Here is my current combo, this is the original numbers matching 340 for my Duster it's a street driven car and full bodied etc. I don;t want any steeper gears then I currently have. I'm looking for more power by tweaking my current combo. Contemplating cam changes and or Edelbrock heads/Indy RHS heads but not sure if there are enough gains with the heads on a mild application.

Thoughts and opinions?

650 Speed Demon mechanical secondaries, on an edelbrock rpm intake

Stock J Heads 2.02 intake 1.60 exhaust and Crane Gold 1.5 ratio rocker arms.

3.55 gears and a 727 with 3000rpm SMR Convertor- stage 2 shift kit from transgo.

It runs a Hughes cam #heh2328al

111deg lobe seperation/installed centerline 108deg
intake lift .506/ exhaust .524
Duration@.050 Intake223deg/ Exhaust 228deg

Engine is .060 over with Keith Black Hypereutectic pistons on stock rods and a stock forged crank.

Ignition is an FBO box
Distributor was curved by Dave's Mopar in Calgary to the engine specs initial timing is 18deg.
TTI Headders with an x-pipe into Dynomax Ultra Flows

The car was tuned with an A/F meter in the tail pipe while driving, prior to the 3000rpm stall the best time down the track was 14.8 with a MPH in the low to mid 90's but the 60 foot was in the 2 second range.

I find the car lacking off the line it won't chirp the tires from a stand still even but with some rpm it goes great. Some guys have pointed that my compression with the stock J heads may be down around 9.0-1, and a head change may help that department out a lot.

Are you sure your J heads are 2.02/1.60 did you have them made or did you find the ultra rear head that Mopar claims they never made, but did!

Those where the size of the valves that where with the engine when I got it, it was rebuilt some time ago before I got the car so its possible it was done by someone or they may be factory.

I am having a body guy weld in new door striker plates so can't check the cranking press. right now.

I am in no way a pro at this but I thought I would share some info with you that may help. My 340 is running a 274/474 mopar cam bored .040 over and has x heads on it and my compression rating is 10.5:1 now the x heads have a 63cc combustion chamber were unless your J's where decked they should be around 68cc. So new heads or more work to yours could help. however you stated that you need more power off the line and I am curious with your set up and only 3.55 gears why you went to a 3000stall seems a bit much to me. Your engine sounds nice and stout hope you can get this figured out.

With that cam ( good match for what you have except for the gear) your cranking compression should be in the 160 psi range. If not, you need to mill the heads some. Your gear is the big hurter. You might want to consider a change to 3.70 or 3.91

if not change the gear, run a shorter tire. i think your car should be a full second quicker than what it is. in comparison, i used to run a 70 duster340 in calgary, bone stock, 3.23 gears, on 205/70/14's. it would consistantly run 14.20's@ 96mph. 60's were in the 2.1's usually.

The convertor was what was recomended to me by SMR with all the specs I gave him. Once upon a time ago the car had 3.91's I got a good center section for $150 so tossed it in and it was great fun around town but to go on a trip of 1/2 hour to 40mins or more sucked the 3.55's is the best trade off I found.


Hopefully tomorrow I can do a compression test and see what numbers it shows.