My car is runnig fine. Just got my new dwell meter in the mail so I thought I'd check the points dwell for the heck of it. The reading at idle is a steady 40 !! Should I just adjust it back to 28-32, put in new points and set dwell to 28-32 or leave well enough alone and continue driving the car until I get some sort of points bounce ?? BTW....., I have a new set of GM points still in the box in my glove compartment. Don't have a new condenser though...... Suggestions welcome.

 

Make sure the dwell meter is switched for 8 cylinder as if its set for 6 cylinder it will read 40*. Instead of a standard GM point I would use either Accel 8140 point & condenser kit or BW 112Hp point. These have the heavier 28-32 oz spring and will rev to 7K with no bounce.

 

With the heavier spring to minimize point bounce, make sure you apply some distributor cam lube to the the rotator.

 

Agree with both Donald and Dan....although the correct Accel Part Number you want is #8104 (and not #8140). I would also "double-check" your new dwell meter with a feeler gage on the (new) points to be sure the meter is functioning correctly.

I remember many years ago buying a new meter and setting the dwell on my friends car. Car would not start. We found that the points did not close, even though the meter indicated the correct dwell value. I would confirm that your new meter is reading correctly before trusting it completely and making distributor adjustments.

Larry

EDIT: Just in case you don't know/remember, adjusting the dwell back from 40 to 30 degrees will increase/affect your initial timing.....so be sure to recheck your initial timing after setting the dwell to the correct value.

 

I have always used the Accel points. They are a heavier duty set and really allow the higher RPM's without the point bounce. A setting of 30 is perfect.

 

All the above info is good.
I personally use the B-W 112HP points for customers' dist, but the Accel are fine.
When I was running points (everything I have now is PerTronix, and I ain't switching back!!), I always tried to set single points at 31deg and dual points at 34 exactly.

Tom Parsons

 

I have this.... http://www.jegs.com/i/Sunpro/885/CP7605/10002/-1 model meter. There's no switch for 8 cyl, 6 cyl etc. You're just suppose to read the correct line on the meter (which I hope I was looking at) and make sure it's swithched to the appropriate thing (volt, dwell, tach). The tach reading was close to the one in the car, the volt reading was high (over 16) when compared to a good known battery tester which reads a little over 14 volts. The dwell read 40....., which may be true since they've been in there a long time !! But...., I thought if the dwell was at 40 the car wouldn't run well. It revs to 5500 no problem with no break-up...... The sad thing is that I don't know anyone still running breaker points whose car I can test the dwell meter on.

 

All the above info is correct, but just know that point dwell is a balancing act. More dwell, equals more coil saturation time (important at high rpms). However, more dwell also means less cooling time for the points to dissipate heat, and therefore less life of the contacts.

In other words, if you like buzzing through the gears, use the max. dwell (32 degrees for single point dist.), and if you are not concerned with high rpm operation, then use the a narrower setting (28 degrees) for longer point life.

One blessing of an electronic replacement (like what Tom uses), is that the design engineer can specify an electronic "switch" (semiconductor) that can handle more heat, which then can allow for more dwell and coil saturation time. However, then the coil itself comes into play. Coils have heat issues too, and an electronic switch adds a small amount of resistance to the circuit (decreasing output), so it is always best to change to the electronic switch's manufacturer's recommended coil! Of course the main downside to an electronic set of points is unknown reliability, and the difficulty in diagnostics and repair. And don't get me started on MSD units as to lack of reliability!

I have had 3 different dwell meters at the same time, and all 3 read a different reading! That includes my Sun Dist. Machine which was the farthest "off"! So like stated above, check the gap with a feeler gauge on a new set of points to determine the right "setting" to dwell reading. Don't just take a dwell reading as gospel, until you know you can trust the meter.

And as stated above, always reset ignition timing after changing the dwell!

Plasticman

 

The engine would not run well, if at all with a dwell of 40 degrees, as they wouild be almost closed. The lower the number, the wider the gap

I agree with the point recommendations. I am running Accel.

