Itinerant Air-Cooled

One of the most aggravating things to do when doing a tune up is getting the dwell juuuust right. I pull the distributor and set statically, but I usually have to putz with it for at least an hour to get it just right.

It usually goes like this.

Pull the distributor, set statically, put back in and check. Hmmm, 49 degrees. Not bad, but I can do better. Stop engine pull cap and rotor, reset points, put cap and rotor back on on, start motor.

Rats, now it 40 degrees. Stop engine pull cap and rotor, reset points, put cap and rotor back on on, start motor.

Rats, now it's 50 degrees. Stop engine pull cap and rotor, reset points, put cap and rotor back on on, start motor.

Dang it! now its 38 degrees. .. aannnnd repeat.

I loooved the GM caps that had the little window, and you could sit there with the engine running, looking at your dwell meter and get it dialed in juuust right.

Get thee a Pertronix!

Try using a vacuum gauge as a guideline and go by 'how the engine feels'.

Dwell is nothing more than another way to set the points besides using a feeler gauge. I always used a feeler gauge. I have Pertronix now and swear by them.

TrollFromDownBelow wrote:One of the most aggravating things to do when doing a tune up is getting the dwell juuuust right.

Make sure the rubbing block is lined up with the breaker cam.

Make sure that your feeler blade is exactly perpendicular to the point contact surfaces.

Occasionally you will find that some chimpanzee overtightened the screw so bad last time that the breaker point assembly has a "ghost memory" that moves your adjustment as you secure the screw. I have been known to just bend the stationary point a little to make damn sure it is where I like, after the screw is secure. The factory gap is .016 TO .018. Relax. Just get the feeler blade to slide through nice at .016 and don't even pull out the dwell meter. It is a 67 hp engine. Delivering a decent spark is not that hard.
Colin

TrollFromDownBelow wrote:One of the most aggravating things to do when doing a tune up is getting the dwell juuuust right. I pull the distributor and set statically, but I usually have to putz with it for at least an hour to get it just right.

I loooved the GM caps that had the little window, and you could sit there with the engine running, looking at your dwell meter and get it dialed in juuust right.

That was always one of my big gripes with Bosch. If GM could do it (and even Renault could do it, for chrissakes), why couldn't Bosch?

There is another way. First, make a little paper template like a degree wheel, except that it had an arc of only 100 degrees.

Here's an image of it ... it should be full size. Print it out and glue it to a piece of cardboard or whatever.



Find a refrigerator magnet so you can stick the hub of the template onto the crankshaft pulley.

Now, with the ignition on and the car out of gear, hook up your static timing light. Rotate the engine until the light goes OFF. This is when the points close. Line up the right side of your template with the crack in the engine case.




Now rotate the engine clockwise until the light goes ON. That should be where the left side of your template lines up with the crack in the case.




If it is, your dwell is at 50 degrees. If it ain't, make the usual adjustment with the point plate and try it again. If you changed the dwell, you'll also have to find out where the new light-off point is, and realign the template so its right side is at the crack when the light goes off. Repeat as necessary. When you're done, take the template and magnet off the crankshaft pulley and put them in your tool box for the next time. (If you leave it on and start the engine, that magnet will fly God knows where and be hell to find. "How does he know this?" I hear you ask.)

The advantage of this method is that you're setting the dwell angle directly, rather than using the point gap. And while you're probably making the same number of adjustments, you don't have to keep assembling and disassembling the cap and rotor and starting the engine.

Hey, ^^^^ that's pretty slick!

Mr. Administrator, can we move this tot the tech tips and tricks forum?