Thermoquad issues...

[Someotherguy]

Hey folks

I just put a thermoquad on my 318 about a month ago, and i cant seem to get this bog at WOT tuned out of it :0/

I adjusted the secondary door up pretty tight, still does it, but i dont think the issue is with the secondaries, because i can hold the secondary door shut and it will still bog out when i blip the throttle to WOT...I think maybe the pump shot isn't good enough for wot...i have a video down below of it doing it...


click image for video...

 

[Meep-Meep]

Check timing, float settings, pump shot (even though that looks OK).

 

[RustyRatRod]

Try reading this.

http://www.forbbodiesonly.com/moparforum/showthread.php?t=38460

 

[Someotherguy]

I've set the timing all over the place trying to eliminate the issue(not with timing light, just manual adjustments), still does it no matter where i set it...

I guess i'll have to crack it open and take a look at the float setting...I also have another thermoquad i can use for parts, so i may just swap them out just incase the floats are no longer buoyant..and check the accelerator pump cup for wear..prolly just replace it also..

 

[Someotherguy]

Try reading this.

http://www.forbbodiesonly.com/moparforum/showthread.php?t=38460

I appreciate the link, i have read this over long ago, it's a great introduction to the tq carb, but it does not have any troubleshooting information...

 

[RustyRatRod]

Then with the engine off, does the carb have a good STRONG double stream of fuel when you open the throttle?

 

[Someotherguy]

yes, it does "seem" to have a nice strong shot out both tubes...problem is i don't know what is a good/poor shot, as this is my first go around with a TQ...

I will post a video shortly..

 

[Someotherguy]

pump shot video...i does look a little weak to me, but i'm not sure

 

[RustyRatRod]

Yeah it's weak.

 

[Hemi Rebel]

Did you take a 2bbl off to put the 4bbl on?

 

[Someotherguy]

Did you take a 2bbl off to put the 4bbl on?

yep, it had a carter 2bbl on it, i swapped a LA 360 intake and the tq in question onto it..

kinda irrelevant information, but this isnt the original engine, the current engine is from a 86 chrysler 5th avenue...a factory roller cam motor...

 

[Hemi Rebel]

You are going to need the cam out of the motor the 4bbl came off of, or a similar aftermarket. I would recommend headers and any other things you can do to improve airflow. That carb came off an engine that moves 360 cubic inches of air per revolution. You stuck it on an engine that can only move 318. The carb is too big for it.

 

[RustyRatRod]

You are going to need the cam out of the motor the 4bbl came off of, or a similar aftermarket. I would recommend headers and any other things you can do to improve airflow. That carb came off an engine that moves 360 cubic inches of air per revolution. You stuck it on an engine that can only move 318. The carb is too big for it.

No it's not. Millions of 318s came with Thermoquads. 800 CFM Thermoquads. That's why they are such good carburetors. You can run them on anything from a 273 to a 440 with only minor tuning and no parts changes whatsoever. Same reasoning why Chrysler used them in just that manner. Besides, what he is encountering is a lean condition. What you describe would mean the carburetor is rich, which it does not seem to be.

 

[RustyRatRod]

Instead of blipping the throttle, open it slowly and steady. See how much of a stream it provides then. It does look weak as if the acellerator pump is not working right.

pump shot video...i does look a little weak to me, but i'm not sure

 

[Someotherguy]

You are going to need the cam out of the motor the 4bbl came off of, or a similar aftermarket. I would recommend headers and any other things you can do to improve airflow. That carb came off an engine that moves 360 cubic inches of air per revolution. You stuck it on an engine that can only move 318. The carb is too big for it.

A spreadbore carb isnt too much carb for a 318, the primaries bores are designed for any small block and the secondaries are designed to only give the engine what it can take.....This isnt a rich bog out issue, it's a lean bog issue...it isnt getting enough fuel...I have verified this by holding the primary choke door mostly closed while blipping the throttle to WOT, it has no problem at all with the choke door partially closed...

sound like a rich condition to you..?

 

[Someotherguy]

Instead of blipping the throttle, open it slowly and steady. See how much of a stream it provides then. It does look weak as if the acellerator pump is not working right.

The carb works perfectly as long as i ease into the gas...I'm leaning more and more to the pump shot isnt strong enough...

 

[egrand1508]

There are a lot of things that can cause bog. TQ's probably are a little large for a 318, but people do run them. Check out this thread: http://www.forabodiesonly.com/mopar/showthread.php?t=27224

The main thing on the squirters is the position of the S link. I can't tell on the video which way you have it but the bottom loop should be on the drivers side and top loop on the passenger.

However, my bet is that it's a secondary air door issue. It looks to me like it should open more smoothly. Maybe the spring is too tight? There are a bunch of adjustments to make on the secondary side and any one of them can affect bog.

Check out this video:
http://youtu.be/UZz6d1u9h08
This guy has several videos about TQ's and he explains a lot.

 

[RustyRatRod]

The carb works perfectly as long as i ease into the gas...I'm leaning more and more to the pump shot isnt strong enough...

No no.....I mean with the engine NOT running. Dont just blip the throttle. Open it slowly and watch the pump shot. It should be steady and strong. Just blipping it doesn't tell the whole story.

It's too bad you're not closer to middle Georgia. I could have it running like a champ in less than a weekend. I build carburetors all the time and specialize in Thermoquads.

 

[Someotherguy]

No no.....I mean with the engine NOT running. Dont just blip the throttle. Open it slowly and watch the pump shot. It should be steady and strong. Just blipping it doesn't tell the whole story.

It's too bad you're not closer to middle Georgia. I could have it running like a champ in less than a weekend. I build carburetors all the time and specialize in Thermoquads.

it isn't a smooth shot, it kinda "sputters" out as i work the throttle...

I wish i had a TQ guy close to me also, i have some experience in quadrajets, and little experience in TQ's....though i do like the TQ better than the quadjet...much easier to work on imo...now if i can only get this one figured out

 

[RustyRatRod]

Yeah if it sputters, it's suckin hind tit. lol If all else fails, send it to me, I'll fix it.