360 with 273 CI manifolds

[swing69]

mild 360 in a non-race application for a 65 Barracuda. I have stock 273 manifolds AND a set of Spitfires on hand that can be used. Summit 6901 cam kit, performer intake, 600 eddy carb., lockup 904, 3.23 gears.

Option 1: use the spitfires. get a custom dual exhaust plumbed up.

Option 2: use the stock 273 manifolds, use the TTI A25MWM6776 2.5" system.

I know the spitfires will flow more, but how much more than the 273 manifolds?

Is there any prep that can be done to better port match the 273 manifolds to the 360 heads? any instructions on this? picts?

 

[krazykuda]

I prefer to use stock exhaust manifolds as I went the header route for a while and too many issues.


I would gasket match the exhaust ports in the head and exhaust to the gasket.

I did this on a 360 that I had in a 74 Charger. I also tried to open up the ports a little and got a little too aggressive and broke through the casing. Luckily, I knew some guys at work with a welder and they let me weld it back up, with a little extra meat for porting. I then took it home and touched it up. Man, the weld was much harder to cut than the cast iron, but I did get it done...

I would go with the stock exhaust manifolds, and open them up as much as you feel comfortable, then have a custom exhaust or tti system back....

 

[chryslerfat]

You wont be able to gasket match with a 360 gasket. In order to seal the manifolds you need to run a set of 273 and 360 gaskets together. You will also need to grind a little off the head and a little off the manifold at the drivers down port or you will break the drivers manifold. Trust me I have done it.

 

[krazykuda]

You will also need to grind a little off the head and a little off the manifold at the drivers down port or you will break the drivers manifold. Trust me I have done it.

Can you post pictures of what you did and where?


I have a 360 going together for a 66 Valiant wagon project in the near future...

 

[chryslerfat]

Can you post pictures of what you did and where?


I have a 360 going together for a 66 Valiant wagon project in the near future...

Sorry I never took pics but it is at the drivers side where the manifold flows down. It hits the emissions port right below the exhaust port on the rear cylinder. Out of the car you will be able to see it good from the rear when you sit the manifold up in place. I did mine in the car which is harder. grind some from both the head and manifold and not all from the head or you will hit the water jacket. Trust me I ruined 1 head the 1st try until I took some off the manifold also.

 

[chewy]

As was said in the sb post, you can come close to port matching them, but may face issues with cracking them under high performance running. The bottleneck with the a body drivers side manifold is more the smashed enlongated flow around the steering.

This is why the tri Ys are soo much more appealing. I remember seeing an article on them in the early 2000's in one of the three main mopar mags, but not remembering which one. Stats seemed impressive compared over to stock early A manifolds. The tri Ys were supposed to be able to get around the steering and maintain better flow numbers.

With headers under the early A hood, heat can quickly become am issue. Ceramic powder coating is recommended to help. You don't want to reach down and have your hand sear to the steering column from inside the car. With headers you also have the dual exhaust problems with the cross member and gas tank.

That said, if u are putting a built 360 in, and have the spitfires in hand, I think get em coated and use them.

 

[trapster]

power steering or manual ?

regular starter or mini ?

 

[amx364]

http://www.forabodiesonly.com/mopar/showthread.php?t=183922
Post about install of TTI x-pipe system in 66 Barracuda---not a 64 as stated. Short story is exhaust is a tight fit and every pipe requires some work to fit car.
http://www.accurateltd.com/A-Body-HiPo-Exhaust-System_p_195.html
might be a better choice in the space.

 

[chewy]

I had that complete hi po exhaust setup on mine. There are some slight differences than the original set of rusty ones I took off mine.

I blew up the muffler playing backfire in 2008 or so. I ended up putting an 9degree offset glasspack in its place, after i rebuilt the engine. With the resonator on behind it, I think it sounds pretty sweet.


Your shorties could be routed into a Y pipe down to single into the Hp setup. Or, There are folks on here who do the modification to the cross member for dual. My next early A car will get dual pipes.

 

[amx364]

You can mod the cross member yourself without much trouble, just selective cutting involved. I failed to take any pictures of the cross member cutting, finished it in one day.

 

[swing69]

You can mod the cross member yourself without much trouble, just selective cutting involved. I failed to take any pictures of the cross member cutting, finished it in one day.

Crossmember cutting????? you mean just the modification on the tranny mount bracket, correct?

Also: I fit 273 manifolds to later 318s. the #7 exhaust "boss" on the lower right corner (just below the air pump port) needs to be chamfered so the manifold fits flush with the ports. I took all clearance off the head side, maybe I got lucky, but didn't hit into water.

I have to look at the gasket situation. I'm not really comfortable with 2 sets of exh. gaskets to make the 273 manifolds fit on the 360.

anyone know of a company that will cut custom gaskets from a template??????? Maybe a custom gasket can be made......

 

[chewy]

Yes, the transmission cross-member needs mods for dual exhaust. The left side should be modified to fit the exhaust. Check the third pic in this post or first pic on the valiant, you can see the modified cross-member.

http://www.forabodiesonly.com/mopar/showthread.php?t=220686&highlight=crossmember

 

[amx364]

Best picture that shows.

 

[66fs]

Crossmember cutting????? you mean just the modification on the tranny mount bracket, correct?

Also: I fit 273 manifolds to later 318s. the #7 exhaust "boss" on the lower right corner (just below the air pump port) needs to be chamfered so the manifold fits flush with the ports. I took all clearance off the head side, maybe I got lucky, but didn't hit into water.

I have to look at the gasket situation. I'm not really comfortable with 2 sets of exh. gaskets to make the 273 manifolds fit on the 360.

anyone know of a company that will cut custom gaskets from a template??????? Maybe a custom gasket can be made......

If you carefully open up the exhaust ports on the 273 DS, Drivers Side, exhaust manifold, port the bottom as little as possible, 360 gaskets work fine. You can use the 71 up 340 and 360 center dump PS, Passenger Side, exhaust manifold on the PS. You should enlarge the bell on the exhaust pipe, but the outlet is in the same position as the original PS exhaust manifold. This gives you larger ports and outlet ID on the PS. Newer 360 heads, mid 70's and up, have smaller exhaust ports than X,J, and 587 head castings. As cautioned above, trial fit DS manifold to the head you want to use since there is interference with 340, 360 and newer 318 heads.