Return fuel line ?

[Art@NissanSport]

Ok, maybe this will help. the car was bought from this site. It is the sixth car down on page 2 of the US cars for sale section. Titled: "1973 Datsun 240z RUSTFREE from Chicagoland". Maybe some of you know this car and might have a better understanding of its inner workings. And never believe the words "RUSTFREE" unless the car comes from my neck of the woods. There is no major rust problems, but there is rust.

[JimmyZ]

Try using a dwell meter to dynamically check the points. (Adjust points first) Dwell is 35-41 degrees. (Stock 240) This will tell you where to look. It might be that the engine rpms are jumping so much that the timing is erratic. If the dwell meter wavers it tells you that it is a mechanical issue with the dizzy or it's drive. (As mentioned above)

My distributor was so badly worn that the rotor began machining the inside of the cap... Metal posts and all! It was a miracle it ran. Turned some new bushings on the lathe and good as new.

If there is little to no wiggle in the distributor shaft then it could be a worn front cover bore. (Where shaft from oil pump to distributor rides).

2c

Good luck

Jim

[JimmyZ]

The car supposedly ran fine until about 150 miles from Albuquerque. They got gas at a station and it ran bad from that point on. We drained the tank and put new fuel filter and gas in.

Did you check the inside of the float bowls for water/crud? If they did get bad gas then some of the crap may still be in the bottom of the bowls. Best to drain and clean them anyway.

Just thinking

[Art@NissanSport]

I replaced the carbs with a tuned set of SU's, so I know that the floats are fine. I will try another distributor, although I tried it before and it didn't make a difference.

Since the owner wants to put a chrome valve cover on it, I'll check the valves and timing chain at that time. it can't hurt.

The cam is not stock and the idle is a little loppy(sp?) so maybe that is why the mark jumps.

[Art@NissanSport]

Final update: The 73 is up and running fine. I put one of my extra dizzys on it, adjusted the valves(8 of the 12 were tight) and replaced the aftermarket cam sprocket with a stock version (the aftermarket sprocket did not have notches). I adjusted the sprocket having to use the third hole to get the notch to line up left of the groove. The timing mark no longer jumps all over the place (probably due to the new(old) dizzy . Also kind of odd was the fact that the cam spray bar was falling apart. I replaced it with another one that I had off a parts car. For a freshly rebuilt motor I'm surprised that it wasn't replaced and I'm also surprised at the timing chain needing so much adjustment. Add to this readjusting the air/fuel mixture on the carbs since there is now a return line and I had leaned it out to compensate for it and it runs great. No backfiring through the carbs or exhaust.

[biddljj]

What is a "dizzy" ?

zdisease

[Art@NissanSport]

I changed the dual point distributor to a single point distributor (dizzy)