Can't spin the wheels on my '72 340 Charger.

[Loa]

Hello,

I know that small blocks make most of their power at high RPM, but I just can't make the wheels spin on my '72 340 Charger. From standstill, if I apply the brakes and push on the gas, the engine stalls instead of revving up to spin the wheels.

Other than that the engine works fine, and the 650 Holley on it works like a charm (starts very easily, idle is rock solid at 850, responds very quickly to throttle...). I have 3.23 gears in the back. As soon as I get to 2500 rpm, the power surges up to 4500. And it makes a lot of power.

I've had the carb adjusted by a pro, so I'm wondering if it's an issue with the engine...

Thanks for any help.

Loa

[c00nhunterjoe]

To be blunt and straightforward, fire your pro. If it stalls when you apply throttle, its not adjusted right. More then likely its a severe lean bog, especially having a 650 on a 340. More details are needed though. What model 750, what distributor, base and total timing, specs on engine build to start

[Loa]

Hello,

I'm not sure what the exact Holley model I have, as the car is still buried under snow. I'm trying to get as much info as I can to fix this as soon as it thaws. It's all mechanical, and replaced an ailing quadrajet Thermoquad late last fall, so I'm not familiar with it yet. The engine only stalls when the brake is on: otherwise the car performs "normally".

As far as I know it's a stock '72 340, with stock distributor. The total timing is around 35*.

Loa

[BSB67]

Could you make the wheels spin before the carb change. 

[crj1968]

The engine only stalls when the brake is on: otherwise the car performs "normally".


Loa

Power brakes?

[Loa]

Hello,

The original carb (quadrajet Thermoquad) was not working well, but the car couldn't spin the tires either.

Yes, there's power brakes.

Loa

[Kern Dog]

The original carburetor would have been a Carter ThermoQuad. The Quadrajet was made by Rochester and was not installed on any Mopar until the mid 80s.
It may have been on the car when you got it but it is not an original carburetor for that car.

[Loa]

Hello,

You're right, it was a thermoquad. I don't know why I called it a quadrajet.

Loa

[John_Kunkel]

Advice to those who can't spin the tires with a Torqueflite......Google "neutral drop". 

[Loa]

I haven't tried that, even though part of me was tempted!     

[ws23rt]

This is funny stuff.
In my 57 desoto I would bring the engine to valve float in neutral. Then punch the R button getting -one- tire smoking in reverse.  Next was to punch the L button.--Lots of smoke

The trans. let me do this and a--(single)-- 95ft black strip lasted for a year in the high school parking lot.

[c00nhunterjoe]

Getting offtopic... but the point has been made. A single barrel 318 pickup truck will smoke a tire. You have a tuning issue.

[Kern Dog]

Maybe you can rig a hose to the windshield washer jug, run it back to point at the rear tires. Fill the jug with WD 40. Push the squirter button as you hammer the throttle and you'll surely smoke the tires then!
(Don't really do this)

[Loa]

You have a tuning issue.

If the engine is running great otherwise, I'm guessing that it's not simply an issue of adjusting the 2 screws. Could the jets be too small?

Thanks

[XH29N0G]

Loa,

I just reread your first post.  I assume this was all done.  but the following is what I would do.

I would make sure everything is OK with the ignition and timing.  This can mask issues with the carb.

Then I would adjust the idle mixture screws using a vacuum gauge.  I assume you have done this before, but if not we can point you in a direction to do this.

I would adjust the idle speed screw.

Then I would check the accelerator pumps to make sure they were working correctly - adding fuel as soon as the throttle linkage was touched.  Usually this means checking the full travel so it does not bottom out.

Then I would check it.  If there is a delay, backfire, or bog when mashing it from a roll at different speeds, there would be  some other adjustments. I see you do not have these, so I don't think that is an issue.  

Setting the main jets is something that requires either reading plugs or an A/F gauge.  

This is a vacuum secondary carburetor, right?

I do not know about the power brake issue, whether that could stop it.  I also have not tried to brake and burn out, but I do remember with my 70 (which had 383 4 bbl) that it was less likely to break the tires loose than my 69 350 2 bbl pontial.  The torque was probably similar, but there was a big difference in total power and total acceleration.  The 70 charger just stayed planted.  Once I got more power it broke loose. 

What tires do you have on the back?

[Loa]

Hello,

Ignition, timing, idle mixture and idle speed screws were all checked and adjusted.

I'm not sure the accelerator pump was though. I'll check it as soon as the snow melts. :-)

It's mechanical secondary 650.

