Selecting Cam, getting that low rpm off-idle response?

gtxrt

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Chrysler rated there cams different can't go by specs or advertise duration. so far I seen 228-241 in the direct connection book [no way], Hughes had it at 214-224, Mebsuta posted 214-225, M posted 208-221 with R. Karashian at 208-220 115 LSA on a 113 centerline. the 208-220 seems the best bet. 208 for factory cam that had to go in the smaller 383. then 12* extra exhaust to keep the power up in higher rpms with the 115 lsa helping too with keeping power up and a smoother factory idle and gas mileage. that's how i remember the cam performing and that idle with the extra exhaust duration in my stock gtx's
 

Mebsuta

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I think it's been measured around 213/[email protected] by a few people. Speed Pro CS-661, Elgin E-1094-P, Clevite 229-2323, Melling SPD31, SUM-6420, etc. I should quit being lazy and go measure it myself.
 

gtxrt

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I think it's been measured around 213/[email protected] by a few people. Speed Pro CS-661, Elgin E-1094-P, Clevite 229-2323, Melling SPD31, SUM-6420, etc. I should quit being lazy and go measure it myself.
i was just guessing, 213-225 was calmed downed with the 115 lsa so wouldn't be surprised that the majority is right.
 

Geoff 2

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My understanding of extended exh duration used by the factories. They used restrictive exh systems & manifolds, small diam pipes [ ever seen 2.5" or 3" on a factory car? ], & some cars only had a single exh. So more exh duration to 'help' evacuate the cyl. So that 'fixes' that problem, but now the overlap is too high. So they fix THAT by widening the LSA.
 

Jonas Nordstrom

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My understanding of extended exh duration used by the factories. They used restrictive exh systems & manifolds, small diam pipes [ ever seen 2.5" or 3" on a factory car? ], & some cars only had a single exh. So more exh duration to 'help' evacuate the cyl. So that 'fixes' that problem, but now the overlap is too high. So they fix THAT by widening the LSA.
In my build I have a 2.5" exhaust system with long tube headers. So evacuating shouldnt be a problem.
 

gtxrt

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My understanding of extended exh duration used by the factories. They used restrictive exh systems & manifolds, small diam pipes [ ever seen 2.5" or 3" on a factory car? ], & some cars only had a single exh. So more exh duration to 'help' evacuate the cyl. So that 'fixes' that problem, but now the overlap is too high. So they fix THAT by widening the LSA.
starting in 1967 in performance cars they used hp exh manifolds with 2.5" pipe with an h-pipe tapering to 2.25" going into the muffler then 2.25 tail pipes some times tapering to 2".
 
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Original hypo 383 four barrel type Cam would be best if you wanna upgrade a little bit go to the street hemi grind but I think you will sacrifice just a little bit of idle
 
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