Advice needed...

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vntned

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So long story short, I need opinions on a camshaft.

Here's my dilemma. I have a '64 Dart that I play with and a '77 D100 I use as a parts hauler.

The Dart has a 360 I rebuilt and put in last year. Specs are as follows:
1970 block 0.06" over (371cuin)
Stock crank and rods
SpeedPro H116CP pistons
Measured 9.4:1cr static compression
Mopar windage tray
CompCams Magnum Muscle 268AH-10
- 222/226 @ 0.050, .464/.464" lift
Cleaned up 587 J heads with 1.88/1.60
Untouched LD340 intake
Stock 340HP exhaust manifold

The dart has a 4spd and 3.55 SG in the back.
While no race car, it's plenty fun to drive on the street with plenty of torque and great street manors.

My '77 D100 has the original 186k mile 318/727 still in it. Low oil pressure due to non existent cam bearings, lots of leaks, and all around tired.

Now I've got a complete 340 out of a '69 Dart. It's original bore, but has been disassembled and needs a basic rebuild.

So here's my thinking. The 360 in the Dart, would work great in my truck given it's superior torque. And the 340 would be more fun to rev in the Dart. So the plan is to do a swap, and drop the 340 in the Dart.

Wanting to keep the 340 on the budget friendly side, I figured I'd skip the stroker on this one and just do a stock rebuild with a few minor upgrades. The upgrades being a hotter cam, stiffer valve springs, roller rockers, good valve job, and top it off with a ported LD340 I've got on the shelf. Nothing crazy, but a little more hotrod than the current 360. I still want to maintain the HP exhaust manifolds for now, maybe drop big coin on TTis down the road.

So the question is, what camshaft should I run? I like the 268AH-10 in my 360, but I want something a little hotter in the 340. The Comp XE series cams seem to be a popular choice, but they're a bit chattery. Would something like one of the old MP 280 cams be better? Just looking for some opinions from somebody with experience.

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I would get something close to the 284/484 cam , maybe a dual pattern vodoo or the comp xe line ?
I know there are better cams, but I had a 284/484 in my 70 340 4speed duster , nothing special 040 forged pistons , stock cr stainless valves , headers , intake, ignition , 750 carb with 4:56 gears. It pulled really hard !!
I had 3;91 gears before .
I would defineately put the 340 in the Dart !
 
I'm not sure why people think the 340 needs more RPM.

In 1971 (first year for the 360) a 340 made 275@5000 and 340@3200
a 360 made 255@4400 and 360@2400

The numbers certainly aren't jaw droppingly different. So close a gear change would be negligible.
 
He said he wanted more cam specifically .
He already has a 268 in the 360.
Im sure his 360 is making close to if not the same hp as a stock 340.
yellow rose said:
I'm not sure why people think the 340 needs more RPM.

In 1971 (first year for the 360) a 340 made 275@5000 and 340@3200
a 360 made 255@4400 and 360@2400

The numbers certainly aren't jaw droppingly different. So close a gear change would be negligible.
Click to expand...
 
HP is a measurement of how much air is pumped through the engine. That amount of air is greatly effected by displacement and engine speed. Since the 340 is 20cuin less than the 360, it would have to turn more rpm to move the same amount of air. All other variables being equal, of course. Besides I love turning rpm, it makes the panties drop!
 
jimmer said:
He said he wanted more cam specifically .
He already has a 268 in the 360.
Im sure his 360 is making close to if not the same hp as a stock 340.
Click to expand...


I was pointing out the RPM difference. People talk as though you have to turn a 340 8000 to run and a 360 can run at 3800 and drag a 340's ***.

At this point in time, 7000 RPM is a dog street engine RPM. Springs, lobe technology, pushrod and rocker development have made the 5500 RPM engine obsolete.
 
I-would-not-put-the-340-into-the-truck-at-3.315-stroke
I-would-gladly-sacrifice-some-torque-in-the-Dart.One-issue-I-see,-is-that-with-a-larger-cam,the-rpm-of--peak-power-rises-about-200-rpm-per-cam-size.And-that-then-puts-the-mph-up-higher-as-well. So-yes-you-have-more-power,but-you-have-to-drive-faster-to-get-it,whereas-gears-reduce-the-mph-to-get-the-power,and-multiply-the-torque-simultaneously.
My-favorite-combo-has-always-been-a-223*cam-in-my-Eddie-headed-11/1-367,68-Cuda-@3650#.It-had-the-strongest-low-rpm-of-the-three-cams-that-my-engine-has-seen.And-that-is-what-made-it-so-fun.
So-yeah-I-see-the-torquey-360-in-the-truck-and-the-340-in-the-Dart.However,in-the-340-I-would-either-go-easy-on-the-cam,or,I-would-increase-the-cylinder-pressure-a bit-to-keep-the-low-rpm-power-up. Or-you-could-fall-back-on-a-higher-stall.
One-thing-I-see-being helpful,-is-a-solid-lifter-cam-of-about-230*.050,-yet-only-260/268-advertised.This-might-work-well-with-9.8Scr-or-more,-making-power-through out the rpm band.
A stick car has a bit of a handicap in first gear at low rpm because the tires are married to the crank, without benefit of the fluid coupling or torque multiplication from the TC. So adequate cylinder pressure is kindof a big deal.
Alternatively, the 3.09 low box can more that make up for a lazy engine........until you get to second gear. 30mph with 3.55s and 26s will be about 2650 rpm in second. A 340 with a 284FTH, at 2650 is gonna be a bit lazy until you get her up to 10.0Scr or better, 10.6 being about optimum.
BUT If you can't get traction,then; big-power, or mega-torque-multiplication is kindof pointless.
At one time I had the bright idea of putting 4.88s behind my A833OD, and GVOD. This gave me ratios of 15.08-11.76-8.15-6.36-4.88-3.81-2.70 and,with somewhere near 430 ftlbs, this would get me up to 6600ftlbs on the start line! and I was ready to carry the front wheels like a SS-hemi of yesteryear. Yeah that was the dream. The reality was that the 325/50-15 BFG-DRs could barely hold 1500ftlbs, so I had to baby it out in 15.08, and immediately hit the splitter for the 11.76 ratio,then gently feed it power, and grab second early; what a stupid idea,I thought.
I pulled those 4.88s out ASAP!
And the trans was the next to go.
The current combo has just up to 4700ftlbs available on the start-line, and it makes a smoking hot streeter!
Happy HotRodding
 
