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  #41  
Old 02-20-2020, 09:45 AM
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Quote:
Originally Posted by rang-a-stang
Right now 1-2 is about 3800 and 2-3 is 4K.


If your engine is set to rev higher, those shift points are hurting you a lot.

I'm on the exact same boat, researching governor springs.
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  #42  
Old 02-20-2020, 10:15 AM
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fulsizjeep fulsizjeep is offline
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Quote:
Originally Posted by rang-a-stang
Axles are stock. My rig was originally a 360 rig and has open 3.54s front and rear. Tires are 285/75-16 which are almost 33" tall. I am not sure if I have an OD part time kit installed or not and do not want to open it to find out. If I could find a cheap set of 4.10's I would install them but I do not care enough right now to drop $500 on axles/gears that are going to go away in the next 3 years anyway.

OK, I get that. But what if it has 16% OD? The end result would be 2.97:1 output. Then add 33s. I am not a fan of the OD kit. Not one bit. Splitting the case in the Jeep is so easy and the cost is 3 quarts ATF and some RTV. Just saying. I'll butt out now...
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  #43  
Old 02-20-2020, 11:14 AM
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Quote:
Originally Posted by fulsizjeep
OK, I get that. But what if it has 16% OD? The end result would be 2.97:1 output. Then add 33s. I am not a fan of the OD kit. Not one bit. Splitting the case in the Jeep is so easy and the cost is 3 quarts ATF and some RTV. Just saying. I'll butt out now...


He doesn't need to do that. Just put the Jeep on jackstands (so there is no load on the torque converter), get the jeep to 65MPH and compared the speedometer reading with the theoretical RPM his gearing would give him. A 16% difference would be very noticeable. Or this could be done on the road, assuming a 10% slippage in the torque converter.
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  #44  
Old 02-20-2020, 11:43 AM
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rang-a-stang rang-a-stang is offline
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Quote:
Originally Posted by Mikel
If your engine is set to rev higher, those shift points are hurting you a lot.

I'm on the exact same boat, researching governor springs.
My cam is advertised as 1500-5500 RPM. I have a spare governor in route and when I get home, I am going to weigh it stock, then shave some weight off the weights, weigh it again, install it, and record the difference. Hopefully that will give me an idea of how much needs to come off to get the RPMs I want. Then I will go from there. I have a feeling I will be doing this a few times before I get it where I want it. I have seen the kits online with weights and springs but also see a lot of "How-to's" on doing it for almost free ("almost" meaning you still have to seal the Governor housing so buy a gasket and a couple quarts of ATF).
Quote:
Originally Posted by fulsizjeep
OK, I get that. But what if it has 16% OD? The end result would be 2.97:1 output. Then add 33s. I am not a fan of the OD kit. Not one bit. Splitting the case in the Jeep is so easy and the cost is 3 quarts ATF and some RTV. Just saying. I'll butt out now...
Quote:
Originally Posted by Mikel
He doesn't need to do that. Just put the Jeep on jackstands (so there is no load on the torque converter), get the jeep to 65MPH and compared the speedometer reading with the theoretical RPM his gearing would give him. A 16% difference would be very noticeable. Or this could be done on the road, assuming a 10% slippage in the torque converter.
I think what I can do is take it for a ride with a GPS speed (I have an old crappy GPS that measures speed) and compare that GPS Speed to my speedo and EFI VSS. My speedo is pretty close from what I can tell so I have a feeling I do not have an OD, now that we are talking about it. My understanding was the stock size tire on a WT Cherokee in 79 was 31.5" tall so I should be in the ball park. Looking here:
https://tiresize.com/calculator/ Looks like I should only be about 5% slow.

No butting out! I appreciate all the inputs/thoughts/time you guys are giving!
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  #45  
Old 02-21-2020, 09:37 AM
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Wagoneer Taylor Wagoneer Taylor is offline
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Unfortunately I don't have anything good to add, but I want to state that I appreciate this thread and am taking notes for my rig.
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  #46  
Old 02-22-2020, 12:05 AM
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PlasticBoob PlasticBoob is offline
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When I had my front driveshaft out and center differential locked, I was easily able to "burn rubber" just about any time I wanted to, even with the Aussie locker. It was nothing spectacular, but it did do it. Of course I have no proof, and will never be doing that again because it is absolute hell on the QuadraTrac chain, but, well, there you go. That was with fuel injection (my own custom tune), Comp Cams 256XE, 3" single exhaust, 3.07s and 32" tires fully inflated.

