My first 521

[thisismatt]

Not an expert. Does the outside plate do anything? It didn't come with a barrel that goes between them with a hole for the throttle cable to go through?

[Corona521]

I was able to figure that part out. I found the holes that aligned

 

 

I got the cables hooked up, Now on to the air filter

[Corona521]

The good news is the carburetor is in and the truck is firing up. The bad news is it sputters off when I let go of the gas.

 

Any ideas?

[Corona521]

The oil light is on. Checked the oil level, which is good.

[mrbigtanker]

Could be just the oil sensor is bad or not hooked up.

[Corona521]

Sure enough, the wire had come loose. Fixed that issue, sensor light is once again off. Thanks mrbigtanker

 

Any ideas on why the truck sputters off?

[Corona521]

a couple of other clues: it smells like gas when i attempt to rev the engine, and there doesn't seem to be a whole lot of power when i rev it-  the gas pedal is nearly all the way down and it barely revs up.

[earlyvws]

Idk know Datsun motors yet. But it sounds like timing. In an air cooled vw motor the difference of a top speed of 75 mph or just 50 mph can come to a fraction of a degree on the dizzy.

 

So I think the principles are the same. You do valves first, timing, then carb. Since I'm guessing datsuns don't need valve adj as frequently u could skip that step, but since the truck is new to u I would actually do it first because I don't know what it is currently, or ever was correct.

[mrbigtanker]

a couple of other clues: it smells like gas when i attempt to rev the engine, and there doesn't seem to be a whole lot of power when i rev it-  the gas pedal is nearly all the way down and it barely revs up.

Are you getting full throttle first of all from the cable you hooked up. Your carb is bolted down tight and not leaking correct.

And did you touch the timing at all.

[Corona521]

I haven't touched the timing. Will check to see about the throttle. I didn't notice any leaks yesterday, but I'll keep an eye out

[earlyvws]

An easy way to find intake leaks is to use a propane torch.

 

With engine running, Turn on the propane gas only do not ignite a flame. Wave the nozzle around all intake components if u here the RPM's speed up u found a leak.

[mrbigtanker]

Well i would lite it, but hey thats me.

[wayno]

Well i would lite it, but hey thats me.

And this is why I said a long time ago, if I see a mushroom cloud south of me, I will know that Mrbigtanker tried doing something epic on his 521, no guts, no glory, now ain't that right Mrbig. :lol:

[mrbigtanker]

You said it Wayno.

[banzai510(hainz)]

adjust the mixture and timming. then set the idle speed

 

also the stock carb 521 linkage will bolt on the weber. the rail where the cable runs it. that will fit if you want to use it.

 

Is this just a DGV 5A. Manual choke/???????????? or auto

 some have the elelctric selinoid thus youll never get it to idle as youell need a 12volt source to open the selinoid for the idle jet

[Corona521]

its a dfev, electric choke. 

[Corona521]

another piece to the puzzle:  before replacing the carb, the truck was running fine until i tried to drive it through the grapevine.  halfway up, the truck seemed to lose power.  i had the gas pedal down, but the truck wouldnt gain speed.  it slowly lost all momentum and i finally pulled over to the side.  thats where all this started. 

[wayno]

How hot was it when it started slowing down?

another piece to the puzzle:  before replacing the carb, the truck was running fine until i tried to drive it through the grapevine.  halfway up, the truck seemed to lose power.  i had the gas pedal down, but the truck wouldnt gain speed.  it slowly lost all momentum and i finally pulled over to the side.  thats where all this started. 

This is a very important piece of information, do you know about exhaust gas temperatures?

The longer you keep it floored, the hotter it gets inside the cylinders, there is a point when metal starts to melt.

[Corona521]

Wayno, the temp gauge was normal. But I had been driving for a while before even getting to the grapevine. What is the worst case scenario if this is this case? Would I still be able to fire up the engine? How would the truck behave?

[Corona521]

How hot was it when it started slowing down?

 

This is a very important piece of information, do you know about exhaust gas temperatures?

The longer you keep it floored, the hotter it gets inside the cylinders, there is a point when metal starts to melt.

Wayno, the temp gauge was normal. But I had been driving for a while before even getting to the grapevine. What is the worst case scenario if this is this case? Would I still be able to fire up the engine? How would the truck behave?

In other words, how can I check to see if this is this case, that my cylinders are toast?

[wayno]

Basically if your floored going up hill, the exhaust gas temp gets higher and higher, there is a point where metal will start to melt

Wayno, the temp gauge was normal. But I had been driving for a while before even getting to the grapevine. What is the worst case scenario if this is this case? Would I still be able to fire up the engine? How would the truck behave?

I have a turbodiesel, I did not really know anything about EGTs before purchasing this engine, there is a point when it just gets to hot inside the cylinders and it starts to melt aluminum, now I don't know how long it would take for a naturally aspirated gas engine to do this, or if it actually could do it, I do know that if your engine starts to knock/ping constantly, you need to stop, because it will melt/break the top of the pistons, this I have herd of second hand from a well known mechanic. 

When I get onto the freeway in my turbodiesel, I can get to 1400 degrees real fast, when I get onto the freeway with my non turbo engine, it still will get to 1400 degrees, it just takes longer.

I don't know what the symptoms are for a melted/broken piston, and yes, if it did not destruct, it might still run, but it will likely have issues, hard starting, uneven idle, a half miss, but these can be caused by a tight valve also, it will back fire out the carb if it's an intake valve, it will be a miss if it's an exhaust valve.

You would need to talk to someone that has melted a piston to know what that acts like for sure, as I have not had that issue yet.

[EastBay521]

engine would start up but shake violently because it is dead on what ever cylinder has a melted or broken piston. ther would more than likely be oil and pieces of metal on the spark pug. but ive only witnessed this on vw engines assuming it would go the same for an L.

[Corona521]

engine would start up but shake violently because it is dead on what ever cylinder has a melted or broken piston. ther would more than likely be oil and pieces of metal on the spark pug. but ive only witnessed this on vw engines assuming it would go the same for an L.

 

its starting up ok, doesn't shake, but also doesnt idle on its own- it will shut down if i release to gas.  occasionally i here a backfire. 

[EastBay521]

does it backfire out of the carb or the exhaust? if its coming from the carb youre probly to lean and if that's the case then youl probly need to turn the idle up aswell. id recommend getting a timing light and a set of feeler gauges to set the timing and valve lash. I don't remember doing any of that when we dropped that motor in. that wouldnt be the reason for it dying but I would do those two things first before I start playing with the carb but others might do things differently that's just me.

[banzai510(hainz)]

go back and time it.

adjust the idle speed and mixture.

 

 

I have had 4 webers and I just bolt them on and they work.

 

maybe the float is stuck and you just ran out of gas. Ck by cyleing the gas and see if it squirts in the main barrel.

 

Driving thru a Grapevine?

 

 

I assume the choke plate is open also when this happens as you have 12volts on the choke coil.

I seen it cut out up hill to another guy and I see the choke plate closed and say why is there no 12volts going to this? Doh!! I just loosen the 3 screws and turn the plate open all the time.