Pointless ignition timing

[ZUL8TR]

I have a stock 1973 Merc 25ss with cd ignition. Is there a way to set the timing without a timing light and creating BTDC degree marks on the flywheel rim and a reference pointer at TDC? Would like to use a procedure of the piston location at the proper position before TDC rather than the engine running with the timing light. What do the Y302 guys do? I have a buzzer box and dial indicater that I use for the Y80 and realize the buzzer box is only for breaker point ignitions. Need to get this engine on the and play.

Thanks

[pro350hydro]

Best way I like to do it is set it with a dial indicator, but then I VERIFY it with a timing light. Why are you so opposed to using a timing light? Timing lights double check your work. Plus you can learn from them...

[ZUL8TR]

pointless ign timing

Best way I like to do it is set it with a dial indicator, but then I VERIFY it with a timing light. Why are you so opposed to using a timing light? Timing lights double check your work. Plus you can learn from them...

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Not opposed to the light and I know how to do that but it relies on the accuracy of the degree marks that I have placed on the rim of the flywheel and the accuracy of the timing index pointer. I have marked the flywheel rim each degree from 36 to 42 degrees using arc distance from the factory TDC tic mark on the flywheel rim and have located a timing the index pointer using a dial indicator for TDC.

I wanted to know how to use the dial indicator and piston position method for the pointless CD ignition mag because it would be another means to set the timing and I think it would be more accurate than degree marks I have made.

I have a Yamato 20ssh Y80 with point type ignition and know how to do the timing with a buzzer box and the dial indicator to get both sets of points to fire 180 degrees apart at the desired piston position.

Thanks

[ricochet112]

I have never seen any way to do this on a breakerless ignition without using a timing light, I don't think it's possible.

[ZUL8TR]

timing with breakerless ignition

I have never seen any way to do this on a breakerless ignition without using a timing light, I don't think it's possible.

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I see you have what looks like in your signatore a Merc 25xs with cd ignition so you would know the procedures for that. But is that the only way the Yamato 302's do it? There is a statement in the 302 manual that indicates the use of a dial indicator and that engine is breakerless. That's what got me questioning the procedure without a timing light for my 25ss cd ignition.

Thanks

[ricochet112]

On my 25XS I extended the adjusting rod to advance the timing as far as it would go, never have checked it in 24 years.

[Team B&H]

This is possible on the 302 because someone previously has put a mark on the cranking plate and a mark on the magneto housing (stator). These marks line up when the magneto fires. Of course all 302 owners don't believe this and verify the marks, don't they? Anyway, then it is a simple matter to set the crank where you want it using a dial indicator/Piston location and then move the mag housing so the marks line up again.

But that won't work on the 25SS because the Yamato has the mag assembly external to the flywheel and the 25SS has the stator and trigger inside the flywheel. If you are so adverse to using a timing light which was also necessary to set up the 302 initially, why not just go out and test the motor. Try it with timing low and keep advancing it until it doesn't run any better. WOW!!! That would probably get the timing right where the motor likes it and not just some arbitrary place where you set it with your dial indicator. Sounds like a speed secret - set the timing where the motor runs best.

[Steve Warnock]

Way to Go Ol'Sammy

A little old school guys. Try it!

Warbs

[ZUL8TR]

25ss Pointless timing

Thanks for the responses guys testing is not foreign to me and I will do just that - run the and keep advancing and check acceleration, top speed, tach and spark plug condition and color.

[johnsonm50]

Learning as we go.. as I understand the points breaking time can be read with as little motion as turning the time base to open one then the other [shoot me now if Im wrong] So could some cdi adapt be made to read current at the plug electrodes at similar base turning speed or does the trigger gap require more speed to render readable current? Or maybe I should have read that into it??

[spud62w]

I remember the first time Team B&H used a timing light on the 25 at Dayton. I don't think I laughed my butt off that hard in a long time. Ask him how it turned out for him.

[Steve Warnock]

Hmmmm!

Standing in the water and a short maybe!!!!!??????

Warbs

[Team B&H]

I don't remember setting the timing on a 25 motor at Dayton but do remember trying to dry one out at Rhinelander back in the old days before kill switches were needed.

[trident]

Timing light

Ummm, lesson many of us learned the hard way... electrifying experience!

Always use an inductive pick-up timing light. Plastic housing preferred.

The 'hard wire' type that clips onto the plug wire with an adapter will knock you right on your keester if you are standing in the water holding it. I had a nice Sears Penske light with a metal housing. Hoo boy! Got a Sun battery powered inductive light, now.

Merc 25SS, 25XS, 402X, 44XS, etc. have very strong ignition systems...

Jerry

[ZUL8TR]

timing light

Ummm, lesson many of us learned the hard way... electrifying experience!

Always use an inductive pick-up timing light. Plastic housing preferred.

The 'hard wire' type that clips onto the plug wire with an adapter will knock you right on your keester if you are standing in the water holding it. I had a nice Sears Penske light with a metal housing. Hoo boy! Got a Sun battery powered inductive light, now.

Merc 25SS, 25XS, 402X, 44XS, etc. have very strong ignition systems...

Jerry

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Thanks on the shock thought
I have a Sears timing light with inductive pickup that requires an external 12v battery to run it. It is for Autos but works for any engine as long as you can get at the plug wire and have 12v