i have a L20B everything stock except headers,and a single 45 weber.the guy i got the engine from said he jeted the weber.but i don't thing he knew what he was doing.from idle(1000rpm)to (2500rpm) the throtle is good but if i stomp on it it sputters.and somtimes i'll hold the throtle to the floor and the engine wants to die.even on the road. if i want to pass half-throtle it sputters.i need help.what could be the reason for that.maybe i need work done to the head??or maybe somthing else??ingnition??thanks for your help

Does it die if you feed it gradually or only if you stomp on it?

Webers have accelerator pump jets, drill them out a very tiny bit (with an appropriate number drill), but it could be the broad difference between idle and secondary jetting. Get a weber expert involved, or borrow the weber tuning book from the local library (If available).

the engine wants to die when i stomp on it.what do you think?

My dad had the same problem in his H20 when i gave him some spark plugs, they were obviously the wrong ones so he put new ones in and it ran fine

Could be fuel OR spark. Check the spark plug wires with an ohm-meter.

- Replace those that are bad
- look for and fix all the vacuum leaks

don't open the carb up until you check the external possibilities. Find out who's the local carb/tuneup guru and buy him a case of beer while he helps you ...

by sputtering do u mean missing. as in the whole car is jerking and shaking cos mine misses when i keep my accelerator at one point (like at a constant speed). It isnt a pleasure to dirve like that i can tell u. I have checked plugs, dizzy, conductivity..everything. I know how u feel mate. Hope u fix ur problem!

in any gear if i pass half throttle then it misses/sputter.


when in nuetral if i rev it slowly its o.k. but when i want an instant rev it sputters.
ONLY IF I PASS 3000 RPM AND THEN STOMP ON IT I GET INSTANT REV.BUT FROM IDLE IT SPUTTERS IF YOU REV IT FAST.HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
LIST ALL POSSIBLE PROBLEMS AND I'LL ELIMINATE.

I doubt if any of us know "all possible problem" that could cause this. However, any Datsun 620 repair book should list the most likely causes in the troubleshooting section. I suggest checking one out from the library, or getting one (Chilton's, Nissan, Clymer's, Motor, etc) from eBay or http://www.amazon.com

This seems to be a bit of a common problem doesn't it? It happens to me to.....going around a corner in 2nd, press the accelerator gradually = no worries. Stomp on it ( and not neccessarily to the floor either) and the whole car jidders and stutters for a bit then off it goes.

When someone figures out what causes their prob, be it spark, carby or gremlins living in the glove box, let us know!!

Cheers