Q: Ram Air III Long Branch Manifolds
Instead of dealing with the problems associated with headers (leaks, etc.) and to just be different, I am considering a set of 1969 Ram Air III “long branch” exhaust manifolds for my 455 with ported 6X heads. Has anyone out there taken a grinder to or otherwise modified a set of these? I am plan to open up the inlets to match the head work as closely as possible and I am also considering having them extrude honed. Does anyone know of a good place to get extrude honing done? While we’re at it, does anyone know if there was an exhaust manifold produced that had better flow characteristics than the Ram Air III long branch?
A: I have the the RA III long branch manifolds installed on my car, (1967). Mine are unmodified, so I can’t speak to modifications you mentioned. However, there is one thing about using these manifolds which is rather annoying and you should be made aware of, (if you aren’t already). In order to use these manifolds, you have to use the oil filter mount which angles the oil filter back towards the rear of the car instead of the standard one which points the oil filter directly down towards the ground.
Even with this angled oil filter mount, you still end up have to drop the exhaust pipe to get the filter off! A royal pain in the backside, especially if you install a cross-over tube, because then you have to drop BOTH sides. I’ve met a few guys which get around this problem by installing a remote oil filter mount.
I think you are making a wise decision by going with the long branch manifolds over headers. I have had all three types of exhaust manifolds on my ‘birds, the stock manifolds, headers, and now the long branches, and I definitely ling the long branches the best. The headers were too noisey and added way too much heat under the hood, especially around the starter. (Kept cooking starter solenoids). The long branches perform as well as the headers, are quieter and don’t through out as much heat.
As long as we are on the subject, does anyone know if there exists a “shorter” version of the PF24 oil filter? If so, it could be used to bypass this clearance problem.
A: I too will be using the LB manifolds and will be using ported 6X heads on a 455 in my 1968 Bird. I enlarged the manifold ports to match the ports on the heads. I had to remove about .060.090 from the top of the openings on each port. The castings I have are reproduction. They look pretty nice and have 2-1/2″ I.D. outlets. I got them from Year One. I didnt get the flanges though. I will need to get those from somewhere. I am going to get the manifolds hi-temp coated too.
I will use the Dr.Gas “X” crossover and mandrel bent tailpipes. All 2-1/2″ system. I will rig up some type of remote filter.
Forget the extrude honing. It is very expensive. I think the price for cast iron manifolds is around $500. It would be wiser to just get some custom made headers and have them coated.
A: I have a 1969 convertible A/C bird with a .030 over 455, 6X heads and LBram air III manifolds. The oil filter issue does not require the remote solution. Point out this concern when getting your exhaust installed, it can easily be worked. I do have to bring the filter down the frame about six inches until the gap between the frame and the exhaust pipe is wide enough but it does not require unbolting the exhaust. Remember these are stock issue manifolds and GM would have never designed them so that it required exhaust unbolting for an oil change. Also, my LB areactually 2.25″ ID and the 2.5″ exhaust slips right over. The onlynegative I’ve seen from these manifolds (if you ignore cost) is that youwill need to install a heat shield for your starter and solenoid. But then GM also chose to use a shield with the stock issue of these cast iron manifolds. Oh and one last thing if anyone can find an exhaust guy that can install a 2.5″ cross over (X or H) with the convertible body pan in place and with more than 3.5″ of ground clearance let us know.
A: I had a crossover installed on my 68. The installer put a bend (about 30 degrees) in the pipe to rout it around the transmission tailshaft. It hangs no futher down than the transmission pan.
A: What about the GM Oil Filter adaptor used w/the Long Branch manifolds ?
A: Soke the header gasket in warn water for about 1/2hr. before installing it will swell up and seal better. Headers are know to warp. This worked on all the headers i have ever ran before.. I put the long branch manifolds on my 1967 not running yet but thay look good. Don’t for get you have to buy the $75 oil filter adapter also..
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Content last modified: January 16, 2014 at 5:27 pm