Daft Question - solved!

[abzadams]

Since the engagement I have seem to have forgotten how to time my car!!
I've just had the distributor rebuild by H&H Ignition, which I would highly recommend.



So I've put the Dizzy back in (TDC was marked etc), rotor pointing to the notch. Set point gap to 0.04, checked dwell at 36 degrees(ish). Start the engine, fired up then used a snap on timing gun and set the idle timing to 5ATDC. Ticked over smoothly. Took the car out to warm in up, a bit lumply. Parked up somewhere there are now houses around. I then checked full advance at 6000 rpm and making sure it was not anymore than 38 degrees, I had to adjust it a little (vac line was off at this point!). Took it out for another spin, it was backfiring, smoking, almost undrivable.
Parked up and did it again, same.
Spent the next 4 hours doing much the same as before, nothing improved.
So now it's back my garage.

What am I forgetting to do!!!?

TIA

[Gary71]

Morning, Timing should be done at idle with the vac hose on. I believe the 6000rpm check is more a check that the dizzy is controlling things properly rather than an adjustment. Earlier cars were set at high rpm.

[chris68]

Hi,

Mine isn't a later car so I've only got a Haynes manual to refer to, but it states for '72 models onwards, timing at 6000 rpm should be 32 to 38 deg BTDC measured with vacuum hose off.

Also, are you sure you were setting the snap on timing light to 38 deg advanced and not retarded?

Maybe, as Gary says, set it to 5 deg ATDC at 900 rpm then just check timing doesn't advance beyond 38 deg at 6000 rpm.

Hope you get it sorted.

Chris

[abzadams]

G,
Thanks for the reply.
It's really weird, some people say that idle timing is not important but full advance @ 6k is. By this I mean that the cars should be timed at 6K (no more that 38 degrees) and let the idle timing lie where it falls.

So the question is, do most people time their cars at idle or 6k, or even a combination of the 2?

[abzadams]

Hi,

Mine isn't a later car so I've only got a Haynes manual to refer to, but it states for '72 models onwards, timing at 6000 rpm should be 32 to 38 deg BTDC measured with vacuum hose off.

Also, are you sure you were setting the snap on timing light to 38 deg advanced and not retarded?

Maybe, as Gary says, set it to 5 deg ATDC at 900 rpm then just check timing doesn't advance beyond 38 deg at 6000 rpm.

Hope you get it sorted.

Chris

Chris,
It's a borrowed light, as my Tacho is getting refurbished, and needed one with a tach function. TBH I dont know if it was set to advance or not. When revving the engine, the pulley marks move anticlockwise

[chris68]

Hi,

I think it depends on the model.

It seems a lot of early cars don't have a dynamic setting at low rpm. The only checks are a static setting (to get it running) then a dynamic setting at 6000 rpm to time it accurately.

Cheers,
Chris

[Gary71]

The Porsche manual says at idle, so idle it is! I've never summoned the lack of mechanical sympathy (and big enough ear defenders!) to take it up to 6000 rpm with my head in the engine bay

[Gary71]

...and it's good to hear you are not using the tacho to set it by, if it's anything like mine it over reads at idle (shows just over 1000 at 900) and under reads above 4k

[butzsi]

Hi, the points gap should be 0.3 mm or 12 thou minimum (did you really mean 0.04 ?) The timing setting at idle should ONLY be done with the engine at FULL operating temperature and having proven that the vacuum retard is operating correctly - when you pull off the vacuum hose with the engine running the revs should increase as the timing advances. If no vacuum is being applied at the distributor then you will end up setting the timing much too retarded. An easy way of checking is to remove the vacuum hose from the distributor and set the timing at idle to 5 degrees BEFORE TDC -then do a road test and see how the performance is.

Chris

[jb]

The first time I did it I failed to read the After in 5 degrees after tdc and set it to 5 degrees before.
When I finally read the manual and set it properly I set the gap a 12 thou but when Bob used a dwell meter on it then 15 thou seemed to be spot on.
Not sure if any of this helps but certainly it was set at 900 rpm not 6000 although a quick check that it advanced sees a good idea

[2.4TE]

I have a 1972 2.4 T/E. Many years ago I had the good fortune to take the Jerry Woods/Bruce Anderson 911 maintenance class. According to them, for this car, points gap should be 0.016". Jerry was adamant the timing should be set at 6000rpm: 30 degrees ATDC. His reasoning was it's better to get it set correctly higher up the rev range to accommodate any wear in the distributor (not an issue for you!).

This is how I set my car. It works nicely. It takes some getting used to at first (noise/heat etc) but it does the job. When I do it, I usually take my timing light and a 13mm spanner (IIRC) with me in the car for a spin to warm up the engine then set it up out in the country somewhere, to avoid upsetting the neighbours!

Thanks for the lead on H&H- I just posted in the 911 section with a distributor issue and hopefully they can help me.

Cheers,

Dave

[Bruce M]

Jerry was adamant the timing should be set at 6000rpm: 30 degrees ATDC.

Do you mean btdc? Or I'm I just confused....

[mycar]

I`m a bit confused by this too. Do you have to time some engines to spark after top dead center ?

Mike.

[Lightweight_911]

Timing should be 5 deg ATDC at idle with the vac hose connected - this will change to ~ 5 deg BTDC at idle when the vac hose is disconnected & should rise to 31-38 deg BTDC at 6000rpm ...

[911hillclimber]

Sorry to be thick, but why does the engine have to be at 80 C?
Is it because you need to hold 6K for setting, or does the car's system use a temperature link in the ignition?