ram air manifolds
 

hi guys, I just inherited some r/a manifolds. one has 478140-1 casting # and the other 9797072-r6 on it. they only have 3 bolt holes on each manifold. was this the way the early manifolds were made? Ive seen other manifolds that have 4 on one and 5 on the other? any info will help. also what are these worth? thanks BLUE TA

According to Wallace's site, the 478140 is 1970 Firebird RAIII. The 9797072 is 1969 GTO RAIII. I haven't seen that many RA manifolds, but I've never seen any with only 3 bolt holes. As far as value......?

Mine have 4 bolt holes on each side. They're factory but numbers are too hard to read.

Almost all of the early RA manifolds only came with 3 bolt holes & they would tent to leak & warp a lot easier. These are good for someone looking for original numbers but if there going on a car that will be driven on the street with normal miles they will be hard to keep from leaking & warping. As far as $$ these may be worth $ 75.00 to $ 200.00 each depending on how bad some one needs them but your guess is just that a guess on those as most want the 4 & 5 blot manifolds because the seal much better. Plus the new ones because of the better metals used in them don't seem to warp any where as bad os the old 3 bolt ones.

Thanks for the info guys, good post Rex, thanks, BLUE TA

My 70 TA had that 3 bolt set up. Reproductions were not available in those days. If you plan to use them, I had good luck with the following. 1. have the manifolds belt-resurfaced. 2. tap the holes in the heads to clean out the rust. 3. install with the shim steel gaskets lightly coated with UltraCopper sealer on both sides. Use new hardware and make sure you have right at 1/2" bolt protrusion. 4. Tighten with a torque wrench. I had a set stay leak free for years.

And let me add to that this, do not use grade 8 hardware as the bolt need to stretch to hold tight thru the heat cycles.

Yes, what Steve mentions keeps the bolts in the "elastic" range. Factory bolts there were probably grade 5. That's also why exhaust manifolds have rather large clearance holes around the bolts. It lets the manifold move slightly through the heat cycle. When held absolutely tight, they warp between the bolt holes. Also why the gaskets are metal faced, to allow slight movement. Good luck.