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Unread 05-08-2015, 07:25 PM   #1
kovic
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1983 CJ5 
 
Join Date: Apr 2012
Location: Grand Rapids, MI
Posts: 748
Vacuum check, and timing check.

Hey guys.

1983 Jeep Cj5
Nutter,
Teamrush,
Weber 38
10* timing

I was talking with Tom (uptillnow) Because I had to order a part for my linkage, which by the way came the next morning, nuts. He got me back into trying things with my carb. He said my issues usually occur when manifold vac is off.

At idle I get around 20, Tom asked what I get with the idle screw in 1/2 turn, its 17-18.

Some know the issues i have had, basically I cannot keep within the 1/2 turn max with the speed screw, it will only idle at 250-300 rpms

Currently I am running 0 vac at s port, 19 or so at manifold, and that is with 3/4th turn in on speed screw.

Tom told me next step is to drill 1mm holes in the trailing edge of my throttle plates.

Here are some vids of what I have going.

http://vid989.photobucket.com/albums...0running_1.mp4

http://vid989.photobucket.com/albums...%20run%202.mp4

kov

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Unread 05-08-2015, 08:12 PM   #2
swatson454
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You know bud, your set up has plagued my woeful mind for more than a year now. Your video looks pretty damn good to me and most guys would be pleased as punch but I have a feeling you're a lot like me so what can we do here?

My first thought is that the "1/2 turn maximum" in the instructions is there because they have to set some sort of a guideline and that one works really well. One thing I learned from Barry Grant (not the man personally but dealing with his company) is to place much more emphasis on throttle plate position relative to transition slot (or enrichment hole in this case) exposure rather than a screw setting. With carbs, we're doing this stuff manually and not every threaded hole starts in the same position and you can't sit there with a lap top and increase the IAB by .2% at 700 rpm.

What's become an absolute doctrine for me is to get it to run the very best that you can, remove the carb and put your eyeballs on the enrichment hole exposure below the throttle plate and the screw settings be damned.

I had a wide-band and a vacuum gauge in the cab for 4 years and I can tell you that you have some wiggle room before the enrichment holes start flowing so try not to get too hung up on the half-turn deal but it's still a really good guide.

Another thing that's sure to spark (pun coming soon) some controversy is the CDI ignition. Regardless of the "engineering facts" that are thrown up around here, the only reason those boxes hit the plugs 5 times per cycle below 3,000 rpm is because they fire the charge horribly with a single shot. There's a place for those boxes and they shine in the right application but this ain't it.

I can't say that that's part of your problem or not but it's something to consider, although I doubt if it matters because you've already got the goods wired in

I wish my phone at the time had the audio that today's iPhones have because the sound is all jacked up but you can surely see the wine basically not moving. And that was before a decent ignition. http://jeepspace.jeepforum.com/video...1610#video1610

I guess to wrap up my ramblings, try not to get too fixated on a screw setting. Flip the carb over and if your enrichment hole exposure is in the green zone, life is good, even if you're at 3/4 in.

Plug gaps between .035 and .040 are a good thing, too.


Shawn
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Unread 05-08-2015, 08:35 PM   #3
kovic
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Yea, its videos like yours that makes me keep striving to find out whats 'wrong' with my engine...

I understand about the CDI, but I had this exact issue before I ever got the msd stuff..

kov
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Unread 05-09-2015, 11:17 AM   #4
swatson454
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Hey Kov,

I watched the first video again now that I don't have any vino in my veins and it almost sounds like you've got the "lean poof", as I call it. I'm wondering what happens if you give the mixture screws another 1/4 turn out.

I'm also wondering what the vacuum port on the back of the intake manifold goes to. It doesn't look like your timing is too stable, either. Loose timing chain? Slop in the distributor shaft?


