• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Thermoquad....how lean can I go ?

Just had a good eye-opener. Swallowing last bite of humble pie! Did a look on WOT (since I didn't know what the heck is was). Backing out of this discussion.

You boys are using info I've never dealt with. Must be the old man in me. Don't even know if I want to have that much info. I'm too used to my old ways. I'll stick with readin' plugs.

Hey, Juergen...hope you get what your after. Good luck on it.
 
..Hello Miller

I don´t have a vacuum leak...the Vacuum is @ 19 Inches of Mercury steady ! All Ports are closed.. only PCV and the Distributor port
are in use.. Also the carb didn´t have limiter caps on the idle screws.. I will take a picture tomorrow ...so you can see the carb.
and the ports also.....

Greetings Juergen
 
Hiya, Juergen. Yeah, understand.

Afraid I'm an old guy, with old school ways, and don't even WANT to know about the newer stuff. Your working on number crunching stuff, via computer type tools. Have no use for them. Sorry, but I didn't realize what you were asking about.

Don't take this wrong...though to me, the smog carb you have was designed to run lean. You have it on a 'non-smog' motor. No tango. That 69 440 was made for gobs of air and fuel. Sadly it was one of the last motors made like that.

I'll be more careful, with my limited advice.

If you know what you want...go for it.
 
Hello Miller...
I don´t took it wrong ... As you could see on the pics from Rockauto.... the carb isn´t a "real smogger "... and I know, that the engine wants some "food"...

If only someone could tell me , if it is possible to rejet this type of carb... or should I buy another one from Rockauto... for example a Carb from a 1973 TRUCK with 440 cui engine..those truclk carbs weren´t smog carbs.. afaik.

The reason for my HUNT after a good TQ ? The TQ is one of the best carbs .. for a streetdriven Car. Just like the Q Jet...
Good milage and power... if I want /need some..

Greetings Juergen
 
It's all preference. 'Some' people like Holleys, too. (No, not me.)

It's what the part was designed to do. Me? I might look at a AVS, late 60s-early 70s. But, that's just me. I'm an AFB kinda guy. End of deal.
 
I think you are running just the way the Chrysler engineers wanted a lean burner to run. the ECU on the side of the air cleaner on a lean burn used a vacuum signal to tell it what the load on the engine was so it could do all the timing adjustments sorta like a stone age version of what cars ECUs are doing today. the dist. on a lean burn has nothing in it no mech or vacuum advance just two pick up coils to tell the box when to fire plugs which where a early type of MSD unit (yes multi spark discharge). Back to your car if the car is running correctly, I would enjoy the gas mileage as long as it is not surging (starving for gas) under steady state cruise there is no problem. If it is idling steady state with 19" call that perfect your only one to be concerned with is the WOT if it is not laying over flat you are probably okay but you might be giving up a few hp, if you can remove linkage between primary and secondaries then wire secondaries shut for accuracy and safety go get a WOT on just the primaries you may just have to reduce the dia of the smallest part of the metering rod you can just file it a little or you can chase all over for the correct rods I am for filing because if you ever make mods for more power you will have to go smaller dia for even more fuel if you get that afr in the 12.5 range connect the secondaries back up then see what afr is if it goes leaner again you will have to pretty much drill the secondary jets or search ebay for thermoquad secondary jets they are the big tall ones N/A new good luck let us know how you do, if you have no drivability problems right now you are very close to correct. BTW you subtract the metering rod dia from the jet so you didn't go up .005 just because the number changed that much you only went up like .0015 or so I didn't go back in thread for math.
 
@ 70bigblockdodge... your answer is very helpful for me ! Thank you again. Next week I will do my "homework " and check the WOT AFR ratings..with the secondarys wired. The jets that are in the secondarys are the biggest ( afaik ) they are 5143.... about the math of the primarys... I made the calculation with "PI "...so I subtrakt the AREA of the rods from the AREA of the jets....

Greetings from Germany
Juergen
 
... recieved another TQ on Monday... now the AFR´s look much better... Idle AFR @14 Cruise AFR @ 15 to 15.5
slighty acceleration @ 13.5 WOT AFR 12.5 - 12.8

Only if I accelerate slowly but steady...the AFR is in the 15th area.... ?? But there is no pinging..or so..

I changed the primary jets..from 0.098 to 0.101 and put some 2086 Rods in... set the float level to 22 mm a little higher than the 25.4 mm . And turned the needletree screw about 2.5 turns clockwise... The IMS are @ 4 turns out.. looks like a little to far out, but the engine " wanted it that way "....

Greetings Juergen

forgot... the car runs smouth now... no hesitations... and the temp on the "autobahn" is @ 185° F ...
 
yeah ... the "autobahn " was made for saving some fuel... no red lights... only pavement ahead of you and your car..

Greetings Juergen
 
That sounds great a BB on the autobahn, BTW pinging and knocking should only be caused by compression and timing too much of one or.both, running lean will only give up power and run poorly.
 
That sounds great a BB on the autobahn, BTW pinging and knocking should only be caused by compression and timing too much of one or.both, running lean will only give up power and run poorly on a otherwise correct engine.
 
....I recived my Strip Kit yesterday !!! So now I can tune my TQ a little... I did some search in the www ...also. I found out, that the TQ has two small "air inlets" in the air horn.... on the smog carbs... according to "DEMON SIZZLER" these holes have to be closed.. ( epoxy ) ...because the air that enters there leans out the idle / primary/sec circuit. I will make a test with some strong tape....
to see how it works... and then I will fine tune my TQ !!

Greetings Juergen


BTW... I also changed my timing curve.... a little 11 deg @ idle 25 deg advance all in @ 2700 upm
 
Hey Juergen what are.you using for your air/ fuel ratios gauge, handheld unit, what brand just looking for some info thanks in advance.
 
... Hi 70bbd I use an " LC 1 Air fuel metering unit from Innovate " with a wide band O2 sensor welded in the Downpipe... awsome system... ( but sadly too accuurate to be true..- makes me crazy )

About the TQ I am giving up ! I will go back to my OEM Cast Intake from 1969... and put a 650 AVS on top... ( still have one laying on the shelf

Greetings Juergen
 
You must log in or register to reply here.

Similar threads

O
Edelbrock 1407 lean at WOT
Replies
16
Views
2K
ohitsjustbrian
O
pedal2themetal
I feel stupid .... air bleeds..
Replies
6
Views
947
pedal2themetal
pedal2themetal
Macdon221
Carter 4429 Whistling and Rich...Help!
2
Replies
35
Views
4K
Macdon221
Macdon221
C
4150 goes lean in gear
Replies
7
Views
1K
lewtot184
lewtot184
Z
Thermoquad without vacuum advance port options
Replies
8
Views
3K
zombezoo
Z
Auto Transport Service
Back
Top