340 cam

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Polara66

Polara66

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I’m building a 73 340 for my 66 dart wagon. It’s 30 over. I’m using 68-71 pistons to up the CR. I plan on using an edelbrock performer dual plane intake that I have. I have an 8 3/4 with 3.55 suregrip and I have electronic ignition. This isn’t a race car, just a street car. I was hoping to get some opinions on a decent cam for it. My car does not have power steering or brakes.
 
268 comp cam 224 230 477 480 110 106
1800 to 5500 shift at 6k
 
Auto with a stock converter? Anything up to about a XE268H or voodoo 268 camshaft. Put about 15-18 initial timing on it, should run well.
 
I third the recommendations above.

I run a Hyd. roller with a 224 intake duration and 3.55’s spinning a 26 inch tire. Very nice and streetable combination.
 
I'm gonna buck the trend.
I would NOT pick any cam until I knew the exact Static Compression Ratio. Doing so, IMO, is a recipe for disappointment.

My choice
would be something on a 108LSA and whatever Ica jumps the Cranking cylinder pressure up to just under the detonation zone with whatever gasoline you intend to run. Solid or Hydro in this application, I don't think is gonna matter much.
If it was me,
I'd set it up to run max pressure at WOT on 89 gas, then run a two-step timing curve, delaying the all-in timing to say ~3600, but bringing the first step in, as fast as possible, then put a smaller than usual 4-bbl on it, like a spreadbore. If I got detonation, I would give the carb an airgap intake and fresh air. If I didn't, then I'd try 87 gas.
Why the 108Lsa?
cuz if you run headers, then size for size, the 108 will give you more overlap which with headers makes more power thruout the rev range.
But if no headers then overlap means nothing except that the intake is closing sooner and your bottom-end will be stronger.
I would choose a cam with a great deal of Power duration to suck every last joule of energy out of the expanding gasses to get as much mileage as possible out of every pound of gasoline, because the price of gasoline is never gonna get cheaper, AND
nothing is worse than not being able to afford to drive your hotrod, cuz it sucks gas.
That's what I would do.

3.55s will get you a crappy Second gear;
3500= 49mph/ 65=4600
so there is NO good reason to stick a hi-rpm cam in this cruiser, You need a cam to cover 3500 to 4600 and nothing more; crap a 318 cam has that covered...........
 
Stick with cams like 340 cam or 268 Comp Cams.
Note. The performer has smaller ports than the 1973 340 TQ intake has.
I know you say you have the Performer but you will be running 318 small ports on a larger 340-360 port head.
It will ne fine low end mid range but will reduce power on upper end.
I ran the Performer on my 1972 340. But was to get mileage up on my 1972 340 Challenger rally.
I also has a 8 3/4 with 271 sure grip as almost all I-10 interstate
A RPM may be better
 
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Howard's cams has a nice 340 replacement cam. I forgot the lift but the duration is 267* / 277*. Performance cams, the ivc gets later like 65* and more. Like you said, compression ratio has to be know or you could bleed off to much cylinder pressure
 
Lunati bracket master 2,I've used it in a 360 with a stock converter and 2.45 gears and open diff ran great! First pass ever with the car was 14.02@101
 
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AJ/FormS said:
I'm gonna buck the trend.
I would NOT pick any cam until I knew the exact Static Compression Ratio. Doing so, IMO, is a recipe for disappointment.

My choice
would be something on a 108LSA and whatever Ica jumps the Cranking cylinder pressure up to just under the detonation zone with whatever gasoline you intend to run. Solid or Hydro in this application, I don't think is gonna matter much.
If it was me,
I'd set it up to run max pressure at WOT on 89 gas, then run a two-step timing curve, delaying the all-in timing to say ~3600, but bringing the first step in, as fast as possible, then put a smaller than usual 4-bbl on it, like a spreadbore. If I got detonation, I would give the carb an airgap intake and fresh air. If I didn't, then I'd try 87 gas.
Why the 108Lsa?
cuz if you run headers, then size for size, the 108 will give you more overlap which with headers makes more power thruout the rev range.
But if no headers then overlap means nothing except that the intake is closing sooner and your bottom-end will be stronger.
I would choose a cam with a great deal of Power duration to suck every last joule of energy out of the expanding gasses to get as much mileage as possible out of every pound of gasoline, because the price of gasoline is never gonna get cheaper, AND
nothing is worse than not being able to afford to drive your hotrod, cuz it sucks gas.
That's what I would do.

