here, just make sure you do get the 2 bolt flange for the 2nd gen F-body.