I have been struggling from day one with my 340 stalling out at idle to WOT.

Lot of suggestions, all very much appreciated.

I've boiled it down to either replacing my Torqer 340 Single plane intake with a idle-5000 rpm dual plane intake or installing a 2000 - 2400 rpm stall converter. The intake I can do myself and totals out to around $250.
The torque converter is (as far as I can tell) going to run $175 - $200 and I will need to have it installed at a garage.

Currently I'm leaning toward the torque converter because the engine performs so well above 2000 rpm with the single plane intake.

So finally my question.
How big of job should I expect it to be to install the converter if done at a garage? Is it a big, medium or small project? Is there a lot more parts to consider other than just the TC itself?

Oh, the trans is a 727 TF and I will be drag racing on a 1/8 mile track.

Thank you.
Joe.

 

Joe -

The torque converter issue, is this: too high a stall and the car (truck) will feel slugglish for daily driving (while TC spools up). Too low a stall, and you'll ether be fighting the brakes or appoaching a stall. The best option is to have the TC "lock up" about where the power band starts. On Hi-perf motors, you will get the sluggish feeling on normal street driving, because the TC and the rest on the engine was build around a 3000 - 6000 rpm band.

The intake things sounds like it makes sense, but without knowing the cams power band (or changing it), the help you get by improving the low-end torque with the manifold alone will be marginal at best, at least that's the theory.

Short version: TC first, manifold and maybe cam second.

Archer

 

stalling from idle to wot is your carburetor it sounds like a holley power valve and/or secondary cam or vacuum spring, the secondary is opening to soon and flooding the system, use a heavier spring for vacuum secondary, change cam on the mechanical.

I have found out that it is a trial and error to find which will work for your application, changing the tc or intake will not solve the stalling

 

Thanks for the replies fella's.

I think I will go with the TC and hope for the best.
I know this won't cure the idle to WOT stall, but it should allow
me to get into the power band for a good launch

Thanks again.
Joe.

 

Not to be a jerk but why not fix the problem first? You can do a torque converter swap if you can do an intake swap. Depends on the shop if it is a big or small job. Only parts you will need is a new converter and fluid and filter.

 

No worries, well taken.
I have what must be a half of dozen or more threads over the last 10 months and $400 - $500 worth of "fixes" trying to solve the stalling problem. I can't, my best bet was the intake, dual plane vs single plane. I am pretty sure with the high stall TC I will get a better launch off the line and to be honest that is what I'm after.

I sure appreciate any thoughts.

Thank you
Joe.

 

Joe,

I thought that you changed out the Holley carb for a Carter or Edelbrock one about 6-7 months ago?

 

It sounds like carburation to me.... Either to little of a "squirt" or to big of a "squirt". Intake change will not 'fix' that problem as was stated up ^^^^^^ there somewhere...

AND a front seal while yer already there... cheap insurance... IMHO..

 

What size Holley carb and what size are the jets?

 

I pulled a 600 cfm Carter 4 bl and replaced it with a 650 cfm Holley double pumper. It's a brand new carb and I don't know what jets are in it. I have made it react a little better with carb spacers, but not much. I have read over and over "you cant have to big of a carburetor". I'm starting to wonder.

Front seal?

Thank you
Joe.

 

you can have too big of carb. if its mechanical. or to big of jets vac sec, squirters injectecting to much or not enough. it hard to tell (over the net without driving it.). im thinking it something simple something we all overlooked,? other than being there to feel it I'm at a loss. i know you been fighting it for awhile and hope you find the cause soon. i have no idea what front seal means??? all i think of is front crank seal on the timing chain cover,

 

Front seal refers to the front pump seal in the transmission. It's the seal that seals the TC to the pump. Very cheap and easy to replace. Well worth doing if you are going to be changing the TC.

What does the truck weight and what is the max RPM that the motor will see? What gears are in the rear axle?

 

According to Holley the stock jet sizes will be 67's (front) and 73's (rear)... First thing i would do is "even" them up, jets are relatively cheap and easy to change... I would think that is the problem, you went from a Carter (vacuum secondaries) To a Holley Dbl Pumper... You can get a "range" of jets and change them till you like the tune... Thats my opinion... And yes i was referring to the front pump seal on the tranny.....

And in my opinion a 650 on a 340 SHOULDN'T be to big....

Oh and on the power valve as mentioned above, stock is a 6.5 if you were wondering on that....

If ya are wondering where I pulled those numbers from it was from here:http://tgsperformance.com/holley.htm

 

Joe -

First hint that the power valve might be a fault (thought we discussed this before somewhere), would be that after a back-fire or two through the carb, you start feeling (smelling) the engine running rich.

Other case for stumbling is dirt on the needle/seat (or in any fuel passage. Sometimes a couple of throttle "punches" might fix it, other times not.