I have 275/60/15 BF Goodrich Radial TA on the back. Brand new.

Thanks for the help.

[comet_666]

Is it getting wide open throttle when you mash the gas?

[Loa]

Good question. I know I checked for my Challenger, but I don't think I did for the Charger. Then again, it reacts very promptly when I push the throttle, so if it's not going all the way, there isn't a lot missing.

But in any case, I can't even go wide open when I try to spin the tires: it bogs down before that.

Loa

[comet_666]

Vacuum secondaries on the carb?

[Loa]

No, mechanical. I think the guy set them up to always open in sync with the throttle.

[John_Kunkel]

You have a tuning issue.

Or some might say you have an insecurity issue. Who cares if it'll spin the tires?

[HPP]

3:23 aren't exactly steep and 340s don't make a ton of torque until higher in the powerband. Combine with a presumably stock torque convertor that is likely stalling at 1800 rpm, and no, you aren't spinning tires.

[birdsandbees]

I always thought the idea was to hook up and go !! Never much of an issue for me with my 2.94's !!! 

[c00nhunterjoe]

It shouldnt bog and shut off, regardless of his torque output.

[birdsandbees]

It shouldnt bog and shut off, regardless of his torque output.

CORRECT! 

[BSB67]

I think the guy set them up to always open in sync with the throttle.

You need to spend some time under the hood of your car, and do some reading.  If you don't want to do that, and if you are not wealthy, this hobby might not be a good fit for you.

Sorry for the brutal honesty.

[XH29N0G]

I  wonder if the 275s and mechanical secondary are playing a part in this.  The BFGs aren't sticky but that is a fair amount of tire. 
The stalling is a puzzle because I would think the converter should let it spin a little, but I also wonder if you could end up just dumping too much gas in with the mechanical secondary and then too much air for the low RPM (too little gas would speed up the too much air part)- especially if your brakes stop you from going forward and your 275's stop it from spinning.  Just some thoughts.

I don't know if what I describe is possible.  I don't have an automatic so have not enough experience.  I had difficulty breaking 245's loose with my 383, but I didn't drop the clutch. 

The funny thing in all of this conversation is that I always thought I was lucky having the car stay planted and then did my best to return it that way when I had the engine warmed up.

Soon the snow will be gone. After that, food luck and have fun working through this.  These sorts of problems are always the most fun to try to solve and just plain think about. 

[Loa]

It shouldnt bog and shut off, regardless of his torque output.

That's why I'm concerned. Maybe a 72 340 with 3.23 can't make them spin 45 years later, but it shouldn't bog down.

[Daytona R/T SE]

Stock 318.

275/60/15 tires on the back.

One foot on the brake,

One on the gas.

[Kern Dog]

Hell yeah, man!  I LOVE to peel out. That stuff is fun!
Hammer the gas from a dead stop and feel the tail end float a bit to the right, feathering the pedal all the way through first, hit second and it is still rolling forward a bit sideways, lift and let it hook up at about 50-55 and straighten it out....
That is something that you don't get with ABS, traction control, FRONT wheel drive, minivans, 4wd trucks, etc.

[Loa]

but I also wonder if you could end up just dumping too much gas in with the mechanical secondary and then too much air for the low RPM

Good point. I'll look it up. I got the car back (with new carb) just in time for the first snow storm last fall and haven't had time to see what the guy did.

Soon the snow will be gone. After that, food luck and have fun working through this.  These sorts of problems are always the most fun to try to solve and just plain think about. 

Indeed! I'm looking forward to finding the solution, but I wanted to get some advice in the mean time. Thanks.

Stock 318.

275/60/15 tires on the back.

One foot on the brake,

One on the gas.

Well, that confirms it: the carb needs to be adjusted. This is exactly what happens on my '70 340 Challenger, as simple as you describe.

Can't wait to get the Charger in good shape!

That is something that you don't get with ABS, traction control, FRONT wheel drive, minivans, 4wd trucks, etc.

Amen!   :-D

Thanks for the inputs guys.

[XH29N0G]

Daytona RTSE, thanks for the picture.  Loa, it is clear some of my suggestions are clearly off base.  I will continue to put them out there in case they help, but it seems like the others here will be able to help put this straight. 

[John_Kunkel]

Hell yeah, man!  I LOVE to peel out. That stuff is fun!
Hammer the gas from a dead stop and feel the tail end float a bit to the right, feathering the pedal all the way through first, hit second and it is still rolling forward a bit sideways, lift and let it hook up at about 50-55 and straighten it out....

