Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 05-02-2019, 10:14 AM   #1
sphanna
Senior Member
 
sphanna's Avatar
 
Join Date: Jun 2010
Location: Polk City, Iowa
Posts: 526
Default 21,23,28 degrees timing question

There was an excellent post by a well respected engine builder a while back that described the max timing for original and HC engines. 21* for 6;1, 23* for 5.5;1 and never above 28* for stock 4.2 head.

I very much would like to find this post. I. printed it so as to have this info but I have misplaced it. Can any one direct me to this post? My search was unsuccessful. Thank you..
__________________
Steve Hanna, Polk City, IA
sphanna is offline   Reply With Quote
Old 05-02-2019, 10:54 AM   #2
40 Deluxe
Senior Member
 
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,774
Default Re: 21,23,28 degrees timing question

Quote:
Originally Posted by sphanna View Post
There was an excellent post by a well respected engine builder a while back that described the max timing for original and HC engines. 21* for 6;1, 23* for 5.5;1 and never above 28* for stock 4.2 head.

I very much would like to find this post. I. printed it so as to have this info but I have misplaced it. Can any one direct me to this post? My search was unsuccessful. Thank you..
This leads to some questions:
1. Where do you set the spark lever to arrive at these settings? It would require fabricating a timing pointer and marking TDC on the pulley, then using a dial-back timing light, and finally marking the timing quadrant so you know where to set the lever.

2. What octane fuel was used to determine these settings? Different octane levels require different timing settings.

3. At what RPM would you go to these "max settings"? Idle? 1,000 RPM? 2,000?
I don't think you can use a 'one size fits all' timing number.
40 Deluxe is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 05-02-2019, 11:11 AM   #3
Jim Brierley
Senior Member
 
Join Date: Jun 2010
Location: Temecula, CA
Posts: 4,066
Default Re: 21,23,28 degrees timing question

I don't have the answer to either of your questions ... but ... generally speaking higher compression does need less spark advance. It also depends on combustion chamber shape and spark plug location. I would think the above stated degrees are a little on the retarded side, especially for stock heads???
Jim Brierley is offline   Reply With Quote
Old 05-02-2019, 11:52 AM   #4
sphanna
Senior Member
 
sphanna's Avatar
 
Join Date: Jun 2010
Location: Polk City, Iowa
Posts: 526
Default Re: 21,23,28 degrees timing question

Sponsored Links (Register now to hide all advertisements)
Quote:
Originally Posted by 40 Deluxe View Post
This leads to some questions:
1. Where do you set the spark lever to arrive at these settings? It would require fabricating a timing pointer and marking TDC on the pulley, then using a dial-back timing light, and finally marking the timing quadrant so you know where to set the lever.

2. What octane fuel was used to determine these settings? Different octane levels require different timing settings.

3. At what RPM would you go to these "max settings"? Idle? 1,000 RPM? 2,000?
I don't think you can use a 'one size fits all' timing number.
40 Deluxe.

re:Question 1-- I reset the retard enough at TDC so that the desired Max advance with leaver full down, my timing light indicates the max advance on the pulley.

#2. I use Non Alcohol 87 oct. However you do have a valid statement concerning octane vs timing.

#3. All max setting are for 2200 rpm or higher. lower rpm requires less advance..For starting I know where to set lever to attain the 0* All settings verified with timing light.

Alternate way : just set timing at 0* at TDC as usual. Then mark or note the position of the lever when arriving at desired advance.. Again verified by timing light.
__________________
Steve Hanna, Polk City, IA
sphanna is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 02:11 PM.