1977 J10 Honcho "Magnum"

[FINOCJ]

Jim previously posted:

[TyTheJeepGuy]

Jim previously posted:

[Jim]

FINOCJ previously posted:

[FINOCJ]

Depends on the system he is running...early TBI systems only controlled mixture, then later added in timing as well. I was just assuming his was only doing mixture based on his comments of needing a timing light and distributor etc.....besides, what is this talk of only rarely needing a timing light - am I the only one who carries one in their tool bag for trail runs (of course, I also carry a set of points as well).

[TyTheJeepGuy]

I think instructions say to disconnect the vacuum advance for my kit.

Edit: when timing not full time. Disconnected and plugged temporarily for timing

[Jim]

FINOCJ previously posted:

[TyTheJeepGuy]

Ok so unfortunately no auto parts stores in my area loan out a timing light. I got one for 45 dollars, figure I will keep this truck for at least a couple more years to make it worth it

I have to say, as a noob, timing an engine sounded super daunting. I might not have nailed it but I solved the obvious problem! The kit calls for 8 BTDC (Before Top Dead Center to potentially save someone a Google search). AMC V8s are usually listed in the cylinder firing order diagrams but just in case, the #1 cylinder/spark plug is driver's side, closest to headlights. I felt like a big time mechanic using a screwdriver and a slight twist to time a big ol v8; I'm not sure why I was ever scared of the job.

The truck idles much better now and more importantly, when you press in the right pedal, the Honcho roars right away!

Also, I finally had luck with not getting screwed by a local shop and got a fair price for a weld up of an o2 sensor bung to replace my clamp-on bung. The clamp on would have been fine but I put it on the wrong down pipe (should be driver's side, was passenger's) and it made it stretch by the manifold too close for comfort. Since I needed the hole I made welded up anyway I decided to have the shop properly weld in the other side for me. half an hour, 70 bucks later and I put the sensor in the new bung and drove it home.

Nothing ever ends with these but before I can call it a baseline for successful conversion, I have a big exhaust leak from where the AIR guard system would have injector pipes/bolts and currently has bolts plugging them up. For some reason I checked Ace hardware and AutoZone and no one has 9/16 18 pitch pipe plugs, so I am "special ordering" a set from teamgrandwagoneer.com. Their prices are fair for them but the shipping kinda stinks.

One thing that is ok for now but for the sake of saving the earth and my own embarrassment at gas stations, if I fill up the gas tank nearly all the way the overflow? hose is rotted and dumps gas on the ground. Safety, environmental, and embarrassment concerns put this at the top of the todo list. I REALLY hope I don't have to drop the tank again to resolve this.

[Jim]

TyTheJeepGuy previously posted:

[FINOCJ]

AWESOME! Congrats - keeping taking it one step at a time. This 'old stuff' is easy in many ways - it was all designed with field repair and maintenance in mind. I find computer stuff way more intimidating. One of the reasons timing the engine has a reputation as difficult is traditional distributors have breaker points under the cap, and getting these set right (called setting dwell or point gap) can be a bit more tedious (but not really that bad). If that isn't set right, then it doesn't matter what you do with the distributor's initial timing, its going to have issues. But once the distributors went to breakerless induction (and later HEI style) ignition under the distributor cap (like yours I would guess), its pretty trivial to set the timing. For those with front mounted distributors like my v6, the scariest part is putting my hand on the distributor also puts it very close to the spinning fan blade and belt drives.

FWIW - I don't know if the TBI system reacts to timing changes in the exact same way a traditional carb might, but typically, here at high elevation (over 5000' and often higher in the mountains), running the initial timing more advanced is pretty standard (was the 8 BTDC the only initial timing figure the kit gives, or did they include a range of initial timing based on elevation?). The lower density air we have causes a slower cylinder burn, so advancing the initial timing a bit helps give a bit more burn time to achieve maximum compression on the piston stroke. Typically, most of these engines can run at least 10 BTDC here at high elevation....that is part of why I keep a timing light in my trail kit...for some of our super high elevation trails that go up to 13,000', I sometimes advance the timing even more at the trailhead when airing down. For my v6, OEM spec is 5 BTDC, and I run 8-9 BTDC here in Denver, and for high elevation trails I can push over 12. At the same time, if you err, its always better to err on the side of slightly too little advance than too much advance as too much can cause pre-detonation (pinging). Coming back from argentine pk trail, I forgot to drop it back down when airing up and it started mis-firing a bit as I returned to denver (I think it was at 14).

Typically the other thing that needs adjusting at high elevation is fuel to air mix - of course that is what the TBI should be controlling and you won't have to touch that, but adjusting the fuel mixture can offset some of the timing issues. The TBI will lean out the mixture as you go up in elevation due to the lower O2 concentration, but I think it will also lean it out beyond the optimal air-fuel ratio in response to timing that is not fully advanced...if the cylinder burn is a little slow and a little late, unburnt fuel/air will get pushed out the exhaust and be registered by the O2 sensor and thus its response is to lean it a bit more. You cannot go wrong running it to spec as the kit says - and it will probably run better using the kit settings than any carb no matter how well adjusted (especially if I am the one adjusting the carb!). Just some small things to play with as you get more comfortable using it - and this is where an vacuum gauge can really dial it in. And of course, if you want to go all out, you can investigate the advance mechanism on the distributor (both the vac advance and the mechanical weights) - for now, just make sure they work (the timing light can show you how these are functioning independently). I can show you how I do it on mine if you are ever interested, or can try it on the AMC...I'd love to see it in use with the TBI. You are past the point and building and now to the fun part of 'tinkering' and fine turning - well done!