That is something that you don't get with ABS, traction control,

Yeah, hook and go....the distinguishing feature of a REAL performance car, not the childish gyrations you describe. But then, I'm an adult so..............

[c00nhunterjoe]

For once, you can have your cake and eat it too in this situation. Smoke the tires and drag the bumper. Lol

[Kern Dog]

Hell yeah, man!  I LOVE to peel out. That stuff is fun!
Hammer the gas from a dead stop and feel the tail end float a bit to the right, feathering the pedal all the way through first, hit second and it is still rolling forward a bit sideways, lift and let it hook up at about 50-55 and straighten it out....

That is something that you don't get with ABS, traction control,

Yeah, hook and go....the distinguishing feature of a REAL performance car, not the childish gyrations you describe. But then, I'm an adult so..............

I've seen your cars and read your posts. Your life is fun to you? That is fine. I like what I like.  I enjoy getting a car sideways and holding it there at the edge of control. I can appreciate the "drag racer" mentality of your generation  where traction and acceleration results in a lower ET. Some people like me enjoy something different. I'm not talking about a standing burnout to generate smoke, I mean smoking the tires while moving. I'm sure the "sport" of drifting is lost on you.

[sccachallenger]

At some point, check the stall speed of the converter.
383 4 barrels and all 340s had very nice stock converters.
Somewhere in the last 40+ years yours may have been replaced with the wrong converter.
The right converter makes all the difference!
And I agree with others, check carb and ignition (and vacuum leaks) first.

[Loa]

Sccachallenger, it's very possible that the converter has been changed: I got this Charger for very cheap and I know that it has extensively been worked on, patched, rebuilt, etc... The front end is from a 74, the back end is from a 73 and the engine is a 72!   I don't care for number's matching or stock-originality at all, nor the resale value. I plan on getting this car in a good shape and drive it for pure pleasure.

I've found a simple method to roughly estimate the stall converter on the net (hold brakes and apply throttle to see where RPM will stop). Two questions: will that simple method be of any real use? and will it even work given the problem I'm trying to solve?

Thanks

[c00nhunterjoe]

With the current running condition of the engine, you will never be able to test stall speed since it coughs and stalls when attemlting to load the engine against it.

[sccachallenger]

Sccachallenger, it's very possible that the converter has been changed: I got this Charger for very cheap and I know that it has extensively been worked on, patched, rebuilt, etc... The front end is from a 74, the back end is from a 73 and the engine is a 72!   I don't care for number's matching or stock-originality at all, nor the resale value. I plan on getting this car in a good shape and drive it for pure pleasure.

I've found a simple method to roughly estimate the stall converter on the net (hold brakes and apply throttle to see where RPM will stop). Two questions: will that simple method be of any real use? and will it even work given the problem I'm trying to solve?

Thanks

yes, that's the basic idea!
I've also heard putting the front bumper (gently) against a big tree or very solid wall is also a good plan if you can't hold it with the brakes.
And 'till you get it running better, you may not be able to do this.
There are numbers on the trans that can be used to see what it came from, or if the VIN pad is stamped,see if the number matches the VIN on the block.
The 340 transmissions had a governor set for higher rpm shifts when in drive.
But even if it matches, the converter may still have been changed.

[lukedukem]

Did you ever get your car running good?

Luke

[Loa]

Hello,

Haven't got a chance to work on the carb yet. One of the brake cylinders burst on me and I've replaced both. I've bled the brakes in the rear but can't manage to bleed them properly in the front. I keep getting bubbles.

So I'll work on the carb when the brakes are fixed. Problem is that I can only work on the car outside (no garage) and it's been raining pretty much non stop!

Loa

[brad mcintyre]

I played with my 383 4bl for a month stalling out when you jump on it put on fuel regulator was getting to much gas and flooding out

[Kern Dog]

My Holley mechanical fuel pump seemed to be lagging, allowing fuel pressure to drop to zero sometimes when the engine was running hot. I switched to a Carter pump. It hovered at 11 PSI. I was told that was too high but the car ran great. Just to appease the doubts in my head, I added a regulator that is limited to 7 lbs, everything over that returns to the tank.

[BSB67]

My Holley mechanical fuel pump seemed to be lagging, allowing fuel pressure to drop to zero sometimes when the engine was running hot. I switched to a Carter pump. It hovered at 11 PSI. I was told that was too high but the car ran great. Just to appease the doubts in my head, I added a regulator that is limited to 7 lbs, everything over that returns to the tank.

FWIW, this is usually due to vapor lock.  A weak pump can be a contributing factor.