340 4 barrel and 340 6 barrel: were they really UNDERrated?

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Swinger 340 said:
The 340's were a SCAT PAC. My understanding, that meant they were in the 13.99 or better range. I still have somewhere, ads from the factory that say the 340's are a high 13 car in the "A" bodies. Also $2,800 for a 2800 lb. car. A dollar a pound.
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Stone stock they are rarely a sub 14 sec car. Would need to be 3.91 gear car with low options (weight). The stock small carter AVS carb is a killer. The 71’s got bigger TQ carb but other stuff hurt a little.

No stock factory 340 A-body weighed anything close to 2800 lbs. Maybe 3100-3200 lbs. for a no option front drum brake car.
 
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Slant six early A bodies may have been 2900 lbs or less but I call BS on any 67-76 A body V8 car being under 3000 lbs.
 
KevinCar said:
I think you nailed it when you said tuning, we all know 5btdc and factory tuning, proper performance tuning of ign curve, carb etc really wakes up the 340, or any motor. 300hp @3100 # can net high 12s, 375hp could be high 11s given a good track and driver. You guys must be hella tuners on points back in the day to get 375hp tho, but with fuel back then and considering a more true 320 hp from factory. I can see it. Those were the days!
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Both my 340's have points (duel). It takes me about an hour to get them just right. I just last year did a tune up on my 69' Dart after 60,000 miles. The points were clean but had a little wider gap. Spend a little extra time in your set-up, it will be rewarding.
 
Swinger 340 said:
The 340's were a SCAT PAC. My understanding, that meant they were in the 13.99 or better range. I still have somewhere, ads from the factory that say the 340's are a high 13 car in the "A" bodies. Also $2,800 for a 2800 lb. car. A dollar a pound.
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I believe every magazine (???) that tested these ran 14.00 or slower. Tick'n off a 13.9 was no walk in the park for these cars from the show room. And those that I know that bought them and tried them never got a 13 either.

Was it Drag Racer Ken Quigly that ran 14.08 @ 97 mph with a '71 340 Duster??
Ronnie Sox got 14.07 @ 100 mph??
 
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autoxcuda said:
Stone stock they are rarely a sub 14 sec car. Would need to be 3.91 gear car with low options (weight). The stock small carter AVS carb is a killer. The 71’s got bigger TQ carb but other stuff hurt a little.

No stock factory 340 A-body weighed anything close to 2800 lbs. Maybe 3100-3200 lbs. for a no option front drum brake car.
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I say the GTS, yes will be heaver, but the 340 Swingers that did not have all the options standard, were lighter, that = quicker.
 
RLF Cuda said:
Having owned my '68 340 FS FB 727 3.55 rear Cuda since June 1969, I know a fair amount about how it ran. I purchased it with 17000 miles on it and the previous owner said it turned 13.7's at 102. I took the car to all the strips in the LA/LB area, especially OCIR, and turned in the 13.50's to 13.60's at 104+ all the time. With 3.55 gears, I went through the traps at about 6200 in second or shifted to 3rd at 5800 but turned the same times. With gears and better tires, it probably would have been in the 12's.
The Mopar Bible had a ET/Speed calculation and with the weight of the car and driver (i weighed 175 back then, not now), the calculations showed about 320 HP which is consistent with other reported values for a stock older high CR 340.
Being an A727 car, it shouldn't have had the 4sp cam, but the way the engine ran, that wouldn't have surprised me. The car was an earlier build of December 7, so how knows what they did back then.
All I can say is that a large number of 340 Dusters and Darts in SoCal at that time could also turn 13.70's to 13.90's if the driver knew what he was doing. So, my 340 was a little faster than most, but not by a lot.
I saved a bunch of timing slips from OCIR and attached a photo to show that this was real. No 0 to 60ft times back then, bummer.

View attachment 1716391757
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How stock was it when you bought it from the previous owner that raced it?

Stock carb, intake, headers?

Was the distributor recurved? Common to have performance turning shops back them with wheel dyno.
 
318willrun said:
I believe every magazine (???) that tested these ran 14.00 or slower. Tick'n off a 13.9 was no walk in the park for these cars from the show room. And those that I know that bought them and tried them never got a 13 either.

Was it Drag Racer Ken Quigly that ran 14.08 @ 97 mph with a '71 340 Duster??
Ronnie Sox got 14.07 @ 100 mph??
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Those magazine cars were tweaked.
 
