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Replacing CD 150 in '69 Alpine

Discussion in 'Huskies, Imps, Rapiers, Fastbacks, etc.' started by Bill Blue, Oct 3, 2021.

  1. Bill Blue

    Bill Blue Platinum Level Sponsor

    I have driveability, searching for the proper high speed mixture. Tends to be too rich. Looking for the proper combo of air jet and main jet sizes. I have decided the jet terminology is confusing. I think the intermediate jet is in reality a full range jet that gets augmented at high speed, which mean the main is really a high speed auxiliary jet. That is the only way I can make any sense of what I see in the O2 meter.

  2. Barry

    Barry Platinum Level Sponsor


    You have actual data (as opposed to conjecture) about how the S&S carb behaves. If the AFR data indicates that the intermediate jet is actually full range and that the main jet is actually a high speed auxiliary, then go down that road and see what happens.

    On a related issue, how did the "vacuum advance port" work out?

    Keep up the good work!
  3. Bill Blue

    Bill Blue Platinum Level Sponsor

    Yes, a different perspective on the problem leads to different actions. Currently busy with 3 and 5 y.o. grandkids. Really puts a hold on test drives.

    Have not really looked at the spark curve, but I think the home brew vacuum port is working pretty good. At least I now think of the 1725 as "a hardworking 1725" instead of " a lackadaisical 1725". But I suppose the acid test on the vacuum port is gas mileage, which is going to be hard to determine as the odometer is an off and on again thing.

  4. Bill Blue

    Bill Blue Platinum Level Sponsor

    Currently have it running pretty good, very responsive up to redline. Seems to be a tad rich in the mower mid range. The current jetting is .060" main (the smallest in the jet jack is .066"), main jet air correction is .066" (comes stock with .040", with instructions to use .060" is the .040 is too small). The intermediate is currently .028". The carb came with a .0265 in the jetting kit, but I drilled it out to .038" doing the initial setup. So I filled that jet with solder and have drilled it to .024". It is now installed but untested. That will occur sometime after we get a nice road desalting shower. Just for fun, I've taken a picture of the tools used to do this. The brass thingy is an intermediate jet. The metering orifice is located in the middle of the jet, close to the threads. The Slivery tool is a pin vise that I used to drill the solder to .024". Just to give everything some size perspective, I've also included a 1/16" drill.

    Shannon Boal likes this.

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