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Basically Stock CJ-7

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Kreep View Drop Down
AMC Apprentice
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    Posted: Jul/04/2020 at 1:40pm
Meet Big Tex, or just Tex for short:



When people ask what kind of Jeep Tex is I usually tell them it's a basically stock 1982 CJ-7. Non-car people respond with an "Oh, that's nice" while those into cars will look at me funny or press for more details. To which I'll respond, "Well, it's got the stock transmission out of an F-250, the stock axle out of a F-350 grain truck..."

Of course nothing about Tex is stock except the grill, bell housing and (for now) transfer case. Tex rides on 43" Super Swamper SX's mounted on re-centered 16.5" military HMMWV double beadlock wheels. The magnesium inserts have been cut down to eliminate the chance of cutting a sidewall at single digit tire pressures. Rear axle is a Dana 70 with ARB locker and 37 spline (Dana 80) 300M shafts and 5.86 gears. Front axle is a  Chevy Dana 60 that's been narrowed 4" and modified to run the springs under the axle. It's fitted with a Lockrite, nickle plated RCV shafts, Dynatrac locking hubs and hydraulic assist steering.  Rear suspension is a triangulated 4-link, front is a custom Deaver spring pack that is 10 inches longer than stock at the rear for increased flex and better ride. The transfer case is the stock Dana 300, but I plan to upgrade the output shaft and convert it to twin sticks soon. The transmission is a T-18a with a 6.32:1 first gear. This puts my crawl ratio at 97:1.

Tex has a full cage, Beard seats, and 4-point belts. In the rear is an 18 gallon stainless gas tank and storage for a cooler, comprehensive tool kit and recovery gear (including a chain saw!).  I've done the vast majority of the work myself and there are a host of "little things" like a crane to lift the spare tire that make Tex really special.  
1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2020 at 1:52pm
After a two years on the trails, Tex is back under the knife. The AMC 304 with GM TBI fuel injection is getting tired with excessive blow by, leaking rear main seal and not enough torque to clean the tires on steep muddy climbs or in mud pits. I'd also like to address a couple of other issues like a mechanical clutch that binds or runs out of travel when the frame is flexed too far. Also, the bikini top keeps getting ripped off by trees...

So, I found this AMC 401 from a 1975 Wagoneer. The oil pickup button came loose and the pickup drowned in sludge at the bottom of the pan. Spun the #7 rod bearing while #6 and 8 were scored pretty bad too.

I got a lot of advice that I should swap in an LS... Main reason I didn't is I was not looking forward to rebuilding the rear crossmember, figuring out fans, shrouds, on board air... a host of little things that are all working great. Plus, I just like the idea of an AMC power plant in my Jeep!

Anyway, the basic plan is to stroke the 401 to a 418, run E-85 at about 12:1 compression. Hoping for 450 HP and 550 ft-lbs.


1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2020 at 3:10pm
I guess I should pause for a moment and go over what I'm trying to accomplish. Tex weighs 5,500 lbs, add two passengers and we're knocking on three tons. As long as I've got good traction this is not a problem, but every once in a while we'll be running a creek bed that dead ends. The only way out is a very steep climb. So you get turning sideways and have about 15-20 feet to get rolling and start the climb. You can't hit it too hard or you will just plow into the bank. As soon as your front tires start to climb you can go to full throttle. I do this in 2nd gear, low range because I don't have enough torque to pull 6,000 lbs. up the hill in 3rd. If traction is good, no problem. But sometimes the tires fill with wet mud and leaves - turning them into slicks. The backwards slide down the hill is scary, brakes will not hold you and you have almost no control but need to avoid hitting trees or worse, getting sideways which results in a roll. I have the same issue in mud pits but without the pucker factor of sliding - you just need to winch or have someone tug you out.

I noticed that after making one of these climbs huge chunks of mud start to fly off the tires when I shift into 3rd and hit 25-30 MPH. So my goal is too make enough torque at 1,000-1,200 RPM to pull up the hill. If the tires plug up they will start to spin and once the RPM's come up to 5,000 RPM or so the mud will clean out and I'll continue up the hill. My plan B is to install a TH-400 but I hope to avoid that as I'll have to rework the rear suspension and tranny crossmember...

