Trying to get the distributor cap off our 87 V12, I have everything out of the way, backed off the 3 screws, cap appears to be glued on. Do they normally stick to the gasket or do I just have to use more force? I don't want to break it.

 

Kind of normal for a car that has been ill maintained.

As long as the 3 screws are undone ALL the way, the gasket has glued it down.

A short blade screwdriver, and a LOT of common sense , will get it loose without cracking/breaking it.

When it rleases, STOP, gather the Grey Matter, and lift it STRAIGHT up. Much deviation from straight up can/will catch the rotor tip and stuff the rotor, oops.

 

I am back,

The ROTOR, and I know you have not asked, but.

It will be stuck to the shaft, fact.

DO NOT, under any brain fade, simply grab it and pull up. You WILL destroy the springs etc in the base, and I will hear you way down here.

Get a helper, have he/she push DOWN on that star wheel, as you pull up, rock and roll, twist the thing, whatever. The Downforce must always exceed your efforts.

Last resort, and more common than you think, cut it off, CAREFULLY, and move on.

Apply a good few drops of ATF down the exposed hole in the centre shaft, and go away, it is now Beer O'Clock. That ATF will soak down and unfreeze that shaft arrangement, but it takes time, sometomes a day or 2.

A simple wipe of the rotor post with oily fingers will help next time. This ATF drops is an Annual thing, and that is how it is.

 

Further to Grant's rotor points, I also suggest a hand on each end of the rotor and rock it up one side and down the other, alternately; this will often loosen it after a few rocks. The point of rocking it is to ensure NO overall upward force on the rotor spindle, as that will hurt the spring mechanism below.
New vented caps are not too dear if it does fracture getting it off:
https://www.ebay.co.uk/itm/186056235...Bk9SR56yhu2IZw

 

My distributor cap was stuck when I first serviced mine after years of being off the road. Stuck to the gasket. Removed with a few taps with a rubber mallet. The screwdriver idea is probably better, but i got the cap off with no damage. After that I was lucky: The rotor wasn't stuck and the weights mechanism was nice and free. So I think the gasket sticking is a thing - especially after its been in place for years. Regular servicing is key to these.

Good luck!

-Dave

 

Well the little screwdriver trick worked, got the cap off in one piece. Unfortunately the cap is screwed, the center carbon bit was missing and there has been a lot of arcing going on inside. The amazing part is it still ran fine. The surprise part was the cap gasket is worth more than the rotor.
I also tested the vacuum advance, big leak, it won't hold vacuum but the mechanical advance was free.

 

Check out britishvacuumunit.com. They can custom make you one with a heavy duty diaphragm, that’s what I use on mine after replacing one a year for 3 years in a row from one of the usuals; the one from BVU has been on there for 5 years/25000 miles.

 

Well done Jim.

How good are these V12's, no carbon brush (common to be missing), and it still does what it does.

Its been a long time., but I only used Echlin USA EP64 Rotor, and EP65 Cap on mine., and the gasket came with the cap.

 

As an alternative I thing the vacuum advance is a standard GM/Chevy part
Given teh age of the car best to replace. The hold pin may be difficult to remove. I had to fashion a punch.

New cap and rotor is well worth the minimal expense. Imperative to ensure the centrifugal advance springs are not stuck and are "very springy."
Lubricate the center of the distro shaft. ATF or synthetic motor oil both work well. You can fashion up a wool or cotton wadding soaked in lubricant to put in the top of the shaft as well. Few of the original waddings are still in place.

 

Not a GM/Chevy part, although people have used a GM diaphragm to rebuild as outlined in Kirby Palm’s “Experience in a Book”….. I wouldn’t, when a good replacement part is available.

 

I have imported one from them. Highly recommended. The 'normal' ones fail very quickly in my experience.

 

sorry for the bad advice on the vacuum advance. i think I got my vars confused

 

You got it right about difficult to remove! I had to remove the distributor to access remove the pin.

Cheers, Dave

 

Well getting the pin out to remove the vacuum advance was a challenge, even with the distributor out of the car. The distributor looks good otherwise, mechanical advance is free and not rusty. I decided this was a good time to change the plugs, glad I did. The last guy only changed 10, the two front ones were Champion and the gap was over .040", the rest were NGK and looked fairly recent with the correct .025" gap.