Timing and misfire

[mangusta]

My t1 is running, but misfiring. Appears to be only on number 1.

We are also unable to static time the dizzy, cannot get it to line up on number 1 within the range of the normal adjustment. Instead, we have reversed the dizzy and put the leads on inverted (it lines up fine when timing it on the position for cyl 4.

We have just re-checked the cam timing, it is correct (flywheel on TDC, cam lines up on marks on the head). Is it possible the Vac advance (Which has a stuffed diaphragm) could be affecting this, or is there another trick to static timing the car?

(Running with the dizzy reversed works ok, except the slight misfire, and the timing on a gun shows it as correct too!)

[Henry]

It will run quite OK without the vac advance, just unplug the two hoses, mark positions first, and plug them with a small bolt to stop vacuum leaks. Would suggest you go back to square one and start again with ignition timing, the mark on the flywheel must be at TDC on cylinder "ONE" remember the flywheel does two revolutions to one on the camshaft. you may be setting the timing with the crankshaft one revolution out!
It may also be a mixture problem, is No 1 injector firing as it should?

[mangusta]

Ah, timing mark on TDC for static time?? I throught it would be on 28, since that's what they run...

We have the cam timing and ignition timing correct, but the dizzy is in half a turn out (Putting no.1 plug lead at the back left corder of the dizzy (from in front of car). Technically this isn't a problem for the engine to run with, since according to the cam angle sensor, the dizzy is still firing at the same point. However, if the static time is meant to be done at TDC instead, maybe that is the issue.

Otherwise, I have a set of injectors coming which have been serviced, one I replace these maybe we will see a change in tune...

Cheers
Paul

[Henry]

Paul, may have mislead you, timing should still be done to the advance mark, 28deg, but if your dizzy is half a turn out it it because you have not set it to TDC (or+28) on No 1 cyl, please re-read my earlier post.

[James]

I think a good start would be getting your dizzy in the right place. Turn the shaft so the marks line up, turn the motor to TDC then slide the dizzy in with the adjustment in the middle. The rotor will rotate as they are helical gears but that will get you on the right tooth. Then fine tune it with a timing light or by ear. I did mine by ear then about 6 months later checked it with a light and it was bang on.

[mangusta]

Sorted it, there was some dubious heritage to the engine, when we changed the timing belt the cam was a tooth out.

This has culminated in discovery that the rotor inside the distributor was upside down.

This, coupled with the offset pin locating the rotor caused it to be outside the range of timing available, not sure how this has happened, but it appears to be right now.

Cheers
Paul