[TyTheJeepGuy]

Thanks James! I'm hoping (and I think on track for, knock on wood) to bring the J10 for the cleanup runs so you're more than welcome to check out whatever you want out on it there of course!

The manual for the TBI kit says 6-8 BTDC. When I was adjusting the timing I can definitely see what you mean, it sure seems happier earlier than later, did not know it was related to elevation. I chalked it up to potential changes to internal engine components like the cam shaft that I unfortunately have no idea what is in it now after the rebuild. I think going off of feel and performance is ok though.

I also experienced the fun of a front-mounted distributor so the belts and rad fan were too close for comfort for sure.

[FINOCJ]

TyTheJeepGuy previously posted:

[TyTheJeepGuy]

FINOCJ previously posted:

[FINOCJ]

TyTheJeepGuy previously posted:

[TyTheJeepGuy]

I'm trying to make it for tomorrow's clean up run. Been working on week on brake jobs, with all this power its now important to be able to stop

I had taken it to a brake shop because I've never worked with drum brakes or locking hubs before, and honestly I just wanted to outsource someone checking the brakes. I have a healthy distrust of shops though, and when they quoted me over a thousand dollars telling me all shoes and rotors need replacing, I said no thanks and picked up the "premium" rotors and shoes from Napa for 180 bucks total, including new drum brake and auto adjuster hardware.

I'm not going to lie, the first drum brake kicked my butt. Then I "wasted" a day cleaning my house because between camping trips and working on the J10 I've let the house go. Then last night, the second drum brake went waaaay faster; although getting those springs on took 100% of my strength. I don't know a better way than brute force, I couldn't find a good leverage point. Unfortunately, when switching the truck to backed-in instead of pulled in, I noticed that my fuel return line is once again absolutely uh, spewing fuel. So I guess I'm dropping the tank again tonight. Also, I looked at a picture of the new brake drum kit I sent to my friends very proudly, and realized that when I switched the shoes around so the shorter pad faced front, the auto adjust screw/gear thing is not pressed by the rest of the auto adjust hardware because its backwards. This is the very first step in assembling the new shoes, so it looks like I'm redoing an entire brake job tonight before I can get to dropping the tank and hopefully fixing the return line leak.

Fingers crossed I can get this beast out for the run tomorrow, if not I'll be in the young gun.

[Steve-O]

Were you not able to screw the auto adjuster all the way together, wiggle it out, flip it around and put it back in? Instead of tearing the whole thing apart?

But I feel for ya man. I just did the rear drums on the YJ, thank God for my Haynes manual...

[TyTheJeepGuy]

Yeah for once the Haynes was more helpful than a YouTube video.

I tried doing that first before redoing the whole break job but I was only successful in getting the auto adjuster pin thing out, couldn't get it back it. I think I pulled a muscle trying and it made the rest of the night's tasks harder.

I eventually got the drum corrected and dropped the back of the tank to get access to the lines to the top. This time it was the send line that was leaking. I ran it with the tank half down to try and see if it would leak before finding out after putting it up again

Friend (Zach, he's been on a few runs but refuses to join the forum I guess) came over and we did the front pads, rotors looked fine. In the cul de sac the truck seemed to stop nicely, pedal still went lower than I liked but thought it was fine. Was heading down the road yesterday to try and make the cleanup run and it definitely wasn't fine. Not sure what it is, but Shane and my brother have suggested somehow its air in the lines. I don't suspect a fluid leak because I couldn't see any leak signs and the fluid levels in the master cylinder never drop.

[speedkills]

I thought air based on your symptoms but if they worked, you changed pads and rotors and now they are soft them I'm not sure how air would have gotten in your lines as it doesn't seem like you ever opened them up. Also didn't realize they were drums, which I don't know the first thing about, so know I don't have any thoughts on what it could be but I'm curious to learn when you figure it out.

[TyTheJeepGuy]

Rear are drums, they say to reverse/forward/reverse/forward til they adjust out (after manually setting them as far as you can).

The subtlety here is that it was stopping alright but then it started taking a lot of pedal and so I went to a shop for a free brake check and they quoted me 1400+ bucks saying both the drum shows and the front pads and rotors were out. From what I could see they were only correct about the front pads.

I was just hoping that replacing the drum shoes (and hardware) and the pads would firm them back up. It did with engine off, but then it goes to floor when its running. Maybe I'll disconnect the vac line to booster and see if it is firm like that just in the garage as a test. There's a whole diag chart and troubleshooting in the manual I'll paste link to below. I was just so disappointed and put off so much to try and make it yesterday that I'm pausing wrenching for a bit to recoop.

https://oljeep.com/edge_77_tsm.html

This website has been a godsend, way better than the haynes manual for some things. So far Haynes was only better for describing how to do the drums.

[TyTheJeepGuy]

https://www.youtube.com/watch?v=tYYMoZGEzCc

Sounds like this guy had a very similar situation and it was the wheel cylinders, which to be fair the shop quoted for and I didn't notice or I would have swapped those when I did the new drum shoes. So I guess I'm still not done with these freakin rear drums Maybe I can replace them without removing the shoes but it will be tight, worst case I just have to do the equivalent of 5 drum shoe jobs, yuck.

[Jim]

If nothing else - it's a learning experience - Class: Life 101

You will KNOW your rear brakes.

A pain now - but the knowledge is in the bank for use later.