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200 I-6 with Holley 1940 carb

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200 I-6 with Holley 1940 carb

Post #1 by [T00lbag] » Wed Mar 13, 2019 2:55 pm

Please help me with a super frustrating problem that I can't seem to find anywhere else.

A 200 cu. in. straight six resides in my 1964 Mercury Comet which is a brother to the Ford Falcon. This engine originally used the hunk-of-junk known as the Autolite 1100 coupled to the even-bigger-hunk-of-junk Load-O-Matic distributor. Sometime in it's life, this car went to the dealership and received the Holley 1940 carburetor as a service replacement part as denoted by the tag affixed to one of the screws. relation to the Holley 1940...How do I adjust the choke/fast idle rpms independently of the overall idle rpms?

I know people normally just turn down the overall idle screw but that causes me other issues...When the overall idle is turned up, the choke/fast idle rpms tend to run super high like the engine is running away. Yet, when I turn down the overall idle screw to compensate for the fast idle, the engine tries to stall at traffic lights during normal driving conditions. Otherwise the engine runs just fine.

So. How do I lower the fast idle speed while retaining the overall idle speed?

FYI. I learned in diesel world so carburetors are not my specialty and I really don't understand the myriad of linkages all over this Holley 1940.

Thanks in advance.

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Re: 200 I-6 with Holley 1940 carb

Post #2 by Econoline » Wed Mar 13, 2019 4:01 pm

It ain't gonna fix itself

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200 with Holley 1940 carb

Post #3 by chad » Wed Mar 13, 2019 6:40 pm

W E L C O M E !!!
to the best forum on our site!

Yeah, a lill different than a diesel. That Load-a-Matic (LOM) & the carb have a feedback system - carb to dizzy (SCV) till '68. Seth got U some quick help. Many of us use the Ford 6 Performance Handbook for all things ThriftPower (the 6 falcon motors, ford goes by families not big/sm block). C Matt at vintage in lines dot com for one ~ $20.
Nother quick review is our 'tech archive' at the big blue box above w/the crossed screwdriver'n wrench. Click there'n go 2 (I think it sez) "LOM/SCV Feedback System". Many of us ditch the 1940 (a ford dealer 'replacement carb') for the 1100/01 or better - the 2100 (a 2v) & the DSII ign.
Lotta great help here, f/u with those references & cm'on back if wishin more help.
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), 250, NV 3550 & DSII to B transplanted, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", tool boxes, etc. Seeking: Hydraulic gear motor for Koenig pto. (413) 259-1749

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Re: 200 I-6 with Holley 1940 carb

Post #4 by StarDiero75 » Wed Mar 13, 2019 8:15 pm

With the 1940, yoy have to manually bend the metal rod comming off the choke. Take a pair of needle nose vice grips and bend it.

Mine didn't have it so i used a small soft metal rod that i bent and cut. It was very easy to bend using that but i dont know how the stock one is

Once you bend it enough to where the choke is closed enough, you shouldn't have a problem adjusting the fast idle. If you're lowering it, its probably starving for gas, which is why it stalls. Make sure the choke is set properly with the rod coming off the choke cam

Good luck
--1965 Ranchero w/1966 200 and 3.03 column shift, 8" rear 2.8 (Yes I know the gearing sucks), 1968 1.08 Autolite 2100 with VI adapter, CRT Performance HEI.
--1961 Studebaker Lark VI, OHV 170 l6 in the process of being resurrected. But it lives
--Creator of the only Weber 32/36 conversion video.

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Re: 200 I-6 with Holley 1940 carb

Post #5 by [T00lbag] » Thu Mar 14, 2019 9:28 am

Thanks for the information. I've actually had pretty good luck with the Holley 1940, although it does need to be rebuilt simply due to age and the ethanol content of todays gas as opposed to 1964 gas. The major problem I had was with the Load-O-Matic. I was never sure what exactly the problem was but I know the vacuum advance didn't work correctly. Of course, this could have been the SCV and I don't know it. What I ended up doing was replacing the Load-O-Matic with a DUI distributor and severing the link to the SCV by switching to manifold vacuum. It only required a plug in the original port of the carb and a tee fitting so I could hook up the line at the manifold.

This problem with the idle/fast idle was something that has been happening all along actually. I just haven't been able to figure out how to decrease the gap between them. And now that it runs pretty well on the DUI distributor, this is more pronounced than it was.

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