Straight through muffler in early 65. The repos from Accurite are low restriction Hemi style mufflers.
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Horse power drop using early A 273 manifolds
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cudamark
Well-Known Member
In '68 and '69, the 273 and 318 used the same exact manifolds, so, how can there be any difference? If your question is whether using the '64-6 LH manifold instead of a '67-up LH manifold, I doubt there would be much difference since the 273HP engine had 235 HP vs. 230 for the stock 318. Now, with engine mods, and/or high RPM, you'd need some dyno testing to see what differences there might be.
I don't think so. I have an NOS 65 muffler and resonator. And I had a 65 Commando Maremount System around 1970 on my 64 Barracuda that had a straight through muffler and resonator for years. Maybe 65 had an intermediate pipe and muffler welded assy like the 67.
Professor Fate
Push the button, Max...
And that's exactly what the OP was pondering: if a 318 swapped into an early A ('64-'66) using the original, and appearingly more restrictive, 273 manifolds pictured in post #8, would see any measurable dropoff in power with 45 additional cubes trying to breathe through them; and if there was any known dyno evidence of this compared to later ('67 and up) manifolds.
Commando was 65-67 only. A Body 273/318 Exhaust manifolds same from 67-69. A stock 2 barrel 318 wished it made 230 hp, more like 150-170 hp.
Ya, look it up. From what I have read, no muffler on the early cars. Way too loud so Ma Mopar added a muffler. May be @65dartcharger can clarify.
pishta
I know I'm right....
Muffler in the 65 catalog. I think the resonator made all the racket. Also note the design of the Y, not what's available today. There are repops that are more of the merge collectors like the ones Cosgig had pics of. I think I'd take this over the merged style, no D shape pinch point per bank. Muff had unique part number in catalog, not shared with any other engine. Aluminized 2660-541 or zinc coated 2660-548. 2660-545 was part number for resonator.
thesiren74
Well-Known Member
We have stock 273 manifolds on a 9.5.1 230@ .050/.480 lift cammed 360 64 valiant and they are awful!!
318 probably not much of a difference but compared to headers when the engine was in my car wow!! Killed power big time.
318 probably not much of a difference but compared to headers when the engine was in my car wow!! Killed power big time.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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IDK about a log to log comparison, but I can offer this;
I had a 73 Swinger with a stock long-block low-compression 318, with a 4bbl,a 2800TC, and 3.23s. Oh, and the factory single exhaust. At the time, it was a lotta fun.
Fast forward a decade or two.
I dragged that smogger-teen out from under the bench one day (Swinger long gone to Mopar heaven), resealed it and dropped it into my 68 Barracuda, as a winter-motor. Pound for pound those cars weigh about the same.
Well now; the Barracuda was set up with a 360/4-speed/3.55s, plus TTI headers and full-length 3" duals.
I dropped the 4-speed out and put the worked A904 in, that had been behind the teen, with it's 2800TC.
I left the TTIs and 3" duals.
And I cannot begin to tell you about the amazing transformation. Thinking it must be the 3.55s, I swapped in some 3.23s, and it was still a powerhouse. I then went to 2.76s where I finally thought the output was maybe a lil less,than what I remembered from the 3.23 Swinger. So I concluded that maybe 2.94s would be close to par.
So the point is that the TTIs and free flowing exhaust were probably worth at least one rear gear change, maybe a tad more. In this case, from 3.23s to 2.94s is ~10%
___________________
I swapped the smogger-teen into that Barracuda, every winter 5 years running; 5 different transmissions and as many rearends, and more.
And every spring, the 367 went back in. Except one spring when the 318 was just so so much fun, I think it was June or July , yeah July long weekend, before the 367 went back in. And after that, it stayed in.
In my wildest dreams I would never have imagined that headers and free-flowing exhaust could wake up an otherwise stock smogger-teen with a 4bbl.. Oh I gotta tell you one more thing, I installed enough valvespring to rev 5500, but usually shifted it at 5200, or less.
Probably not what you were interested in, but I thought it could be useful.
I had a 73 Swinger with a stock long-block low-compression 318, with a 4bbl,a 2800TC, and 3.23s. Oh, and the factory single exhaust. At the time, it was a lotta fun.
Fast forward a decade or two.
I dragged that smogger-teen out from under the bench one day (Swinger long gone to Mopar heaven), resealed it and dropped it into my 68 Barracuda, as a winter-motor. Pound for pound those cars weigh about the same.
Well now; the Barracuda was set up with a 360/4-speed/3.55s, plus TTI headers and full-length 3" duals.
I dropped the 4-speed out and put the worked A904 in, that had been behind the teen, with it's 2800TC.
I left the TTIs and 3" duals.
And I cannot begin to tell you about the amazing transformation. Thinking it must be the 3.55s, I swapped in some 3.23s, and it was still a powerhouse. I then went to 2.76s where I finally thought the output was maybe a lil less,than what I remembered from the 3.23 Swinger. So I concluded that maybe 2.94s would be close to par.
So the point is that the TTIs and free flowing exhaust were probably worth at least one rear gear change, maybe a tad more. In this case, from 3.23s to 2.94s is ~10%
___________________
I swapped the smogger-teen into that Barracuda, every winter 5 years running; 5 different transmissions and as many rearends, and more.
And every spring, the 367 went back in. Except one spring when the 318 was just so so much fun, I think it was June or July , yeah July long weekend, before the 367 went back in. And after that, it stayed in.
In my wildest dreams I would never have imagined that headers and free-flowing exhaust could wake up an otherwise stock smogger-teen with a 4bbl.. Oh I gotta tell you one more thing, I installed enough valvespring to rev 5500, but usually shifted it at 5200, or less.
Probably not what you were interested in, but I thought it could be useful.
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They were loud since the muffler was 2 1/2 inlet with a 2 1/4 core straight through. Not sure when they put the baffled muffler on the Commando. I know the baffled muffler was on the 67 for sure as I have that system NOS as well. I have an Accurate system on the 66 Formula S. I got the straight thru muffler since that was what I had on my 64. Not sure if the straight through muffler is still available from Accurate. The Accurate system is not the same as the OEM system, but fits well and is very similar in sound and power to the 65 Commando exhaust.
Yes it must have been a rumor I read about there being no muffler in 65. I edited my post above. The original mufflers were straight through and there was a service bulletin about the issue. Here's a good thread from a few years back with some good photos and information. The real 273 HP exhaust sound
I do remember taking the resonator off the 64, it went back on real quick.
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