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1979 Datsun 620 Motorhome, upgrade & restore.


Deleteme

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I could not identify the leak after it hit the fan. Gonna go look again today.

It was I assume pure antifreeze, I added water when I saw it was low, perhaps the lower boiling point of water caused high steam pressure.

 

Where is the thermostat coolent opener thanglejag valve? the piece on the engine connected to the top radiator hose?

 

When I removed the fuel rail to get at the left carb bolt I learned the bolt holding the rail also bolts down a coolent senseing/distribution area.

 

Idle is not ok, I need to understand the choke mechanism, the one top butterfly, it opens too much when I start the pickup.

 

The butterfly goes from closed to open a few degrees, but it's enough to make it scream.

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The thermostat is located in the thermostat housing just under the thermostat cover. The thermostat housing is on the engine side of the upper rad hose and bolted to the side of the head. The thermostat cover has two vertical bolts holding it to the housing. Before removing be sure you have a new gasket for it. I would advise buying a new $10 180F thermostat rather than mess with the old one. Do NOT get a $1.99 special from WallMart. It's not worth over heating your engine, blowing a rad or hose, warping a head or a tow home.  

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Thanks Mike, I'll go grab those in a bit.

Solved carb problem again.

I was wrong about the spring.

 

Turns out the bottom butterfly that's actuated by the throttle cable...well the adjusting screw is set too high.

 

The top choke mechanism...I don't understand. It's got a dial for lean and rich, and it is what makes the choke spring into place.

However...turned to the left it is springy, turned to the right and the choke flaps in the wind.

The original carb is set to the right and operates fine, springy. I don't understand.

 

IMG_20180306_142350.jpg

 

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The choke is temperature related. It may be flappy today but at -10 it will close. The choke is best set on cold days.

 

 

That fast idle adjustment is set at the factory and shouldn't need adjusting. I believe a certain size drill bit is placed to hold the throttle open and the adjustment made to it. Generally 1,800 to 2,200 RPM is the fast idle range. The linkage for the fast idle can also be bent to add more/less fast idle in relation to the choke setting. This moves that small plastic cam up and down those steps on it.

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Well I did adjust that screw and mirrored the other carb. It stopped screaming.

 

It is still going too fast, setting the idle doesn't even come into play yet.

I can't figure out how to slow it down.

 

It's not getting any throttle, so wtf.

Fast idle...too fast.

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Success!

 

Turns out the rebuilt carburetor had a spring installed backwards, causing it to be in the way of the fast idle cam, so the cam would never step down.

 

Armed with a thermostat and it's housing gasket, coolent and hoses - plus a new 12 mm wrench - Should fix up fine.

 

Now for this wrench fabrication...

 

throttle getting stuck? Binding somewhere? Good idea to get a tach..really cheap.

Fast idle cam getting stuck against spring.
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Only the two upward facing bolts (one long one short) need be removed to get the thermostat cover off to get at the thermostat. They tend to corrode in place and are hard to 'snap lose'. I would use an anti-seize compound on the threads when you put together again. Maybe loosen when the engine is hot?

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Alright, pulled the rad off.

New hoses on.

Old piece of shit won't come off hose clamps replaced.

 

Pulled off smog air pump, wouldn't come off bracket, fiddle fucked bracket off.

 

Pulled off rest of emissions crap.

It bothered me too much.

 

Replaced rad thermostat and gasket.

 

Bent wrench.

Broke wrench.

Wrench Still works.

Hate cast iron.

Need forged.

 

Left charcoal canister?

 

Where to connect these vacuum lines?

Distributor vacuum advance, and other vacuum below carb that causes surging when not capped.

 

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If too advanced it will ping but most likely...

 

Wrong plug make

Dirty plugs

Bad wires

Cracked or carbon tracked plug insulator, cap, rotor or coil.

 

Spark ALWAYS looks for the shortest easiest path to ground. You have to make the spark plug gap the easiest path.

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You only replace things that are proven to have failed. Replacing things can easily put a defective part in causing all kinds of problems like....  There nothing as frustrating as diagnosing an ignition problem that points to a coil but it can't be that because... "Well it can't be the coil!!! I just put a new one in" and much running around and later it turns out to be.... that new coil. Don't fix what ain't broken.

 

The stock coil is always better than a bought one.

 

Wait till dark and watch under hood while you rev it up. Doesn't always show up because it's hard to simulate a load on the engine, but if you see blue flashes it's a problem.

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  • 2 weeks later...

The BPT valve was cracked in half next to one of the mounting bolts.

The bolts we're so rusted, and one was hard to reach.

I used gasket maker to seal the crack and the idle slowed right down.

It ran so smooth.

 

Did not solve hesitation.

Sprayed carb cleaner in top of BPT valve, engine responded.

Hack sawed top of BPT valve off, sealed vacuum.

Runs like bag of shit and won't idle.

No longer hesitates.

 

Shouldn't effect engine at idle anyways. Wtf.

 

What is port for, that is next to the vacuum advance on the carb? it pushes air.

I have it capped.

 

Installed tachometer, "idles" at 900.

 

Turning idle mix screw does NOTHING.

Indicates I still have a leak?

Used carb cleaner method, intake manifold gasket suspect, but did not respond to dubious amounts of cleaner.

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That’s hilarious and fun. Hand painted art in the engine bay, Definitely, unique Customization, and doesn’t take away from the originality of the vehicle. I like it.

 

I once had a stock 2 year old Toy prerunner that was stolen from my apartment garage. Cops found it and asked me to identify it. Thieves had removed all contents, swapped body VIN tags, repainted it, Dyed the interior a diff color, screwed a giant aftermarket tach into the dash, removed the tow hitch, trailer, plug, and every other accessory i’d added. Cops had acid washed the frame and got the VIN numbers to appear where the thieves had ground out the frame VIN numbers. They wanted my personal identification, and I couldn’t make it. Finally I found a little hand-made L bracket Tucked up under the frame that held the aftermarket trailer plug. It was the only thing I could identify on the truck as mine.

 

You’ll definitely be able to identify that vehicle as yours, at a glance.

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