Doesn’t start well, and runs bad.

[toon_herit]

Been on this a while. A 1978 260Z which ran okay until I put into the garage, and 8 weeks later it started but ran rough. It’s always been a poor starter and taken a few seconds to get up to 6 cylinders running
Anyway, decided to try to fix it.
New plugs, plug leads, 280Z dizzy, ignition module, coil, fuel pump, filter and limes.
Checked timing, and camshaft correct, 1&2 lobes on camshaft at correct angles, no. 1 piston at the top, crank pulley at TDC mark, dizzy rotor at 7pm ish and no. 1. All leads in the correct order and spark at each plug.
Doesn’t start (mostly), and when it does briefly it back fires through carbs.
Have rebuilt the carbs and new needles and jets, and reset the floats.
Carbs are round top 240Z.
is it simply just lean or rich? (Have set the carbs as default, ie mixture and tried checking the spark, but doesn’t run enough).

 

[jonbills]

distributor setup sounds about right, but best to confirm timing with a timing light. you're looking for maybe 5 - 10 ° btdc at cranking speed. backfire through the carbs can mean too much advance.
Also confirm plug leads are in right order (153624).
If sparks are all good then check the fuel.
Are the sparkplugs getting wet with fuel?
will it start on easystart?

 

[Rob Gaskin]

Are you using a mechanical or electric fuel pump?

 

[toon_herit]

Spark plugs look okay, just slightly rich if anything. May take all out again and clean them. Haven’t tried easy start, but will have another play this week.

I’ve disconnected the the mechanical pump and put in a new electric pump. When I bought the car it was running an electric pump feeding the mechanical pump. I replaced the electric pump but then decided to bypass the mechanical one just in case. The fuel flow is good, but haven’t yet checked the return lines, but can’t really see how that would affect anything as most cars with SU’s don’t have returns.

cheers.

 

[Bazzateer]

Dizzy 180 degrees out?

 

[toon_herit]

Update time.
After a few hours I’ve got it sorted, and running good.
The 2 main problems were trusting the crank timing mark, and getting the 2 green wires from the dizzy the wrong way round. I assumed the latter didn’t matter, and tracing the wires should have be right.
The new dizzy plate helped even though it was maxed out and the dizzy orientation being further than expected. I also changed the ignition module, but don’t believe that contributed.
Was going to get it professionally tuned but it’s running well (with the 280ZX dizzy) and starts first time (never done this before) and the plugs now show as decent mixture across all cylinders.
Cheers.