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My 620 build thread.


J's 620

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It doesn’t puff blue on cold starts, just when some good throttle is added in. I’m adding a lot of oil, like a qt per week. It’s never used as much oil as this. This is an issue after the cylinder head was in the machine shop. All my seats and guides were “good” and the seals were new. 
I’ll have to park it for a few days until I find time to do a compression test. 

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I just started it up and I can’t really tell if it’s condensation or blueish smoke right away. As soon as I give it slight throttle I can see the smoke. It’s definitely doing that plug wire thing, I pull the wire off where I hear it arcing and it runs just fine, seating the wire it goes back to a misfire. 

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I cleaned up the plugs the best I could. I didn’t get a compression test kit today so I’ll be doing that tomorrow. Anyway here’s what I found: 

 I forgot to take a pic of the #1 but looking at the pics, you’ll get the jist of things. 
 I see soot which explains the soot in the tail pipe, and when checking oil level I’ll admit I also overfilled a bit. I drained a good qt or so and added new oil. The oil that came out of the pan seemed really REALLY thin for a 10w-40, and it’s hard to find an oil at that viscosity that isn’t a synthetic/ blend. 
 When I started it back up it ran well, but any throttle pushes out some bluish smoke and holding at a high idle puts out a steady cloud of it. 

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35916AED-0331-4BC1-8770-B101DFDB4535.jpeg

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Posted (edited)

Hmmm...now that I’m looking at these pics, it’s going to be hard to tell how oily/sooty they really were.  I think the sunset gives them more of a tan color too.

Edited by J's 620
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1 hour ago, J's 620 said:

 

35916AED-0331-4BC1-8770-B101DFDB4535.jpeg

I see three things here to address. First, the side electrode is worn down so much that it isn't over the center electrode and the edges are rounded instead of squared off. Second, the center electrode is similarly worn and rounded. Both of those contribute to an excessive gap with poor ionization properties. Third, the fouling on the threads would suggest that the plugs are too long and extending too far into the cylinder. All in all this is not going to give you a good spark for that good burn. Unburnt fuel is the source of the fouled plugs and the stinky exhaust. Buy the right plugs and check the gaps.

I won't speculate on your oil issue.

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Drain the oil. Get an old oil can and measure 4 liters out and pour them into the engine. Now check the dip stick. Does the full mark agree with what you put in????? Never over fill or it will get thrown around in the crankcase and over load the rings and get burned. If you've been putting 5 liters in no wonder it's always 'low'. Need to eliminate the chance of over filling the oil. 

 

Those sort of look like iridium plugs but what make??? Buy new NGK B6ES plugs. Or what ever came in your '76. 

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These are the ngk b6es (r?) they aren’t iridium I think they were the platinum. I didn’t get the copper. AFAIK these are the correct plugs. 
 

the plugs are “side gapped” and the gap is at .040 which the year calls out for. It might be .044 can’t remember off the top of my head right now, but I just follow what the specs say for this year.

 

for oil, I’m only putting in about 4 qts and some change. I think 4.3 is what it calls for. 

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Those are not the proper plug for the L20B. They may work but often problems turn out to be something added that is not what was on the original vehicle. Plug gap for the 620 was 0.032" for a points distributor. 0.040" would be better for the '78 and up engines with the high output EI distributor. I would get the NGK plugs for it or at least change the gap to 0.032" and see how it runs.

 

4.3 liters is for a change plus a filter.

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Posted (edited)
5 hours ago, datzenmike said:

Those are not the proper plug for the L20B. They may work but often problems turn out to be something added that is not what was on the original vehicle. Plug gap for the 620 was 0.032" for a points distributor. 0.040" would be better for the '78 and up engines with the high output EI distributor. I would get the NGK plugs for it or at least change the gap to 0.032" and see how it runs.

 

4.3 liters is for a change plus a filter.

On a California 76, the Haynes/chiltons says I have the electronic distributor, gap to .040, it’s not a matchbox though. I just checked my receipt for my current plugs, they are the ngk bpr6es. So that is the copper according to the part number.
I’ll get some new plugs at any rate. This morning my oil level was just under the full, I’ll check it after work to see if it’s changed. 

Edited by J's 620
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Be honest those plugs loook good but would run the more stock type plugs

 

I would just buy the diesel oil the thicker stuff 15-40 if your worried about viscosity.

20-50 stuff when you see it in the stores

 

dont over fill it.

 

pull the crank case vent tube at night and shine a flash lite across it   at idle you see lots of smoke then its blowby

My Banzai 510 I could see smoke come out from side of hood at night when other cars light went across hood. My crank vent was open cause I had sidedrafts

 

quart a week is getting high.  I had a beat100$ 510 that I ran out of oil . and then figured it out. after that it was a 1 quart every 2/3 days.  Oh also found out the main brearing was on wrong blocking the oil hole!!!!!!!!  crank was fucked

Edited by banzai510(hainz)
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I picked up a compression test kit but haven’t had a moment to try it out. I’ll have to find a way to extend the hose so I can read the gauge while I crank the engine over. I don’t have an assistant to help. 
 Anyway I got new plugs, the bp6es or bpr6es copper, the ones my 76 and what the 77-78 call for, the threads are the same length but the center electrode is much wider. The ones I pulled were a bpr6egp, definitely not right and I’m not sure how I ended up getting those, unless I was looking at the wrong receipt. Those are a platinum plug. This time I sort of split the difference on the gap going .035” instead of the .040. The plugs came with a .032. Still burning oil. 
Compression test will be next. And a valve lash check. 

