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78 620, L20B foreign matter in combustion chamber.


Atikin9000

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Weird carb? Meaning fake weber? Empi Crap? If so, spend that 350 or so and get it running or else, a year from now u will be diagnosing still. If real weber adjust accordingly...go on Pierce manifold tech page.

I found a 32/36 with manual choke for $190 on the pierce manifolds website, thanks for the suggestion.

 

Anyway thanks guys, I’m just going to save myself the headache and purchase a new carb.

 

Although I did get the truck running much better and have been driving it around.

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Weird carb? Meaning fake weber? Empi Crap? If so, spend that 350 or so and get it running or else, a year from now u will be diagnosing still. If real weber adjust accordingly...go on Pierce manifold tech page.

No, it's not a DGV at all. I think it's a Solex 34 34, which was mostly used on Fiats and also sold as a Jeep conversion carb in the 80's and 90's.

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I found a 32/36 with manual choke for $190 on the pierce manifolds website, thanks for the suggestion.

 

Anyway thanks guys, I’m just going to save myself the headache and purchase a new carb.

 

Although I did get the truck running much better and have been driving it around.

Good idea.

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Went out to start the truck tonight, and it’s continuing the missfire, I took a sound clip Incase some one has a good ear. I still plan on going with a new carb I’m just double checking and seeing if it’s something as well as the carb.

 

 

 

This is with the choke off and at operating temp.

 

 

I’m going to pull the spark plugs and take a look at them tomorrow.

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I don't know if anyone has suggested this, but while it is idling pull each plug wire off the cap and see which cylinder is missing, the idle will not change when you pull that wire, once you find which one it is then slowly get end of the plug wire closer and closer to the plug cap hole till it starts arcing, does the engine smooth out?

If it does smooth out then it likely has something to do with the plugs or wires, if it keeps on missing then you know which cylinder it is, if it has 2 cylinders next to each other that don't change the idle when you pull the plug wires then let us know.

If removing every plug wire changes the idle then it is something else.

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I don't know if anyone has suggested this, but while it is idling pull each plug wire off the cap and see which cylinder is missing, the idle will not change when you pull that wire, once you find which one it is then slowly get end of the plug wire closer and closer to the plug cap hole till it starts arcing, does the engine smooth out?

If it does smooth out then it likely has something to do with the plugs or wires, if it keeps on missing then you know which cylinder it is, if it has 2 cylinders next to each other that don't change the idle when you pull the plug wires then let us know.

If removing every plug wire changes the idle then it is something else.

 

Currently doesn’t want to idle, I’m gonna get a buddy to help me tomorrow and I’ll try pulling the wires and see what happens.

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I've lost track after 22 pages

 

It should idle below 1,000 when warmed up. I can't hear a miss in the video but not saying it isn't there. I suspect there are multiple things wrong here and each needs to be addressed and fixed before jumping on to the next and leaving it.

 

 

What is the timing set at? Was the timing checked and set?????

 

Were the plugs, wires, cap and rotor replaced?????? yes or no.

Were the valves set?????????????????????????? yes or no

 

Was a compression test done? what were the numbers???

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Mix screws were turned out almost a full turn, leaned the mixture out today, pulled the wires while it was running and it turned out to be the #2 sparkplug, and it was fouled out. Replaced plugs and messed with the carb today, runs better than it ever has.

 

I got lucky and it was something stupid.

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sometimes its the valve lash that falls off

Lash is at .010 .012

 

Head is very nicely rebuilt, oversized seats, new ferrea valves, new springs.

 

It’s the junky carb, I’ve been putting it off since the weather is bad but I’ll older a new 32/36 very soon.

 

 

Also I have to really thank you for your video uploads, with out that and the help of people here I wouldn’t have driven my first datsun.

 

I used to post under a different name here and I no longer can recover the account and there’s threads of me posting about trying to buy a 620 in like 2010-2011, so it feels amazing to have a running driving truck of my own finally.

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