I have a fresh short block 340 that I am looking to get into the 12s with. 30 over, stock stroke, replacement "10.5" compression pistons. No cam or heads yet. Victor intake, msd ignition...3.91s and an auto trans (2400 stall converter but realize it'll prolly need more). This is another "budget build" and not looking to run spray or forced induction.

Set of cleaned up Eddie heads. Cam and rockers for 600 or so gross lift, mild 240 ish@50 flat tappet cam and a nice 750 carb and your there. It would get well into the12's with a different convertor.

9.5:1 CR
224@.050 duration
273 rockers
2.02/1.6 pocket ported irons
Air gap w/750 Edelbrock/650-700 Holley
1-5/8" headers/2.5" duals

= = = = = = =

12's on a budget!

Want more?

Upgrade to 1.6:1 roller rockers, and correct the geometry.
Get a good 32-3500 converter

I bet that above combo wouldn't run 12's in a stock weight car with that 2400 stall convertor.
The stock cam is about that big, and stock 340 is 10.5 compression, not 9.5. Sounds like a mid13's combo to me....... But who knows.

Yeah, I originally built that combo to go high 13's in a stock weight '72 Duster. It actually had a smaller cam, performer (no RPM) manifold, and a 625 Carter AFB. It went 12.90s with a 3.55 gear and 2200 converter.

Changed to 1.6 rollers, air gap manifold, and a 750 Edelbrock carb, did a little more work to the heads, and went 12.30s. It's ALL about the combination.

Great job. Surprising ET. Impressive.

Thanks!

I never expected those results myself, but it definitely changed the way I cam my engines these days, especially pump gas street motors.

I did get ahead of myself when I hit submit on that last post. I forgot to mention that we changed the gear from a 3.55 with a 25.5" tire, to a 4.10 with a 28" tire, and the converter to a 3500 when we went 12.30s. I'm sure the converter helped a lot, but the gear probably not so much with the tire change.

My wife's Challenger, though it is a 360. 9-1,224@050" hyd roller. ported smog castings, LD340, 650 Holley, TTI headers and full exh. 275radials 3.55, 4 speed 2.42 1st gear. In street trim 12.70@108.
doug

Awesome loving the info guys and do appreciate it! I do have some altitude fighting me, 2700 and in the summer a lot of times 4000+ corrected. Ideally I'd like to run iron heads simply for the originality look but obviously there's a time to draw the line on et goals vs looks.

Most of our Mopars members over cam their small blocks. Matts 1970 duster runs 10.50's with a 520 solid Racer Brown cam at over 3000 pounds.

easier to do in a Duster. The Challenger is probably 800lbs heavier.
So using a stock bottom end 340 you'll want as much compression as you can handle. You'll need a decent set of heads, decent cam, and much more stall. Now if you want to use a 440 it's much easier.

My husband's small block '72 Challenger weighs 3,340 pounds. My small block '73 Duster weighs 3,300 pounds. Both all metal body full interior street cars.

.

3,340 w/ gas and all fluids? I think the shipping weight on Challengers was almost 3400??? Plus a 71 Duster had a shipping weight of 2900lbs. 73's got a bunch of bumper...lol

Both had 1/2 tank of gas, all fluids, same weight on 2 different certified scales. The Challenger is a 727 auto and the Duster a 4-speed. I know that heavily optioned big block/Hemi E-bodies can be porkers, especially convertibles.
The '73 Dusters do have a bunch of bumper, lol. And they have some door and roof reinforcements the earlier Dusters don't have.

My buddies 73 Challenger 340 with auto weighed 3500 when he had it weighed.

The Challenger is certainly heavier, but unless it is a highly optioned BB/Hemi convertible, I doubt it's anywhere near 800 pounds.

Btw, what does the compression do for it?

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That's what I'm talking about, Doug! A car that is a pleasure to drive, and still gets it done when the pedal is on the mat. Very nice car!

A 360, j head with an xe268H in a Demon can run 12.50's or better in the right hands.

Takes work to fine tune the combo and with an auto, the converter is key.

I would not use a victor intake on a 340 unless it has plenty of stall. The TQ the victor leaves at lower rpm compared an Air Gap is pretty big. If you have to accelerate through that range, the victor will lag.

ST-21 cam? 254* @ .050??