Timing a 4.5

[WANT '71 280SEL]

Next Sunday Tim, (remember him with the '72 280SEL) and I are going to try and time his 4.5 I drive a diesel so neither of us are very inclined. I know one wire goes to the #1 cylinder, then doesn't another one go to the + terminal on the battery? We then would disconnet the vacuum line from the distributor, or leave it on? I've read conflicting things about the vacuum line. What should we set it at and we point the gun at the balancer, but what will we look for. I know to expect a flashing light, but the rest I'm lost on. Where do we adjust it if it is off? Really, we're both kids just trying to figure this out.
Thanks
David

[WANT '71 280SEL]

anyone?

[Tomguy]

One terminal to the (+) on the battery, one to the (-) (red and black, respectively). Disconnect he #1 plug wire and put the timing light's spark lead (blue on mine) on it. Mine doesn't work if I reconnect the wire to the plug, yours might or might not.

Before starting the engine, clean off the balancer well, and then try to find the 0° mark (it'll be surrounded on either side by increasing numbers). Find 5° ATDC - remember, it rotates clockwise, so if you're looking from above it will be to the left of 0°, if doing it from underneath as I did, it will be to the right of 0°. Mark it with paint, chaulk, or whatever you like that will make it easier to see.

From the top (again, find it before you begin this) look down between the water pump and dizzy. You'll see the pointer (about 1" long). You may have to move the rad hose to see it.

Lastly, loosen the set screw on the dizzy before beginning this (but not TOO loose) so you can move it while the engine is running to set it properly.

WITH THE VAC CONNECTED, start the engine and point the light at the pointer, and depress the trigger. The line you marked should line up with the pointer. If it's too far to the left, turn the dizzy left. If it's too far to the right, turn the dizzy to the right. Once the line is lined up, just to check, pull the vac line - idle should increase and timing should advance to between 5-10° BTDC. Reconnect the vac line, idle should go back down and the line should line up again.

Tighten the set screw, reconnect the plug wire, and that's it. But make sure you set dwell BEFORE timing!

[WANT '71 280SEL]

dwell?? Can you post a pic of the set screw, or at least describe where it is?
Thanks
David

[j9fd3s]

Originally Posted by WANT '71 280SEL

dwell?? Can you post a pic of the set screw, or at least describe where it is?
Thanks
David

its right where the dizzy meets the engine, theres a nut there. the hole is slotted so you can move the dizzy around

[Tomguy]

Dwell is the point gap. Just saying, every time you screw with the point adjustment, you mess up the timing.

The set screw is on the LH side of the dizzy, under the triger point connector. You may want (or need) to remove the plug/wires to see it.

[WANT '71 280SEL]

Aren't the points under the cap? Then I can use feeler gauges to chech the gap? What sort of clearances am I looking for?
Thanks
David

[Tomguy]

Yes the points are under the cap, and no, you don't set them with a feeler gauge - the proper way is using a dwell meter (many tachometers double as dwell meters). Just hook it up to the ignition PRIOR to the ballast resistors (or at least I have to with mine). If it runs ok as is, then just leave them alone (maybe clean them with stiff paper) and set the timing.

[230/8]

Want '71 280SEL:

Whoa...Step back, take a deep breath and relax. You began the thread by saying you know nothing about setting timing and from the content of your questions it seems to be a pretty fair personal assessment. Tomguy has just told you how to do it, and, to hopefully ensure you don't screw it up, he gave a small bit of advice to avoid messing with the dwell or your work would be for naught. If you have no skill at this, do yourself a favor, get a Haynes, read it and compare the pictures to the car so you are more familiar with the subject. It will save you mucho grief.

Stay focused, set the timing, it's pretty easy, don't attempt the points or dwell unless and until you have a more comfortable understanding of what you are setting out to accomplish. Start small and work yourself up to more complex jobs. If you monkey with the points without knowing what you are doing, then you may end up towing it to an indy shop to get it running again.

For what its worth...

230/8