Timing Late Spit 1500

[AlanT]

Hi All,

I set my resto up at 10 degrees before TDC as per this label…but it runs far better at 16 degrees. Is this because the fuel has changed so much since the ‘70s? I’m assuming Spits are no different to any other classics in that it’s just a case of ‘what runs best is right?’

Thanks 

 

Alan

 

[NonMember]

It's unexpected for a classic to want more advance on modern fuel. Normally, you'd expect to have to retard it a little.

One possible reason for wanting more (static) advance would be poor centrifugal advance behaviour. This can be due to rust or gunk sticking it all together. If you have a timing light it's worth checking that the ignition advances properly as the revs rise.

[AlanT]

Thanks.

Seems unlikely as the distributor is new. I’ll check with a light

[dougbgt6]

13 minutes ago, AlanT said:

I’ll check with a light

Timing chain and gears can be worn, making strobe setting unreliable. Best way is by ear, turn dizzy to maximum revs then back a gnats.

Alternately turn dizzy for maximum vacuum, then back one bar.

Doing them in tandem is satisfyingly exactly the same.

Doug 

[Clive]

23 minutes ago, AlanT said:

Thanks.

Seems unlikely as the distributor is new. I’ll check with a light

Worth checking you are getting the correct full advance. Possible the new distributer is incorrectly calibrated (seems to be a real issue) so needs extra advance at idle to compensate. 

But I have been tuning by ear for 25 years. Set as per dougs method, but then advnace until you get pinking under load, then back a smidge. But of te corve is miles out, it really will be wasting fuel/power

[AlanT]

Thanks Both,

I agree. By ear is best. The chain isn’t rattling and looked ok when I changed the seals last week so my guess is it’s the new dizzy that’s a bit out. 

[Pete Lewis]

what strobe do you have ,

on many the pick up is polarity conscious   if its one with an arrow on the clip pick up and you fit it reversed you get silly timing reading 

make sure the arrow faces the plugs 

Pete

[AlanT]

You’ll like this @Pete Lewis

[AlanT]

Made by my brother years ago. Works really well!

[Pete Lewis]

Aha  nice bit of DIY   just to double check have you checked with a small bulb across the points/elec pickup  for the  static setting

does this confirm what the homemade  strobe is showing ???  

worth a test 

Pete

[Chris A]

15 hours ago, AlanT said:

You’ll like this @Pete Lewis

I hope you don't drive down the road with it connected and the light on the car roof or dashboard ✋👮‍♂️

[dannyb]

My Spit 1500 is also 16 deg advanced. This was set up on a rolling road.  I checked it when I got home so I could make a note of it. 

Danny

[AlanT]

I did the bulb check. Danny, it’s reassuring to know that there are others! I checked the advance using the light and it’s also fine.

But as for the carbs…a bit of work required! 

[Pete Lewis]

if you have the dizzy vac connected at idle or a fast idle you will get some advance from it which you need to add to the static 10deg 

too much advance  can   cause piston burning you may even get silent pinking as whats going on inside will be hidden 

doing a small bulb test which also works with most electronics  is a good   back up  check 

when over advanced the idle will often give a small kick/throb  as the firing tries to kick backwards 

pete