67 Dashpot Question - Pontiac GTO Forum
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post #1 of 15 (permalink) Old 08-01-2018, 03:03 PM Thread Starter
 
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67 Dashpot Question

I have found a guy who can repair the dashpot for my 67 GTO, but he is asking a question as follows.

Notice as well, that -typically, these type devices MAY ALSO have a Dash Pot function. That is, this unit may really also be a “Shock Absorber” and may have a calibrated leak inside that allows air pressure escape at a specific rate. I do not know that for sure---but, during the “Malaise era” of smog control during the 80’s- it was not unusual to have a “Tapered rate” throttle closure device that took a high intake manifold pressure ( Like during heavy deceleration where the vacuum would peek as over 20” HG—and suck in way too much fuel from the idle circuit due to high vacuum under the throttle‘s butterfly valve-- - and allow the throttle to close more slowly---to avoid a high amount of suction and excessive rich mixture – basically high HC unused fuel out the tail pipe--- and sometimes also to avoid backfiring.
Calibrated Vacuum leaks are tricky- specifically when also having a vacuum source as does this one. Do your research and verify that it is bad, and exactly what it is supposed to do—and let me know. It MAY be OK as is????
Does anyone know if there should be a calibrated leak in a 67 dashpot? I thought all it did was to just back off idle at higher vacuum, but his write-up made me question.

Thanks,

Dan
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post #2 of 15 (permalink) Old 08-01-2018, 04:35 PM
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No, it just pulls in with manifold vacuum. No leak that I am aware of. (The one on my '67 is original and still works fine....as it has for the last 35 years and 130,000 miles I've owned and driven the car........
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post #3 of 15 (permalink) Old 08-02-2018, 12:56 PM Thread Starter
 
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That is amazing that it is still working after all this time.

Thanks for the information. Since I had the stock one still on the car, I decided to go ahead and have it fixed. I understand that these are rare and even more rare in working condition.

Thanks again.
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post #4 of 15 (permalink) Old 08-03-2018, 05:26 PM
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I know. I think the main reason is that the car has always been in use since 1967....never parked or side-lined. It has over 250,000 miles on it now, with me putting the last 130,000 on the car in the past 35 years. Original carb, original distributor, original engine. I think when cars sit for 10-30 years, all sorts of bad things happen.
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post #5 of 15 (permalink) Old 08-06-2018, 07:29 PM
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Quote:
Originally Posted by Colorado67GTO View Post
That is amazing that it is still working after all this time.

Thanks for the information. Since I had the stock one still on the car, I decided to go ahead and have it fixed. I understand that these are rare and even more rare in working condition.

Thanks again.
Here is how you fix it for those that are interested in the DIY method.

Order Bendix part # DA-102 dashpot, remove adjuster bolt.
Now place bracket in vise and saw it off close to the round post.

Set aside.
Now place the can of the original in the vise by the hose end.
Pry with a large screwdriver until the post separates from the can.
Now you can grind/file flush with the bracket and knock out the insert.
Now drill out original bracket with 1/2" drill bit.
Fit new pot onto bracket with some JB Weld.
Let set overnight.
Replace adjuster bolt and mount on carb.
Here are pics of repaired part.
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post #6 of 15 (permalink) Old 08-09-2018, 09:39 PM
 
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Colorodo 67GTO.I have a question about the dashpot.Did you have it repaired,and if so ,how was the repair.Was it made to look like original or was it just made finctional.I'm asking this because I have a dashpot that is not working.Applying vacuum to it does not move anything.I think the diaphragm is shot.I have been unsuccessful in finding anyone who repairs these.If it is ok with your repair guy ,could you supply his contact info either in this thread or PM.It would be greatly appreciated.
Thanks
Bob
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post #7 of 15 (permalink) Old 08-10-2018, 08:48 AM Thread Starter
 
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I can’t speak for the results yet because I just sent it off, but here is the website. It looks like he does really good work. It isn’t cheap. He will be charging me $125 plus $9.50 shipping.

Vacuum Advance Repair
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post #8 of 15 (permalink) Old 08-10-2018, 10:37 AM
 
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Thanks for the info.I will be contacting them.If they turn out like his pictures and work good,then I think the price is worth it.PLease let us know how it worked out.
Thanks
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post #9 of 15 (permalink) Old 08-11-2018, 09:35 AM
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Adjustment for this pot is vac disconnected and plugged, RPM set at 1050 in neutral.
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post #10 of 15 (permalink) Old 08-24-2018, 04:44 PM Thread Starter
 
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Wow. Buyer beware.

I received the invoice for the work on my dashpot and it was more than twice the estimate. He did not contact me to let me decide if I wanted to proceed. Pretty shady.

I haven’t received the part yet, but by the picture, it looks like a really good job, but way beyond my comfort level for what I wanted to spend.

To be fair, when I complained to him, he said I should pay whatever I feel is fair, so he did give me that option. I will still pay the full amount because this is not about the money but about my ability to make the decision on how much I spend.
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Last edited by Colorado67GTO; 08-25-2018 at 11:13 AM.
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