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Just got a 72 510!!!!


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You may be running too small of a jet, which results in a lean misfire. Here's an obvious way how to tell if the jets aren't the right size: If the jets are too large, you'll step on it and it'll bog down for a second(throws more fuel at it than it can handle), then take off. If they're too small, it'll fall on it's face when you give it the pedal(runs out of fuel altogether). What do the plugs look like?

If the weber came off a L16 or something like that, and you put it directly onto a L20B(larger displacement engine), I'll bet dimes-to-dollars that's what's going on. Webers are pretty easy to tune; good thing, because in my experience, you can run em without a good dial in, but to get primo results, you tune! Hope this helps:thumbup:

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Yes fuel did come out from the carb when I gave it gas. I adjusted the floats and havent seen that problem again. As far as timing goes, I can not get a good solid idle when adjusting the dist. cap. I am wondering if I need to cokpletely remove the bolt and adjust past the typical bolt adjustment? Also, I checked all jets and mixture screws. Everything seems to be in order. I know I am going to need to perform proper timing at some point but I want to fix the carb issue first. Maybe I should just get the dual 40 weber dcoe's I want and start over you know?

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I know I am going to need to perform proper timing at some point but I want to fix the carb issue first.


Now that you mention the timing issue, I'd definitely get the timing where it ought to be before you start messing w/ the carb. Make sure that the timing is right where it ought to be. Your engine won't run for beans if it's running way out of time.

If you have to adjust the timing past the point where you should be able to, there's a chance that the distributor drive(the long shaft that connects the distributor to the oil pump.. driven by the crank) is a tooth off. This happened on my brother's 521, and it ran extremely retarded, and when we tried to advance it up, it still wouldn't advance enough. I think there's 20 teeth on the distributor driver, so even if you are one tooth off, that's 18 degrees.. yeah, quite a bit. you can check that by getting the engine @ TDC, and removing the distributor. If the little slot is pointing at around the "11-11:30 o'clock" position, that's about where it ought to be.. If not, then you have to unbolt the oil pump(4 bolts; right below the crank pulley, on the OUTSIDE of the engine.. thank God), and drop it down enough to move the dist. driver over a tooth. I use a magnet to hold the drive up in place from the distributor side(top), just so it doesn't slide out and fall out. I know it sounds involved, but it's not. Super easy...

You want to check your timing first, though, and make sure that this is the issue. It's not a long process to correct a problem, but it is if you're trying to correct a problem that isn't there..

Also, you said that it wouldn't hold the same timing? That could be a stretched timing chain as well. Good Datsun engineering allows for the timing gear on the camshaft to adjust, if that is the problem... get yourself a good "Clymer" manual.. this is all covered in it. If you can't find one for 510s, you can usually find a good Haynes(Haynes were actually worth a damn back then).

Happy Wrenching!

Edited by MicroMachinery
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Should I manually rotate the fly wheel till the notch hits TDC? Then pull the dist. off? Then I will see a slot at 11-11:30 if the teeth are correct? I think I can handle that. But, why would the carb immediately die when I hit the throttle? Thats what makes me think it's a carb issue but I'm just not sure. I will definately focus on timing first, thwn work my way to the Weber. Also, I am considering some dual weber 40 dcoes. What do you guys think? I dont want to overdo it, just want to achieve 160hp and then concentrate on the interior..

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Yes, manually turn then engine over until the mark is at TDC. If you want to make things easier on yourself, you can get a 1 1/16" open end wrench and rotate from the crank bolt, rather than turning the flywheel. Now you're ready to remove that distributor and see if you're where you ought to be. 11-11:30 is the ticket.


Are you sure that the carb is failing you when you hit the gas? If the timing is in fact too retarded, it just flat won't run in the low RPMs. Example: When you're adjusting the ignition timing by turning the distributor, and you turn it one way(advanced), the engine speeds up. Likewise, if you turn it the opposite way(retarded), the engine slows down. Your engine is more responsive the higher your advance is.. to a point; there is a definitely a point where too much advance is very destructive to your engine(spark knocking, pinging, etc).

If your timing is too far retarded, the car will fall on it's face when you hit the gas, simply because you're not making the same power that you do when it's more advanced. The engine is designed to run optimally at a certain degree of timing; the trick is to find that sweet spot. Manufacturers' recommendations are a good starting point(base timing), but road testing is the best way to dial it in.

Hope it helps.

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Are you sure that it was 180 out? Was the engine on TDC Compression? Or was it on the exhaust stroke when you checked it? There are 4 strokes to this engine(Intake, Compression, Power, and Exhaust), and two of those engine strokes the piston is on Top Dead Center (0 degrees). If it won't turn over, you MAY now have it 180 out... other than that, was the oil pump/distributor driver where it was supposed to be?

Edited by MicroMachinery
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