Swinger 340 said:
I say the GTS, yes will be heaver, but the 340 Swingers that did not have all the options standard, were lighter, that = quicker.
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A 69 swinger with rubber mat, no radio ordered, manual steering, manual drum brake, dog dish hubcaps, bench seat… is still a 3100-3200 lbs car.
 
I had this idiot swear at FBBO that his '70 Satellite weighed 3200 lbs. When I asked him if he had ever weighed his car, he admitted that he didn't need to because the published specs for his car were 3200 lbs.
Yeah...My EX wife is only 115 lbs too....

01 A2A.JPG
 
318willrun said:
I believe every magazine (???) that tested these ran 14.00 or slower. Tick'n off a 13.9 was no walk in the park for these cars from the show room. And those that I know that bought them and tried them never got a 13 either.

Was it Drag Racer Ken Quigly that ran 14.08 @ 97 mph with a '71 340 Duster??
Ronnie Sox got 14.07 @ 100 mph??
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I believe the quickest '68 GTS magazine test was a 14.39 beating a 440 R/T that ran a 14.40. The hemi in the same article was running so poorly they couldn't get it into the 14s. Also, remember curb weight and test weight are NOT the same thing. They advertised curb weight (no fluids). My son's '67 Barracuda fastback with only two bucket seats and a HEAVY roll bar with a 383/4sp weighed in at just over 3,200 lbs.
 
autoxcuda said:
Those magazine cars were tweaked.
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100%

there is no way that they sent bog standard units plucked from dealer inventory. they were special prepped heaters just for publication.

and if you think otherwise, or if you think it was only ma mopar playing the funny business then have i got a bridge to sell you!
 
Tweaked in what way ?

Tuning ?
Bug's worked of them ?
Better tolerances ? or pick the fastest that probably had better tolerances.
Actually put non stock parts and or mods to them ?

First two ain't so bad what most would do if running them regularly.
Third one is somewhat cheating.
Fourth would be a for sure cheat.
 
My 68 gts 340 auto 3.23s spring clamps timming bump otherwise stock with the chit small stock carb ran 14.30s@ 97 mph with 85k on it
Had drum brakes console power steering factory undercoating weighed 3610 with me in it 1/4 tank of gas
3.91 cars turned 99 mph
With a 4spd 3.91s sticky track timming bump and you had the smaller cc chambers i could see the mid 13s it was not the norm
Bigger carb traction and a tune with a good driver was low 13s@103 to 105
Think ronnie sox ran 13.98@100 4spd 3.91 duster
Never forget sucking the paint off a 69 ss 396 4spd 4.56 headers chevelle he had a big mouth 5 cars outta the hole he was comming but coudnt get by me before the 1/4 ended he was pretty quiet after
 
The worst ringer of all time was the GTO (I believe a '64). Royal Pontiac pulled the 389 and put in a built 421. I believe the magazine tests had it running 12s...
 
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RLF Cuda said:
Having owned my '68 340 FS FB 727 3.55 rear Cuda since June 1969, I know a fair amount about how it ran. I purchased it with 17000 miles on it and the previous owner said it turned 13.7's at 102. I took the car to all the strips in the LA/LB area, especially OCIR, and turned in the 13.50's to 13.60's at 104+ all the time. With 3.55 gears, I went through the traps at about 6200 in second or shifted to 3rd at 5800 but turned the same times. With gears and better tires, it probably would have been in the 12's.
The Mopar Bible had a ET/Speed calculation and with the weight of the car and driver (i weighed 175 back then, not now), the calculations showed about 320 HP which is consistent with other reported values for a stock older high CR 340.
Being an A727 car, it shouldn't have had the 4sp cam, but the way the engine ran, that wouldn't have surprised me. The car was an earlier build of December 7, so how knows what they did back then.
All I can say is that a large number of 340 Dusters and Darts in SoCal at that time could also turn 13.70's to 13.90's if the driver knew what he was doing. So, my 340 was a little faster than most, but not by a lot.
I saved a bunch of timing slips from OCIR and attached a photo to show that this was real. No 0 to 60ft times back then, bummer.

View attachment 1716391757
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The story does not add up
6200 in 2nd even with a 27 inch tire is 96 mph with zero slip if already in the traps you are not getting to 103 104 mph
100% stock a-bodys factory timming and small carb do not run 13.5 to 13.7
 
273 said:
Tweaked in what way ?