3.55s will get you a crappy Second gear;
3500= 49mph/ 65=4600
so there is NO good reason to stick a hi-rpm cam in this cruiser, You need a cam to cover 3500 to 4600 and nothing more; crap a 318 cam has that covered...........
Click to expand...
But a 318 cam has crap for power
 
Dan the man said:
Howard's cams has a nice 340 replacement cam. I forgot the lift but the duration is 267* / 277*. Performance cams, the ivc gets later like 65* and more. Like you said, compression ratio has to be know or you could bleed off to much cylinder pressure
Click to expand...
Got the link to the Howard’s cam?
Listing advertised duration doesn’t really help that much. Knowing the over lap amount does.
 
I would use the Comp Cams 270S Magnum cam. It is a solid lifter cam, but is designed with a 0.015" range of valve lash which changes the duration 10*.
You could go to the next up, 282S, but if you have an auto trans, the lumpy idle might be a concern.
 
a-bodyguy said:
268 comp cam 224 230 477 480 110 106
1800 to 5500 shift at 6k
Click to expand...

crackedback said:
Auto with a stock converter? Anything up to about a XE268H or voodoo 268 camshaft. Put about 15-18 initial timing on it, should run well.
Click to expand...
I have a 69 Barracuda with a .030 over 340, 4 speed, 3.55 gears, headers, Eddy Air Gap and 750 CFM Eddy carb. It has the Comp XE268H cam. It has a very nice and lumpy idle. Not a fender shaker, but you definitely know it has a high-performance cam. I have never had it on the track, but it runs like a bat out of hell. It will also melt the back tires on demand. I HIGHLY recommend this cam. I am no automatic transmission expert, but I would be shocked if your car would run well (pulling away from a stop that is) with a stock converter. I hate to disagree with @crackedback, because I respect him and agree with 99% of his posts, but I think you will want to upgrade from a stock converter with a XE268H. I say that because before I converted from an automatic to a 4 speed, my 340 had a cam similar to the XE268H in it, and with a stock converter, it would fall on its face from a dead stop. I swapped to a milder high-performance converter (2400 stall maybe), and it made a world of difference.
 
harrisonm said:
I have a 69 Barracuda with a .030 over 340, 4 speed, 3.55 gears, headers, Eddy Air Gap and 750 CFM Eddy carb. It has the Comp XE268H cam. It has a very nice and lumpy idle. Not a fender shaker, but you definitely know it has a high-performance cam. I have never had it on the track, but it runs like a bat out of hell. It will also melt the back tires on demand. I HIGHLY recommend this cam. I am no automatic transmission expert, but I would be shocked if your car would run well (pulling away from a stop that is) with a stock converter. I hate to disagree with @crackedback, because I respect him and agree with 99% of his posts, but I think you will want to upgrade from a stock converter with a XE268H. I say that because before I converted from an automatic to a 4 speed, my 340 had a cam similar to the XE268H in it, and with a stock converter, it would fall on its face from a dead stop. I swapped to a milder high-performance converter (2400 stall maybe), and it made a world of difference.
Click to expand...
Same deal below. Same converter stall. 24/2500 area. I’d call it a hair low but it’s OK. Car drives normal and a little stall when you hammer it.
rumblefish360 said:
I third the recommendations above.

