Divorced choke and their 2bbl/4bbl variants.

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8v-of-fury

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Hi there all!

Back story;

1988 smogger 318, ESA/ELB deleted and am running a new kit to convert back to conventional electronic ignition as well as a Edelbrock Performer and 850 Thermoquad (non feedback) carburetor. Rest of the engine is bone-stock.

Problem;

The engine was obviously originally a 2bbl ESA/ELB feedback carburetor abomination lol! I have gotten rid of all that non-functioning tomfoolery in lieu of a junkyard carb, used manifold and an ebay dizzy/ignition kit ;). The ignition and everything are damn fine quality and the carb freshened up very nicely with some pine-sol and a rebuild kit.

HOWEVER, the choke linkage I had to modify to accept the much wider Thermoquad sitting high and mighty. Before the rod went straight up to a much taller two barrel carb's choke linkage. On this one, it seemed like it was gonna work well this way (been like that over a year, but now it seems to be not functioing correctly.. not coming on).



I wonder, how strong is the up force of that spring supposed to be? I may have to remove the rod and add some length to one of the up right pieces in order to get some oomph back out of the spring.

Question;

Does anyone know, or have pictures of a stock/factory 4 barrel Thermoquad equipped small block for reference?? :)
 
Two questions; 1) is the electric assist hooked up to the run circuit? and 2) is the choke plate swinging free?
If yes and yes, I expect the heater element has failed, or the bottom of the link has become dislocated from the coil.
Everything worked at one time, so a longer link is not the answer, I don't think. Besides the one you have can be adjusted for more preload by unbending the 90* corners some.

As to the up-force? On the electric assist models it's normally plenty strong. I can't give you a number or a description. Plenty is all I got!
 
Yes, the 12v assist is hooked up. Last I checked it had 12v with the key on, but I haven't checked recently. Yes, the choke plate swings free on the carb.

Simple test would be to pull the choke out of the manifold, energize the coil and see if it retracts?

I do recall watching videos and remembering the 2bbl, when you pumped the gas the first time on a cold engine you could audibly hear the choke plate slammed shut. I may just need to source a new one then hopefully.. lolol

Any word on the 4bbl variant of the divorced choke?
 
If you manually set the choke Via your hand it will properly pull up on the secondary lockout tab. When the choke worked properly it did keep the secondaries offline until the choke heater allowed enough movement to allow secondary lockout to be disengaged.

I am not with the car for another 2 weeks, so I am just getting thoughts and practices together for that time.

I think if I unbeND my rod a bit, and make sure the heater coil is free moving it should be able to work well.
 
^ That right there is a very informative and interesting read for anyone!

I will have to give that a going over once I am back with the car and adjust everything to how it says. Cause I feel like the choke may be completely dickered! lol
 
That information seems good, but here is a short version I use. At 68 degrees F, the choke should "just fully close", after throttle is depressed once, to set fast idle cam. At that temperature the choke just makes it closed, when engine starts, the vacuum on choke pull off, opens it some. When car is warmed up, choke should be fully open.

It is possible to fabricate new operating rods. This is done when installing thick thermal base spacer , or changing to alternate carb type. The "C" clip notch can be cut by grinding the set out a fine hacksaw blade. I find a very old coat hanger, is the correct diameter for the rod. A vise and small hammer helps with bends.
 

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Very nice! That seems like a damn good idea, however this one was plenty long for my application. I do believe a re-bend with proper settings in mind will yield the results you need.
 
To recap on this, I ended up finding the correct part number for a 4bbl small block choke and then referenced that to a number that was supplied via parts places.

CV164 which is then superseded by CV174 is the correct choke linkage when using a Thermoquad on a small block. I have seen the number also cross reference to the big block applications.. I do not have those in front of me to confirm however.

This should button up my choke issues quite nicely!

As you can see below, there is a SLIGHT bend like the one pictured two posts back and it is barely visible in this photograph.

 
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