Tuning ?
Bug's worked of them ?
Better tolerances ? or pick the fastest that probably had better tolerances.
Actually put non stock parts and or mods to them ?

First two ain't so bad what most would do if running them regularly.
Third one is somewhat cheating.
Fourth would be a for sure cheat.
Click to expand...

Different timing, non stock advance curves, different jetting.

They were build for press fleet. All kinds of little things.
 
Thats correct mph is hp 97 mph is a high 13 with a good 60
99 mph is mid 13 with a good 60
103 105 is in the 12s
stock timming small carbed stock tires coudnt 60 foot to get those et times@99 mph
 
Newbomb Turk said:
Six pages in and I need to say ET doesn’t mean JACK ****.

So stop using it.

MPH is HP.

Looking at ET is idiotic.
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Yep.

The good 340 cars ran the MPH (98-100), which is enough to grab a 13.20-13.50 timeslip... IF you could get it to hook. No OFF THE SHOWROOM car was going to do that and slog a 1.85 or better 60'. It's the low 13's drivetrain tied to a 15.00 chassis conundrum.

You start tuning, curve distributor, tune carb up (or put a 440avs on it/looks stock), take off air cleaner, eject PCV, clamp the snot out of the springs remove rear clamps, soak tires, ditch sway bar links, loosen front end, change/drill shocks of fluid up front and on and on on on on. It's not SHOWROOM anymore the moment you turn a wrench on it.

Back to the sidelines.
 
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Rule of thumb of "Potential" is distance divided by MPH. So, 1320 divided by 99 mph shows "potential". HOWEVER, most street cars cannot hit that potential due to the need for a great 60 ft time. With street tires, and factory converters, that 60 ft isn't happening, and neither is the ET. To run the MPH divided by distance you almost have to be set up like a bracket car. High stall, good gears, tires that bite.
 
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RLF Cuda said:
Having owned my '68 340 FS FB 727 3.55 rear Cuda since June 1969, I know a fair amount about how it ran. I purchased it with 17000 miles on it and the previous owner said it turned 13.7's at 102. I took the car to all the strips in the LA/LB area, especially OCIR, and turned in the 13.50's to 13.60's at 104+ all the time. With 3.55 gears, I went through the traps at about 6200 in second or shifted to 3rd at 5800 but turned the same times. With gears and better tires, it probably would have been in the 12's.
The Mopar Bible had a ET/Speed calculation and with the weight of the car and driver (i weighed 175 back then, not now), the calculations showed about 320 HP which is consistent with other reported values for a stock older high CR 340.
Being an A727 car, it shouldn't have had the 4sp cam, but the way the engine ran, that wouldn't have surprised me. The car was an earlier build of December 7, so how knows what they did back then.
All I can say is that a large number of 340 Dusters and Darts in SoCal at that time could also turn 13.70's to 13.90's if the driver knew what he was doing. So, my 340 was a little faster than most, but not by a lot.
I saved a bunch of timing slips from OCIR and attached a photo to show that this was real. No 0 to 60ft times back then, bummer.

View attachment 1716391757
Click to expand...
You didnt say if your car was modified in any way or if it was showroom stock, you purchased it used, did the previous owner do any changes to it that you know of? The whole conversation here seems to say that a stock 340 wont run what you said you ran, but you are showing proof in the slips.
 
Kern Dog said:
Mopar Muscle magazine August 2017:

View attachment 1716390853

While looking through this, I ran across this article:

View attachment 1716390854

The text of the article stated that with this test engine, they claimed to use the stock cam, stock compression ratio but roller tipped rocker arms…

View attachment 1716390856

They show 320 HP compared to the factory rating of 275 on the 4 barrel.
Really? The 68-70 440 Magnum had 100 cubes on the 340 and has been found to actually register between 335-350 Hp despite the 375 HP rating.
Taking it further, they swapped on a 6 barrel induction and scored 356 HP.
Again, really ??

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I ask this because it seems exaggerated to me.
I’m building a 1990 360 with compression in the mid 9s, #308 heads, 1.6 ratio rockers and a Hughes roller cam with .544 lift, approximately .100” more lift than a 340 cam. I’ll be running a Holley 750 and 1 5/8” headers but I can’t imagine that I’d be at 376 HP with my combination. Their claims seem too high.

View attachment 1716390858
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Sure they were under-rated, but they were also dyno’d differently. I think thw article's results are higher than actual.
 
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