How much ignition advance for a flathead?
Thread Starter
|
Senior User
Joined: Aug 2004
Posts: 328
Likes: 0
How much ignition advance for a flathead?
How much advance do I dare go on my stock flathead? The repair manual talks about 24 deg. at WOT. I assume this includes mechanical plus vacuum. I know on SBCs you can go up to 36 deg. mechanical plus add around 15 deg. for the vacuum advance which adds up to around 50 deg. total advance. Just wondering if the old specs aren't outdated because of the lower octanes back then. Anybody just time by ear and advance it until it pings on acceleration then back it off a little? Thanks.
Post Fiend
Joined: Jun 2001
Posts: 7,493
Likes: 7
From: Erie, pa
JDM
Check out this site, these are THE Flathead experts.
http://www.btc-bci.com/~billben/flathead.htm
Check out this site, these are THE Flathead experts.
http://www.btc-bci.com/~billben/flathead.htm
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
Unless you've replaced the stock distributor, there is no mechanical advance. The Load-A-Matic distributors are only vacuum advance plus the static setting. In general, flatties don't like much advance, and run hot if you go overboard.
A lot of people set their timing by vacuum: set at idle, engine warm, at the least amount of advance that gives the highest amount of vacuum. Then take it out on the road and get into high gear, and about 1500 RPM. Accelerate with full throttle and see if it pings. If it does, back off a couple degrees, repeat until no more rattles.
You would think with octanes in the high 80's even for regular, and compression ratios in the 7:1 range (stock) they would be in fat city, but I've found the stock settings are even good at 5,300', where OHV engines like another 2 - 4 degrees. Go figure!
A lot of people set their timing by vacuum: set at idle, engine warm, at the least amount of advance that gives the highest amount of vacuum. Then take it out on the road and get into high gear, and about 1500 RPM. Accelerate with full throttle and see if it pings. If it does, back off a couple degrees, repeat until no more rattles.
You would think with octanes in the high 80's even for regular, and compression ratios in the 7:1 range (stock) they would be in fat city, but I've found the stock settings are even good at 5,300', where OHV engines like another 2 - 4 degrees. Go figure!
Thread
Thread Starter
Forum
Replies
Last Post
Argess
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
6
Jul 9, 2009 07:11 PM
DrFord
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
5
Jun 30, 2001 09:34 AM
