Daytona Sensor CD-1 ignition
07-23-2025 | 01:24 PM
#21
Registered
Joined: Aug 2013
Posts: 150
Likes: 5
Let's hope for something simple and not a Daytona issue.
Fuel filter clogged with water?
Distributors can have mechanical failures as well, throwing off timing.
I just had a customer's carbed 454 in a Chev truck come in, found the base HEI timing was 60° advanced. Not a typo. Had to use another timing light to confirm. That's with the vac adv unhooked. Used premium fuel, never any detonation. But I think it smoked the rings. The distributor was loose. Not my work...lol.
Fuel filter clogged with water?
Distributors can have mechanical failures as well, throwing off timing.
I just had a customer's carbed 454 in a Chev truck come in, found the base HEI timing was 60° advanced. Not a typo. Had to use another timing light to confirm. That's with the vac adv unhooked. Used premium fuel, never any detonation. But I think it smoked the rings. The distributor was loose. Not my work...lol.
what do you recommend as timing ? 35 at 3000 ?
07-23-2025 | 08:05 PM
#22
Registered
Joined: Aug 2019
Posts: 1,238
Likes: 418
From: BC
Timing is very much a specific situtational requirement.
Guided by rules, not always firm.
WOT: Unless you have fast burn chambers and high port swirl, you need at least 31-32° adv. Very rarely would you go over 36°
Load Load and High Vacuum: timing can be really high... 46° area. Lean A/F mixtures need more time to burn. High vacuum from minimal throttle opening, crrates a very low dynamic compression. The lower pressure slows the burn down. Needs more timing.
Mechanical distributors were never able to account for low load advance. Vaccum adv distributors were able to help out, and the engine becomes more efficient.
Typically, marine engines want to good timing under load, certainly under acceleration. Light planing cruise, there may be some room to increase timing, but the risk is higher.
Essentially, 34-36° adv timing timing is the ballpark area. SBC/BBC. Vortec chambers will generally want less.
If your compression is too high on a marine engine...and you've retarded the ingnition to account for it, (29-30° area), the peak cyl pressures are not at the optimal crank angle, and the fuel is burning more than you want as it's blown past the exh valve/port. This creates a hotter than normal exh valve, and adds detonation issues.
Guided by rules, not always firm.
WOT: Unless you have fast burn chambers and high port swirl, you need at least 31-32° adv. Very rarely would you go over 36°
Load Load and High Vacuum: timing can be really high... 46° area. Lean A/F mixtures need more time to burn. High vacuum from minimal throttle opening, crrates a very low dynamic compression. The lower pressure slows the burn down. Needs more timing.
Mechanical distributors were never able to account for low load advance. Vaccum adv distributors were able to help out, and the engine becomes more efficient.
Typically, marine engines want to good timing under load, certainly under acceleration. Light planing cruise, there may be some room to increase timing, but the risk is higher.
Essentially, 34-36° adv timing timing is the ballpark area. SBC/BBC. Vortec chambers will generally want less.
If your compression is too high on a marine engine...and you've retarded the ingnition to account for it, (29-30° area), the peak cyl pressures are not at the optimal crank angle, and the fuel is burning more than you want as it's blown past the exh valve/port. This creates a hotter than normal exh valve, and adds detonation issues.
