Hey all, I've got a real caper here with my '68 Merc 650 that I've been trying to tune up and diagnose misfires on for some time now. Haven't posted a lot but I love this site for all of the info it's granted over the years. Hopefully there's someone who help solve this caper!
Symptoms are basically that she's running rough, smoky, and leaking excessive (much more than previous seasons) fuel mixture out the water/exhaust, especially noticeable at idle. Other symptoms too, like shutting off at random, hard to start...
So far I've rebuilt the water pump, fuel pump and carbs, I've tuned the two carbs to the best of my ability, changed spark wires and plugs, pressure tested the LU gearbox, tested the rectifier and charging system, and compression is good (118-128). Now I've focused my attention entirely on the ignition system and found something peculiar:
When I attach the induction coil of a timing light to the 1st cylinder wire, I see it firing at 8* BTDC at idle. Strange thing is, when I attach the coil to the 2nd, 3rd and 4th cylinder wires, instead of seeing the light ONLY match to the marks of the specific cylinder just shy of their TDC alignment marks around the flywheel, the light aligns with the ALL of the TDC marks for Cylinder #1 firing again at 8* BTDC.
In other words, are the plugs really all firing at the same time as the 1st cylinder due to some issue in the cap, etc?
I don't know much about these pointless CD ignition systems from the late 60s, so I can use some clarity here. What it leads me to believe is that, if my timing light skills are worthy, there is a short somewhere in the distributor or switch box or something to that effect that is causing all cylinders to fire with the first cylinder, instead of 1 - 3 - 2 - 4.
Is this possible? I've only worked on automotive engines before this and it's been a long time since I've needed to use a timing light.
Thanks all in advance!
Symptoms are basically that she's running rough, smoky, and leaking excessive (much more than previous seasons) fuel mixture out the water/exhaust, especially noticeable at idle. Other symptoms too, like shutting off at random, hard to start...
So far I've rebuilt the water pump, fuel pump and carbs, I've tuned the two carbs to the best of my ability, changed spark wires and plugs, pressure tested the LU gearbox, tested the rectifier and charging system, and compression is good (118-128). Now I've focused my attention entirely on the ignition system and found something peculiar:
When I attach the induction coil of a timing light to the 1st cylinder wire, I see it firing at 8* BTDC at idle. Strange thing is, when I attach the coil to the 2nd, 3rd and 4th cylinder wires, instead of seeing the light ONLY match to the marks of the specific cylinder just shy of their TDC alignment marks around the flywheel, the light aligns with the ALL of the TDC marks for Cylinder #1 firing again at 8* BTDC.
In other words, are the plugs really all firing at the same time as the 1st cylinder due to some issue in the cap, etc?
I don't know much about these pointless CD ignition systems from the late 60s, so I can use some clarity here. What it leads me to believe is that, if my timing light skills are worthy, there is a short somewhere in the distributor or switch box or something to that effect that is causing all cylinders to fire with the first cylinder, instead of 1 - 3 - 2 - 4.
Is this possible? I've only worked on automotive engines before this and it's been a long time since I've needed to use a timing light.
Thanks all in advance!