Archer

 

Joe,

Talk to Ricky.

https://moparforums.com/forums/f4/ri...639/#post62967

 

HI,
the 650 Dbl pump cames with 67 pri. jets & 73 sec. jets
and a 6.5 power valve in the pri. only
When a carb only has a pri. PV and no sec. PV you do not want to square off the jets
you need to keep a 5 to 6 jet # spread
the first thing to do is take a vacuum reading @ idle in gear
and whatever that reading is cut that # in 1/2 and that will = the size of power valve you need
example 9" of vacuum needs a 4.5 PV 7" of vac. needs a 3.5 PV and so on like that
After the Power is correct
then run it at part throttle for about 1/4 mile and kill it without letting it idle
and look at the spark plugs and if they are white go up 2 jet sizes if black go down 2 jet sizes
do this untill they are tan to brown
then make a wide open pass and kill it without letting it idle
and do the same thing with the sec.jets untill the plugs are tan to brown.
I do not think the converter is the fix.
I would do all of this with the carb first and after that if it does not do right for you the next think I would look at would be replaceing the intake
I hope this helps
Thanks

 

Wow guys, some great information! Thank you!

I have noticed over the winter months that the engine was running really rich.
I've not been driving it, just watching the speed channel, getting all worked up and going out back and warming her up from time to time. Anyway I understand that Holley has fixed the blowing out the power valve (back firing) problem when they designed in a pressure relief tube.

I have suspected that even the Carter 600 cfm (vacuum sec.) was to big and that the 650 Holley DP might have been a step in the wrong direction. But there it is, a brand new carb and I'm not taking it off

Thanks for the info on the jet sizes guys, this is something I can get working on although I will not be able to drive the truck for a couple more months.

I've bookmarked both the references.

Thank you
Joe.

 

Any Holley made since 1992 has the power valve blow out pertection
but if the power valve is too big for the vacuum reading it will be very rich # idle
also on the jets you can get them in packs of two using part # 122- the size you need
example a size 69 will be part # 122-69 for a pack of two
Thanks

 

Hey guys, I got out there today and warmed up the engine.
At idle out of gear, my vacuum is 17hg. In gear it drops to 13hg.
My carb is a Holley 650 DP #4777C. And near as I can tell from MrOldFart's table he linked to the carb does have a 6.5 power valve.

So this means the Power valve I have is like perfect?

The slower I accelerate, the less the vacuum drops off and the better the take off, I've always noticed that it's when the vacuum drops suddenly below 5hg is when the stall takes place. Could it be that I need a even smaller power valve?

Thank you
Joe.

 

with 13" of vacuum in gear
the 6.5 PV should be great
but if your cam is that mild I sure would not think about a high stall converter
from this point on I would work on the jetting
and maybe change to a idle to 5500 dual plane intake
Thanks

 

Sorry I missed your questions Tim.
Seems I looked up the weight awhile back and the '90 Dakota
with a stock 4cyl 5 speed tranny was around 3100 lbs.
My truck might be a little more (340/727). Max rpm's?
shoot, when driving it 'sounds' like I should limit it to around 5500,
but I really am not sure about an exact number. Last fall we installed 3.55 gears.

You know, this stall problem happens in or out of gear, meaning even with no load on the engine she stalls when I tromp it down. Just thought I should mention that.

Thank you
Joe.

 

Hey, I would also look at the Accelerator pump adjustment
Look down in the carb without it running
move the throttle and see if the two sprays of fuel shoot as soon as the throttle moves
if it is not instant back off the nut on the pump arm 1 full turn counter clockwise
then check it again
do this until it is instant
@ wide open throttle you should be able to push the pump lever into the dia. housing about .010"
just so it is not bottomed out at wide open throttle
on a dbl. pump do the same thing on the sec. pump
but it should spray as soon as the sec. starts to open
Thanks

 

Thanks Ricky, I have done this and both pumps are squirting gas out of their respective nozzles with the slightest movement. One thing I'm totally convinced of "it's getting gas" there's no question about that .
Maybe too much gas?

Thanks again, any help, idea's are greatly appreciated.

Joe.

 

You may have already checked these but I throw them out there anyway. Fuel Filter, Fuel Pump and also check for bad lines to the tank.

 

Hey Dan, I sure appreciate any idea's. And everything adds to the trouble shooting data base.

Ricky, I been down the swapping out jets road and various other carb components when the Carter was on there. See that's the thing, I swapped out entire carburetors only to find the exact same problem all over again. Maybe because they both were to big...

Tonight I bit the bullet......

I bought a Edelbrock 2176 Performer Dual plane idle-5000 rpm intake.
Something is telling me it's in the air velocity..... We'll see.

I sure appreciate everyone's input I let you know in a couple of weeks how it goes. Maybe later in the summer I can look into a High Stall Torque Converter.... fun stuff!

Joe.

 

Joe,

You should be able to sell that single plane intake to help re-coop the price of the dual plane. I honeslty think that you will be much happier with the dual plan as well.