Join Date: Jan 2015
Location: Injun Territory, 'Merica!
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At least 3 different reproduction company's have produced reproduction Pontiac RA manifolds. Have purchased through all of them. In the late 80's, a buddy & I even sold Delfield (RARE) numerous original round port castings to cut up to help develop his round port manifolds, he ended up going with the '73-74 455SD design.
Here are the companys, each has it's own versions.
Classics of Ohio:
Repro RA manifold supplier to PY, Ames, Y1, etc through the 90's & 00's.
Examining used Classics RA manifolds, look for the CM casting on the manifold.
-Pluses: Several of Classics styles of ductile iron RA manifolds are the most authentic looking, correct amount of bolt holes, correct casting numbers. Have ordered several sets over the years & they have held up well.
-Negatives, occasionally will get a manifold where the head pipe mtg holes are not drilled perfectly on center of each boss, have to send it back.
Prev Performance Years founder, C Casperson, his wholesale entity. Distributed by Ames or through Pypes, most likely others now as well.
-Pluses, another quality ductile iron casting, bosses are drilled & tapped correctly, oversized 2.4-2.5" Outlet avail.
The Best pricing.
RARE, Delfield's near 3 decade entity.
Pluses: Quality ductile iron casting. Fairly wide product range. Availabilty of std or oversize 2.4-2.5" outlet.
negatives: not many, though price can be a little high, doing a High End restoration on a round port '68 1/2, 69, or '70-72 Pontiac A-body, RARE's version leaves a bit to be desired.
Last, whatever version you decide to purchase, there is significant power to be gained from having a pair of quality mandrel bent down pipes bolting up to the manifolds. You will leave quite a bit of power running muffler shop bent headpipes that kink down along the bend coming out of the headpipes. This tight bend coming out of the manifold needs to be mandrel bent. RARE currently sell sells a mandrel bent shorty headpipe section, so does PYPEs. For nearly the last 20 years, I've constructed the first foot of over a dozen pair of Pontiac headpipes using commonly avail J bend mandrel tubing. Not that hard to do with access to friendly muffler shop to make the flange, the rest is careful cutoff wheel work & TIG welding. Pontiac actually went the exact same route on the factory headpipes for the '73-74 SD Firebirds: flanged mandrel bent piece, then wire welded to the 2 1/2" diam headpipes.