Spark plug cans

[lutronjim]

I have a 'connect and cruise' package installed in my 70 C10 chev truck - LC9 and 65e tranny. I have headers installed and 3 plugs had to have the can and 'boot' removed because they kit the headers.

I am having loss of power at high altitudes and skipping - above 3000' or so.

Chevy dealer claims its because the cans are missing, spark is jumping to headers. The is at least 1/2 inch between the wire and header. Since the plug gap is maybe .060 inches this doesn't seen possible to me. They claim the load on the engine is causing the spark to jump.

Does anybody know the real purpose of the cans and boots? I have heard radio interference suppression and wire insulators because of heat.

Thanks

[BR3W CITY]

You mean the metal collar that sits over the boot on some trucks from the factory?

I thought that thing was just so you didn't yank the wire by the lead and pull it out of the boot. Are the "cans" aluminum? If not, then the chance of it arc'g against them directly is the same as them arc'ing against the header.

It IS possible to wear out a plug boot and arc against headers...but the wire assembly has to be worn out for it to happen (and usually only on tight clearance headers). The whole reason for the boot it to shield it from that happening (you can still find pre-40's trucks that have clip-on wires with no boot at all). For that arc to travel 2.5" of air space it would be CRANKING some serious voltage out....I've got welders that won't bridge a 2.5" gap.

[lutronjim]

Aluminum cans. The gap is .5in. Like I stated I have heard heat shield and radio interference shield,

[clinebarger]

At night, Start the truck up, Using a spray bottle with water, Mist the plug wires, If they arch.....You have plug wire issues.

The "Cans" are for heat protection....When running Headers, You have to have something to protect the Boots.

What Headers are you running, If you have the Doug Thorley tri-y swap headers.....You need MSD multi angle plug wires & "Fire Sleeves" http://www.jegs.com/i/DEI/186/010552...FUs8gQodYQEA7w

[lutronjim]

This is a LS engine - coil per plug. The MSD wires appear to be only for HEI distributors.

[BR3W CITY]

Originally Posted by lutronjim

This is a LS engine - coil per plug. The MSD wires appear to be only for HEI distributors.

?? You are aware that is still has plug wires, right?

http://www.summitracing.com/search/d...ng&keyword=MSD

Here is every MSD wire for an LS engine.