I have a big Holley 1940 on a 170. Rebuilt and it runs well enough though I think it's a tad rich. When I got the car it had a massive vacuum leak from between the big bore carb and small log 170 head, I cut a spacer plate and no more leak. Also had a PCV valve that was sized for a much larger engine, idled much better with correct PCV for a 170. Despite that the tail pipe was black with soot, though who knows when I got it as it had a loadomatic and this 1940 does not have a SCV. Now using a distributor with mechanical and vacuum advance. It's in a '64 Falcon with 3 speed and 3.50:1 gears, MPG is a disappointing 17-ish. Only had one Falcon before, a 63 with 144, 3 speed, unknown rear gear and I recall that got 25-30 MPG.
Carb stamping:
D7JL 9510 A
7937 2284
From my understanding this was a service replacement carb available in small and big versions. The big version I have I think was more commonly used on the small 250 or either of the big sixes.
Hot start it is finicky, I think accelerator pump shot was not helping since it wants the throttle cracked open slightly to start hot. I moved the accelerator pump linkage from the middle slot to the smallest slot closest to the throttle shaft, should give a little less shot. Also adjusted the accelerator pump linkage to spec on the rebuild kit of 27/32" or .844". It was at about .950" before. Have not test drove since it's raining today.
It has a 662 jet in it. Looks like a Holley jet but not sure, I did not compare to a standard Holley jet or try one when rebuilding it. Not sure what the suffix number is about but I believe it's approximately a 66 jet size.
Looking at the chart here (https://www.carburetor-blog.com/knowledge-base/1940-jets/) they list all these carbs as coming with a .068" which would be a Holley 67, regardless of application. Anyone know if these take a standard Holley jet? It looks like one but not sure if there may be a small size or thread difference. Don't want to pul lthe choke horn just to find it's a oddball type of jet I don't have. Anyone run a big 1940 on a smaller six and find a jet size that works well?
Carb stamping:
D7JL 9510 A
7937 2284
From my understanding this was a service replacement carb available in small and big versions. The big version I have I think was more commonly used on the small 250 or either of the big sixes.
Hot start it is finicky, I think accelerator pump shot was not helping since it wants the throttle cracked open slightly to start hot. I moved the accelerator pump linkage from the middle slot to the smallest slot closest to the throttle shaft, should give a little less shot. Also adjusted the accelerator pump linkage to spec on the rebuild kit of 27/32" or .844". It was at about .950" before. Have not test drove since it's raining today.
It has a 662 jet in it. Looks like a Holley jet but not sure, I did not compare to a standard Holley jet or try one when rebuilding it. Not sure what the suffix number is about but I believe it's approximately a 66 jet size.
Looking at the chart here (https://www.carburetor-blog.com/knowledge-base/1940-jets/) they list all these carbs as coming with a .068" which would be a Holley 67, regardless of application. Anyone know if these take a standard Holley jet? It looks like one but not sure if there may be a small size or thread difference. Don't want to pul lthe choke horn just to find it's a oddball type of jet I don't have. Anyone run a big 1940 on a smaller six and find a jet size that works well?