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He was talking putting the 360 in the truck, and the 340 in the dart with more cam.
AJ/FormS said:
I-would-not-put-the-340-into-the-truck-at-3.315-stroke
I-would-gladly-sacrifice-some-torque-in-the-Dart.One-issue-I-see,-is-that-with-a-larger-cam,the-rpm-of--peak-power-rises-adout-200-rpm-per-cam-sise.And-that-then-puts-the-mph-up-higher-as-well.So-yes-you-has-more-power,tho-you-has-to-dride-faster-to-get-it,whereas-gears-reduce-the-mph-to-get-the-power,and-multiply-the-torque-simultaneously.
My-fadorite-comdo-has-always-deen-a-223*cam-in-my-Eddie-headed-11/1-367,68-Cuda-@3650#.It-had-the-strongest-low-rpm-Of-the-three-cams-that-my-engine-has-seen.And-that-is-what-made-it-so-fun.
So-yeah-I-see-the-torquey-360-in-the-truck-and-the-340-into-the-Dart.Howeder,in-the-340-I-would-either-g0-easy-on-the-cam,or,I-would-increase-the-cylinder-pressure-quite-siqnnificantly-to-keep-the-low-rpm-power-up.Or-you-could-fall-dack-on-a-higher-stall.
One-thing-I-see-as-good,-is-a-solid-lifter-cam-of-adout-230*.050,-yet-only-260/268-adertised.This-might-work-well-with--9.8Scr-or-more,-making-power-from-low-to-high-
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Click to expand...
 
And my bellhousing doesn't have room for a stall convertor, the clutch seems to take up too much room.
 
vntned said:
HP is a measurement of how much air is pumped through the engine. That amount of air is greatly effected by displacement and engine speed. Since the 340 is 20cuin less than the 360, it would have to turn more rpm to move the same amount of air. All other variables being equal, of course. Besides I love turning rpm, it makes the panties drop!
Click to expand...

Mathematically you'll move the whole powerband up about 300 rpm if you built the 340 to the 360 specs you have now. Plus the new cam.

Staying with the 3.55 gears ? If so I wouldn't venture to far with the cam.

Probably an xe268h or xe275hl or similar would be my choices.
 
273 has a good idea;
if you have room cylinder-pressure wise,put the cam that is currently in the 360 into the 340Dart, and a lil smaller cam in the 360 TRUCK.
See at 9.5 Scr, the 360 is currently low on cylinder pressure. You don't notice it because A) it's a 360, and B) you have a lightweight-A, and C)you have a clutch.But with the next smaller cam, that pick-up will really jump.
But if you put that same 268AH cam into the 340 at the same 9.5Scr, then you are gonna lose a bunch of torque at lower rpms, and if you install the 284, it will be even worse, and now you have the unhappy consequence of having to drive deeper into the carb all the time, and you can't seem to keep the fuel-tank full.Your first thought will be to ditch the 3.55s and the next one will be headers, so there goes about a grand.
So, Ima thinkin, to get around that, get you a Solid lifter cam of 228ish@.050 and fast ramps to keep the pressure up at low rpm, and of course lotsa pressure. Without headers and a free-flowing exhaust, there's not much point in running a big cam, because the overlap period is neutered.You end up with a wicked sounding idle, a pig on gas, a soft bottomend and a choked top with a missing spike from the stalled overlap.
Remember how much power 340s picked up, back in the 70's with nothing more than headers and a re-tune? And that was with just 44* of overlap. A 284/292/108 has 72* of those ........... almost none of which are gonna do anything except make a wicked sounding idle, waste lotsa fuel,and make the bottomend soft ........until the headers go on, with the matching exhaust.Then the spike will be there. Without cylinder pressure, the bottom will still be soft. And you can't change the fact that it will be hard on gas; the extraction period is NOT street friendly at just 102* when installed at 104 degrees..
 
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