Timing
Posted: Fri May 04, 2018 1:21 am
Curious what timing folks with aftermarket heads are running. I knew the more efficient the chamber design, the less total timing needed, but I ran across a pretty reputable site that had done a bunch of dyno testing of different SBF heads. The optimal timing for the Edelbrock heads I’ve got was 28 WOT and IIRC 41 cruising.
That works out for me since the distributor I’m using hasn’t been made for awhile & when I bought it the advance springs were included but not the stop bushings. I ordered MSD and Pro Products kits & while the bushing ID is right the OD has been a guessing game.
Only two will really work...using 16-degrees initial I’ve got a choice of 24, 29, or 39 total (the last is with no bushing). Given what I’d read, I went with the one they have 29. There was a noticeable difference from 24 (kinda expected that) so I called it good after getting the right spring combo to have all the advance in by ~2600rpm.
Edelbrock recommends 36 total for these heads though. If I calculated right compression is 10.7:1 so even with 93 octane and a decent amount of cam overlap, I don’t really want to flog it with too much timing. I guess I’m stuck anyway since I don’t have an option between 29 & 39 right now.
I still need to adjust the vacuum advance for part throttle/cruise but the heap runs pretty good so far so I guess I’m just curious!
That works out for me since the distributor I’m using hasn’t been made for awhile & when I bought it the advance springs were included but not the stop bushings. I ordered MSD and Pro Products kits & while the bushing ID is right the OD has been a guessing game.
Only two will really work...using 16-degrees initial I’ve got a choice of 24, 29, or 39 total (the last is with no bushing). Given what I’d read, I went with the one they have 29. There was a noticeable difference from 24 (kinda expected that) so I called it good after getting the right spring combo to have all the advance in by ~2600rpm.
Edelbrock recommends 36 total for these heads though. If I calculated right compression is 10.7:1 so even with 93 octane and a decent amount of cam overlap, I don’t really want to flog it with too much timing. I guess I’m stuck anyway since I don’t have an option between 29 & 39 right now.
I still need to adjust the vacuum advance for part throttle/cruise but the heap runs pretty good so far so I guess I’m just curious!