J Heads on a 1970 Challenger 340? Who can solve a mystery?

[kawahonda]

Good responses, guys. Are you saying that 13's are achievable with stock intake and stock heads (cleaned up, of course)?

Obviously, a cam, springs, torque converter, and rear end (3.91 or above) would be necessary.

I will keep my single point dizzy and have it re-curved. I don't drive the car often enough to demand electronic ignition.

I thought this was pretty interesting. This is why I thought the air-gap was a given"

https://www.hotrod.com/articles/mopp-0102-1970-340-high-performance-mill-dyno/

Stock: 281 HP w/ AVS carb (they didn't try to tune it)
800 CFM carb: 316 HP
Headers: 330 HP
Air Gap: 354 HP
Springs: 355.9 HP
268 cam: 391 HP

[1 Wild R/T]

Good responses, guys. Are you saying that 13's are achievable with stock intake and stock heads (cleaned up, of course)?

Obviously, a cam, springs, torque converter, and rear end (3.91 or above) would be necessary.

I will keep my single point dizzy and have it re-curved. I don't drive the car often enough to demand electronic ignition.

I thought this was pretty interesting. This is why I thought the air-gap was a given"

https://www.hotrod.com/articles/mopp-0102-1970-340-high-performance-mill-dyno/

Stock: 281 HP w/ AVS carb (they didn't try to tune it)
800 CFM carb: 316 HP
Headers: 330 HP
Air Gap: 354 HP
Springs: 355.9 HP
268 cam: 391 HP

The Air Gap by itself isn't gonna do nearly that much.... You've been asking about a 440 AVS, they aren't anywhere near 800 CFM, I believe the number is 670 CFM.... The 340 AVS is around 600 CFM... Are you planning to run headers?  Take away the headers & a big carb & suddenly that manifold doesn't do much, it's the total balanced package that makes the big numbers...   

And FWIW the stock iron manifold isn't a bad piece, pretty tall, good sized ports, in NHRA Stock class racing your required to run stock heads & intake.... Wanna be competitive?  I can't believe I'm reading the index right but if I am you need to run a 10.51 just to hit the index, winners are often a half second or more quicker....   I know there's allot of tricks in those "Stock" cars, seen a few while watching Steve Wann building engines but there is still allot more stock then you'd think to run those numbers....

[RUNCHARGER]

If you had a brand new 1970 340 all fresh I believe you could get the car into the 13's with convertor, gears and tires.
I think your engine will be down a bit on ring seal and valve seal so I would be tempted to wave a wand over the heads and freshen them a bit. Then to seal the deal I would replace your worn stock cam with something more modern and a 440 AVS would help top end.
This car (the 69 Cuda) ran in the 11's with a stock intake manifold but the heads had light porting and of course headers and a medium sized solid lifter stick. The intake is better than most and I love showing them to the Chevy guys when you beat them.