Electric choke on Holley 1920
- Thread starter cerb
- Start date
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What does the other side of the carb look like. The choke is on the opposite end of the throttle linkage.
BillGrissom
Well-Known Member
The Holley 1920 was used on many six cylinders by several others (GM and Ford?) and varied over the years. The first kit was likely for a Holley 1920 designed with an e-choke so was a repair kit, rather than for retrofit, but just guessing.
I retrofit the one in photo 4 on my 1969 slant years ago (J.C. Whitney catalog). It didn't fix my problem, which was a failed "choke pull-off". That is the vacuum pod at top in your first photo. I didn't know much then, and thought that was a damper. It's purpose is to let you set the choke fully closed to start easy when cold and cranking. As soon as the engine fires and speeds up to generate intake vacuum, that pod slightly opens the choke so it doesn't run rich. The manual shows how far (drill bit as gage). Usually the rubber diaphragm cracks. Can test with a vacuum pump. If none, a simple test is to remove the vac hose, push the rod in, plug the vac hole w/ your finger and let go of the rod and see if it doesn't move out (much, will a little until vacuum builds inside). I think w/ today's web, you can find a replacement pull-off pod.
BTW, my slant idled lean for decades, wanting to die when leaving a stop, and unscrewing the idle mixture screw full out didn't help. That was over 3 replacement carburetors (rebuilds from auto parts), another intake manifold, several "valve jobs" (pro mechanics claims), and finally even a whole new long-block (cyl 6 no compression). So, I changed everything under the carburetor and it still idled rough, so tried a 4th carb and it purred like a kitten. Conclusion: many poor 1920 rebuilds. It has a sealed metering block, critical for idle mixture, which gets clogged and few rebuilders touch it. Some guys here posted how to blow them clean with air.
I know your carb sounds a bit complicated, but appears a simple 1960's one. Take a peak at the last-gasp carburetors, such as Thermoquad or Quadrajet, esp. 1980's ones with electronic O2 feedback, and you'd wonder WTF, not to mention the clutter of poorly-documented vacuum components and air-injection pump, all to meet emissions. Some claim today's engines "too complicated to fix at home", but EFI and distributor-less ignition can be easier to diagnose and repair. At least my Chrysler 1996 2.4L and 2002 3.8L haven't stumped me, but then I'm no BMW fan.
I retrofit the one in photo 4 on my 1969 slant years ago (J.C. Whitney catalog). It didn't fix my problem, which was a failed "choke pull-off". That is the vacuum pod at top in your first photo. I didn't know much then, and thought that was a damper. It's purpose is to let you set the choke fully closed to start easy when cold and cranking. As soon as the engine fires and speeds up to generate intake vacuum, that pod slightly opens the choke so it doesn't run rich. The manual shows how far (drill bit as gage). Usually the rubber diaphragm cracks. Can test with a vacuum pump. If none, a simple test is to remove the vac hose, push the rod in, plug the vac hole w/ your finger and let go of the rod and see if it doesn't move out (much, will a little until vacuum builds inside). I think w/ today's web, you can find a replacement pull-off pod.
BTW, my slant idled lean for decades, wanting to die when leaving a stop, and unscrewing the idle mixture screw full out didn't help. That was over 3 replacement carburetors (rebuilds from auto parts), another intake manifold, several "valve jobs" (pro mechanics claims), and finally even a whole new long-block (cyl 6 no compression). So, I changed everything under the carburetor and it still idled rough, so tried a 4th carb and it purred like a kitten. Conclusion: many poor 1920 rebuilds. It has a sealed metering block, critical for idle mixture, which gets clogged and few rebuilders touch it. Some guys here posted how to blow them clean with air.
I know your carb sounds a bit complicated, but appears a simple 1960's one. Take a peak at the last-gasp carburetors, such as Thermoquad or Quadrajet, esp. 1980's ones with electronic O2 feedback, and you'd wonder WTF, not to mention the clutter of poorly-documented vacuum components and air-injection pump, all to meet emissions. Some claim today's engines "too complicated to fix at home", but EFI and distributor-less ignition can be easier to diagnose and repair. At least my Chrysler 1996 2.4L and 2002 3.8L haven't stumped me, but then I'm no BMW fan.
slantsixdan
=..=
That's correct. The kit you need is indeed a № 1231.
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Thank you for confirming that! Will 1231 also fit a later manifold?
slantsixdan
=..=
A № 1231 will bolt to any Slant-6 exhaust manifold, though if you're using a '70-'72 manifold (with the open hole at the top of the choke tower) you will need to seal off that hole, either with the original choke cup and (no longer available) gasket or with a custom-made blockoff plate and gasket.
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