timing and points gap thread

[Shuie]

My tach has started bouncing at high rpms and while at idle. The car is also slightly stuttering at idle. Doing a search I found that a bouncing tach indicates either a bad voltage regulator, bad ground, failing CD, or the points. I’ve had a failed CD box already so I hope that’s not the problem. It’s been about 2000 miles since the timing was set and the CD box was replaced, so I’m suspecting the points.

I have never set the points or the timing on a car before. Reading through the old threads I’ve seen a lot of reference to 'setting the points' and 'setting the timing' but I’ve never seen any pictures or diagrams on how to actually do it. The only thing I’ve seen so far that I think I understand is the pulley mark diagram on how to get the engine to TDC at #1. I’m considering a pointless conversion, but I want to try to set the points first.

I’ve got a set of feeler gauges and an inductive timing light. Does anyone have any pictures or a basic set of instructions on how to do this? Is there a good thread or a tech article that covers this process?

TIA

[Bill Verburg]

I always prefered to pull the distruibutor to set the point gap. Most manuals will suggest setting the engine to TDC on the compression stroke for cyl #1, but that is not really necessary, just pop the dist cap and note where the rotor is pointed and replace at the same position.

Once the dist is out, place it in a vise(use a protective towel and light grip). The spec for a '72 Bosch dist is .35mm or 0.014" You need to develop a feel for the correct amount of friction between the feeler and points also keep the feeler perfectly parallel to the point face and of course be sure that there is no oil or other contaminant on the feelers. There is one hold down screw on late dist. snug it up a tad but do not tighten(just enough that the points gap will stay fixed on its own), set the rubbing block on any of the cam high points, use a flat scredriver to gently pry the points to the correct gap, tighten the screw fully , recheck. Lightly grease the cam from the caplet supplied w/ the points kit

once you are happy w/ the point gap reinstall the dist in the same orientation as when removed(you did note where the rotor was pointed , right?) Gently snug up the 13mm dist bolt.

Start now check the dwell which is the most accurate check on the point gap. The spec for a Bosch is 38&deg &#177 3&deg less dwell means more point gap I always liked set at the low end of the spec.

Gotta get to work now i'll finish later or someone else can jump in

[RoninLB]

There is a break-in of new points on the points rubbing block to the cam lobe on the dizzy. It's usually rechecked within 500mi or the points adjustment always close up, sometimes leading to a mis or other problems. Dwell meter usually gets hooked up to the dizzy external wire connector, not the coil.

101 Projects For Your Porsche by Wayne Dempsey p68-p73

[Paulporsche]

I like to set the points by pulling the fuel pump relay so the car will not start, having my helper turn the car over, and adjusting the gap to 38 on the meter by inserting a slot screwdriver against the nib on the plate and twisting while the car is cranking. This moves the points, opening and closing the gap. A little tightness on the screw before I start helps hold the points in place. I then tighten them down, and recheck.

It only takes a few minutes and you know it is accurate.

I haven't used the feeler gauge in years.

Don't forget to lube the rubbing block.

Good luck.

Paul

[RoninLB]

Originally posted by Paulporsche
I
It only takes a few minutes and you know it is accurate.

Don't forget to lube the rubbing block.

absolutely the best.. I didn't want to overload the newbe.

[jpnovak]

Take out your dist. and install a Crane XR700 or Pertronix system. More stable spark and no points to adjust... Ever!

Do a search and you will find pros and cons of each system.

[tobluforu]

I have a 72 as well-great choice in years!!!!
If you have a dwell meter-use that. If not get a feeler gauge, it works just as good. This is best done with lots of light. If you have a shop light, position it so you can see into distributor (I have a bicycle light that fits over my head for night riding –it’s great for working on cars). Now pull the distributor cap off and move it to the side. Get your 19mm wrench, put it on the crankshaft bolt (that's the lower pulley) and turn engine over by hand. Look into dist. and watch the points open and close. You will see lobes on the dist. that causes the points to open and close. Hand crank engine over until points are fully open. Now pull the points out. The best screwdriver to use is one that is magnetized, That's so you don't drop that tiny screw when taking it out and putting it back in. Small needle nose pliers work great to unplug that little electrical clip. Now install points. This will take a few tries to get just right. There is a notch in the points on the right side of them. You will se this when looking into dist. You use that notch along with the 2 little raised dots on the dist. to adjust the points. Use a screwdriver to do this. You tighten down that little screw just enough so it's tight, but will move when you put the screwdriver between those 2 dots and notch in points. Once you think you have them adjusted right, tighten that tiny screw, and turn engine over by hand. Watch the points open and close and check again. This will take all of 15-20 mins.
Always keep a spare set in your car.
That's it.

[Early_S_Man]

Sherman,

The usual recommendation is to use Bosch hi-temp grease [Pelican sells it -- yellow tube] on the cam and rubbing block ... though I have used a thick silicone grease like Dow Corning 112 quite successfully.

You can file down used points, but a dwell meter can give you a meaningfull reading as is ... but the feeler gauge won't work until you do dress the points!

If you feel like getting a DMM with dwell, tach, and duty cycle fun ctions ... the SunPro CP7678 is a good one for the money. Sun is selling them now at a clearance price of $59.99 ...

http://www.sunpro.com/cgi-bin/web_store.cgi?page=cp7678gs.htm&cart_id=1149281_9806

ps ...

Dwell and tach meter measurements are made at the distributor, not the coil, on CDI ignition systems!

[tobluforu]

s_man-what do you mean by "dressing the points"? I understand that a small dab of the grease that comes with points goes where you just mentioned above. Are you referring to that?
Thanks

[Early_S_Man]

blu,

'Dressing the points' ... refers to filing down the 'high points' resulting from pitting so that a feeler gauge can be used to measure the gap accurately.

The grease only goes on the cam and rubbing block!

[Zeke]

Warren once had a post about pulling the rotor and filling the shaft with oil. There is a felt in there to hold the oil. I assumed that the oil seeped out of a tiny hole in the shaft where the rubbing block contacted the cam bumps. Right or wrong?

[Early_S_Man]

Milt,

No, the oil under the felt plug is strictly to keep the camshaft from seizing on the drive shaft and locking up the centrifugal advance mechanism ... here is the infamous 'distributor lube' thread:

distributor lube...

[}{arlequin]

I'm going to sound really bad here... what's "dwell"?

[JP911]

I just installed the Pertronix Ignitor and it works great! Based on past threads I will keep a spare set of points in the toolkit, but the car is running smoother (no more bouncing tach).

[Zeke]

Dwell is the amount of time the points stay closed with respect to the turning of the crankshaft. It is measured in degrees of distributor rotation.

[}{arlequin]

Cool. That actually makes sense. Thank you.