Carb to swap or not?

[Mr Grumpy]

OK Friends, here's the thing, when I got my 76 Newport it was hardly running, the previous owner told me he'd replaced the ign system, (which was evidently untrue) and it didn't have the original Carter Thermoquad on it either.
I found that it had a TQ from a 318 lean burn motor so i hunted for and found a correct used carb which I put new seals and gaskets in and rebushed the throttle shaft.
Not knowing what had really been done to the ignition I put new plugs leads and distributor in and replaced the fuel pump too, they're not expensive items, and I wanted to have a solid base to start.
I now find that once it's fired and warmed a little it runs passably well and will restart on the key no problem, but cold starting it doesn't want to know. It has the heated bimetal spring gubbins in the manifold and the relay thing next to it for the choke, but I've no idea how to test them.
Various friends are telling me to junk the TQ and go with a Holley or Edelbrock as they'll be much easier to set up and more reliable. That will mean however using an adapter plate and probably some linkage modification too.
Then there's the question of what size carb, I've seen folk recommending 600cfm which is what I ran on my 318 Truck years ago and seems a little small for a 400, the TQ is rated 800-850.
I can get a guaranteed reman TQ from rockauto way cheaper than any Holley or Eddy also, and about the same cost as a pro rebuild of my existing unit.
What are your thoughts?

 

[cbarge]

Seen your post on FB
Get a vacuum gauge!!! Lol!
Make sure the new TQ has a vacuum port for the vacuum advance.

 

[Dana]

Friends don’t let friends junk Thermoquads

 

[Mr Grumpy]

Seen your post on FB
Get a vacuum gauge!!! Lol!
Make sure the new TQ has a vacuum port for the vacuum advance.

Which post on fb?
And yes I intend to get a vacuum gauge.

 

[Mr Grumpy]

Friends don’t let friends junk Thermoquads

Can I give you a call next week?

 

[lemondana]

Pretty sure the 1976 TQ's are Lean Burn also. Find an earlier one and redo that one and let us know how it goes.

 

[david hill]

TQ's are notorious for there many problems. My cure was to install Edelbrock 1405 w/ the Chrysler kick down adapter, install a 1"carb spacer at the same time to prevent fuel boil off. If interested I'll send you some pics of the install.

 

[1970FuryConv]

Hi Grumpy,
If the problem is mainly at cold start, I think you're on the right track with the choke problems:
Does the choke valve close when the engine cools off?
Closed

If it stays wide open, where the valve plate is vertical, you're going to have a lot of problems at start up in cold weather.
Another question, is there battery voltage at the choke connector when ignition is on? If not, you need to track down the broken wire/short to ground. Or simply run a new wire from an ignition-on source.

As far as driving performance, I agree with disconnecting the lean burn, and rewiring for conventional ECU. I have read too many bad things about lean burn. In fact, my auto shop teacher told us long ago that Chrysler mechanics were getting rid of lean burn to fix engine performance issues. The problem was that the EPA was catching some dealerships doing it, with major fines the result. Now, however, no one knows what lean burn is, so get rid of it.

 

[Mr Grumpy]

Thanks for your replies, it's not a lean burn car, has a standard mopar ign system and current carb is not a lean burn one.
From what I understand lean burn was on 78 on and some late 77 cars, this is a 76 with no cat.
I'll have a check of the choke with a meter when I've cleared some snow.

 

[CBODY67]

Seems like '76 could or couild not have the Lean Burn System? But I suspect that with the prior owner replacing "the ignition system", it probably did have the Lean Burn (which ran very well when new!) from the factory.

Many of the reman TQs are "multi-fit" in engine sizes. If the car runs well when warm, then any cold start issues would most probably be related to the choke thermostatic coil adjustment. The "heat" assists getting the choke open sooner for decreased cold start emissions, ONCE it starts.

When the engine is cold, the choke plate should close. Then when the engine starts, the choke pull-off should pull the choke plate open so the engine doesn't run too rich and then die. As the engine (and the choke heater) warms, the choke should progressively open until it's completely open. Just as with ANY OTHER carb.

BE AWARE that the new Holley Street Demon carb is a pretty accurate copy of the TQ. Other than the secondary throttle valve and base plate that will bolt onto non-spreadbore intake manifolds.

Enjoy!
CBODY67

 

[Dana]

Can I give you a call next week?

