Advance ignition-SC3.0 engine with Zenith TIN 40

[DJIPI]

Hi there,
I need your help, could somebody give me the advance ignition values for my US 1982 SC?
This engine runs with Zenith TIN 40 carbs.
Thanks from Belgium, and happy Christmas to all of you!!

J-P

[Trackrash]

Is the vacuum unit disabled and locked?

Is the distributor the original US '82 unit?

From what I have read you should set the total advance at 30 degrees. It may be that you will have to have the distributor recurved for it to run correctly with carbs.

[DJIPI]

Hello Gordon,
thanks for your help, here are the answers to your questions:
-the former owner of this car was driving the car without vacuum for brake assistance.
So we drilled one carb cylinder and connected the line to the brake assistance.
-yes, the distributor seems to be the original unit.

For your information, the engine was running perfect when we receive the car!

So, only 2 changes occured, that could be the reason of our problem:
-new vacuum connection
-we had to take the distributor away, therefore, bad position when we installed it back??

Thanks again for your help, and have a good christmas eve
J-P

[DJIPI]

perhaps I should add this: SSI heat exchangers and Burch exhaust

[chris_seven]

If it was running well then you need to consider the reason for the issue if it now doesn't run well.

If it ran well without vacuum why have you Connected the vacuum?

If you look at the advance characteristics for an 82 Euro Spec SC then connecting the vacuum unit may not be the best idea.

Are the cams standard and do you have standard compression?

If you only have one cylinder connected you will have quite a poor function for the vacuum system but you can buy a 'pulse damper' to smooth this out.

I think you need to use a good quality timing light and see if you can look at the basic curve.

Could you also let us know what static advance you have set and what problems you experience.

I have run Zenith carbs on an 82 SC without a re-curve but at quite high levels of advance at 6000rpm.

[DJIPI]

Hi Chris,
the reason of this issue is most probably:
""-we had to take the distributor away, therefore, bad position when we installed it back?? ""

This engine was running very well before, but we do not know the former advance characteristics and want to get them back - therefore my question about the expected values of the distributor advance for this engine - do you remember your advance values at idle speed and 3000/5000 rpm with the 82 SC? .

Other answers:
-vacuum connected for brake assistance (not to the distributor)
-no idea about the engine specs, should be standard specs.
-US car with US engine, 180HP,
-problem that we experience: metal against metal shocs when starting the engine, distribution chain?, almost solved with tuning of the distributor position.

Sorry for my poor english, thanks for your help,

J-P

[VFR750]

The 82 distributor doesn't have a large enough amount of mechanical advance to extract the most power from carbs. What you can do is disable both vacuum ports and set about 10 BTDC at idle. Then, as you pass ~1500 rpm you'll see the mechanical advance kick in and peak around 3000 at roughly 25-27 BTDC. It should stay there past redline.

I use a 78-79 distributor and it has more mechanical advance. I see around 30 BTDC at 3000 to redline. Still too little but close enough for now and it's safe.