Guys Chime In -340 Cam Advise Needed!!!

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lucahemi

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Car has A/C and looking to get the most out of a 340 on the street.
1972 Demon - 4/Speed with a 355 Rear End
Car is 3o Over / Kb Hyper Pistons #246 / TTI Headers / Have J and X Heads/ Stock Thermo Quad . Stock Manifold / 15" 275/60s Rear
Looking for power 1500 -5000 range
 
The stock 340 cam. It has a power band from idle to 5800. It's a good grind.
 
I have a 69 Barracuda340 4 speed. I have the Comp Extreme Energy 268. It is an awesome street cam. I am at 375 HP.
 
lucahemi said:
Car has A/C and looking to get the most out of a 340 on the street.
1972 Demon - 4/Speed with a 355 Rear End
Car is 3o Over / Kb Hyper Pistons #246 / TTI Headers / Have J and X Heads/ Stock Thermo Quad . Stock Manifold / 15" 275/60s Rear
Looking for power 1500 -5000 range
Click to expand...

You have a wide range of Cams to chose from.

Components
* 1972 Dodge Demon
* Shipping Weight > #3200 lbs. / Curb Weight #3350 lbs. {Approx.}
* 4-Speed
* 3.55 Rear
* 275/60 x 15" {28" Tall}
* KB Pistons {Most likely 10.0-1 Compression Ratio w/64.0 CC Heads}
* 340 'J' Cylinder Heads {Excellent Breathing}
* 1972 Thermoquad {#6138} > 737 CFM Rating
* 1972 Stock Cast Iron Intake Manifold {#3512100} {A damn good Intake}
* TTi Headers {Excellent Exhaust Flow}
* Air Conditioning {Horsepower and Torque loss at low-RPM's}

Goal > Power Range 1500 to 5000 RPM's {Street Driving with an occasional 'Blast'}

Let's see what we can 'Dial In' the Cam Computer for a good fit.
 
My wifes combo was a comp XE274, eddy air gap intake, holley 650 DP on a stock 10.5:1 compression 340. She pulled a 12.9 with sticky MT drag radials. I like comp cams
 
Since the OP wants to cap it off at 5000 RPM's.

He would be better off with the Comp-Cams XE-262H.

This way he could maintain the 'stock' 340 Valve Springs.

Camshaft Specifications

...............Comp Cams XE-262H ....... Comp Cams XE-268H
Lift........................ .462"/.470" ............ .477"/.480"
Duration ................ 262*/270* ............. 268*/280*
Duration @ .050" .... 218*/224* ............. 224*/230*
Overlap ................. 46* ........................ 54*
LSA ....................... 110* ..................... 110*
Center-Line ............ 106* ..................... 106*

RPM Power Range .. 1300 to 5600 ........... 1600 to 5800

What looks better with >
* Air Conditioning
* Stock Intake Manifold
* Stock 'J' Cylinder Heads
* Stock Thermoquad {737 CFM's}
* 15" Tires {28" Tall}
 
OP: check you piston PN; that is not for a Mopar SB. Compression height and pin diameter are not right for stock rods. Perhaps a typo?
 
I had the 256/262 for a while- really wish I'dve stepped up from that. Even if you're not looking for the end of the powerband, there's not much reason to put a smaller-than-stock cam in a 340- especially if it's not under 9:1 and doesn't have tall gears in it.
 
I would look for a cam that has a lift in the mid to upper 400's and keep the duration @ .050 right between 218 to 224. Lsa of 110 or 112.
 
Guys
The pistons are # 243.
The car had a purple cam and the idle was rough. After research on the teardown it was index wrong. I don't want to get to erratic as the TTI headers are wrapped around the steering column and a rough idle causing major clanging on the idle circuit
GH
 
A/C, tall tire, 3.55 means don't over cam. I run a XE262 in the same setup, ported J heads and it pulls hard to 6K.
 
Call Hughes Engines and pick their brain.
 
mderoy340 said:
A/C, tall tire, 3.55 means don't over cam. I run a XE262 in the same setup, ported J heads and it pulls hard to 6K.
Click to expand...
Right- so the factory over-cammed them? A/C, 3.2s, and PB. That 268's not a far at all from identical to the factory 340 cam. The smaller cams and small port intake are the strangest upgrades I ever see people do to a 340- in my mind anyway.

My stroker with 2.45s has gobs of torque with the XE274 in it.
 
Ditto, Hughes makes really nice cams , especially for small blocks
 
Infecteddog said:
Right- so the factory over-cammed them? A/C, 3.2s, and PB. That 268's not a far at all from identical to the factory 340 cam. The smaller cams and small port intake are the strangest upgrades I ever see people do to a 340- in my mind anyway.

My stroker with 2.45s has gobs of torque with the XE274 in it.
Click to expand...

I simply wrote what I run in my street car that I drive everyday and advised OP not to over cam. Never said the factory over cammed or the 268 was bad.
 
lucahemi said:
Car has A/C and looking to get the most out of a 340 on the street.
1972 Demon - 4/Speed with a 355 Rear End
Car is 3o Over / Kb Hyper Pistons #246 / TTI Headers / Have J and X Heads/ Stock Thermo Quad . Stock Manifold / 15" 275/60s Rear
Looking for power 1500 -5000 range
Click to expand...

Do you want to cap it at 5000 RPM's..
 
10200702 lunati voo-doo ....not a big lope idle at all when installed straight up....but pulls unreal from from 1000-5000.....will be so much fun to drive with that 4-speed and 355's ....put you back in the seat power ....can use the cheap 65 dollar comp single springs too with all stock valve train ...the whole voo-doo line is heads and tails better than any other grind with the same range specs ....there fast ramp lobes are still way ahead of any production cam ...head to head ...that includes comp big time ...it is all in how they excellerate on the road ....not a dyno ...
 
Guys 6000 is good all in.
When I posted 5000k its a street car. Didn't want allthe power on the top side.
 
268XE. I put one in a 3.54 tri power 340 4 speed e body, stock manifolds. Great idle, power, mid range. Shoved it in dot to dot, too. You won't regret it.
 
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