340 tuning

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old swinger

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1 have a 340 with j heads slight match port and bowl work 0 deck pistons running 231 238 @50 cam .485 .501 lift 110cl installed at 106 hp electronic dist. mopar msd 6al box 650 dp holley 340 victor intake looking for tuning tipps 67 74 jets .028 squirters 12in vaccume running 6.5 pv bad bog in transition 904 torqueflie 801 turbo action converter 3.55 gear have pink pump cam on secondary comes on ok from launch but bad at low speed rolling to full throttle not real experienced with holley dp any help much appreciated cruise seems ok
 
Two things. First, do us all a favor and use punctuation and separate sentences. Not being the grammar police, but it sure helps make reading easier.

Ok. You have a bog because IMO you have the wrong carburetor. On a mild build with an automatic, you need a vacuum secondary carburetor. A 3310 750 would probably work fantastic as is.
 
check to make sure that the accelerator pumps are adjusted correctly...if you move the throttle the pumps should squirt...also at wide open throttle there should be .015 clearance between the levers...also check the squirter size too...the number is stamp on it...

and as always make sure your timing is correct.....

[ame="https://www.youtube.com/watch?v=b4eJXoEraVk"]Accelerator Pump Adjustment - Holley Carburetor DIY - YouTube[/ame]
 
Holley has a pretty good website with DIY video's on it.
Also I would suggest buying a book on Holley carbs, they are really reasonable.

What is your initial and total timing?
 
A Victor intake?And a 650dp,And no stall spec. =Mismatched. Nice cam, dont change it.

You need a nice dualplane intake, and a vacuum secondary carb(as mentioned), and quite possibly a bit more stall,and likely more low speed timing.
I would change the intake before anything else.
 
I also have a LD340 intake which would probably work better . thanks for help also have been looking into timing and pump tuning of carb . Again thanks for pointing me in the right direction.
 
old swinger said:
I also have a LD340 intake which would probably work better . thanks for help also have been looking into timing and pump tuning of carb . Again thanks for pointing me in the right direction.
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No "probably" to it. The LD340 will stomp the Victor in your situation. That will be a good swap.
 
To he OP, what is your base and total timing?

Also, you do not need a vacuum secondary carb. Your DP will work just fine, in fact better if tuned properly.

You can tune that victor to work. DOn't change the intake. It isn't your problem.
 
I'm siding with changing the intake. I won't waste my time debating it.
I had a 650 DP provide similar performance to a 750 vacuum, but that was on a race-only combo. A 3310 would work better, be easier to tune and provide better gas mileage on yours..
 
Locomotion said:
I had a 650 DP provide similar performance to a 750 vacuum, but that was on a race-only combo. A 3310 would work better, be easier to tune and provide better gas mileage on yours..
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Agreed and that is why many recommend vacuum secondary carbs for "street" or "auto" cars.
 
my initial timing is at 8degree before on crank damper at idle . have cheepo billet distributor set 26 degree total no vaccume. Im going back to mopar distibutor and have been reading up on how to limit mechanical advance to 18-20 degrees to pick up inintal to 14 degree . Any help appreciated on distributor tech ,springs to use ext .
 
Find the point the engine wants at idle and go from there, not the other way around. Don't just pick a number. Initial at 14* is stock camshaft 340 territory and you have a bunch more camshaft than a stock engine.

If it starts when hot with 20*+ no reason to not run it there. The idle will be tons better!
 
And if you have a 3800 TC, the 650dp is a fine starting point. But yeah, fix the timing. 8/26 is waaay laaazy. You cant solve that with all the pump-shot in the world, on that Victor.
install the LD, bump the timing to 34 max, call it done.Lets go have some fun!Then you can sneak up on the power timing.

If youre running 8/26 that means theres 26-8=18 in the centrifugal currently. The target power-timing on your 340 is probably 36. So 36-18=18idle timing. nothing wrong with that. Try it. Actually, as above set the all-in to 34. That will get you 16 initial. Then sneak up on the power timing. If you end up at 36/18 that would be a big improvement. Write that power-timing number down. Then go sneak up on the idle timing. If its happy at 16 to 18 you are done. But if it likes 20/22/24 or whatever, then you are needing to mod the centrifugal.
Certainly you can do it from the bottom up, but you better not go full load/wot, at the risk of detonating the pistons out of it.
 
old swinger said:
my initial timing is at 8degree before on crank damper at idle . have cheepo billet distributor set 26 degree total no vaccume. .
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Now here it is in black and white.

As I said, your issue ISN"T the double pumper. It ISN"T the Victor intake.

Leave the current dizzy and curve in it and try.

Try 18 initial, 36 total.
 
roccodart440 said:
Now here it is in black and white.

As I said, your issue ISN"T the double pumper. It ISN"T the Victor intake.

Leave the current dizzy and curve in it and try.

Try 18 initial, 36 total.
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All of that still doesn't mean his induction system is not a mismatch, because it is.
 
thanks guys im gonna try timing and setting intial up with vaccume gage, doing some tuning and tweeking this weekend . See how it goes then check back in.
 
My last 340 had Holley strip dominator and 650dp, similar cam and compression. It liked almost 20 degrees initial timing. I agree that intake is not the best for the combo and if you have another dual plane intake already, I would definitely be changing them out at some point. But get the timing figured out first, then mess with the carb.
 

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gtsdude said:
But get the timing figured out first, then mess with the carb.
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Bingo

Timing then set carb. If you don't end up happy then change your intake. If that doesn't make you happy then change carb last.
 
roccodart440 said:
Bingo

Timing then set carb. If you don't end up happy then change your intake. If that doesn't make you happy then change carb last.
Click to expand...

Best advice so far. Start cheap and easy and go up from there. DO NOT change all these things at once. Do one at a time that way you can see how each change affects your motor.
 
installed recurved mopar vaccume advance distributor and redone timing,set timing to highest vaccume reading and retuned carb over break. Also reinstalled ld340 intake while at it and wow what a improvement launches much better also driving and throttle response more along seat of pants feel I would expect from a 340. thanks for pointers and getting me back to basics of driving a fun hp car. NOW Im going for body repair , but this was more fun.
 
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