I estimated them based on the Mopar Performance cams in the catalog... They don't list them in the service manual, so I winged it...
Replacement 68 340 four speed cams
- Thread starter FWDLK Frank
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I estimated them based on the Mopar Performance cams in the catalog... They don't list them in the service manual, so I winged it...
I agree,I think hes shooting for 10:1 or 10.5:1
BSB67
Well-Known Member
Generally speaking, the very fastest hydraulic FT cams will have about 42 to 44 degrees less duration than their advertised duration at 0.050”. Examples are Lunati Voodoo and Comp’s Mopar only HL lobes. This rule will change a bit if the supplier’s advertised duration is measured at something other than 0.006”.
Most every MP HFT cam I’ve measured runs about 48-50 degrees less duration at 0.050 than advertised duration.
Most every MP HFT cam I’ve measured runs about 48-50 degrees less duration at 0.050 than advertised duration.
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Thanks, Karl. I thought that was right.
Mine was NOT a 73 car or motor or 4000lbs. It was a 68 formula S 4 speed with 27+ inch tires 3.23 gears and still pulling at over 6500 rpm. And the tach checked good to my Snap-on meter. You figure it out. Or are you math limited too.
The 340 cam intakes at .050 were around 210-212 for auto and 220-222 for the 4 speed.
Must have been the .85 of adv duration deal they used to use in that spreadsheet? Cool spreadsheet.
Had a few results from a cam doctor. The old reliable 214/224 was bigger than a stock auto cam.
Must have been the .85 of adv duration deal they used to use in that spreadsheet? Cool spreadsheet.
Had a few results from a cam doctor. The old reliable 214/224 was bigger than a stock auto cam.
Stock 340s dont rev 6900 in 4th thats 165 mphMine was NOT a 73 car or motor or 4000lbs. It was a 68 formula S 4 speed with 27+ inch tires 3.23 gears and still pulling at over 6500 rpm. And the tach checked good to my Snap-on meter. You figure it out. Or are you math limited too.
Valve float way before that
Drag limited no shot
The amount of hp to reach 165 is crazy
stock 340s make at best 340 hp with the big carb downhill with the wind
my math is fine unlke your tach
Typical sized cars heres the formula ( yours would be worse)Mine was NOT a 73 car or motor or 4000lbs. It was a 68 formula S 4 speed with 27+ inch tires 3.23 gears and still pulling at over 6500 rpm. And the tach checked good to my Snap-on meter. You figure it out. Or are you math limited too.
Top speed (mph) 20 times cube root of horsepower
Example 400hp cube root is 7.36; times 20 is 147 mph
the hp climbs exponentially much high the faster you go aka drag limted
So your magic 340 was making what 550 600 hp @ 6900 with stock valvetrain gotcha
rusty would need about 700hp no problem with his magic low comp 340 at 4000 lbs
Some of us nostalgically remember our cars being faster than they were. A '70 340 Dart went 14.5 in the quarter. The fastest car back in high school (45 years ag) was low 13s and it had been heavily modded.
You tell that to the FIVE other guys who were in the car with me all looking at the speedometer.
Using an online calculator, and using the 2.76 gear my car had with the 25.7" E 70 14 tires, I got 5412.61 RPM at 150MPH. So more speed was a 100% possibility. I buried the speedometer in that car more times than I can remember.
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junkyardhero
Well-Known Member
don't nobody let physics get in the way of piss poor hot rod folklore!
ya know them pesky things like frontal area, drag coefficient, rolling resistance, **** like that.
possible, sure. probable, nah.
ya know them pesky things like frontal area, drag coefficient, rolling resistance, **** like that.
possible, sure. probable, nah.
No they weren't. They were recaps. They were all I could afford. Hay, I don't really give two ***** if you fucks don't believe it. I was there. I lived it. I know what the car did and so do a lot of other people. I didn't need yalls' approval before I found this place and I sure as HELL don't need it now.
Gee I guess you never heard of a tune up. O wait you thought putting spark plugs in was a tune up. Valve spring maintenance is part of a real man’s tune up. O wait have you ever heard of points? Ya this was on points, but you probably don’t know what a distributor machine is either. I just have to wonder why my cars were freaks or maybe because I knew what I was doing, even back in the day. Here’s a real brain teaser, why would you put a toggle switch on your points? And it’s Not for a kill switch.
You do know tire ratings are for a set extended period of time don't you? I have a feeling some commenters here haven't intentionally set out to see what a car could do "flat out." Even a lowly stock 305 2 barrel '78 camaro with 3.08 gears can top out the 130 mph speedometer. I can tell you from first hand experience from "the death seat" that Dunlop Qualifier G/Ts will leave brownish colored rubber tracks on the road with the combination of speed and downforce.
They're not interested in real world experience. All they can get their heads around are specs, slide rules, calculators and the like. Half of these guys have probably never been triple digits in their lives.
I worked in a Sunoco gas station in the 60’s and they had come out with Kevlar belted tires in the late 60’s, they were great but I can’t recall what name they were. And we sure used up a lot of Volkswagen front tires and fortunately I never had issues but I always kept good rubber, brakes and steering on my hot rods.
Wow. Do you feel better now? Anger issues perhaps? After being around here for awhile you would think you knew better than to rant on folks like that. Nobody cares if you went 150 or not. I try not to ridicule people here on their false or mistaken claims or call bs. Why would one do that? Plus I know some of you are old and don’t have all of their faculties.
Ps I wasn’t even commenting on your claim. I was just joking that the tire technology didn’t support that kind of speed back then.
Did I reply to anyone? No. Then shut up.Wow. Do you feel better now? Anger issues perhaps? After being around here for awhile you would think you knew better than to rant on folks like that. Nobody cares if you went 150 or not. I try not to ridicule people here on their false or mistaken claims or call bs. Why would one do that? Plus I know some of you are old and don’t have all of their faculties.
Ps I wasn’t even commenting on your claim. I was just joking that the tire technology didn’t support that kind of speed back then.
Slide rulers. Well I think I can beat that I was just diging around in my car and found a floppy disc. Damn where in the hell did that come from?? Guess it’s time to buy another one. Car not disc.
mopar head
DoD Alien/Squatch slayer
Cabin fever up in this beech too 
No cabin fever at all. I just don't like people insinuating I'm lying. I have no reason to do that.Cabin fever up in this beech too
I’m going with old and crotchety.
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