1986 Eating Dizzy Cap & rotors
11-17-2018, 12:51 PM
#1
Melting Slicks
Thread Starter
1986 Eating Dizzy Cap & rotors
The fellow at the auto parts store mentioned to check the timing because the arcing on the contacts of the cap are all on the ends of the different positions. Just changed this ~ 3 months ago and it failed again. He also said that the timing chain may be stretched and the timing I think I have is wrong. Something about the bearing where the rotor go could be bad as well. Any thoughts or ideas?
Thanks,
Robert
Thanks,
Robert
11-17-2018, 03:09 PM
#2
Melting Slicks
Thread Starter
So I should also add that running the engine with the bad cap too long cause me to foul a whole set of spark plugs that were only ~1000 miles on them. I'll never buy NGK again even though it probably was my fault for not fixing it when it first developed a stumble. Installed a set of Autolite platinums and just took it our for a spirited long drive and it runs and sounds great.
What would be causing the cap/rotors to go bad?
What would be causing the cap/rotors to go bad?
11-17-2018, 03:39 PM
#3
Is this an original 1103680? Miles? I'd think very likely housing/main-shaft issues.
11-17-2018, 06:33 PM
#4
Melting Slicks
Thread Starter
If this is a "rebuilt" distributor it may be possible that components were mismatched and that the pick-up and reluctor firing points are no longer in sync with the rotor tip. I'v'e seen this on two "Cardone" rebuilts, although not the identical distributor to the one in an 86.
The rotor tip is almost never "aligned" with the terminals in the cap. The normal range of timing is 38-ish degrees of crankshaft, which is 19 degrees of distributor. So the rotor-to-cap relationship varies by about 20 degrees. 10 degrees each direction. If your engine is only burning the edges of the terminals and rotors, either there is a parts problem (indexes in the wrong place), installation problem or the timing is incorrect.
Have you verified that the balancer hub has not spun, and that the marks are correct?
Have you verified that the timing advances properly and fully with a timing light? If the EST connector is broken, there will be no timing advance. Engine will run like poo, and the plugs will foul.
Are you disconnecting the EST connector to set the base timing?
A suggestion: Set the crankshaft timing marks on 0 degrees TDC. Don't worry about #1 or #6, either TDC will work. Remove the distributor cap and look at the rotor tip. The rotor should be about 8-ish degrees before the center of the cap's terminal. IF it is way off, check the balancer marks. Remove #1 or #6 spark plug, and insert a screwdriver to check that the piston is at the top of the bore. If it is not, the marks are wrong.
If the timing is correct, the indexing of the cap and rotor is correct, and the ECM is properly advancing the timing, the cap terminals wear evenly. If any of these are wrong, they won't.
The rotor tip is almost never "aligned" with the terminals in the cap. The normal range of timing is 38-ish degrees of crankshaft, which is 19 degrees of distributor. So the rotor-to-cap relationship varies by about 20 degrees. 10 degrees each direction. If your engine is only burning the edges of the terminals and rotors, either there is a parts problem (indexes in the wrong place), installation problem or the timing is incorrect.
Have you verified that the balancer hub has not spun, and that the marks are correct?
Have you verified that the timing advances properly and fully with a timing light? If the EST connector is broken, there will be no timing advance. Engine will run like poo, and the plugs will foul.
Are you disconnecting the EST connector to set the base timing?
A suggestion: Set the crankshaft timing marks on 0 degrees TDC. Don't worry about #1 or #6, either TDC will work. Remove the distributor cap and look at the rotor tip. The rotor should be about 8-ish degrees before the center of the cap's terminal. IF it is way off, check the balancer marks. Remove #1 or #6 spark plug, and insert a screwdriver to check that the piston is at the top of the bore. If it is not, the marks are wrong.
If the timing is correct, the indexing of the cap and rotor is correct, and the ECM is properly advancing the timing, the cap terminals wear evenly. If any of these are wrong, they won't.
