Trying to sqeeze more out of my 340

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joes68340s

joes68340s

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I am running a 71 340 Duster drag car 2950 without me. 13-1 comp small 570 lift solid cam mild port X heads strip Dominator manifold 780ish carb 4.88 gears 29x12 slicks. It barely 60s in the 1.59 to 1.62s. 727 Coan 5200 convertor and runs 11.33-11.40 at 118 mph. I don't want to tear into motor but Im looking for some way to pick up 60 ft . Oh yah it traps at 7100-7200 rpm Back to the motor I had thought about moving to rpm airgap in hopes of picking up some bottom end or carb spacer on the Dominator. Any thoughts I would like to hit high ten with it if possible without opening motor.
 
Try a M1 or Super Victor intake.What RPM are you launching at?How old is your converter/tranny? I run a 10.5 to 1(pump gas) Eddy headed 410c.i with M1 intake,AED850 dp,904 with 8 inch 4500 Coan.Rear is Dana 4:30 with 29.5x12. 3180 lbs with me in it.Car runs 10.60@123 mph 60ft 1.44.Crosses the stripe at 6200 rpm. View attachment image.jpg
 
Well Im not throwing money for heads on that motor. low 11s will just half to do.
 
Well, I am not sure how much a Victor or Super Victor would add without better heads. You are really at the point where heads is where the bottleneck is. After that, it will be cubic inches.
 
I agree with these guys, the heads are the limiting factor, then eventually you're gonna want a stroker crank, bigger cam, bigger carb.

If you can video tape your tachometer during a run it would tell you if you're converter is really stalling at 5200 or not. Stock stroke 340's have to Rev. I really like 8" ATI converters, I drive them on the street and at the track they will 60 foot in the 1.3's. If you can bring your 60 down a tenth it can equal 2 tenths in the 1/4.
 
at 118 mph ...low 11 is what you got power for.....with 5200 stall speed....the only intake I would change out to work be a 340 Victor...not a mopar m1 nor a super victor...
 
As stated before better heads and intake with that compression ratio..
 
Ok, if I were to look for heads at this point what would be the better for my setup as I have JE domed pistons. And obviously I would want to use the heads for future engine.
 
Don't know all your suspension data but I put on a set of assassin bars and good shocks. Out of the box went 1.51 60ft no tuning yet. That's something that will go with whatever motor choice you make.
 
Full Caltrac setup with adjustable rear shocks. Im still looking for more out of them.
 
Are you sure the convertor flashes to 5200? Years ago I was running a $225.00 GER convertor in my Demon and everybody was telling me I need to buy a good convertor. I bought a $600.00 Coan 10in Race convertor and put it in the Demon and I slowed down over a tenth in the 60 ft. Now I want run anything but a PTC convertor.
 
No Im not sure. It dosent like to be loaded just flashed off idle and Im not sure I don't think it does.
 
What's your 1st gear ratio in your tranny? 2.75? For a 904 about 250.00. 727 triple that price. But it would help your 60 ' time if you can keep traction. Just a thought.
 
If you have a vs carburetor, switch to a dp. You might try a Super Sucker type spacer. And sealing the carb to the scoop.
 
Have a dp that I just had a bunch of work done to it. I need to work on better 60s. It will pull the front tires off the ground when I hit it right.
 
what tranny arte you running 904 with low first gear will help if not, remember when looking at heads going from steel to aluminum you will loose some compression for heat disapation and will have to have some milling done to make for it, the super suckers work great and may help, what hood and scoop are you running, could go with a roller cam but that a thousand bucks or so
 
Im not sure what to do about the pop up piston and a small closed chamber head. I am running a 727 not sure whats going to cost more a conversion to 904 or heads.
 
take weight out of the car.......

what shocks are on the front of the car?
 
go with a good 904 with low first gear if you like your motor set up, you are pretty well gauranted to pick up et 1 to 2 tenths, make a ram air kit for your carb if you have the factory scoop and hole cut in hood , take a old factory air cleaner lid , turn upside down, cut center out to match carb , jegs or summit sells some foam that a couple inches thick and the same wide, glue around outside of the lid, make a bracket to hold it on good, may have to trim for hood to shut good, go try it at track, it was the cheapest hp and et ever got around a tenth, good luck:D
 
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