Another issue I've got is heat. CJ grills do not accommodate large radiators and once they get some mud and debris in them... I solved this for the 304 with a 10-blade fan from a HMMWV (if it can cool a 6.2 diesel...) a heavy duty Hayes fan clutch and sinking the winch as low as possible.
1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2020 at 3:26pm
Short block is back from the machinist. Had it checked, line bored, zero decked and honed .020 over. I could have picked up a few cubes boring it out more but felt the thicker the cylinder walls are the less heat is transferred to the coolant. I'm using Molnar 6" rods with the 2.1" journals. I had the crankshaft offset ground to a 3.8" stroke. I did this partly because a when I talked with an older machinist I trust is said "you're going to need all the stroke you can get" and because my research on E-85 indicated it would tolerate compression ratios over 13:1. Working with the AMC camshaft spreadsheet I was having trouble hitting my target of 12:1 with flat top pistons. Early on I was leaning towards the K1 stroker crank, but wasn't sure how Plan B would work with the earlier style crankshaft flange.

Here is a shot of my low tech torque wrench calibration setup:



1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2020 at 4:51pm
Stats on short block:
    Bored to 4.185" with a torque plate
    .10 over mains (1-4 .0019" clearance and .0025 for #5)
    Internally balanced
  Molnar AH6000LLB8-A rods (Thanks ProStockTom!)
    6.0" long
    2.1" big end
    .927" little end
  RaceTec Pistons
    AutoTec 4032 Forging A4119F
    1.295" Compression Height
    -7.5 CC Dish
    504 grams
    Wrist pins .927" diameter x 2.7" long x .180 wall
  Total Seal MS0690 065 rings
    1/16" Gapless AP Steel top ring
    1/16" Napier 2nd ring
    3/16" High Tension oil control ring 
  King Bearings
    AM-Series Main Bearings MB5518AM 010
    BB-Series Cam Bearings CS526BB 
    XP-Series pMax Black Rod Bearings CR-807XPN
  ARP Main Studs 135-5402
  Rollmaster Red Series Timing Chain 

Block prep:
I'm using "BJ Builds an AMC" as a guide. I re-drilled the main bearing oil feeds with a long 5/16" bit. Yes, the holes did not go all the way through. I installed a plug in the driver's side oil galley with a 0.200" hole, reduced the four rear camshaft bearings oil supply holes to 0.150 and did the lifter valley drain mods. 

Here is my setup for measuring thrust end play, I got .0045



My machinist told me the main clearance was .0019 for #1-4 and .0025 for #5. I believe in double checking everything and panicked when plastigauge showed main clearance was too tight. I pulled out my mics and bore gauges and got:
  #1 - .0017
  #2 - .0016
  #3 - .0018
  #4 - .0015
  #5 - .0020 

I felt better. Lesson learned: plastigauge let's you know you are in the ballpark, it's not accurate.
1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 70BBOAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/04/2020 at 6:25pm
Going to be a monster! Love it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/05/2020 at 3:21pm
Here it is getting ready to fit the rings. I used the torque plate per Total Seal's instructions. I checked, it does make a difference, the gap closes a little without the torque plate. 




Edited by Kreep - Jul/05/2020 at 3:25pm
1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
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Post Options Post Options   Thanks (1) Thanks(1)   Quote jav343 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/05/2020 at 3:52pm
Really digging the fact you're keeping AMC power under the hood. I like this Jeep!
2000 Dodge Durango SLT 4.7L, 1997 Jeep Wrangler 4.0L, 1968 AMC Javelin 5.6L 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/05/2020 at 4:55pm
Thanks Folks!

Let's take a minute and talk about pistons. Keeping the heat in the combustion chamber helps the engine run cooler and increases cylinder pressure thus producing more torque - especially at lower RPMs. Initially I thought about going with hyper-eutectic pistons due to the lower thermal conductivity. But the trade off of increased brittleness wasn't worth it. I also considered thermal coatings but doubt they have much effect given how thin the insulating coating is. Since I don't plan on any power adders I don't need the full tilt 2618 forged pistons.

So forged 4032 alloy seemed like a good compromise. I got lucky by asking the machinist to go easy on the bore. It turns out RaceTec has forged blanks for my 4.185" bore, $600 for a set of 8 machined to my specs. These are in their lower performance AutoTec line, note the equal sized valve reliefs.





1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kreep Quote  Post ReplyReply Direct Link To This Post Posted: Jul/05/2020 at 5:11pm
So, the reason I post build logs is to 1) share tech, 2) get answers to my questions, and perhaps most importantly to share my mistakes so others don't make them. Here is my first one on this project. Gapless rings have a very thin lower ring. Everything went fine on cylinders #1-7, but on #8 I guess I got tired and didn't get the end of this ring tucked into the groove all the way. I'm using a tapered ring compressor and this thin ring bent and bit into the piston. Not the end of the world, $75 and 10 days later I had another piston...



1982 Jeep CJ-7
http://theamcforum.com/forum/basically-stock-cj7_topic106501.html
https://www.pirate4x4.com/forum/jeep-hardcore-tech/1361601-basically-stock-cj-7-a.html
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