New to me 73 duster 340

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t2ae said:
So update. The block is bored .60 over. Has a 9 1/4 rear end with the 3.23 gears with a tork lock gear carrier. Trans shift kit is set to shift at 5k. Has j heads that are ported with triple seat valves.
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Post a pic of the rear axle

axle ID.jpg
 
I’ll be happy to. I just found where he had specs typed out. So I don’t know if that is 100%
 
Also found he had a summit 600 carb new in the box. Any reason to swap that out for the older Holley 600 on the car? Other than it is newer and chrome?
 
t2ae said:
.Also found he had a summit 600 carb new in the box. Any reason to swap that out for the older Holley 600 on the car? Other than it is newer and chrome?
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I don't remember if you told us what type of intake (model and single or dual plane) was on your 340. I've never been a fan of the Holley 600 vacuum secondary carbs, but given that you have a brand new in the box one available, I'd swap it out to eliminate the carb as a culprit to the poor performance. I'm assuming both carbs are vacuum secondary and not double pumpers? A lot of people will disagree, but I always lean towards a double pumper Holley for a car tuned for performance, especially on a single plane intake. Properly set up they will run circles around vacuum secondary carbs. I think you need to optimize the combo you have and then determine what you want to with the car. As mentioned before, make sure your getting the right amount of timing and fuel delivery. The stock vacuum secondary spring (black, I believe) may not even allow the secondaries to open fully, which will definitely kill acceleration.
 
middleagecrisis said:
I don't remember if you told us what type of intake (model and single or dual plane) was on your 340. I've never been a fan of the Holley 600 vacuum secondary carbs, but given that you have a brand new in the box one available, I'd swap it out to eliminate the carb as a culprit to the poor performance. I'm assuming both carbs are vacuum secondary and not double pumpers? A lot of people will disagree, but I always lean towards a double pumper Holley for a car tuned for performance, especially on a single plane intake. Properly set up they will run circles around vacuum secondary carbs. I think you need to optimize the combo you have and then determine what you want to with the car. As mentioned before, make sure your getting the right amount of timing and fuel delivery. The stock vacuum secondary spring (black, I believe) may not even allow the secondaries to open fully, which will definitely kill acceleration.
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Thanks for the great reply! The intake is a ld340 , yes both carbs are vac secondary unfortunately. Just the one that is on the car is an older Holley and the one in the box is a newer summit.
 
I don't know much of them but some carbs you can adjust the secondary spring tension so it pulls open easier (faster) not sure on yours. Probably some Holley online videos?
 

Vacuum secondary??

That’s your performance issue. That’s the difference between the AVS2 and the Performer. The Performer is mechanical secondary where AVS2 is vacuum and your engine if cammed up, doesn’t have vacuum.
 
Wvbuzzmaster said:
Vacuum secondary??

That’s your performance issue. That’s the difference between the AVS2 and the Performer. The Performer is mechanical secondary where AVS2 is vacuum and your engine if cammed up, doesn’t have vacuum.
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Interesting!
 
middleagecrisis said:
The stock vacuum secondary spring (black, I believe) may not even allow the secondaries to open fully, which will definitely kill acceleration.
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I agree with this. The stock Holley spring and an aggressive cam do not go together. I have a spring kit, and just put in the lightest spring, see how that works, then go up from there if necessary.
 
middleagecrisis said:
It’s not going to perform like a modern turbo charged engine. You should still feel the engine pulling harder and revving faster as the RPMs build with a high-performance cam. Does the car have fresh super unleaded fuel in it, or is the fuel old? Also, with the engine off and the air cleaner off, if you actuate the throttle lever on the carburetor, do you see it squirting gas into the primary side of the carburetor? The accelerator pump definitely needs to be working on the carburetor to get it moving. A carburetor that needs to be rebuilt definitely won’t do any favors for the way the engine runs.
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I don't drive my 340 Dart much these days, about an hour each month, to keep things in working order. I do need to replace the accelerator pump every two years.
 
Yes, that’s the only thing I can think of with the mechanical event distributor. That would explain why you would have to have it at 30° advanced to run correctly. I’m sure somebody else will reply if they have any ideas.
 
t2ae said:
Is it crazy for the engine to want to be around 30 advance at idle?
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I didn’t consider the distributor could be set up with a locked out mechanical advance. Does the timing light show advance beyond 30 degrees when you rev the engine?
 
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