It appears the anti-flash shield on the distributor has been missing since I bought the car last fall. I didn't realize there was such a thing until I saw a picture of a distributor on another car.

There is no apparent damage inside the cap and I'm getting a new shield, but my question is what does the shield do and what happens when it is missing?

Thanks.

 

I'm wondering the same thing.

I have purchased a new distributor cap, rotor and flash shield for my 1988 V12 XJS.

First problem was the new flash shield was slightly larger than the old one and the 4 screw holes wouldn't line up. I managed to file the holes in the flash shield until I was able to screw it into place.

Next problem, the new flash shield diameter it slightly larger than the old one and the new distributor won't fit over the flash shield! I seem to have a never ending problem these days of parts not fitting correctly.

Which takes me to my question, what purpose does the anti-flash shield serve? What would be the consequence of not fitting it?

 

Mine has had no flash shield since 1996, and no issues that I am aware of.

My understanding is that it was to shield the pickup from HT spark flash, dunno, does not sound right to me.

Mine went west when the cap exploded and imbedded itself in the bonnet insulation. Part was NLA at the time, and I simply went without and thought no more of it until I read this thread.

 

If a Lucas dizzy, I presumed it was also to protect the bits below, plus to be a secondary protection against explosive gases in the dizzy catching fire, in addition to the ventilation system.
Does the Marelli dizzy have a shield?

 

Right, well the author of this thread and Grant both have/had been using their car without the shield.

I'll take the gamble it's not really required as I'd much prefer to be able to use the new distributor cap, but if I need to use the shield I'm back to my old distributor cap.

The car has been getting some attention, steering rack rebuilt and installed with new mount bushings, new radiator, new injector wire harness, ignition wires etc

 

Go for the new cap and forget the shield, as long as the vent system is connected properly, say I.

 

Ope. No shield in the Marelli dizzy. It is basically hollow.

 

Yes vent system is all connected

 

My 84 had a flash shield, but it was cracked and had a piece broken off, when I bought a new flash shield not only the hole did not line up but when fitted the dizzy cap would not fit so I left mine off and have had no ill results

 

I replaced mine (Welsh Jaguar I think) and had no issues with fit.

I am of the opinion though that it is a non-essential part. Somebody at one time probably thought there was possibility engine fires were coming form spark escaping from inside the distributor and came up with this idea.

Leave it out and move on. Not worth the time worrying about. BUT....by all means lubricate the distributor shaft while you are in there. Clean out any old hardened grease and make sure the centrifugal advance springs are "springy"

I use a bit of synthetic oil to lubricate the wadding in the top of the shaft and let it soak down. I have refreshed this two or three times over the years (about every five years or so and have never had any of the issues associated with sticky centrifugal advances (which can lead to engine fires)