Thanks,
Robert
11-17-2018, 08:03 PM
#5
Safety Car
One thing that you did not mention is what type of ignition system are you using? I like MSD systems and on my Pickup the small diameter distributor cap and rotor would barely last a year. I learned that the air inside the distributor will get charged up (Ionized) and Carbon Tracking starts to occur. Under U/V you could see the tracks if you have them.
If your Corvette is using the Box stock ignition system then you have little risk of tracking. Hotter than normal (aftermarket) ignition coils can promote the carbon tracking. I am a big believer in Hot Ignition systems so I am sure I am burning all there is in the Combustion Chamber.
I don't have too much trouble with the large diameter Distributor caps getting carbon tracking.
I recently bought a MSD Distributor cap/Rotor combo for my C3's 427's MSD Distributor and it destroyed itself while cranking. I had it on the right way and it was all put together properly but there one spot inside the Distributor cap where the rotor hit and gouged out pieces of the New Distributor Cap. I called MSD up and they sent me a new one and apologized for my difficulty. Still having problems with their production staff in China getting the parts right. I looked at the old cap and the new cap and there were some serious changes made. They use some metal like aluminum for their contacts instead of the old standard of Brass. I might start cleaning up my old Distributor caps as they were batter made.
I hope that you find the issue affecting your Corvette so you can solve it easily. I like your Avatar, I fly old piston powered aircraft. In your Avatar is that aircraft the B-58 aka "Hustler" that the AF did not appreciate enough? I don't know if I have ever seen the B-58 in service but they sure are a beautiful aircraft.
If your Corvette is using the Box stock ignition system then you have little risk of tracking. Hotter than normal (aftermarket) ignition coils can promote the carbon tracking. I am a big believer in Hot Ignition systems so I am sure I am burning all there is in the Combustion Chamber.
I don't have too much trouble with the large diameter Distributor caps getting carbon tracking.
I recently bought a MSD Distributor cap/Rotor combo for my C3's 427's MSD Distributor and it destroyed itself while cranking. I had it on the right way and it was all put together properly but there one spot inside the Distributor cap where the rotor hit and gouged out pieces of the New Distributor Cap. I called MSD up and they sent me a new one and apologized for my difficulty. Still having problems with their production staff in China getting the parts right. I looked at the old cap and the new cap and there were some serious changes made. They use some metal like aluminum for their contacts instead of the old standard of Brass. I might start cleaning up my old Distributor caps as they were batter made.
I hope that you find the issue affecting your Corvette so you can solve it easily. I like your Avatar, I fly old piston powered aircraft. In your Avatar is that aircraft the B-58 aka "Hustler" that the AF did not appreciate enough? I don't know if I have ever seen the B-58 in service but they sure are a beautiful aircraft.
11-17-2018, 09:43 PM
#6
Melting Slicks
Thread Starter
Box stock distributor 1986. The plane in the avatar is an RA5C vigilante. It was a recon/spy plane for the Navy. It looks like the Hustler with the wing tanks on though.
PS: The AF didn't like the Vigilante either as it was designed as a strategic thermonuclear strike bomber. It was later redesigned as a reconnaissance/electronic intelligence gathering platform and the USN bought a lot of them.
PS: The AF didn't like the Vigilante either as it was designed as a strategic thermonuclear strike bomber. It was later redesigned as a reconnaissance/electronic intelligence gathering platform and the USN bought a lot of them.
Last edited by 3D-Aircrew; 11-18-2018 at 10:47 AM. Reason: added vigilante video
11-27-2018, 08:57 PM
#9
Melting Slicks
Bend up the center metal strip on the rotor to make sure it contacts the button? If that don't work cut a hole in the side on the old cap & rotor to check the distance from the rotor tip to the cap terminals. I don't rem the spec but it can be googled.
What is your plug gap?
What is your plug gap?