I have run out of the good AC Delco primary choke controls [part # 7038237] and have not been able to find more. I have looked at several aftermarket ones. They either work too fast or are too long. The quality of other parts are not very good either. If you have a carb that is running, but not to expectation, and has a good AC choke control with 38166 stamped on the arm, then give me a call. (270-737-4467) Otherwise, I will no longer be building Q-jets, because of the poor quality parts. I am still able to get distributor parts. So curving distributors should not be a problem. See my ad in Parts for Sale.
John, If they work too fast, would it be possible to epoxy the vacuum hole and redrill it with a precision drill set? I remember Greg Gessler doing this to tailor the dampening effect of the vacuum breaks.
Lucky me I looked in my parts stash and have a complete NOS bracket with both vacuums including the one John mentioned. Wish I had more.
My timing stinks. I just bought a carb yesterday on eBay without a choke coil and was going to send it to you for a rebuild.
Adam, I believe John is talking about the small vacuum diaphram on the front of the carb also known as a vacuum break or choke pull-off. Not the choke thermostat. Check the number on the one you get.
I'm not fully knowledgable on carbs, can you rebuild manual choke carbs, or convert them to manual choke?
I believe John is referring to the choke pull-off, the metal one at the rear of the carb from 70 and newer. I've also found them to be turning into unobtanium. The front pull-off helps control the secondary door opening rate. Whereas the rear one pulls the choke link once the thermostatic coil heats up and you come off fast idle. I've been stockpiling old nonworking cores as they can be rebuilt. Its not a quick repair as you have to cut them apart, replace the diaphragm and then put the halves back together and refinish them. It would be hard to do this as the part would be cost prohibitive to the customer. Enclosed are a couple photos from a carb I did recently of what John is looking for. John I'll try to give you a call this afternoon.
I was under the impression you could weld the hole shut and redrill it to the correct size and it would work correctly as the delco part did. Can anyone verify that? I was thinking Norm Deihl used to do that.
That is what I was asking. The nipple is plastic, so just epoxy over the hole and re drill? Will that work?
Dave, the number John gave is for the plastic vacuum break not the metal one. I have one. It is stamped on the arm.
Yes, I understand that now. It was just confusion in what it was called. I've never called it a primary choke control, but a primary choke pull-off (even though it has nothing to do with the choke itself), and the rear metal one the secondary choke pull-off. And to answer your question Larry, yes you can just fill the hole and redrill to tailor the secondary opening rates. That along with adjusting the spring tension has always allowed the proper fine tuning.
Dave, The front one has a dual purpose. It opens the choke a small amount (against spring tension)when the engine fires. It also slows the secondary air valve opening rate. The Rear one has a delayed effect(through an internal bleed), and opens the choke a bit more. And yes, I remember Greg Gessler altering the size of the hole to tailor the opening rate. I was wondering if John could measure the size of the hole, and just alter other choke pull offs to suit his purpose.
