distributer timing
 

I have a 79 SC. I have taken the oxygen pump and air conditioner out and I've installed a 74 exhaust system. John Walker did my transmission and installed 7:31 differential. I have installed webers, but am having trouble with my timing. I can get the car to run good at low rpms or high rpms, but not both at the same time. I have figured my distributor will do 17 degrees of timing. The vacuum advance does not do much, only a couple of degrees + or -. I think the distributor needs to be re-curved. Anybody have any ideas? Thanks. Johnhttp://www.pelicanparts.com/support/...s/beerchug.gif

When you say 17 deg of timing....is that distributor degrees....or crankshaft degrees?
If it's distributor...then you should be in the ballpark....5 deg ATDC for the static....and 17 dist deg (34 crank deg) will bring you to a total of 29 deg advance.
Very close to the optimum of 35 deg as the group has said before.
It looks like you need to get about 2 - 3 more from the dizzy.
You might investigate the slot or limiting device on the dizzy plate...perhaps lengthening it will give you the right amount.
Bob

I set the timing 5 degrees btdc with vacuum off...at 2800 rpms it goes to 21 degrees and no farther. With vacuum on, it goes to 10 degrees btdc and will go to 22 degrees at 2800 rpms. I've been doing this with an adjustable timing light. Since it needs to go to 35 degrees at 6000, it seems that I need the distributor recurved. Any ideas????? Thanks...John

Well, you could just set the timing so the max advance is 35° and not worry about the idle timing. Drive it and see how it runs.

Tom

just for the hell of it, pull off the vacuum hose and plug it. set the adjustable timing light at 35°. raise the rpm up to where the timing stops advancing. (that point will be well below 6000 rpm). this is when you want the Z1 mark on the pulley to line up with the notch on the fan housing. turn the dist body until it does. the idle speed will go up as the timing is advanced, so correct that to 1000. leave the hose off. try it now.

The distributor curve extends beyond 2800 rpm. Check the overall timing advance at 5000-6000 rpm. If it doesn't reach approx. 35º, I suggest you follow Bob's advice and check the advance stop in the distributor. If the dist. limits the advance to only 22º and you set the timing to 35º@6000, you may end up with too much initial advance. For example: 35º overall = 22º dist. advance = 13º initial (which may be okay depending on knock factors like fuel octane, air temp., engine load, compression ratio, altitude, etc.).

With your setup, you could probably disable (plug) the vacuum hose as this is a device for retarding ign. timing at idle. What are your Weber jet settings?

Sherwood Lee
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