Instead of doing the header thing, I thought that I could use a set of hipo 340 exhaust manifolds on s 273,4 BBL, 10.5:1 motor that I am finishing up. I don't like the chassis headers and the fenderwells are not practical for the street. I'm hoping that the 2 1/2" exhaust system should be a breeze on a '66 Valiant. Anyone done this?
340 EXH manifolds on 273
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Home made or TTI exhaust?
chryslerfat
Well-Known Member
The ports are not a direct match but they can be used sometimes with a double gasket. IE; a 273 manifold gasket next to a 340 gasket.
Treblig
Well-Known Member
You have to have manual steering. If you have manual steering then you can use the 60s 340 driver's manifolds. I've seen some members who have used the 360 magnum manifold on the passenger's side. You'll have to grind the casting numbers off the 360 magnum to get some clearance but it will fit in an early A.
Treblig
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Treblig
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chryslerfat
Well-Known Member
True the left manifold will hit a power steering gear so as Treblig said you will have to run manual.
Treblig
Well-Known Member
I used the 340 driver and the 360 magnum on my '69 318. I really didn't like the difference between the 318 exhaust port shape/size compared to the 340/360 manifold port shape/size. They don't seal that good but I've heard that some members do actually get them to seal. So as not to have to deal with any potential leaks I bought some 302 casting heads that have the closed combustion chamber and the 340/360 exhaust port size/shape.
Treblig
Treblig
Rapid Robert
Well-Known Member
On a side note if you ain't already I would suggest adding a scallop on the pass side of the trans crossmember like it is on the drivers side so your dual ex pipe on that side will tuck up nicely into it & not hang down. cut box/weld to restore the OE strength. On the magnum manis, I would get the '92/early '93 ones which have ~2&5/16" outlets as opposed to the later ones with the 1&7/8 outlets.
Treblig
Well-Known Member
"On the magnum manis, I would get the '92/early '93 ones which have ~2&5/16" outlets as opposed to the later ones with the 1&7/8 outlets."
The early magnum manifolds might work but the 96/97/98 Jeep Grand Cherokee passenger is the only one that (IMO) works best. The early (92/93) manifolds are great for the B body cars but it's up to the OP. The 340 (60s) driver's manifold can't be beat for the left side!!
treblig
The early magnum manifolds might work but the 96/97/98 Jeep Grand Cherokee passenger is the only one that (IMO) works best. The early (92/93) manifolds are great for the B body cars but it's up to the OP. The 340 (60s) driver's manifold can't be beat for the left side!!
treblig
I would say any manifold newer than 1969. The 273 and 318 manifolds are the same up to 69. 340 manifolds would be good as well as some Magnum manifolds. You can use the search function for "273 exhaust manifolds" or even "318 exhaust manifolds." The 340 manifolds have bigger ports and larger outlets.
Treblig
Well-Known Member
The 60's 340 driver's manifold paired with the 360 magnum passenger's manifold would be the absolute best (and cheapest) for great flow. You can also use the 340 (70s) passenger's manifold (I have some of these for sale right now), it has a smaller outlet 1 7/8" compared to 2 1/4" for the 340 driver. The 273/318 exhaust outlets are 1 5/8". I think you can use the 60's 340 passenger on an early A but I don't know anyone who has done that.
Treblig
Treblig
Treblig
Well-Known Member
The intake ports are quite a bit bigger on 360 heads. If you got the right cam it should work, I'm sure there are other members who have used 360 heads on a 273...hopefully someone will chime in. As far as the 340/360 manifolds are concerned it would work out perfect since the 360 heads have the same exhaust port size/shape as the 340 driver & 360 magnum exhaust manifolds. But you wouldn't be able to use the old 273 exhaust manifolds, I don't think they would seal.
treblig
treblig
If you are talking about a 273 you don't put 360 heads on one.
Treblig
Well-Known Member
Maybe you could use 302 casting heads??? They have the larger exhaust ports and were used on 318 engines.
Treblig
Treblig
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