my 340 wont rev past 4000rpm

[505challenger]

i have a 73 chally with a 340, performer rpm intake, x heads, 10-1 comp, lunati voodoo cam (duration at .050 is 226/234), headers.  the carb is a road demon 625, i think the carb may be choking it up a little.  the car in first gear wont rev past 4000rpm, i tried to free-rev it and the needle swung past 6500 .   another thing, when i putt around in third at about 1800 rpm and give it a decent bit of gas i hear it pinging(on 91 octane).  i have my base timing set at 13 degrees.  any direction is greatly appreciated.

[GoodysGotaCuda]

Certainly look into lack of fuel for your pinging and not being able to rev. Watch 'free-revving' like that, it's an awesome way to bend valves...damhik!

[Aussie Challenger]

Check ignition, I have had several distributors that had wrong springs and they wouldn't allow enough advance, also check to make sure that ignition coil is putting out enough voltage. Both of these problems have caused motors to not want to rev under load. Is it pinging or detonating?

[505challenger]

its detonating, how do i check and see if i have enough advance in the distributor?

[Aussie Challenger]

Easiest with a timing light, rev up to about 2,500 and see if the timing advances, you don't want any more than 34* - 36* total mechanical.
The other way is to remove the distributor cap and see if the rotor can be turned or advanced a bit, not as accurate but will give you some idea if the distributor is not seized in the advance area.

[Moparal]

Easiest with a timing light, rev up to about 2,500 and see if the timing advances, you don't want any more than 34* - 36* total mechanical.
The other way is to remove the distributor cap and see if the rotor can be turned or advanced a bit, not as accurate but will give you some idea if the distributor is not seized in the advance area.

Good advice   and I think after this, you should consider a bigger carb cfm to

[dodge freak 2]

The carb size is not stopping it from revving. Just for kicks before I swaped over to the dual quad 340 intake Edelbrock d 66 I had found two new 500 Carters. I took my Demon 650 dp off the rpm intake and put one of the 500 Carters on it and drove it for a few days. Motor ran smooth all the way past 6,000 rpms. Was down on power very noticeably but other than that the motor ran great.

I would look to timing and valve springs. The timing might the reason for the pinging in 3rd gear and the valve springs for the 4,000 rpm red line.

But it could be the fuel too, what fuel pump are you running. Still after letting up on the gas and trying again it should rev higher since the carb fuel blows filled back up. So I be more incline to think weak valve springs.

[505challenger]

update:  i didnt have much time to mess with it yesterday, but i pulled the cap of and checked to make sure the dist was allowing advance.  the rotor does move but i dont think its enough, tonight i plan on setting the total timing to 34 degree's, i gave it a little bit more timing yesterday and was able to hit 5k,  when i try to set my total timing later today i guess ill find out if the dist is advancing enough.  i have a chance to buy an 800cfm holley (vacuum secondary) carb, do you guys think it would be too big.  gas milage is not a concern.

[Chryco Psycho]

if the price is good on the 800 grab it , being a vacuum secondary it will not overcarb it although it is on the larger sixe for a 340 , I would typically use a 700 - 750 with a 340

[UKcuda]

On a lively 340 even a 600 cfm carb should rev. freely way over 4K.

Keep playing with carbs and timing, but if you still can't get it to rev. consider whether the cam is timed right.

Many years ago I bought a 1971 R/T 340 Challenger.  The seller (original owner) had rebuilt the engine.  It ran really strong to about 3K but after that it started to dog out and wouldn't go far over 4K no matter what. 

I tried all sorts and got it better but still it wasn't right.  I finally tracked it down to the cam was too far advanced; I degreed it properly and it went like hell in the night.