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I don’t doubt however that my valve seals are bad knowing how shitty the machine shop was. At one point they said they lost the seals or I never brought them in. WTF. Either way it’s bad news if the seals are bad or I’m getting blow by. 

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16 minutes ago, J's 620 said:

I picked up a compression test kit but haven’t had a moment to try it out. I’ll have to find a way to extend the hose so I can read the gauge while I crank the engine over. I don’t have an assistant to help. 
 

Easier than extending the compression tester hose would be a remote trigger for the starter....

You dont need all the power on just the starter to spin....

All you really need is a push button and some wire to connect between the battery and the small spade on the started.... I generally would use a relay but that was to power the coil also... but for what your doing a simple push button will be fine.... technically you could just attach a wire to the starter and just touch the battery terminal and remove it..... again on the small spade not on the the larger ones, let the solenoid do its job......

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8 hours ago, Crashtd420 said:

Easier than extending the compression tester hose would be a remote trigger for the starter....

You dont need all the power on just the starter to spin....

All you really need is a push button and some wire to connect between the battery and the small spade on the started.... I generally would use a relay but that was to power the coil also... but for what your doing a simple push button will be fine.... technically you could just attach a wire to the starter and just touch the battery terminal and remove it..... again on the small spade not on the the larger ones, let the solenoid do its job......

Hmmm I didn’t consider the remote button. That’s an idea there. 

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Driving around this morning I lost my hi beam function. I’ve previously lost lo beam so I’ve been using hi beam here and there because I’ve failed at troubleshooting the issue. I hear the relay click, I can feel it too. Seems like the relay with all the red wires and the relay with all the black wires could be for lighting. They both feel like they click when I pull the knob to turn on lights. I got no voltage at the light plugs just now, hi and lo beam, but testing the plug with red wires I have voltage. I guess it’s a step forward. 
 I really believe this is a ground issue, as I am also not able to get my front turn signal to work or my rear passenger side marker lamp won’t come on. If I put a bulb in the front turn signal socket I blow a fuse almost instantly. 
 
there’s no news on a compression test, I need to buy the remote start trigger still. Major maintenance hasn’t been afforded by my schedule lately, so I’ve just been babying it. Driving real easy on it. I need to change my jets, it’s a bit of black smoke from the exhaust quite often. There’s a bad oil leak as well, and I can’t pin point it, it’s above the oil pan, I’m sure of that.  
 

now that I think of it..... this headlight issue came after I put in some aftermarket 5-3/4” with replaceable bulbs. Same 55W nothing special. After doing some searching, I’m now remembering this. 

Edited by J's 620
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Find the light relay on the passenger side inner fnder. There is only one light relay, with Red, Red/Black, Red/Yellow and Red/White wires.

 

Using a test light check the solid Red wire has power when the headlight switch is pulled out to the second (headlights) position.

 

With the hi/low beam switch in the low beam position check that the Red/Black wire has power

With the hi/low beam switch in the high beam position check that the Red/White wire has power.

 

Does the relay click? Then power should switch from one to the other.

 

 

 

If they do go to the headlight plug and test the Red/Black and the Red/White wires for power. Got power? 

 

Are headlight bulbs burned out????????

 

 

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11 hours ago, datzenmike said:

Find the light relay on the passenger side inner fnder. There is only one light relay, with Red, Red/Black, Red/Yellow and Red/White wires.

 

Using a test light check the solid Red wire has power when the headlight switch is pulled out to the second (headlights) position.

 

With the hi/low beam switch in the low beam position check that the Red/Black wire has power

With the hi/low beam switch in the high beam position check that the Red/White wire has power.

 

Does the relay click? Then power should switch from one to the other.

 

 

 

If they do go to the headlight plug and test the Red/Black and the Red/White wires for power. Got power? 

 

Are headlight bulbs burned out????????

 

 

 It’s a 76 mike, don’t think I have those relays on the inner fender, the 78 parts truck does however..... I only have the 3 relays under the glove box. There’s a relay with a cluster of black wires, the middle relay has some green wires, the far right has the red wires. I had 12V at those red wires on the plug when my headlight knob was pulled out. Nothing at the headlight socket though. When I get back home I’ll do some more troubleshooting. 

Edited by J's 620
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I have the wire diagram and I suppose what's shown could be in the cab. I'm used to the '78 I had.       

 

It will be the red wires relay.        

 

You can't have 12v on all the wires because it can only be hi or low.  So if power on Red/Black the Red/White has to be off.                 

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