Lean Burn Carburetor Refresher

streetmachine

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Hello again, I'm trying to remember something from a while ago in regards to these carburetors. But, I'm trying to remember if a Lean Burn carburetor can be jetted properly to run properly once you run an electronic ignition? One thing I've come across with the later carburetors as well is the lack of idle speed adjustment as well on the later car applications.

I'm just curious because I have a 79 TQ from a LB car application and I have freshly rebuilt TQ with an 80 truck application. The '80 truck carburetor is less complex and allows me to adjust the idle speed and I think a vacuum port to allow the advance from the distributor as well.

I've read a couple of times a LB carburetor even if jetted properly still may not function correctly or be good enough plus they don't have the port for the vacuum advance. Just curious. Thank you in advance.
 
I have 1406 Eddie's on after replacing the Lean Burn system.

I don't have any love for TQ's going all the way back to when I bought my new 73 Ralleye Challenger w/340.
 
ever have a tq apart? the jets unscrew like an afb. take them out and use a tip cleaner for a torch tip to open 'em up a little. too rich? fill them back in with solder and redrill to the correct size. the boss is present for the idle screw. drill it, tap it, put a screw in it. don't forget those rubber o-rings between the bowl and the throttle plate. port for vacuum advance would require different throttle plate or some really artful drilling. good luck, SG
 
ever have a tq apart? good luck,
Several. Horribly complex. Reassembly is like trying to put back a spring wound watch after exploding.
I have my theory on why they suck for tunability: Transition!
You tune for smooth transition in one operating range and you take away from another operating range. You take it apart a hundred times to tune one problem area and a problem shows up somewhere else. You're playing Whack-a-mole with them. Just not worth losing your sanity all in the name of "originality". I'm never playing that suckers game again with those pcs of crap.
 
Oh! And trying to accurately drop in those F&$#-ing no gawdarn good sonovabitch metering rods... :mad::mob::BangHead::soapbox:
 
I had a 360 with a ThermoQuad that I drove daily about twenty-five years ago. Over seven years, the only issue I can remember with the carb is that it idled through the main jets. The engine speed was correct so I left it alone.
 
As I said before...

I had a brand new 73 Challenger w/340 and a TQ. Two carbs under warranty and the mechanic talked me into a Holley carb. Never had another carb problem!
 
When they work they are awesome. Most everything on a lean burn needs fattened up, if you haven't strayed too far from stock you can just open the main jets up a small amount and the rods stay the same, the secondaries also opened a bit they are the tall ones at the rear screwed into the air horn. The vacuum can be plumbed to manifold vacuum if you do not want to drill the venturi port. A/F gauge is worth it if you are serious about getting it right. Good luck
 
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Several. Horribly complex. Reassembly is like trying to put back a spring wound watch after exploding.
I have my theory on why they suck for tunability: Transition!
You tune for smooth transition in one operating range and you take away from another operating range. You take it apart a hundred times to tune one problem area and a problem shows up somewhere else. You're playing Whack-a-mole with them. Just not worth losing your sanity all in the name of "originality". I'm never playing that suckers game again with those pcs of crap.
i used to run two of them on a single plane offy manifold just to f''k with people. SG
 
Thank you everyone. I bought a spare from a 1980 360 truck application which has less emissions stuff. The other thing I noticed with the one Lean Burn is the lack of adjustment for the curb idle. I'd had my dealings with a 1406 Edelbrock and my biggest issue is boiling fuel in the bowls even with gasket to reduce the heat. Right now I'd love to buy an MSD Atomic Kit but, I have other priorities and with this TQ I wanted to keep it looking somewhat factory and my cruise control.

The other thing I like about the TQ is the sound especially when they are tuned pretty decent. I had the factory 9226S on my LRE done by Demonsizzler when he still did TQs and that truck sounded awesome at WOT.
 
Thank you all. I'm going to try out a rebuilt truck TQ which is non-lean burn.
 
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