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Finally got some pictures of the '77 620.


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I've been trying for a long time to get this truck to my house so I could work on it. It's my mom's truck, and she can't do any of the work. It's been in the family since new, my grandfather bought it new. The original L20 was replaced many, many years ago when it bit the dust and it currently has a L18 that was recently rebuilt and a 4 speed manual. Truck runs decent but has a hesitation off idle, the carb needs some adjusting for sure. Warm idle is really rough and low. I'm going to hook up a tach and mess with the carb. The paint is awful, it has a cheap respray with some single stage crap that has faded and started cracking.


I need to try to get this back to her by Christmas, so my plans for now are to get it running smooth, replace the leaking master cylinder, get the headlights to work, get it to pass smog, and lower it a little. The wheels clean up well and look good on the truck.





















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It's pretty straight body wise, the red was faded really bad when it got repainted but as you can see it now needs another paint job. This time though it needs to go down to the metal since the paint is cracked all the way through in some areas. I love this truck though. I have tons of memories riding in this thing. When it had a shell on it; the bed was carpeted and had seat belts, so all us kids would ride back there.

My main concern is getting it to legally pass CA smog. It doesn't seem to run dirty. It has a cat on it but it's some old junk that is so far from the manifold that it probably gets luke warm. I'm going to put a new cat on it as close to the manifold as I can. I also bought some parts for the AIR pump off here a while back. Once I get the smog squared away it's easy sailing.

........except the headlights. The wiring is awful in this thing, there has been a lot backyard guys through the years that "fixed" various things.

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  • 2 months later...

Finally had some times to dig into this. First thing I tackled was the headlight problem. First I played with the switch, it was hard to operate so I took it apart and cleaned the contacts and put the dielectric grease in it. Worked great but still no lights. I checked fuses and power at the fuse block, wasn't getting anything. I tested the lights themselves and they checked out good. First diagram I found of the fuse block turned out to be the wrong. I finally found a correct one and started looking at the fuses. All the glass fuses looked good but I started replacing them and found that several fell apart when I removed them. So instead of screwing with those garbage glass fuses I replaced the fuse block with a modern one using blade type fuses. Headlights work fine now.


Have a few other things to address on the interior. Haven't got the tach installed yet but I verified it works. It's and old tach that I found, it matches the vintage of the truck pretty well. Next I started the truck and tried to find all the vacuum leaks, HAHAHA, impossible. So I looked at the air pump hanging off the side of the engine and noticed my dad put it on wrong and also that I'm missing another bracket to be able to secure it to the block. I'll be hunting for that or making something up. Then I can get all the vacuum hoses sorted out. Still doesn't run smooth after it idles down, most likely due to vacuum leaks and probably needs carb work.


On to the pics, Don't mind the destroyed dash panel, It basically crumbles anytime it's touched. Debating on finding a good one or making something out of sheet metal and painting it.













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Haven't made any progress with how this thing runs but i bought some motor mounts to replace the completely shot ones.


Also got the exhaust out and cut off the old plugged up cat. Cat was falling apart as soon as i removed it. Going to put a new one on with band clamps instead of welding the whole exhaust together like the last person. Not doing this till everything else is sorted out.


Next on the list is to find or build the adjuster for the air pump and start installing all new vacuum lines. Then on to carb tuning.


Right now it idles like poop and sputters till around 3k rpm. Sounds like its misfiring. Did plugs and wires but haven't touched distributor or carb.

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I had checked the timing before and there are about 19 marks on the crank pulley. Last time it was registered my parents took it to a shop and they said they had to retime the engine because the guy who rebuilt the engine did it wrong. It used to run smoothly, that's why I'm leaning toward a carb or vacuum issue. I've read up on the timing positions and how to set it so if i need to set it i can.


On the passenger side under the dash there is a junction box with i think 6 wires that says electronic ignition on it.

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So I had some issues with my old profile not letting me sign on or change my password so I had to create a new profile. Was also having trouble with that but finally got one to work. So this is my thread that I'm bringing back up.


I have made significant progress on the truck since the last post. Where to start.....rebuilt the carb, drained old gas and put 5 gal of fresh gas. Ran better but not great. Checked timing and found it way too far retarded. After adjusting both positions on the distributor still could not get the 10-12 degrees of timing. Conclusion was someone didn't clock the oil pump correctly and therefor the distributor was clocked incorrectly. So we slotted the front adjuster(radiator side) to get enough adjustment and then set the rear adjuster in the middle. After that is was close ~15 degrees. Just a small adjustment and we got our 10 degrees. Bam ran much better after that, was still spuddering though. Pulled the valve cover and found every single valve was too tight. I mean so tight the smallest feeler gauge wouldn't fit and the valves were hanging open. Readjusted the valves to .010 intake and .012 exhaust while engine was hot. Fired it up and it ran BEAUTIFUL. Held steady 17in of vacuum and no spuddering. Pretty sure this thing is ready to test drive.


Next on the list is to replace all rubber fuel lines, get new master cyl since mine is leaking, clean and adjust all drums, install cats and pass smog, do some serious suspension overhaul. DRIVE THAT SHIT.







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Thanks redeye, I sent you a message.


Thanks Draker, it's definitely close. Smog is the biggest hurdle but it's running great now so I think after the egr gets hooked up and I put some cats on it, I'll be able to pass just fine. I'm going to use two cats just because I have them.

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Didn't put the cats on yet. Had some side work and my water pump on my daily driver went so I've been driving this with paper plates on it. It's running great minus a stumble off idle pretty sure it's accelerator pump related. I'll get it over to smog next weekend if I have time to put the cats on after work this week.

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Wasn't able to get to the smog shop last weekend, life is always so busy and projects get pushed to the back burner. We'll see how this weekend goes. I did get the cat converter in place and the thing hardly stinks at all from the tail pipe. Only the test will show how it's actually doing though. I really need to get into the accelerator pump though, it's really annoying trying to drive around town with the bog off idle. I searched a couple threads with the same issue after the carb rebuild and I'm going to have to pull the pump apart and make sure everything is free and check balls are doing their thing. I followed a nice detailed diagram so I'm sure they're in correctly but maybe I forgot to clean out the passage.

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Yeah my buddy owns a smog shop so he's going to run a pretest to see where I'm at and then I'll tune accordingly.

On another note some parts came in today. I'll drive to work tomorrow and install everything there. Life is just easier when you have access to a lift and air tools and vacuum bleeders etc.


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Got the shocks installed but work was busy so I didn't have time to do the master or the belt. Couldn't leave on lunch to go to the smog shop either. Will have to wait till next Saturday when I don't work. Did get to check out the accelerator pump and it's just dribbling out fuel when pushed so I need to take it apart and see if it's still clogged up or the check balls aren't doing their thing.

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Checked out the accelerator pump and adjusted the linkage. Everything inside looks good and now I get a strong spray of fuel when hitting the throttle but the damn thing still wants to bog. I don't understand what else it could be. It didn't get any better at all. Didn't take it to smog because it's annoying to drive when you have to sit there and play with the pedal to not stall the thing at every stop. Right now that is the only thing holding me up from getting it smogged and driving it.


Anyone have any suggestions?

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