Setting Dwell on 72 2.4

[GotaT]

Ok guys, I'll soon be installing my fressh top end rebuild w/ New cams and want to know more about setting the Dwell. I understand in order to get started w/ setting the timing I'll first need to set the point gap to ? .. need to look it up. Then get the motor running at good idle and and warmed up and set the timing to I believe 5degrees ATDC . Now with my new cams it may be a little different.. but regardless Ill be able to find out optimum power once I get there. So.. How do I set the Dwell?

[Eagledriver]

You don't need to worry about setting the dwell. It will be close by setting the points gap. The dwell is only important in early ignition systems without the CD box. I think the gap is set to .025 but I'm not sure. Yes 5 degrees ATDC is correct with the vacuum hose connected. Then check at 6000 RPM with the hose disconnected. You should get 30-35 degrees BTDC at 6000 RPM. The pully is marked with all these settings.

-Andy

[GotaT]

Sounds simple enough... Thanks

Anyone know off hand what I need to set my points gap to? Is this measurement set when the engine is at TDC for #1?

[RoninLB]

.35mm or .014"

set at high point of dizzy cam lobe

check after 100mi & 500mi due to gap closing as points "break-in"

if using Bosch grease on cam 1,000mi may be necessary for points break-in.

as point gap changes so does your ignition timing.

if manually turning engine to find top of dizzy cam lobe Only turn engine clockwise when viewed from rear of car looking forward. This is normal direction of engine operation.

use Bosch points.

[GotaT]

Is dizzy = TDC?

[RoninLB]

if engine can't be turned loosen the distributor hold down nut and rotate to find top of dizzy cam.

some install new points .002" wider to help compensate for early wear.

[Eagledriver]

Dizzy = distributor.


You are setting the points at the most open part of the cycle. Look at how the points open and set them so that the most they open is the amount you are setting. (.14 inches).

You probably don't need new points. They will go pretty much forever in a CDI system.

-Andy

[GotaT]

Eagle, Is it typical that the the points will/should be most open at TDC of any cylinder? And do i set them to .14 in OR .014 ?

[gigem75]

I'll chime in, you set them when they are open the widest up on the cam of the dist. of any cylinder, not necessarily when the piston is at tdc

[GotaT]

So, then As i turn the motor from the crank when the Cam opens the most is when i'll set it. Now before I can ensure that this position is correct I'll need to time the Car to the 5degrees ATDC.

[gigem75]

set your points first.
Then set the engine to 5 ATDC on #1
The rotor should point to #1
rotate the dist. clockwise just until the points close
rotate the dist ANTI clockwise until the points just open.

(some use an ohm meter to tell when the circuit is broken, your eye will get it close enough to start)

Check again to insure the rotor is at #1 spark plug wire. I have put a magic marker mark on the side of the dist when the rotor points to #1 as a reference.

tighten dist.

you have just set the static ignition timing and it will start, well at least it should.

a word of caution. Do not tighten the screw that holds the points down to tight. If you strip those threads you have opened a can of worms. snug to tight is all you need.

[Bill Verburg]

Pull the distributor, it's not hard and all you need to do is note where the rotor points when before you pull it. Put it back in the same place, thats not hard either there are only 3 gear slots that are even close/

Put the distributor in a bench vice, clean it lube it, install points. Set gap to spec which is .3 - .35mm(0.012 - 0.014"), fine tune w/ a dwell meter, spec for a Bosch is 38 +/- 3. Better to set to the low end of dwell which corresponds to a wider gap. The gap closes up as the rubbing block wears.

[J P Stein]

*****can the points & go with a Pertronix unit and never worry about point gaps again.