Ignition timing

[Sgt_Lemon]

I recently fitted a ported and polished head with fast road cam. I have set the timing to the factory spec 6 degree mark however the idle is rough and jumpy. Would adjusting the timing to the smoothest idle off ear be best or are these just symptoms of the cam, head etc.

[Ben Lessani]

Is your static timing actually correct?

[oakgreener]

You haven't disturbed the wiring to the throttle body switches?

[Sgt_Lemon]

I used a timing light with an advance adjuster and set it up as described on the "how to tune your 8v" thread. I also occasionally get a symptom of an air leak with a hunting idle occasionally but not always.

[gazareth]

hi what camshaft you got? you will definatly get a rough idle if you put to wild a cam in. if it was mine I would set timing to standard and go out for a long run with it. as long as you got no pinking and it pulls well and doesn't guzzle the gas should be sound. ideally you should get it on dyno though.

[weazgti]

What's with setting up the gun with advance? I didn't think that was needed for 8v s.
I used to use one from about 1952 with just a stobe and it did the job.

[gazareth]

if your timing it of a tdc mark you need to adjust gun to 6 degrees advance but if your timing it of a mark on flywheel that's 6 degrees of tdc then you need to set gun to zero degrees.

[weazgti]

I see. I didn't think bout the op setting gun to zero. I thought advance had been dialled in but on the tdc mark.

[gazareth]

yeah same effect either way. as long as you don't do both or you end up with a can of marbles under your bonnet

[Sgt_Lemon]

I thought a rough idle may be because of the high lift cam, the fuel economy has shot down 10 mpg. Not sure if its because I enjoy a heavy right foot even more now,  will see what I get with a long motorway drive today.