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I wouldn't bother there is plenty of good info on this site that can be more than helpful
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So sorry for the delay in responding to your post. In addition to our 1969 Mach 1, there was a 1968 Cobra Jet that according to its license plate it said something like "RealCJ" and it appeared to be an actual Cobra Jet. I'm not sure if you are asking about "Newer" CJs, but am pretty sure that you weren't. I know Ken, aka KJ428SCJ was there as we spoke at length about several things, but he was there with a 2013 Mustang, I've forgotten what kind it was.
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General Discussion / Re: single diaphram vacuum advance unit
« Last post by Dave R. on Today at 09:18:27 pm »
Thanks Gerald. I will replace it. Good idea on using the pump in conjunction with the timing light. Appreciate that.   Dave R.
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General Discussion / Re: single diaphram vacuum advance unit
« Last post by geraldt52 on Today at 07:57:50 pm »
... The arm seems to move at about 5" and seems all in by 12"...
That's not unreasonable.
...The diaphragm seems to lose vacuum until I pump it up to about 7" then it holds vacuum for about 20 seconds. At 12" the vacuum holds and creeps down to 11" after a minute and down to 10" after 2 minutes. After 3 min. the reading is 9". It takes 4 1/2 min. to creep down to 8". Another minute and 15 seconds the vacuum falls to 7 " and then it falls immediately to 0". Does this sound right?
No, it should hold vacuum as well below 7" as it does above 7".  It sounds like you have a small leak, but make sure that the leak isn't in your setup instead of your advance unit.  It'll probably work like that, but for how long before it gets worse?...plus, there are no good vacuum leaks.  Leaking down over a few minutes is nothing, but instantly falling off under 7" is not so good.  Of course you don't need a vacuum advance at all, if you want to just plug the lines.
...Now you have to figure out how that movement translates into additional spark advance at the cruise vacuum.
I agree.  Put a timing light on it when idling hot, apply the vacuum with your new vacuum pump, and you can see and record how much vacuum advance you are getting with how much vacuum.
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General Discussion / Re: single diaphram vacuum advance unit
« Last post by Dave R. on Today at 07:56:34 pm »
It is strange that it leaks down immediately until it has 7"+ of vacuum. With more than 7" it leaks very slowly as I noted above. Guess I'll replace it. Even though a dual unit is correct I am not interested in concours correct. Thanks.   Dave R.
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General Discussion / Re: Air cleaner bracket manifold bolt
« Last post by sah62 on Today at 07:37:09 pm »
Yes, the bolt is too short if used with a spacer (confirmed: no spacer) and too long if used without a spacer.
But I doubt AMK sells a bolt thats too long. That means that either the bolt hole is obstructed or the cylinder head is not correct.

10 min ago I went to the garage to take a closer look and to my surprise, I have never noticed, I saw that the left front bolt has a stud. I assume that this is the missing one. I will remove it tomorrow and see if it fits where it should be and if there are any differences in length.

I think this is relevant (from the intake ID page, https://www.428cobrajet.org/id-intake):

"1969 and 1970 owners take note: your intake manifold was bolted down with bolts that included studs for mounting accessories. All 1969 and 1970 CJs have a studded bolt in the third mounting hole on the driver's side of the intake that was used to mount a bracket for the shaker hood scoop. Even Q-code cars should have this studded bolt because the engine assemblers didn't know if the engine would be going into a Q-code car or an R-code car when the engine was assembled. 1970 cars used a second studded bolt in the second bolt hole from the front on the driver's side that was used to mount the rev limiter ground wire."
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General Discussion / Re: single diaphram vacuum advance unit
« Last post by Jiffy on Today at 07:11:11 pm »
If it leaks it's no good. Replacement dual vacuum units are available or Tim O'Connor can rebuild your original unit.
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General Discussion / Re: single diaphram vacuum advance unit
« Last post by rockhouse66 on Today at 05:16:52 pm »
It probably shouldn't leak down at all, but since it is being supplied with vacuum continuously when in service, I think the one you tested will probably work just fine.

Now you have to figure out how that movement translates into additional spark advance at the cruise vacuum.
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I find the Sikora book to be useful, but it is now rather old.  I would not consider it the "bible" for what you are trying to achieve.
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General Discussion / Re: Air cleaner bracket manifold bolt
« Last post by gregb on Today at 04:45:28 pm »
Take that bolt/stud out and compare it to the bolt you removed.  Either it's the wrong one, machined wrong, or it's not going in the hole properly.  Can you thread the old bolt in easily?
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