I run a Hyd. roller with a 224 intake duration and 3.55’s spinning a 26 inch tire. Very nice and streetable combination.
Click to expand...
 
harrisonm said:
I have a 69 Barracuda with a .030 over 340, 4 speed, 3.55 gears, headers, Eddy Air Gap and 750 CFM Eddy carb. It has the Comp XE268H cam. It has a very nice and lumpy idle. Not a fender shaker, but you definitely know it has a high-performance cam. I have never had it on the track, but it runs like a bat out of hell. It will also melt the back tires on demand. I HIGHLY recommend this cam. I am no automatic transmission expert, but I would be shocked if your car would run well (pulling away from a stop that is) with a stock converter. I hate to disagree with @crackedback, because I respect him and agree with 99% of his posts, but I think you will want to upgrade from a stock converter with a XE268H. I say that because before I converted from an automatic to a 4 speed, my 340 had a cam similar to the XE268H in it, and with a stock converter, it would fall on its face from a dead stop. I swapped to a milder high-performance converter (2400 stall maybe), and it made a world of difference.
Click to expand...
I'm running the 484 purple shaft in my Duster with a 2200 Mopar stall, a 489 case power lock with 4:10 Richmonds in it, 225/60/15, from a dead stop,when you mat the gas, you're going to let out of it, quick, because it starts to come around, INSTANTLY! Now on the other end of the coin since I upgraded to 295/ 50/15s I need more stall! Lol
 
harrisonm said:
I have a 69 Barracuda with a .030 over 340, 4 speed, 3.55 gears, headers, Eddy Air Gap and 750 CFM Eddy carb. It has the Comp XE268H cam. It has a very nice and lumpy idle. Not a fender shaker, but you definitely know it has a high-performance cam. I have never had it on the track, but it runs like a bat out of hell. It will also melt the back tires on demand. I HIGHLY recommend this cam. I am no automatic transmission expert, but I would be shocked if your car would run well (pulling away from a stop that is) with a stock converter. I hate to disagree with @crackedback, because I respect him and agree with 99% of his posts, but I think you will want to upgrade from a stock converter with a XE268H. I say that because before I converted from an automatic to a 4 speed, my 340 had a cam similar to the XE268H in it, and with a stock converter, it would fall on its face from a dead stop. I swapped to a milder high-performance converter (2400 stall maybe), and it made a world of difference.
Click to expand...
then it was tuned wrong
xe268h 727 3.55s should be instant tire smoke at will if you so choose
i have the 268h 218 454 lift 110 106 it had 3.23s stealth and a 650 dp the xe268 only had 6 more degrees of duration
with the 3.23s and my cam in 100k lower end stock 340 from a dead stop punch instant tire smoke all the way through 1st 45 feet 5600 rpm 10 or 12 feet into 2nd
now it has 3.91s will roast the tires all the way thru 1st and 2nd 5600 both gears if i choose 90 feet
 
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That's why it says "UP TO"

Would I run the voodoo or XE268, sure. Have before in other stuff. I wouldn't go bigger than those with a stock converter. Better with a higher stall, absolutely. That's why the qualifiers are there.
 
Ironracer said:
I'm running the 484 purple shaft in my Duster with a 2200 Mopar stall, a 489 case power lock with 4:10 Richmonds in it, 225/60/15, from a dead stop,when you mat the gas, you're going to let out of it, quick, because it starts to come around, INSTANTLY! Now on the other end of the coin since I upgraded to 295/ 50/15s I need more stall! Lol
Click to expand...

484 on a 108 installed at 100-102... Runs pretty snappy.
 
i liked the 484 in my 318 340 heads and spray
sounded better then gk243@50 108 106 501 in my 340
cant find that cam
 
crackedback said:
484 on a 108 installed at 100-102... Runs pretty snappy.
Click to expand...
It's a virgin bore, with them old heavy TRW forged 10.5 :1 pistons, a seven quart Milo pan, baffled, with tray, ARP rod bolts, Cloyes timing chain, a hogged out, big valve J heads with MP heavy duty rockers, a Ported Strip Dominator, high volume oil pump, fully grooved Mains, a little 750 vacuum on the top dumping out through some Patriots. I'm kind of thinking I should have CL'd cam cuz I did not do it. I sent it straight up....
 
rumblefish360 said:
Got the link to the Howard’s cam?
Listing advertised duration doesn’t really help that much. Knowing the over lap amount does.
Click to expand...
Part # 710031-12. .450" / .465" x 267* / 277* duration @ 0.050" 213* / 223* LSA 112*. I looked, but I couldn't find valve overlap. I think it's a pretty close replacement 340 cam.
 
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