Thank you for the definitions.
The smallest bushing MSD makes for their billet series is 18deg and it doesn't have vacuum and my engine won't idle at 10deg @ 1000rpm with my 270deg cam - so that combo won't work.
For now I'll stick to 18/39deg @ 1000rpm & 15inHG till I receive the air/fuel ratio lambda gague I just ordered
Search found 3 matches
- 2021 Sep 12, 23:28
- Forum: Speed Shop & Engine Talk
- Topic: 351W / 408 Timing
- Replies: 5
- Views: 2574
- 2021 Sep 12, 22:14
- Forum: Speed Shop & Engine Talk
- Topic: 351W / 408 Timing
- Replies: 5
- Views: 2574
Re: 351W / 408 Timing
I don't believe I'm slow - having been working on cars since I was 15 some 43 years ago - but - i don not understand what you mean by "ignition timing".
I understand mechanical timing set by the position of the distributor, I understand centrifugal timing set by the springs and bushing in the distributor and I understand vacuum timing advancing the distributor according to vacuum in the manifold (connected to the carburetor spark advance port).
What do you mean by "ignition timing"?
If my mechanical + centrifugal (no vacuum on my MSD distributor) at 18deg initial (at 1000rpm idle) and get to 39deg by 2800 rpm (21deg bushing) is this close to what your testing has recommended?
I will say this weekend in experimenting, she wanted a bit more mechanical advance at idle - liked 20deg and vacuum was close to maxing out at 15-16inHg - but that would have required me to change the bushing which I wasn't ready to do.
Thank you for your response and assistance.
Side note - good to hear that RHS heads are, in your experience, the most efficient heads ever built for a SBF. BUT if RHS heads are "efficient" giving an even and complete burn - then they would require LESS advance in order to compete the burn 10deg ATDC (or whatever the best ATDC position might be) - isn't this correct? Then why 39deg BDTC?
I understand mechanical timing set by the position of the distributor, I understand centrifugal timing set by the springs and bushing in the distributor and I understand vacuum timing advancing the distributor according to vacuum in the manifold (connected to the carburetor spark advance port).
What do you mean by "ignition timing"?
If my mechanical + centrifugal (no vacuum on my MSD distributor) at 18deg initial (at 1000rpm idle) and get to 39deg by 2800 rpm (21deg bushing) is this close to what your testing has recommended?
I will say this weekend in experimenting, she wanted a bit more mechanical advance at idle - liked 20deg and vacuum was close to maxing out at 15-16inHg - but that would have required me to change the bushing which I wasn't ready to do.
Thank you for your response and assistance.
Side note - good to hear that RHS heads are, in your experience, the most efficient heads ever built for a SBF. BUT if RHS heads are "efficient" giving an even and complete burn - then they would require LESS advance in order to compete the burn 10deg ATDC (or whatever the best ATDC position might be) - isn't this correct? Then why 39deg BDTC?
- 2021 Sep 11, 16:45
- Forum: Speed Shop & Engine Talk
- Topic: 351W / 408 Timing
- Replies: 5
- Views: 2574
351W / 408 Timing
Car / Engine profile: 1970 Ford Mustang - 351W stroked to 408 by Carolina Machine Engines (CMEngines dot com) - RHS heads (64cc chamber / 180cc intake runner) - Edlebrock RPM Performer intake - Quick Fuel SS-VS-780 carb - Cam 270deg duration / 230 @ 0.05 lift / 110 lobe - MSD Pro Billet & 6AL Plus ignition & Blaster II coil - BBK headers with dual exhaust and X pipe
She stand dyno'd 440hp/470ft-lbs around 4700rpm (need to go break out the dyno sheet to confirm)
Was reading a page on Ignition & Timing http://www.efidynotuning.com/saftot.htm that had a MBT reference page http://www.efidynotuning.com/mbt.htm posted in 2013 / last updated in 2018
Not sure what the last two number mean (N/A and Cruise)?
MAKE CID LITERS CONFIG CYLINDER HEAD MAKE/MODEL/SPEC Boosted N/A CRUISE
FORD 302 / 351w 5.0 / 5.8 SB v8 RHS NO 22 39
Does this mean 22deg initial advance and 39deg max advance?
I've been running 14/35 (blue 21deg bushing with 1 silver & 1 blue spring = centrifugal starts at 1300rpm and maxes at 2800rpm)
I'll say that at idle - 900rpm - vacuum goes up as I increase advance all the way up to 20deg - which is scary given the cam would let it go to 45deg total advance with the cam I have in there.
I've read a not of sites that say SBFs can only handle up to 35deg advance - although not sure what that even means - "handle" to me means the bottom end max torque and there are a lot of 700hp/600+torque SBF out there.
Please clarify the 22 & 39 numbers and any advice would be greatly appreciated.
She stand dyno'd 440hp/470ft-lbs around 4700rpm (need to go break out the dyno sheet to confirm)
Was reading a page on Ignition & Timing http://www.efidynotuning.com/saftot.htm that had a MBT reference page http://www.efidynotuning.com/mbt.htm posted in 2013 / last updated in 2018
Not sure what the last two number mean (N/A and Cruise)?
MAKE CID LITERS CONFIG CYLINDER HEAD MAKE/MODEL/SPEC Boosted N/A CRUISE
FORD 302 / 351w 5.0 / 5.8 SB v8 RHS NO 22 39
Does this mean 22deg initial advance and 39deg max advance?
I've been running 14/35 (blue 21deg bushing with 1 silver & 1 blue spring = centrifugal starts at 1300rpm and maxes at 2800rpm)
I'll say that at idle - 900rpm - vacuum goes up as I increase advance all the way up to 20deg - which is scary given the cam would let it go to 45deg total advance with the cam I have in there.
I've read a not of sites that say SBFs can only handle up to 35deg advance - although not sure what that even means - "handle" to me means the bottom end max torque and there are a lot of 700hp/600+torque SBF out there.
Please clarify the 22 & 39 numbers and any advice would be greatly appreciated.