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Ignition Timing Issue

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Djk1216

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My 1987 Crusader 454 engines were working great BEFORE I tried to tune them up. I only replaced the plugs, caps and rotors ( have prestolite electronic ignition) and when I checked the timing, the light was finding the timing mark about 2 " away from the 10 deg Btdc mark. I adjusted the timing to be 10 deg btdc, and ran the boat. Smooth as silk up to about 2400 rpm and then it started to choke out as if the timing wasn't advancing.

Question 1: How could I have an initial reading from the timing light be so far off when the boat ran well previously ?

All wires are in the correct spot in the dist. cap. I am using wire # 1, 750 rpm. Plugs are all set to the correct gap. And when I replaced the old cap and rotor, I saw no change. I even tried using a different timing light with no change.

Question 2: If I can't resolve the first question how do I get my engines back to the correct timing ( where they were before) ? I have no marks to reference against. I have been doing this work onthese engines for 20 years and have never experienced this before. And I'm seeing the same effect on both engines

THANKS FOR ANY HELP !
 
Wow! That's a toughie.

All I can think of is you have ignition wires crossed someplace and/ or you used the wrong wire with the timing ight--it happens. Suggest you take a break, then dive back in there and triple check everything.

Jeff
 
Your #1 plug is the one opposite the fuel pump nearest the alternator, correct? Same for LH/RH engine. Same timing shift on both engines? You are using the line on the harmonic balancer or using the dimple on the flywheel?
 
Thanks for the replies. The #1 is near the alternator and marked on the top of the block. I'm using the timing mark on the flywheel also where the indicator is that marks the degrees before and after TDC.

I double checked the plug wiring into the distributor, and that No wires were crossed and that I had the correct plug wire. I also checked all the plug wires just to see if anything else worked.

Its a mystery because I've been doing it for 20 years on these engines and never had an issue before.

The boat ran amazing before and it makes no sense why timing reading would be so far off. And now that it's at 10 deg btdc, it won't ru up to higher rpm. One engine I might be able to explain but both are doing the exact same thing. Even with the old parts. Any other thoughts?
 
You should verify that cyl 1 is at TDC, using a stiff wire in the spark plug hole, checking both the flywheel mark and the balancer mark. It sure sounds like its running with retarded ignition now.
 
Have you tried the indicator at the front of the engine on the harmonic balancer? Does it match the 10 degrees btdc you are reading at the flywheel?
Make sure the rotor is pointing to number one at the distributor when number one cylinder is at top of compression stroke.
 
I'll check out your suggestions. Thanks.

But one more question, if the boat ran fine before is it possible that I did something to the distributor to offset the timing or timing advance just by changing the rotor and cap ? Replacing the old cap and rotor didn't change it back.
 
Your outer ring on the harmonic balancer may have slipped.
This would throw the TDC marking off.
If the flywheel has been marked accurately for #1 TDC, roll the crank around and align these markings.
Compare this to the markings of the harmonic balancer and timing tab.

You're on the right track, ya just need to find #1 TDC, and then go from there.
Once you get this in order, see your OEM specs, and check the progressive ignition advance up to the limit RPM.
This will show you the progressive advance up to the Total Advance limit RPM.

BASE is BASE all day long.... but TA is of more importance.
 
Ricardo, Thanks I'll check the outer ring on the harmonic balancer. But could this happen to both engines at the same time ?
 
I reviewed everyone's suggestions and realized that what I was calling the flywheel is actually the harmonic balancer - my bad -rookie mistake. It is the reading at the harmonic balancer that is off on both engines.
 
Good to have a true common reference point for making the measurement as well as describing the issue. I'd say it is highly UNLIKELY that both of your balancers has 'slipped'.

I'd make sure the advance function is still working in the distributor. All of the old prestolites I've worked with have the spring-weight system and they have short lifetimes relative to the rest of the engine. FWIW, 2" along the balancer is about 28 degrees of crankshaft rotation. You didn't state which 'side' (of the TDC mark) the timing mark was shifted. if it was 'advanced', based on the math, it is possible the distributor was frozen in a full advance state and you adjusting the timing 'back to spec' induced the rpm limiting issue.
 
Yes, I did take you to mean "flywheel"! Some are indexed for timing. In fact, it's not a bad idea to have indexed these during an engine build. There is no chance that these marks could change on us..... whereas a balancer may change if the outer ring was to slip!

The ONLY method for finding or locating true TDC, will be a PPS procedure. (PPS = positive piston stop)
It's a hassle to do, but it's the only method that will accurately locate true TDC.
The catch is..... we can't accurately time an engine without accurate TDC markings.

The only alternative would be to replace the harmonic balancers with new..... and hope to hell that they're accurate.

However, the PPS method will give you some peace of mind!

All you need is a PPS....
pic_installation.jpg


a good 360 degree wheel, and a temporary wire pointer.
images


Keep moving the pointer until the reading is equal in either crankshaft direction until the #1 piston gently reaches the PPS.
Shoot for approximately 30* in either direction (it may be 29*, 31* or 34*.... doesn't really matter).
Once equal, remove the PPS, rotate to ZERO...... there's your TDC.

.
 
A little more investigation and found that makomark had it pegged. The spings, counter weights in the distributor were stuck in the advanced position and when i set to 10 btdc I was retarding the advance significantly. I reset the timing to 26 deg btdc at high rpm, so I was back where I was before and the boat ran great. Thanks to all for your help. I learned a lot and hope I can return the favor to the group in the future. Now it's time to put in new distributors.
 
Djk1216 said:
  1. The spings, counter weights in the distributor were stuck in the advanced position and when i set to 10 btdc I was retarding the advance significantly.
  2. Now it's time to put in new distributors.
Click to expand...

You were effectively setting BASE to a system that had no progressive advance to offer.... but I understand what you mean! Good catch and good call on the new distributors! :cool:
 
glad you found the issue and have the solution in sight. I'd suggest the mallory as a replacement. on your vintage you want two standard rotation distributors - they will go into either side just fine.
 
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