Shawn
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Unread 05-10-2015, 09:58 AM   #5
kovic
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Hey swat, I was also wondering why timing mark seemed a little wild. Maybe chain was not replaced a rebuild? Or could the cheap timing light cause it? I dunno, the vac line at back of manifold goes to my TAC. Here is how it sounds with mixtures 1/4th more out.

http://vid989.photobucket.com/albums..._233510600.mp4

Kov
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Unread 05-10-2015, 10:48 AM   #6
swatson454
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Video isn't up. Did it help at all?


Shawn
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Unread 05-10-2015, 03:04 PM   #7
kovic
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Sorry. Video should work now. I am not sure if it helps, I guess I don't know what it should sound like, I didnt notice the "lean poof" that you did. Does it sound any better to you.

Of course it didn't allow me to back out the idle speed screw and it stay the same rpms.

kov
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Unread 05-10-2015, 03:13 PM   #8
swatson454
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I may be able to hear a faint little something in there (a hair better than before) but man, that thing sounds like it's running really well. You're as picky as me!


Shawn
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Unread 05-10-2015, 04:15 PM   #9
kovic
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Yea its odd, its not very consistent. Seems to run great one day, then the next it has a little shake to it... Its more frustrating because I know about the stinking only 1/2 rule, and Im way off, 3/4th to 1 turn in to get the rpms I want....

Heres another vid from today.

http://vid989.photobucket.com/albums...un%20again.mp4

Seems my only other option is to drill holes in the plates. But even then I know its more of a cover up.

kov
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Unread 05-10-2015, 04:35 PM   #10
swatson454
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I think it sounds great, man. Like I said, this isn't NASA stuff so I honestly wouldn't get caught up on the setting. You've pulled it off and the enrichment hole exposure was good, right?

I didn't hear any hiccups this time, either. Now here's something I've recently heard from guys I trust; CDI ignitions often want a couple extra degrees of initial timing over a good inductive ignition. I don't remember where you are but maybe your engine is one of those that responds favorably to that move.

Yours sure doesn't sound any different than mine. Probably have to jack the volume way up. Hell, you've probably seen these already.






Shawn

Edit: I don't know what's happened but photobucket isn't running my videos they way it used to. Now they're all twitchy and I have no idea why.
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Unread 05-10-2015, 06:12 PM   #11
kovic
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Ya know, When I dink with the timing if I advance it a bit the idle does speed up, however, again, I see that 10* 'rule' or strong suggestion and I just go back to that. In fact a shop I took it too set it to 8*.. ran pretty good, but they had the idle speed in a little over 1 turn. I dunno man, Maybe ill check the timing chain or something.

This is a curse I guess lol. I want to much perfection.

Thanks for your help.

kov
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Unread 05-10-2015, 07:13 PM   #12
swatson454
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Let go of the 'rules' and use the force They're really just guidelines anyways.

Seriously though, if it responded favorably to an increase in timing, let her have it. When the idle comes up, drop it back down with the idle screw. Just pay attention to how it sounds and if it knocks under acceleration or surges any when you cruise.

Everything you've done has been spot on so I have no doubt you'll get it perfect. There's absolutely nothing wrong with 12* if that's what it wants. And there's no such thing as too much perfection. I'm the same way dude. I could over-think a cup of coffee if I'm in the right mood


Shawn
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Unread 05-10-2015, 08:04 PM   #13
kovic
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Should I just turn the Distributor until its at its highest idle speed?

kov
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Unread 05-10-2015, 08:16 PM   #14
swatson454
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I've never had any luck with that and I don't recommend it. I'd consider 12* to probably be about as high as you should go but like some of those pros were talking about, a CDI often requires a little more so who knows.

Don't be shy, you can always come back down a little.


Shawn
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Unread 05-10-2015, 09:01 PM   #15
kovic
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Yea I'll dink with it when I got time,and as for the enrichment hole, I'm not sure how to tell if its exposed without pulling the carb off, but if it gets exposed at 1/2 turn in, then it is for sure exposed.

Kov
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