My 99.9% stock 340's would run 14 flat go 165 and get about 20 mpg on snow tires with no posi. no o.d. Stock exhaust system. I have plenty of witnesses. There may be some better stuff out there but it always worked for me. Now add 1.6 rockers, 11.0 to 1, o.d. 4.10's headers etc. what would you get today. Add a high-pressure fuel system. Wow just imagine what you'd get out of that little 340 with a 55 year old cam. O, with 55 year old heads to boot. Now ...
Replacement 68 340 four speed cams
- Thread starter FWDLK Frank
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Dan the man
Well-Known Member
165 mph in the quarter mile?
Right. All the Chrysler stuff was given advertised.
Swinger 340
Well-Known Member
I like my "OLD" simple stuff. I hear people spending thousands to gain .20 in the quarter. I don't get it, when the consistently maters. Chrysler did it right, with DC help.
cookietruck
Well-Known Member
I like this cam for a modern version of the 340 cam.
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no, 1/8 mile. lol But top end.
junkyardhero
Well-Known Member
what was the .1% that wasn't stock?
I for one can vouch for the 340s top end charge. My 73 340 Rally Charger with 78K on the clock hauled me and five friends out to the junkyard one Saturday in 1981. One of the guys in the back, Jeff Clark said "hay Rob, will it bury the 150 speedometer?" I said "I don't know, I ain't tried it yet." Then I firmly planted my foot on the floor and just held there. I had the needle pointing a little past straight down before I lifted. 150 was about at the 5 o'clock mark. The car was all original with the original 73 supposedly "lower" performance 340, stock manifolds and stock exhaust right down to the original mufflers and slotted exhaust tips. I routinely outran a school friend's 70 396/375 Chevelle. Pissed him off so bad every time he demanded a rematch. I remember only once when he got me and it was by a bumper. We all knew that car was faster and quicker than it "should" have been....and it was. It had to be all over 4000 pounds that Saturday with six of us in it. I think their curb weight is a tick under 4000. 3850 or some such? Here's the car. The guy I got it from got drunk in it not once, but twice. Hit a brick mailbox the first time and a brick wall the second time. His dad took the car from him and that's when I paid 300 bucks for the car. We found good fenders, bumper and grill for it in a local junkyard. That's why the fenders are brown. You can see the damage on the hood. That car would slap move for a big car.
Yep,
For what its worth, Schneider ground me a 264/274 .445/.450 222/230@ .050 110 lsa solid for my sons 72 340 auto Dart with 587 1.88's. power brakes and oem exhaust.
Larger carb.
Here's the specs on most of the factory stock camshafts for a SB....
I made a spreadsheet of camshaft specs and did calculations forward and backward to check if the specs were correct... I did find a few with some conflicts and was able to correct most of them from doing the math forward and back and checking with the listed specs for the cams...
Do you have the old DC catalog(s)???
Would you mind sending me a copy or pictures of all of the camshaft spec pages for all of the engines and from which catalog (year) that they are from??? Slant 6, SB, BB, & Hemi.... I would love to add them to my spreadsheet... I only have the Mopar Performance catalogs to use for specs, but would love to get the info on the old DC catalogs...
Lets see if this is more readable... (For us old guys with 'old eyes'...)
Rusty, its stories like the one about your 73 Charger and your write up RRR guide to hot rod bliss that got me interested in building a simple 340 combination.
Im 56 so i missed these cars when they were new so i want to experience the "legendary 340 " in 1968 specs... engine builder is machining the block now and estimates early spring, hes also going to break it in on the dyno, i"ll share the results....
Im 56 so i missed these cars when they were new so i want to experience the "legendary 340 " in 1968 specs... engine builder is machining the block now and estimates early spring, hes also going to break it in on the dyno, i"ll share the results....
No, the 52° overlap is based on the seat-to-seat duration numbers and matches with the lobe separation and duration figures as you can see in my charts that I posted above... I used data straight from the factory service manuals for my spreadsheets...
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114 is correct as you can see in the spreadsheet info that I posted...
Isn't seat to seat duration (advertised) and duration at 0.006 (SAE) the same?
It depends on the manufacturer and how they spec their cams... Every manufacturer has "their" way of doing it... Some do it at just after .000", some at .001", and some at .006"...
That's why sometimes it's better to compare the @.050" numbers as to the advertised duration numbers, it eliminates the 'room for interpretation' out of the different ways the different manufacturers spec their cams...
One of the reasons that I made my spreadsheets so I could get a better feel for the numbers and try to compare them more accurately...
Sorry its getting real deep
73 low comp 340 nor a hi comp 340 is not going 150 mph in that boat@ 4000 lbs the amount oh hp to do that would be double what that makes and then some
a bodys are drag limted long before 165 mph 99.9 stock
135 140 yup
145 prolly not
ive been 6100 in drive with a 27 inch tire and 3.23s with a built 340 and nitrous i had plenty of motor left
drag limted period@6100 rpm
Plus, by comparing the advertised duration to the @.050" duration, you can get a feel for the ramp speed that they use to open/close the valve...
Slower ramp speeds set the valve down more gently... Faster ramp speeds get the valve open faster so it flows more for the given duration, but sets the valve down quicker/harder... Setting the valve down too hard may slam the valve down to where it increases wear/beats up the seat...
You have to balance them to pick one that best fits your needs...
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BSB67
Well-Known Member
The 0.050” duration numbers are significantly incorrect.
Definitely. The 340 4 speed cam is 240/247 in the spreadsheet vs 221/227 from Oregon Cam who based their grind on a factory cam.
cookietruck
Well-Known Member
I was going to mention that. I just had an ultradyne H31 ground. It’s a 280 (adv) duration cam and [email protected]. So the valve events on the intake lobe are the same as the spreadsheet if ICL are the same.
I doesn’t seem likely that a factory 268 cam has the same 050 numbers and valve events as an ultradyne 280 cam.
Also ken at Oregon cam said the ‘68 340 cam was 221@050 according to a post around page 3 or 4. I think that would be the 4spd cam.
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