340 cam duration @ .050

[coupe32]

I've got an original 340 cam out of a 68 dart gts 4 speed. I can't find the duration @ .050 listed anywhere. The cam is in good shape and I was thinking of running it again possibly in my 340. Any one know what the duration @ .050 is for this cam.

[pishta]

can you mic it?> Ill take a shot:68 4 speed cam= 284/292@.464 duration (unknown @) Auto had a different cam as well as all 340's after 69 I believe, that was 276/284 @ .459 lift.

[TK]

may i point out that duration at fifty is a bad way to judge small cams, bigger cams its more usefull, so, why do you want to know?

[pishta]

Didnt Mopar measure at .003, Or some strange number that didnt cross over very well?

[TK]

um, yeah, i have somwhere alil bit o info...............looking........................ ...................

[76Charger]

Can't you just multiply the advertised duration by .850 to find the duration at @.050, crane has 340 blue print cams, they are supposed to be exact reproductions the part number is crn-969361. The specs on that cam for the duration @.050 is 210/221. Hopefully this will help you in some way.

[coupe32]

I wanted to compare the duration of a hughes 1423 cam to the 68 340 stock 4 speed cam.

[jasontlit]

According to what my book/magazine/catalog pile has to offer:

Ma Mopar lists...340 cam 268/276 duration, .429/.444 valve lift, 114 center line

Now, we know that isn't at .050, but...

Crane's blueprint musclecar cam states a 210/221 @ .050 with identical valve lift and cl. as Ma Mopar


So, Hughes' 1423 will give you a bit more duration. That's the same cam that I run in my 340. Lots of low and mid-range grunt!

[dodger1]

For what it's worth, 1968 OEM 340 manual trans cam had .445/.455 lift, intake open 26deg. BTDC; Auto trans cam was .430/.445 lift, intake open 22 deg. BTDC. 69 thru 73 340's, both auto and stick, were .429/.444, intake open at 22 deg. BTDC Haven't got the rest of the timing info. Mopar Perf. Catalog lists P4452782 as a replacement cam for "Muscle car-factory original", lift is .429/.444", and duration at .050 is 228/235, 114 deg. centreline, the same as the 69-73 340 cam. I'm runing P4452759 in my 360, .430/.450 lift, 221/228 duration, 110 deg. c/l, more exhaust lift but less duration than the 340 auto. All the lift ##'s are for the stock "1.5" rocker ratio. Cheers!

[coupe32]

Thanks everyone for the info. I'm running the 68 340 now with a tremec 5 speed. I ran the car with the stock 68 340 out of the dart 4 speed. Now its in my 32 coupe. I ran the car a while with everything stock from the original 68 engine until the rebuild. It seemed to have more low end get up and go before I switched to the 1423 Hughes cam. I was just trying to decide to put the old cam back in or just leave it alone. I had the old cam checked out by a machine shop and according to them its in good shape. Thanks again

[norcalcuda]

My experiance with MOPAR cams is, the equation of multiplying by .850 for duration @ .050, ain't even close! I've measured a .509 cam (248 deg.@.050) and a .474 cam (232 deg.@.050). I've dealt with Hughes Engines before, they want to know your car's specs. exactly, comp. ratio, weight, trans., gear ratio, and what you intend to do with it(street only-street/strip-strip only-etc.) They are serious about choosing your cam, you'll see! The MOPAR cams we're all used to are good, but, there's better stuff out there. (why they never published the @.050 specs., I'll never know.)

[fastback340]

Mopar says to multiply the factory cams by .77 to get duration at .050 and there aftermarket cams by .85 This isnt going to be %100 accurate but will get you in the ball park.

[fastback340]

Originally Posted by dodgetkboy78

may i point out that duration at fifty is a bad way to judge small cams, bigger cams its more usefull, so, why do you want to know?

Throw that crappy Mopar Performance engine manual in the garbage. If you pick your cams by Mopar Performance recommendations your goiing to be very unhappy. 90% of the info in those books may have been good 25 years ago but they need to update them bad.

[TK]

Originally Posted by fastback340

Throw that crappy Mopar Performance engine manual in the garbage. If you pick your cams by Mopar Performance recommendations your goiing to be very unhappy. 90% of the info in those books may have been good 25 years ago but they need to update them bad.

then why dont you write a book then?
im not picking cams from that manual, im saying this from experience.

[fastback340]

Why dont I write a book ? Because I dont know any weres near enough about building info to write a book.

I do know if you pick a cam by lift instead of duration at .050" you can end up with a real slug.

Lets use the Mopar Perf. 284 484" cam for example. The cam has 246 degrees of duration @ .050"

Now compare that to the Comp Cams 280 magnum. It has almost the same lift at .480" and simular advertised duration, but only 230 degrees of duration @ .050"


Now go and stick bolth those cams in your average street car with 3.55 gears a 11" converter and 9:1 compression.

The magnum cam will be a much better street peice. Thats why I feel that picking a cam any other way is a bad idea. Ofcoarse LSA and lift have to be considered too, but duration at .050 is extreamly important.

[demonman]

bobby, he's right, quit arguing and go work on your racetruck

i think what dodgetkboy78 is saying is that its not ALL you should look at

[TK]

deek, you jerk, come here pick in on me, ive been workin on my ram, when you figure out how to use your computer, go to the off topic forum, and look at well.............or, call me turkey :flip:

[fastback340]

Originally Posted by demonman

i think what dodgetkboy78 is saying is that its not ALL you should look at

That I agree with but duration @ .050" will give you a pretty good idea of what the rpm range is going to be. Advertised duration is pretty much useless because you never know were the Cam company is measuring it from. It could be at .006" or .020"

I'n not Flaming you dodgetkboy I just think duration @ .050" is a very important figure for choosing cams.

[TK]

yeah, i know, im on hte phone right now with demonmann ie deek, he sais i should quit being so touchy, am i being touchy?
PS i dont have any mopar perf engine books yeah, i know, i should get some :chainsaw:

[fastback340]

Originally Posted by dodgetkboy78

, am i being touchy?
PS i dont have any mopar perf engine books yeah, i know, i should get some :chainsaw:

Not really. Its hard to tell sometimes over the computer though.

The books arent bad for some info though. I think alot of people who are new to cars or Mopars can get steered the wrong way though. If you get a chance look at one. They can be good for a laugh.