Thermoquad?

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340wedge

340wedge

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Okay here goes, I just purchased two 4973 1971 Thermoquads which were advertised as parts carburetors. One is complete, one is mostly complete. The air/fuel mixture needles are broken in both base plates. I am thinking am easy out to remove the broken off needles. or drilling and re-tapping? Either way I need to purchase new air/fuel mixture needles. Does anyone know the part# or size of them? I see many years for them but not 1971 which I know if a one year only animal. Thank you !
 
Great carbs & I wish you luck. Did the screws break because the steel corroded with the alum base?
Not sure what the thread is but AFB, AVS or later TQ screws might be the same thread & could possibly work.
 
These are the Thermoquads with the mixture screws that you want.
4972, 4973,6138,6139,6318,6319, 6339,6340.
Carter #30a-207.
You can buy the mixture screws on eBay.
www.ebay.com

CARTER THREMOQUAD YF YFA IDLE MIXTURE SCREWS 30A-207 | eBay

Find many great new & used options and get the best deals for CARTER THREMOQUAD YF YFA IDLE MIXTURE SCREWS 30A-207 at the best online prices at eBay! Free shipping for many products!
www.ebay.com
 
Good luck with drilling them out, if I were you, I find a competent machinist with expertise in that sort of thing.

I’m a retired tool and die maker and I also have a TQ base with a busted screws. My plan is to get the base plate hot in a pot of boiling water, repeating the process over and over, heating, cooling to try to soften up the corrosion. penetrating oil between heat and cool cycles. Then drilling out the jet with a left hand twist drill in a precision milling machine setup. That way if it loosens up while drilling it will back out. Drill with the base plate hot. Set a precision spindle stop and drill.01 at a crack.

If you do happen to get them out, you have to figure out the thread pitch in the hole to help you search for a replacement jet screw.
 
Thank you all, I appreciate the information townsend, it was just what I was looking for. Ch1ll, you obviously have much more experience than me being a tool and die maker! I am going to experiment on the base that is worst first. Sending them to a pro may be a real option. Do you think an ultrasonic cleaner may loosen some of the corrosion. My plan was to do that, then use some tap magic or 50/50 and try a screw extractor and maybe some heat at the same time.
 
340wedge said:
Thank you all, I appreciate the information townsend, it was just what I was looking for. Ch1ll, you obviously have much more experience than me being a tool and die maker! I am going to experiment on the base that is worst first. Sending them to a pro may be a real option. Do you think an ultrasonic cleaner may loosen some of the corrosion. My plan was to do that, then use some tap magic or 50/50 and try a screw extractor and maybe some heat at the same time.
Click to expand...
If you use a professional grade ultrasonic cleaner it may help some, harbor freight ultrasonic cleaner,? No.

Heat, cool cycling and drilling it out hot are paramount I would think cause the aluminum body is going to expand more than the steel screw jet. That may give more room for penetrating oil to get between the two. Out of all penetrating oils on the market, I like PB blaster the best.

As for a screw extractor, that would be one small one. Definitely would not want to get that busted off in the hole.
Generally I don’t like taking a hammer to anything I’m working on.

The hard part of the whole deal is when to stop messing with it and and just send it off to a place like woodruff carbs.
 
Oh, by the way, by cooling it, I mean throw it in the freezer for 3-4 hours.
 
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