I just scored a built 360 and am wondering how much HP I would lose if I installed it in my 4speed 64 Valiant using the original exhaust manifolds? It has J heads with the big valves, a custom valley pan, full port and polish, solid lifters and cam, LD340 manifold, etc. etc. Currently there is a very healthy 318 doing the duties in the car and I really enjoy it's pep. BTW I am on a tight to non existent budget. Will this be a largely wasted effort without headers and major exhaust work?
I could put the engine into my 84 D150 using magnum exhaust manifolds but . . . :sad1: I can sort of hear the responses in my head already, but say it anyway.
Thanks!
I would vote against using cast iron manifolds (having done this swap myself, back in 1972,) for two reasons: 1. I bought a complete 1971 340 motor and transmission (A-833 4-speed,) and attempted to drop it into my '64 Valiant's engine bay, (this had been a V-8 car from the factory,) and found, to my dismay, that the manifolds which were the good '71 340 Hi-po ones that the passenger side looked kind of like a header, hit the inner fender panels solidly on both sides and although I could get the motor on its mounts, the manifolds were wedged against the fender panels on both sides with it in place.
I still wanted them in there, so I took the car to an exhaust shop and was going to pay to have some 2 1/2" head pipes attached to the manifolds and run back to some glass packs.
The guy looked at it for about fifteen minutes and finally said, "There's just no way to get a pipe on that driver's side manifold; too much stuff (torsion- bar, clutch linkage, etc.) in the way... sorry."
So, I put some el-cheapo (HEDMAN) , fender-well headers on it which worked well.
Secondly, I have since read two exhaustive (no pun intended) reports that tested L-A motors with several different kinds of headers and exhaust manifolds and determined that even the best 340 manifolds cost a LOT of power, compared to even the cheapest headers; that driver's side manifold is a real performance-killer!
On the other hand, I have read on FABO that some folks have actually used the 340 cast iron manifolds in a '64 A body with no interference, so go figure... Production difference in bodies, I guess...
Another worthwhile option might be Dakota 318 Magnum exhaust manifolds, but I have heard that the '92-'93 manifolds have a larger outlets than later ones, so, you might want to consider that. I think they are not a slam-dunk in a '64 A Body, but the necessary hoops you have to jump through to make them work are minimal...
Good luck; hope this helps...:blob:
