Quick dwell setting question
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
Quick dwell setting question
Hi guys,
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Hi guys,
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
How do I set the gap at .018" at the cam apex...I'm not sure what that means?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
You bump the engine to get the cam follower of the points to get max gap, or the apex of the dizzy cam lobe.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Hi guys,
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
I have a 1970 350/350. Trying to get the timing and dwell set properly. I have a digital volt meter that has dwell meter setting...when I have tried using that, the reading bounces all over the place.
I just got a friend's old school dial/meter and connected it (negative to ground and positive to the negative lead of the coil)...and it is reading ~8 degrees! I believe this should be set at 30 degrees. I'm not sure if I should trust this meter either? Is it possible for the car to run with a dwell at 8 degrees? Or is this meter not right either?
The car tends to diesel a bit after shutting it off, and if this dwell is that far off, and then the timing is far off as well, that could explain a lot!
Although a dwell meter is more accurate a .019" feeler gauge is all you need because the dwell time (coil saturation time) isn't real important.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Using a feeler gauge on used points introduces inaccuracy due to the pitting caused by metal transfer. They will be too open.
Safety Car
Joined: Dec 2012
Posts: 3,815
Likes: 1,726
From: Summerville SC
Here's my $.02 from another old geezer that used to know what points are…Turn the engine over until the apex or high point on the dist lobe is opposite the points. Use a feeler gauge to set it at about 19 ( a matchbook cover will also work enough to get it started, but then a feeler gauge will probably be easier to find nowadays than a match book), start the car then use an allen wrench ( or there are even special tools that have a spring in the shaft to enable you to FINE TUNE the dwell with the engine running. Get it to spec, then adjust the timing. And as said above, the most important thing is to plug the vacuum.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
Something just occurred to me....I know I need to plug the vacuum to set the timing, but do I need to plug it to set the dwell? Could that be why it read so low as I did not have the vacuum plugged when I did it?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Dwell meters usually have a 4 cylinder scale, a 6 cylinder scale, and an 8 cylinder scale and if its set to the wrong scale you'll get a wrong reading. The specs call for a dwell angle of 28 to 32 degrees so you have some leeway. With the Pertronix point eliminators being readily available and inexpensive I can't understand why people still run points. The constant side pressure of points causes upper bushing wear but the Pertronix doesn't which makes the Pertronix a nice upgrade.
Burning Brakes
Joined: Sep 2001
Posts: 1,193
Likes: 194
From: East Coast
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Vacuum has zero effect on dwell. None, nada, zip, zilch. It DOES have an effect on timing.
If you use a feeler gauge to set point gap, wash it down completely with alcohol. A trace of oil on the feeler gauge blade will very effectively insulate the contact points. And without contact they won't work.
If you use a feeler gauge to set point gap, wash it down completely with alcohol. A trace of oil on the feeler gauge blade will very effectively insulate the contact points. And without contact they won't work.
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
Vacuum has zero effect on dwell. None, nada, zip, zilch. It DOES have an effect on timing.
If you use a feeler gauge to set point gap, wash it down completely with alcohol. A trace of oil on the feeler gauge blade will very effectively insulate the contact points. And without contact they won't work.
If you use a feeler gauge to set point gap, wash it down completely with alcohol. A trace of oil on the feeler gauge blade will very effectively insulate the contact points. And without contact they won't work.
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
The feeler gauge will get you close....assuming there isn't a giant nub/pit on the contacts as Big2Bird mentions. If it's that bad then it's time for new points anyway.
The other old school way is to have it running...turn the adjuster in until it starts to falter/die. Back out a half turn. Still need to ck with an accurate dwell meter.
Good points will last a long time. Stay away from the cheapie stuff.
JIM
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
I went and purchased and installed a new points/condenser set. I still can't get my digital voltmeter/dwell meter to read anything that makes sense...it jumps all over the place, even as high as 1000. When I connect the old school dial dwell meter, I can't get it above 10 degrees. How many turns of the screw would you expect it to take to get it from 10 to 30? Is it 1 full turn? more? Would you expect that I would have to turn it clockwise or counter clockwise to get it to increase from 10 degrees?
Could my coil be bad? Or if it was bad would the car not start/run at all?
Could my coil be bad? Or if it was bad would the car not start/run at all?
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Your dwell meter sounds a little flaky.. The colored lead from it (yellow or red usually) goes to the distributor side of the coil, and the other lead to a good ground.
Most GM points come from the store close enough to get the engine started for the final adjustment. At least the ones used since they invented the window type distributor cap
Most GM points come from the store close enough to get the engine started for the final adjustment. At least the ones used since they invented the window type distributor cap
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Your dwell meter sounds a little flaky.. The colored lead from it (yellow or red usually) goes to the distributor side of the coil, and the other lead to a good ground.
Most GM points come from the store close enough to get the engine started for the final adjustment. At least the ones used since they invented the window type distributor cap
Most GM points come from the store close enough to get the engine started for the final adjustment. At least the ones used since they invented the window type distributor cap
Try another meter. Actron has one for $20.
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 878
Likes: 60
From: Minneapolis, MN USA
Thanks guys - I agree that my electronic meter is flakey. But what about the old school dial type? Is that wrong too? Do I have two bad meters?
Gets back to the basic question - do you think the car should even run with a dwell setting of ~8-9 degrees and a timing of ~8 degrees BTDC?
I tried it again, if I turn it CCW, it would reduce the dwell a bit, and then nearly die...that was after maybe 1/2 turn? If I turn it CW about 1/2 turn, it might come up to 9-10 degrees dwell, but then if I go further it again starts to die out.
Gets back to the basic question - do you think the car should even run with a dwell setting of ~8-9 degrees and a timing of ~8 degrees BTDC?
I tried it again, if I turn it CCW, it would reduce the dwell a bit, and then nearly die...that was after maybe 1/2 turn? If I turn it CW about 1/2 turn, it might come up to 9-10 degrees dwell, but then if I go further it again starts to die out.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Look at 427Hotrod's post above- Old school way to set dwell-
And both of your meters are funny. Batteries in them? Some do some don't.
IF it's running, the dwell HAS to be close- and 8* BTDC is also close.
And both of your meters are funny. Batteries in them? Some do some don't.
IF it's running, the dwell HAS to be close- and 8* BTDC is also close.