Thermoquad

[aceofspades]

I read the TQ thread. Interesting.

The TQ on my '79 Chrysler 300 with the glorious"lean burn" system runs great.

However, there's one small hiccup... At low acceleration it's great, if you mat it to the firewall it runs like all hell, but if you depress the pedal halfway during acceleration it sputters a bit. No smoke or anything.

It got a complete tune up last summer so that's all good.

Any suggestions on what the issue may be?? Thanks in advance.

 

[rumblefish360]

How is it at low speed or a slight pedal push?
All original and stock?

 

[69L48Z27]

I had the same issue on my Lil Red Express. Make sure the accelerator pump is working. I really had to screw around with a couple new pump kits until I got one that would stand up to the new gas we have now.

 

[aceofspades]

It does fine at low acceleration and yes, all stock original.

That's right, the lil red express had the same engine. Accelerator pump does make sense. Someone mentioned the choke pulloff valve but.....

 

[69L48Z27]

If the choke was the issue, any part of it, you would have much more drivability issues than what you noted.

The pull off opens the choke about 1/4" as soon as the engine starts, vacuum. Then the choke spring will heat up and pull it completely open.

 

[aceofspades]

If the choke was the issue, any part of it, you would have much more drivability issues than what you noted.

The pull off opens the choke about 1/4" as soon as the engine starts, vacuum. Then the choke spring will heat up and pull it completely open.

That's what I was thinking. Didn't make sense. I'm leaning towards the accelerator pump. No pun intended.

 

[WileE]

You still have the lean burn ?

 

[aceofspades]

You still have the lean burn ?

Yes, I stated that in my original post.

 

[WileE]

Yes, I stated that in my original post.

Sorry... my hearing ain't what it used to be

 

[aceofspades]

Sorry... my hearing ain't what it used to be

HOW'S THIS!! lolol

 

[66chargerpat]

Isn't there another pull off for the secondary air valve on the back of the carb? I have the old competition series 850 TQ and it has a pulloff that holds tension on the airdoor to stop the door from opening too fast, so it doesn't lean out and bog out. Pat

 

[aceofspades]

Isn't there another pull off for the secondary air valve on the back of the carb? I have the old competition series 850 TQ and it has a pulloff that holds tension on the airdoor to stop the door from opening too fast, so it doesn't lean out and bog out. Pat

Possible, I think these were 750 cfm but it's something to look into.

 

[mopar 3 B]

Isn't there another pull off for the secondary air valve on the back of the carb? I have the old competition series 850 TQ and it has a pulloff that holds tension on the airdoor to stop the door from opening too fast, so it doesn't lean out and bog out. Pat

There is a link that locks the secondary door untill the chock opens completely. Have you checked the main meters to see if the plunger is free. If not a little carb cleaner may be all it needs.

 

[WileE]

HOW'S THIS!! lolol

That's better. Type on the left side, it's my better ear.

 

[rumblefish360]

As tested by Chrysler;

The 1-3/8 primary TQ flows 737 cfm
(Primary is said to flow 225 on this primary size)
The 1-1/2 primary TQ flows 787 cfm
______________________________

Race 4846 = 815 cfm (1.186 Venturi)
Race 4847 = 915 cfm (1.250 Venturi)
These carbs have single ring boosters FYI

 

[aceofspades]

Thanks for the advice guys. I'll take a peek at everything now that I have some guidance. Just the slightest of hesitation in one little spot. Other than that it runs incredible. Cold start is never a problem in this weather and when you kick it down that Thermoquad will sing you a tune.