backfires from the carb

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HI there all .. I been trying to get my 520 back on the road , with no luck. I switch the L 16 for a 78 L20 with the remote ignition box( :( ) I been trying to get it to run but all it does is crank an backfire from the carb, nice lil puff of smoke comes out .. First i thought it was the wiring to the remote Igintion box, but i think thats correct. I have a spark tester and it shows the piston is getting a spark.. I have changed 3 carbs already, 2 stock and a 32/36 weber that i have used on my Toyota in the past. so i dont know whats going on.. :mad:

Any help u guys can give me would be great......

[DaTsUn72WaG]

hmm, i had the same problem after putting together an L16 when i changed the head and gasket. umm, id make sure that your distributor is in time. and that the timing chain is set right, you could be off a tooth and its sparking after or before compression in each cylinder

[datzenmike]

When the motor is at TDCCompression, the rotor should be pointing in the 4 o'clock position and at the #1 plug wire on the distributor cap. It rotates counter clockwise to the #3, #4, #2 plugs in that order.

 

Check that the plug wires are correctly placed on the cap and go to the correct spark plug. Be sure! Easy to mix up.

[banzai510(hainz)]

You should have installed the L20 with the stock distributor!!!!!!!!!

 

pull the L16 dizzy with mount put on side install motor.

 

put motor on TDC,instll dizzy till it locks that #1 and go 1 3 4 2 counter clockwise fire order.

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wow that would have been a whole lot easyer, but im sad to say i dont even know where the L16 dizzy is anymore.. this whole eng swap thing started like 4 years ago , plus i moved to top it all off..

 

Thanks for the Info guys i will try it out and see what happens.. im ready to drive my truck again.. my house needs lil work and it would be great having the truck, to haul stuff around........

[banzai510(hainz)]

look at this.

just buy some piggyback connectors so you dont have to cut wire and go back to stock if needed.

 

Ps you need to keep the ballast in the system or it might fry it.This drawing is for the later EI type coils(.7ohms resisitance)

 

the bottom is a stock 510 but should be very similar. youll need the HOT START wire that bypasses the coil to get it to start if still using the ballast.

 

You might need someone to come over and fix this otherwise this truck is going to the dump. This is a ez fix

the 620.com has some drawings(mostly 620) and might be same as the 520/521

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Thanks Banzai for the drawings.. It looks like i was right my wiring is correct, the only difference is that i have a condencer on the black &white wire . just like it shows on the 620 technical site.. the next step is to try checking my timing like datsun72wagon said maybe i did jumped a tooth on the dizzy shaft.. Oh and dont worry Banzai about this truck going to the dump , i have too much stuff into it to junk it.. It will see the road again one of this days :D....... i will take pics to show u guys that great day. :)

Thanks again for u help ....

[banzai510(hainz)]

Line moto up to TDC keeping the chain titie and ck the timming marks and the oil pump spindal position.

then install the dizzy and see where the rotor is pointing.

make sure it line up on a plug wire and you will assign that as #1 plug wire then go Couter clock wise. 1 3 4 2.

 

Now if another dizzy of anther L motor its important to get the correct mount that belong with that distributor(dizzy) so you have enought timming movement. The only otherway to cheat the sysytem is remove the 10mm bolt that it holds to the timming olate and move or more retard or advanced

 

rememeber when its pointing towards the #1 plug wire the points will be open.

 

so gap the points say at about .020 on the hum of the cam lobe

 

Datsun72 Wag,

bre620 lives in Longveiw. If you need some stuff cked out maybe he can help or some other local before you hack up a stock datsun wiring .

There is not need to cut anywires on a 510. You can use pippy back jumpers or other stuff. Esp on a clean rust free wagon!!!!!!!

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Just to keep u guys updated.. I pull the dizzy and moved the dizzy shaft . that did the trick about it backfiring thru the carb. it trys to start but it dies rite away, to make it more fun my starter decided to give up..:mad: So after getting a rebuilt one. I changed carbs with the ones i have here and no luck. I think the timming is correct now, cause it wants to run but the carbs are crap. My next move is get my dads 79 620 and barrow his carb for a while.. if thats it i send my out to get rebuilt.....

 

Thanks guys for ur help .. lets see what happends now :D