Yes sir, anytime

 

[CBODY67]

Thanks for your replies, it's not a lean burn car, has a standard mopar ign system and current carb is not a lean burn one.
From what I understand lean burn was on 78 on and some late 77 cars, this is a 76 with no cat.
I'll have a check of the choke with a meter when I've cleared some snow.

Factory Lean Burn cars had a "Non Cat" decal on the lh front door (usually below the latch mechanism in the door) AND "no cat converter" under the car. If it might have been a converter car, the pipes would probably indicate such with a pipe where the converter would normally be. PLUS the related heat shielding that attached to the floor pan under the passenger compartment on that sidel Probably with no restrictor in the fuel tank filler neck for "Unleaded Fuel Only" and no such notation on the instrument panel fuel gauge also?

If the choke thermostat has been replaced with a generic unit, it might not be adjusted correctly. The resistor for the heater is there to get things openned quicker, but considering the decades we went without them, might not be completely necessary for the choke thermostat to operate. FWIW

CBODY67

 

[Mr Grumpy]

Factory Lean Burn cars had a "Non Cat" decal on the lh front door (usually below the latch mechanism in the door) AND "no cat converter" under the car. If it might have been a converter car, the pipes would probably indicate such with a pipe where the converter would normally be. PLUS the related heat shielding that attached to the floor pan under the passenger compartment on that sidel Probably with no restrictor in the fuel tank filler neck for "Unleaded Fuel Only" and no such notation on the instrument panel fuel gauge also?

If the choke thermostat has been replaced with a generic unit, it might not be adjusted correctly. The resistor for the heater is there to get things openned quicker, but considering the decades we went without them, might not be completely necessary for the choke thermostat to operate. FWIW

CBODY67

Would be nice to live in a climate where it was unnecessary but I'm in Quebec.

 

[cbarge]

You are in good hands with Dana regarding a carburetor.

Thermoquads are great carbs yet misunderstood and underrated.
On my 73 Satellite wagon,I have a 800CFM TQ and its number says 77 400 HP without leanburn.
I am averaging 18-20 MG with the car--thats IF I do not open her up!
There is nothing like the sound of a Thermoquad at WOT!!!

 

[Mr Grumpy]

You are in good hands with Dana regarding a carburetor.

Thermoquads are great carbs yet misunderstood and underrated.
On my 73 Satellite wagon,I have a 800CFM TQ and its number says 77 400 HP without leanburn.
I am averaging 18-20 MG with the car--thats IF I do not open her up!
There is nothing like the sound of a Thermoquad at WOT!!!

Love the video, the whine from the manual box is magic too.

 

[cbarge]

Love the video, the whine from the manual box is magic too.

 

[70bigblockdodge]

View attachment 433229
View attachment 433230

Done right.

 

[LocuMob]

You are in good hands with Dana regarding a carburetor.

Thermoquads are great carbs yet misunderstood and underrated.
On my 73 Satellite wagon,I have a 800CFM TQ and its number says 77 400 HP without leanburn.
I am averaging 18-20 MG with the car--thats IF I do not open her up!
There is nothing like the sound of a Thermoquad at WOT!!!

I forgot how much I miss driving a 3 on da tree, until I watched this video. Brought back a bunch of memories of being young. Kids don't know what they're missing.

 

[HWYCRZR]

I just got my carb back from @Dana today. Not a thermoquad, (Carter)but happy the way it turned out. Started right up. I thought it was running fairly smooth before, but now much smoother. Can’t quite take it out on the road yet. We got a fresh 3-4” of snow today.
Idles great though.

 

[Mr Grumpy]

Ok folks update time.

I had a couple of good chats with Dana from Woodruff Carburetor (what a damn nice man he is.) and we went through what was going on and he gave me some great pointers and advice.
Turns out the dual ballast resistor was wired wrongly for a start, but most of my issues were carb related, for instance I had the idle jets running way too lean. The major problem though was getting the choke system set up properly, it turned out to be a combination of incorrectly set and adjusted links and a bellcrank that wasn't properly seated on its shaft.

So this morning I was in my unheated garage, it was -18°C outside (that's a slice under 0°F for you still in old money), 1 pump on the accelerator pedal and then leave it and turn the key, she spun over 2 or 3 turns and fired right up.
Suffice to say I'm a very happy bunny, just got to wait for better weather so I can get out on the road with the behemoth.

So if you have any carb needs don't hesitate to contact Dana at Woodruff and support a great independent business and forum vendor.

Thanks again Dana, I owe you a big drink man.