340 dog out of the hole/no low end torque??

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340Duster247

340Duster247

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Hey guys , I have a old problem from last summer that I haven't addressed yet, my 340 duster seems to be a slug off the get go for whats been done too it. I've yet to take it to the track (this summer I will get you all times)
I've only tested lightly on the street, and from a stand still, on the 2step, it just barley hazes the tires and comes out slow until about 4200rpm. (I have a video I can try and share)
To me it feels like symptoms of to little convertor, but I had recently installed a 3500-3800 stall TCI.

Here is my combo.
340- .40 over balanced
Air gap intake
Holley 750
150 shot nitrous(not used during tests yet)
Eddy heads rpm
Digital 6plus MSD
Lunati cam 60405
Ad dur 284/292
@50. 242/252
Lift. 533/552
Lsa/icl 110/106
Rpm range 2500-6600
727 trans
TCI 3500-3800 stall
8 3/4 rear with 4:30 gears
315/60/15 Mickey Thompson drag radial.

I've replaced everything on the car EXCEPT the transmission. Supposly from previous owner has a shift kit......

My engine was built by a respected engine builder in my city, and I didn't like my first camshaft and replaced it with the lunati.
Both have produced shitty vacuum at idle.(4-4.5")

My timing is set 21 degrees initial 34 total. I'm gonna lock it out at 34 this spring.

Does anyone have any ideas why it might be so lazy. Too much tire???
I'm gonna try and post some videos.
Thanks for the help guys. If I've left anything out let me know
 
do you have a adjustable valve train? the vacuum seams way low to me, may be valves are being held open slighty.
 
I'm guessing converter. A quality 8 inch would probably perform much better than that 10 in TCI Super Street Fighter or whatever it is you have.
 
Not enough gear, or converter with those giant tires...
You say it feels like it comes on at 4200, why would you not want a converter that would flash there?
30" diameter tires? You're drivin' around with 3.73s and 26" tires...with a huge weight penalty on the tires...
 
What is your compression?
 
71beater said:
Not enough gear, or converter with those giant tires...
You say it feels like it comes on at 4200, why would you not want a converter that would flash there?
30" diameter tires? You're drivin' around with 3.73s and 26" tires...with a huge weight penalty on the tires...
Click to expand...

Because I'm not rich?? How would I have know it would of come in at this rpm before. I'm sure if I had unlimited amounts of money I could just buy conveter after converter. Lunati said at least 3200 rpm stall so I went with 3500-3800.
I got a tci because in canada it's harder to get a lot of the parts you guys can. So certain speed shops here can only supply us with brands they deal with.
If I was to get a custom one made from some specialty american converter company the shipping,duty and tax would kill me
 
That cam if fairly aggressive, what is your initial timing set at?
What ignition set up?
 
from many different 340 combos, a stoke stroke 340 does not produce a lot of torque, that the nature of a 3.31 stroke, the tires and gear combo are a big prob, keep the gear and drop down to a 275 or better yet a 255 tire which would be a 27 inch tall and put your convertor and gear to working great, you could bump the timing up a couple degrees and try that may help some, if your running a 904 you could get the low gear sun gear set out of a 999 which helps a lot, if the convertor don't work well call ptc and get them to build one for your combo, good luck:D
 
do you have a manual valve body! your video sounded like you were just letting the trans shift it self!
 
Next time you want Trans parts or a converter call TCS in Langly BC they make a lot of the stuff other guys are selling .
 
Thanks guys!! I'm gonna try a smaller tire for sure in the future. This is without the nitrous so once I spray I'll see how it does with the 315s.

I'm still concerned with the vacum but I've gone over that battle on another thread. Will figure out the bugs this spring.
 

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Thanks canucky. I'm from Victoria originally and drive there often I'll keep that in mind.
 
that vac seems low even for that cam im thinkng you should pull at least 8 or 9 in .
 
345man2 said:
from many different 340 combos, a stoke stroke 340 does not produce a lot of torque, that the nature of a 3.31 stroke, the tires and gear combo are a big prob, keep the gear and drop down to a 275 or better yet a 255 tire which would be a 27 inch tall and put your convertor and gear to working great, you could bump the timing up a couple degrees and try that may help some, if your running a 904 you could get the low gear sun gear set out of a 999 which helps a lot, if the convertor don't work well call ptc and get them to build one for your combo, good luck:D
Click to expand...

Yep, what he said.

What rpm do you leave at? Can you foot brake it past 2K?

My old 340/W2 combo was painfully slow off the line. My best 60 ft was 1.75 leaving just above idle.
 
345man2 said:
from many different 340 combos, a stoke stroke 340 does not produce a lot of torque, that the nature of a 3.31 stroke, the tires and gear combo are a big prob, keep the gear and drop down to a 275 or better yet a 255 tire which would be a 27 inch tall and put your convertor and gear to working great, you could bump the timing up a couple degrees and try that may help some, if your running a 904 you could get the low gear sun gear set out of a 999 which helps a lot, if the convertor don't work well call ptc and get them to build one for your combo, good luck:D
Click to expand...

My engine builder said the same thing about the 340 torque. I'll see how the car does when I spray it.
 
jimjimjimmy said:
that vac seems low even for that cam im thinkng you should pull at least 8 or 9 in .
Click to expand...

Yah definitely!! The last cam had poor vacuum and we blamed it on my previous shitty cam.....switch to this lunati and still low. I've checked everything can't figure it out yet.
Frustrating for sure
 
rmchrgr said:
Yep, what he said.

What rpm do you leave at? Can you foot brake it past 2K?

My old 340/W2 combo was painfully slow off the line. My best 60 ft was 1.75 leaving just above idle.
Click to expand...

I'm at 3200 rpm there foot braking on the 2step. Gonna test with less rpm
 
315/60 is about 30" tall and with a 340, it would have at least 4.88's in it for getting it to leave. More like 5.13 or lower. Comparatively speaking, you have a car similar to a 25" tall tire with 3.23's, same as a stock 340 Duster from the factory.

Low gear set would help a lot.

When you punch it, what does the converter flash too on your tach. If it's pulling straight from wherever you are footbraking it, it's way too tight. Take it off the two step, footbrake it and see where the tach jump to when you hit the throttle with no wheelspin. IMO, it's way below where the engine is really going to start making steam. I'd guess the tq peak would be in the 4800 range with peak HP at around 6200+.

No offense to lunati or any cam manufacturer, this is a case where they suggest stuff for a general build and you are way outside their expected parameters. Putting that same cam in a 273 or a 408 is going to want a very different converter. Part of the reason I can't stand any catalog "suggestions" they make. It's not your fault, you followed what they suggested.

Double check your preload on the lifters. That is extremely low vacuum for that camshaft.
 
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