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Unread 04-25-2013, 05:41 PM   #61
swatson454
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Quote:
Originally Posted by firemanjim7 View Post
Thanks Swatson. I've been alittle busy to work on the jeep lately I haven't given up on it though. Just those dumb a$$ e's at CRT.
Don't sweat those clowns. If the curve they actually installed is 20*, we can get you squared away. I'm not sure I'd bother calling them again.


Shawn

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Unread 04-25-2013, 06:02 PM   #62
86cj74.2L
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If 20 is too much, The recurve kit from mr gasket gets you a bunch of springs and a 15 degree mechanical advance weight set. (Plus a adjustable vacuum advance canister too I think)
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Unread 04-25-2013, 06:57 PM   #63
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Quote:
Originally Posted by 86cj74.2L
If 20 is too much, The recurve kit from mr gasket gets you a bunch of springs and a 15 degree mechanical advance weight set. (Plus a adjustable vacuum advance canister too I think)
I got springs! And I'm not scared to use them!😡

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Unread 04-25-2013, 07:04 PM   #64
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I'm not sure 20 centrifugal is too much. But, I think it depends on when it's all in.

My old 258 sang like a canary at 12 initial, and 35 total at 3000 RPM.

Matt
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Unread 04-25-2013, 07:56 PM   #65
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Quote:
Originally Posted by Matt1981CJ7
I'm not sure 20 centrifugal is too much.

Matt
Me either. We'll get it.


Shawn
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Unread 04-25-2013, 08:19 PM   #66
86cj74.2L
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You guys are almost making get the junkyard HEI dizzy and put the correct gear (which i got from JH) on it and slap it in the CJ and try again with heavy set of springs.
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Unread 04-26-2013, 07:58 AM   #67
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Quote:
Originally Posted by 86cj74.2L
You guys are almost making get the junkyard HEI dizzy and put the correct gear (which i got from JH) on it and slap it in the CJ and try again with heavy set of springs.
Come to the dark side


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Unread 04-26-2013, 10:19 AM   #68
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Quote:
Originally Posted by swatson454
Screw CRT. Here's something you can try since you like road testing.

From David Vizard's Smallblock Chevy book:

"At this point I'll assume you have an HEI with a selection of advance springs and adjustable vacuum. The first step is to install the strongest springs at both locations on the distributor's advance mechanism. If your vehicle is a manual transmission, all of your tests can be done on a lonely stretch of road with a stopwatch. The technique involves choosing a suitably low starting rpm and timing the vehicle between two speeds. Let's assume that the motor has the potential to pull from 1,500 rpm. With the strongest springs installed, take off and have the clutch fully engaged in second or third gear at an rpm lower than the test's starting point. For example, we're working here with 1,200 rpm. Floor the throttle and time how long it takes to reach 2,500 rpm (my insert: floor it at 1,200 rpm and time it from 1,500 to 2,500 rpm). Progressively lighten up the primary spring until the best 1,500 to 2,500 rpm results." DV

Me again. I'm going to paraphrase this part because it's buried in a lengthy section on timing automatics. From here, you'd run either stopwatch trials from 2,500 rpm to redline or you could go for top speed. Increase the initial advance no more than two degrees at a time until your time or mph falls off or you hear detonation. If you hear detonation at a lower rpm, you may want to add the next heavier spring on one side of the advance mechanism and keep going with your high-speed testing. If you find out that you started your initial spring test with too much timing to begin with, you may have to pull several degrees out and start over. It's a little bit of back and forth but you can narrow it down nearly as good as being on the dyno.

Clear as mud?

Shawn
Hey Shawn. This confused me alittle. I thought we wanted the mechanical to come in earlier thus using weaker spring? I can tell ya this in 2nd gear this thing will wrap 4k in a heart beat and 3rd will get there pretty quick also. Matter of fact I can hit right at 70mph in 3rd and when I go to 4th it's all down hill from there. Maxes out at 73 mph.

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Unread 04-26-2013, 10:29 AM   #69
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Jim,

Did I miss where you plotted your total curve? You have to give us some info for us to help you.

Ideally, the centrifugal should kick in just off idle, say around 900 -1000 RPM, then it should smoothly and gradually climb and max out around 3000 RPM.

I'd shoot for 32-36 degrees total (Initial + centrifugal) at 3000 RPM.
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Unread 04-26-2013, 10:47 AM   #70
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Quote:
Originally Posted by Matt1981CJ7
Jim,

Did I miss where you plotted your total curve? You have to give us some info for us to help you.

Ideally, the centrifugal should kick in just off idle, say around 900 -1000 RPM, then it should smoothly and gradually climb and max out around 3000 RPM.

I'd shoot for 32-36 degrees total (Initial + centrifugal) at 3000 RPM.
I can't slip nothin past you Matt. I'm planning on plotting that this weekend. Just too many irons in the fire right now so I tried a quick fix. I know without a baseline to go by y'all are shooting in the dark.

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Unread 04-26-2013, 04:30 PM   #71
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Ok with my initial set at 14* it's coming in at 700rpm and 36* @ 2700rpm.

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Unread 04-26-2013, 05:04 PM   #72
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Quote:
Originally Posted by firemanjim7
Ok with my initial set at 14* it's coming in at 700rpm and 36* @ 2700rpm.

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I'm sorry that 36* was total.

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Unread 04-27-2013, 02:26 AM   #73
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The total is good, but that's a pretty aggressive curve.

I'd slow it down with some heavier springs. That would bring it in a little later, and max it out later in the RPM scale.

Good luck,

Matt
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Unread 04-27-2013, 07:50 AM   #74
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I'd install the heaviest springs, set the initial at 10 and try Vizard's procedure I posted earlier. I'll be shocked if you can start the curve at 14.

Good luck!


Shawn

Edit: I may know a guy who's got a D.U.I. curve sitting in a drawer that "he" will send you but I'd like to see you exhaust your tuning efforts on the CRT first. It's just good information for the whole JF crew
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Unread 04-27-2013, 09:54 AM   #75
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Quote:
Originally Posted by firemanjim7 View Post
Hey Shawn. This confused me alittle. I thought we wanted the mechanical to come in earlier thus using weaker spring? I can tell ya this in 2nd gear this thing will wrap 4k in a heart beat and 3rd will get there pretty quick also. Matter of fact I can hit right at 70mph in 3rd and when I go to 4th it's all down hill from there. Maxes out at 73 mph.

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I overlooked this.

Graphs are always helpful in showing large fubars. We can know right-quick if something is haywire. Once you get pretty close, however, the only way to dial in what YOUR exact vehicle combo wants for timing is to either get it on a dyno or track test it like Vizard mentioned.

His test starts out with slow (safe) timing and works towards more-aggressive timing as long as the engine continues to show improvement.


Shawn
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