Exhaust options- 340 in '65 Valiant

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Gib Warnick

'65 Valiant signet
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I am in process of planning for a '72 340 in a '65 Valiant with a 904 trans.
The idea is to have the appearance of a 273 commando car but be a 340. It will be a pump gas mild street motor-more low end torque than high rpm horsepower. 600 cfm Eldebrock carb on a Performer intake to start. The question I would like your opinions on is about keeping the stock 273 exhaust manifolds with dual exhaust vs TTI headers-How much extra power/performance will it really cost me for a street car? The cost and aggrevation of the TTIs and liking the sleeper appearance.... What do you think guys? Thanks,
 
djvcuda was running a set of 340 manifolds on his 360 in a 66 cuda and they even choked it down.. the 273 manifolds on a 340 head is gonna really hold it back.. he put on a set of spitfire headders and man it made a huge difference. i couldn't believe it... my opinion is you spent the money to do a 340 why kill it with 273 manifolds... ever compair the ports on your 340 to the manifolds ports?? huge difference...


TTI isn't the only option out there... you have spitfire and dougs for under carriage headders. the spitfires being the cheapest.. yea they wont give you the "sleeper" look but the spitfires are a shorty headder so unless the hood is open you will never know they are there..
 
This is all up to you and what your main driver is. Is it being stealth-like or is it performance? As mentioned above, there are other choices other than TTI for your vehicle. Personally, I would not run the 273 manifolds. I am not suggesting the TTIs either but it would bebefit the motor to let it breathe more so than the 273 manifolds. I realize that this is supposed to be a mild street motor and perhaps a budget build. This is where you want the most bang for your buck. Again, TTIs may not be the answer but one of the other more affordable aftermarkets may be. Good luck.
 
In my opinion if you are going to run exhaust manifolds at least run a 340 or other large bore type. If you want to run a stealth type header then the Spitfire short header is a good solution. Thats what I have for my 1964 Valiant. If you run those 273 exhaust manifolds on the 340 you are going to substancially reduce the exhaust amount.
 

I'm planning the same thing, 340 in my '65 Barracuda. I plan to use the 553/549 340 exhaust manifolds. I don't like the look of headers, the problems of headers, the heat of headers or the cost (although the manifolds are getting pretty pricey!). I've been thinking about it for a long time now, probably a couple of years at least, maybe three years now.

There's interesting reading about headers vs. manifolds here -> http://www.moparts.com/Tech/Archive/exhaust/9.html The manifolds perform quite well in the dyno tests, results shown on that page.

Also everything you need to know about headers in early a-bodies here -> http://www.earlyabodyforum.com/board/messages/394/418.html
 
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