Click on image for the lowdown. 
====
| | | Forums66 Topics128,023 Posts1,055,370 Members48,420 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Jun 2023 Posts: 102 'Bolter | | 'Bolter Joined: Jun 2023 Posts: 102 | Hey guys,
I have a 1961 235 engine running on 6 volt battery still with standard coil, points, distributor. My question is: what is the best dwell angle to be achieved for this system/engine?
I hooked it up to a dwell tachometer the other night and was getting right around 29 or 30. I have read some say these earlier engines on 6 volt should aim for closer to 40 for a better performance. Others say between 28 - 33 is good. What do you guys say? Right now the points are gapped at .016 to achieve 29/30 dwell. I realize reducing the gap is what would be required to get higher dwell.
Also, one guy said the spark plugs should be gapped at .40 even though most manuals I've read say .35. What do you guys say?
52 Chevy 3100
Jesus said to him, "I am the way, the truth, and the life. No one comes to the Father except through Me." -John 14:6
| | | | | Joined: May 2015 Posts: 10,997 Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums | | Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums Joined: May 2015 Posts: 10,997 | FWIW, the 47-51 Truck Service Manual says 0.018" point gap for readjusting old points and 0.022" for new points. There's no dwell spec.
Spark plug gap spec is 0.040" for 1948 trucks and 0.035" for 1949-1951 trucks.
Kevin 1951 Chevy 3100 work truckFollow this saga in Project JournalPhotos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together. | | | | | Joined: Oct 2021 Posts: 6,690 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,690 | Just set the points according to Spec. Anywhere in the specified range will be fine . There is no performance advantage to be gained by going full on OCD with a tune-up on these engines.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Jan 2014 Posts: 3,677 'Bolter | | 'Bolter Joined: Jan 2014 Posts: 3,677 | Good thread on the topic - https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1509755/1I’d trust Jerry’s advice here on the 6 volt dwell. FWIW, I prefer using the dwell meter over feeler gauge to set points. I run 12v system. Never considered the 6v ignition being different. Interesting. Trying to think my way through that….more dwell means more time for the coil to build up voltage and send a stronger spark? Needed more in the 6v setup because you’re beginning point is a lower voltage?
1951 3100
| | | | | Joined: Jan 2022 Posts: 2,436 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,436 | FWIW, the 47-51 Truck Service Manual says 0.018" point gap for readjusting old points and 0.022" for new points. There's no dwell spec. Also FWIW, 1951 GMC Maintenance Manual specifies 31-37 degree dwell with a .022" point opening. This is with a Delco 1112360 distributor that I think was also used on some Chevy trucks of that era.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
| | | | | Joined: Feb 2004 Posts: 29,746 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,746 | Never considered the 6v ignition being different. Interesting.
Trying to think my way through that….more dwell means more time for the coil to build up voltage and send a stronger spark? Needed more in the 6v setup because you’re beginning point is a lower voltage? The 66% dwell time gives a stronger magnetic field as the coil builds up to produce a hotter spark when the points break. Using Jon G's improved condenser would probably allow the 12V system to use the longer 6V dwell setting without a danger of point burning and/or metal transfer from one point contact to the other. If the high voltage induced in the primary windings as the points break has not fully dissipated before the points close again, an "arc weld" situation can happen that transfers molten metal from one contact to the other. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Dec 2017 Posts: 1,652 'Bolter | | 'Bolter Joined: Dec 2017 Posts: 1,652 | If the last four digits of your distributor's Delco number end in 2403, the dwell angle can be anywhere in the range of 28-35 degrees, according to the Sun Electric Company and AEA tune up charts.
Last edited by Dragsix; 09/18/2025 9:05 PM.
Mike
| | | | | Joined: Jun 2023 Posts: 102 'Bolter | | 'Bolter Joined: Jun 2023 Posts: 102 | Thanks guys. As always... you've been helpful.
52 Chevy 3100
Jesus said to him, "I am the way, the truth, and the life. No one comes to the Father except through Me." -John 14:6
| | |
|
|