Quote:
Originally Posted by Mikel
I would bet good money that the bulk of your problem is not the engine, but the rest of the drivetrain. Modern vehicles have lower axle gear ratios, with OD transmissions with tightly spaced gears, high stall lock-up torque converters... And lower first gears (4.03 for the 6L80, 2.8:1 for the AW4, vs 2.48 for the TH400). That's how modern vehicles with small engines feel peppy.

This is the best wisdom in this entire thread.
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  #47  
Old 02-22-2020, 12:07 AM
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PlasticBoob PlasticBoob is offline
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My advice: do whatever you want with this one, and make sure your NEXT FSJ is smog exempt at all costs!
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  #48  
Old 02-22-2020, 08:05 AM
Ristow Ristow is offline
 
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take the little stamped cover off the end of the low range unit so you can see the input shaft. put rear axle on jack stands. turn driveshaft and observe input shaft rotation compared to driveshaft.



geez guys.....
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  #49  
Old 02-22-2020, 08:22 AM
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Quote:
Originally Posted by Ristow
take the little stamped cover off the end of the low range unit so you can see the input shaft. put rear axle on jack stands. turn driveshaft and observe input shaft rotation compared to driveshaft.



geez guys.....


Good one!
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  #50  
Old 02-22-2020, 12:42 PM
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I've been looking at a LS swap myself. 5.3L seems like the choice for what I want. I know MSD and Holley both make simplified ignition and EFI solutions.
I'm hanging up on how far i want to go. I have a whole 2008 Tahoe to pull from. Do I just get mounts and an adapter plate or pull the whole driveline?
I'm no expert, what would you guys do?
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  #51  
Old 02-24-2020, 04:52 PM
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rang-a-stang rang-a-stang is offline
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There are LOTS of options for simplified harnesses these days for an LS. Or DIY. A harness/computer can be had for as little as $1000 outright; Less if you have a trade in. There is a guy here in Oxnard that builds/sells them on Craigslist for $600 including braided sheathing and a computer reflash to get rid of unwanted features.

This weekend I went cruising for both EFI data logging and to see if I have an OD in my case. Speedo is exactly the same as my VSS (makes sense since the VSS is inline with the speedo cable) and speedo is about 8% slower than my GPS reported speed which makes sense because of tire size. I figured if I had an OD in my case, the speedo would be off more but as I type this, it dawned on me that that is a wrong assumption. Speed is measured at the output shaft of the Xfer case and would not be effected by a change in the XFer case gearing.

So, I guess what I can do (aside from opening my case and counting teeth on the cogs, or comparing revolutions between the shaft seen when opening the little cap on the reduction unit vs the rear drive shaft) is to calculate what my cruising RPM "should" be and looking at my data log and see what it actually is.

Tonight I swap governors. That should help a little. I am going to continue tweaking my fuel tables too (that is helping alot). I do not want to mess with my timing yet.
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  #52  
Old 02-24-2020, 05:17 PM
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Keep us updated!
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  #53  
Old 02-28-2020, 11:20 AM
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rang-a-stang rang-a-stang is offline
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Shaved down my governor and got the shifts up to about 4.6k RPM. More info going into my build thread.

It runs terrible trending toward OK at 4k RPM+. I'm tuning that now. We'll see what that does.
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  #54  
Old 02-28-2020, 07:03 PM
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Progress! (kind of)


If you haven't run the engine beyond 4K RPM, your fuel maps are probably in need of work.
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  #55  
Old 02-28-2020, 09:34 PM
Rusty76 Rusty76 is offline
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I not so secretly hope you eventually do a 5.3 swap. You are very good at posting and I know I would learn a massive amount from it. Keep up the good work.
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