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!