Re: 1940 Super 8 160 Model 1803 Project
Posted by Jim On 2010/10/15 0:53:53
So after the initial test run, I felt the car was just a bit sluggish at cruising throttle applications and it seemed like timing was a bit retarded. I decided to check the points, lube the advance mechanism, verify the vacuum advance operation, and set the timing with the stroboscope.
My hunch was right (this happens once in a while) the vacuum advance was dead, leaking so bad that it would not hold a single inch of vacuum. This was really disappointing because I had planned to take the car to Friday and Saturday night cruise in and the annual orphan car show here in Phoenix Sunday morning.
As always, when rare parts are needed, Flackmaster to save the day. Waiting for me upon arrival from work was a new old stock Autolite vacuum advance. By 5:45 I was happily putting test miles on the car noting the improved throttle response, smoother cruising operation, and running a few degrees cooler. Thanks Dave!
For the benefit of those that might not know how to test the vacuum advance, simply use a hand held vacuum pump such as a Mighty Vac, or if you like connect a hose and suck. The diaphragm should draw the arm and advance the distributor ignition plate. If it advances and holds vacuum, you are in good shape. If it does not hold vacuum, or never moves, and builds no vacuum, you have a bad diaphragm. This can cost 6.5 degrees of total advance. That is a substantial amount to run late. I tend to make testing the vacuum advance a part of regular ignition test and tune. Below are some images of testing old and new.
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My hunch was right (this happens once in a while) the vacuum advance was dead, leaking so bad that it would not hold a single inch of vacuum. This was really disappointing because I had planned to take the car to Friday and Saturday night cruise in and the annual orphan car show here in Phoenix Sunday morning.
As always, when rare parts are needed, Flackmaster to save the day. Waiting for me upon arrival from work was a new old stock Autolite vacuum advance. By 5:45 I was happily putting test miles on the car noting the improved throttle response, smoother cruising operation, and running a few degrees cooler. Thanks Dave!
For the benefit of those that might not know how to test the vacuum advance, simply use a hand held vacuum pump such as a Mighty Vac, or if you like connect a hose and suck. The diaphragm should draw the arm and advance the distributor ignition plate. If it advances and holds vacuum, you are in good shape. If it does not hold vacuum, or never moves, and builds no vacuum, you have a bad diaphragm. This can cost 6.5 degrees of total advance. That is a substantial amount to run late. I tend to make testing the vacuum advance a part of regular ignition test and tune. Below are some images of testing old and new.
Attach file:
(35.91 KB)
(29.68 KB)
(34.13 KB)
(30.44 KB)
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