Miss-matched heads & manifolds?

[gtxdude]

Hello there, just picked up a 64 Valiant with a mid 80's 318 in it. I've been trying to track down a exhaust leak from both sides. I thought maybe the exhaust manifold gaskets were leaking or maybe a head gasket. Some quick info for you, the seller said he a had some 360 police heads put on a couple of years ago on this 318. I have not verified that yet. Any way it's using 273 exhaust manifolds and I realize that they are not big enough to cover the ports on the heads! It looks like they filled the bottom of the ports below the exhaust manifolds with JB weld or something. I can look it up but I'm trying to save time here do I need to get different 360 exhaust manifolds to match up? Are the old 273 manifolds to small? How about 318 manifolds will they work on 360 police heads? A lot of questions, I have to run now but I will check back later.

 

[dodgetkboy78]

Filled the ports or is there holes for the air pump? Your best bet is to get 360 manifolds for gasket sealing AND performance.

 

[gtxdude]

That makes sense about the air ports, is that a California thing. You can feel the exhaust coming out of the holes even though they tried to fill them. How about a little JB weld? The 360 heads make the most sense. Mopar in the Park coming up in three weeks should be some there. thanks

 

[discharger1332]

you going to have a hard time finding manifolds to fit that car. factory ones and really expensive headers are the only options for 63-66 a bodys. at least thats what i remember going through with my 65. good luck

 

[gtxdude]

Are you saying the 360 exhaust manifolds wont go around my steering or they won't clear the engine compartment sides. Maybe thats why he put the 273 manifolds back in. I could throw a set of 318 heads and manifolds on, would that work and clear everything?

 

[hcharles]

My mopar heads have air holes, and it ain't from California. Mine are being drilled out and tapped, with allen head plugs.

 

[moper]

Yeah, they should be AIR injection holes and they should have run a tap into them and pluged them with grub screws. This should be able to be done in the car, but you need to pull the manifolds...

 

[66fs]

Are you saying the 360 exhaust manifolds wont go around my steering or they won't clear the engine compartment sides. Maybe thats why he put the 273 manifolds back in. I could throw a set of 318 heads and manifolds on, would that work and clear everything?

64-66 273 exhaust manifolds will work with 340/360 heads. You need to use 340/360 gaskets. I slightly ported the top and sides of the manifolds but, do not let the sealing surface get too thin. The passenger side can be switched to a 71 up 340/360 manifold, but the "bell" has to be reformed for the bigger outlet on the exhaust pipe. Other than that they are the same , with larger passages and outlet. A good custom exhaust guy should be able to do this.

 

[Oldmanmopar]

64-66 273 exhaust manifolds will work with 340/360 heads. You need to use 340/360 gaskets. I slightly ported the top and sides of the manifolds but, do not let the sealing surface get too thin. The passenger side can be switched to a 71 up 340/360 manifold, but the "bell" has to be reformed for the bigger outlet on the exhaust pipe. Other than that they are the same , with larger passages and outlet. A good custom exhaust guy should be able to do this.

This is the correct answer and couldn' have said it better. Plug the holes with 1/4 inch long 1/4 20 set screws . You can run a 1/4 20 tap in without drilling.

 

[gtxdude]

Great info guys, I'll have to remove the manifolds and then clean out the air holes since they are mostly full of JB weld or something like that. It hard to believe that they wouldn't have done that when installing! Maybe it's bubble gum in there!

 

[66fs]

I remembered on the way home the drivers side manifold hits the head. On my J heads I had to grind clearance on the top edge of bolt boss, others have said that it hits on the exhaust/egr port face. It is supposed to be thin there. Check it when you get the drivers side maniflod off and cleaned up.

 

[Cudafever]

This is the correct answer and couldn' have said it better. Plug the holes with 1/4 inch long 1/4 20 set screws . You can run a 1/4 20 tap in without drilling.

I will 3d that and here is cutaway to help understand.

a little hard to see with that tiny pic. left had side, just below the exh out let you will see the groove.

 

[gtxdude]

I've one side tapped out will do other this weekend. When I put the 1/4 set screws should I use some kind of loctite (blue or red?) to seal them?