I set mine at 29 degrees, as they usually "seat in" very quickly, and go to 30.

Always lube points when installing, both new and used, but lube sparingly. Too much will get on the contacts, and mess things up.

I apply lube sparingly to the cam, and spread it evenly all the way around. Do not leave any globs or excess.

A gap gauge should only be used with new points, or used points that have been filed flat.

 

I have that exact meter and now you have me wondering how accurate it is . Are you sure your reading the 8 cylinder scale? 40 on the 6 cylinder scale, is 30 for a 8 cylinder. Very easy to read the scale wrong on that meter.

 

HOLY COWS! you guys are all right on (who woulda thunk about dwell in this day and age of electronics). as a mechanic in the 60s-70s i did tune ups every day. on chevys, VETTES and also on fords and MOPARS. cars back then could only get about 3000 miles before needing a tune up (points, condensor, cap, rotor and spark plug replacement) AND checking the plug wires.
we used to eyeball the point gap and check on a sun scope after the tune up (it was fun, i got pretty good).
MOPARS and fords were a pain, because if the dwell was off, you had to pull the cap and rotor off and adjust dwell with a screwdriver between the points plate and the dist plate.

GM and vettes had the best design, you would just open the little window in the cap and adjust the point dwell with a 1/8 allen with the engine idleing and watch the dwell reading on the sun scope.

i always set dwell at 28 degrees in single points (because the nylon piece that rubs on the dist. shaft cam as it wears will bring the dwell closer to 32 degrees. (the specs were 28-32 dwell)
as the degrees dwell increases, the timing retards.

dual points were a different matter. dual point dists. have 2 sets of of points that are slightly offset on the point plate. i would set each set of points at 28 degrees, giving a combined dwell of 34-36 degrees dwell and let them wear. while delco made a dual window cap to adjust the dual points. they were obsolete by the 70s, so we would just put a little piece of match book cover between the points under the window and set the other points at 28 degrees. then use the 1/8 allen to adjust the second set of points to 34 degrees. then set the timing.

as tom says, now i just forget all old skool noncince and run pertronix. but it is fun to remember the old days...

 

Must have been something in the air back then?

 

I found a co-worker who's got a couple of old cars and YES......., has a dwell meter. He's going to bring it to work so I can borrow and compare the reading with my new dwell meter. He's an old timer so who knows when and/or if he'll even remember to bring to work. I'll give him a couple of chances then I'll have to call him at home one evening to "go put in in your car now while we're talking about it..... the dwell meter......, go put it in the car........., NO...., not the timing light, I have one of those..... THE DWELL METER !!! Remember, I'm going to borrow it from you"

 

What happened to turning the allen wrench clockwise till the engine died then turning the allen wrench counterclock wise 1/2 turn and starting? Or was it the other way around? I can't remember!

 

I've installed a LOT of point sets over the years, and never heard that one.

The points installations I remember best (or worst) were the Ford Y-blocks (272, 292, 312 engines) with the distributor mounted way in the rear, and NO allen wrench adjustment screw. Just a screwdriver slot......lots of trial and error....since tightening the hold down screws always affected the gap/dwell by a few thousands/degrees. And if you weren't careful, you could drop/lose those tiny mounting screws.

Those were the days. Especially in the summer on a hot/warm engine.

Larry

 

Yep, that was the ballpark setting to get you going (which ever way it was, I've forgotten too).

 

we used a old pack of matches. the paper cover. jim

 

On our old Corvettes with the 891 dual point dist you have to pull the cap and set them like you would a Mopar or Ford. No allen keys for us.

Bob

 

The nice things about the Fords, though, especially the SB 289, was the fact that you could use the solenoid mounted on the firewall as a bridge to crank the engine over while you were doing the point setting. Ford had the right idea on the distributor--mounted up front and independent of the intake manifold. That was a good idea.

 

The Ford 289 engine series (221, 260, 289, 302) was a very nice setup. And they ran well too. The fender mounted solenoid was a BIG help for just about any kind of engine work.

Larry