Just finished fitting spark plug wires routed under headers with heat resistant tubing routed up back of engine to distributor.
Having second thoughts on #8 (passenger side rear) despite using ceramic boot and spark plug booty, it is routed between header into head exhaust and lower header collector which will put allot of heat on this plug both below and next to it.
Looking for feedback from anyone who has run #8 wire down in this configuration, did it hold up?
I'm thinking about running this wire up over the valve cover by the oil dipstick to avoid the "heat sandwich" it could face in the current setup.


Passenger side, #8 plug

#8 plug, closer view

#8 plug, underneath looking up.

 

Factory wiring method is over the top on the pass side. 90° boots on #6 & #8. Usually works fine with headers. Especially stainless ones that are coated, which drastically lowers the amount of heat they throw off. Just FYI, the heat conductivity of stainless is around 40 - 50% as much as plain mild steel (half or slightly less as much energy allowed to pass through), and the coating further reduces that to probably around 30% or so of what plain mild steel would allow. Not that much more heat than manifolds, IOW.

 

My BBC is a little different but the application is the same. My headers are coated and I still run the protective sleeves over the plug boots.

The coated headers reduce a whole lot of heat but they still get hot. Just run the wires and secure them so they can't vibrate loose and touch the headers.

 

Decided to go with 1-7 spark plug down and #8 up. I epoxied a spark plug holder to the oil dipstick tube to keep the #8 wire away from the headers.
It's a little unconventional but after trying a few options, appears to be best solution to avoid the heat. Mallory ceramic plug boots should keep the plug ends safe from the heat.


Driver side

Passenger side

 

What oil dipstick and tube is that? Mine had to be mangled to work with the headers and it doesn't pull out very smooth. It also had to be angled much more than yours to line up with the header bolt hole. I bought a Lokar flexible dipstick but it wouldn't fit in the block.

As far as plug wires go I haven't had any issue with routing them all down from the top using center bolt valve cover wire retainers and 90 degree terminal ends with Ac Delco plugs.

 

That is the stock oil dipstick. I had "issues" making it fit so decided to cut the flange that bolts to the block and reposition it to work smoothly before welding the flange back to the tube.
Routing them down seems the best approach to avoid the heat except for #8 which had the header collector right under where the down facing spark plug wire/heat shield boot had to slip through.
I see allot more space routing this one up so we will see. .

 

here's the best pic I could get of how I routed from the top