Bought a replacement set of "OEM-style" ignition wires for my 1985 IROC with 305 TPI. Two of the wires have straight boots and the rest are 90 degree boots. Anyone know for sure if this matches original, and if so which cylinders get the straight boots? Can't go by what's installed now because they are replacements from a previous owner and are a mess. Thanks.

 

That's how they are. Straight boots go to the plugs that are up against the exhaust manifold outlets.

 

IIRC, weren't OEM numbered

 

Was looking for a display tpi pix but I've seemed to mis-placed them.

 

Thanks gents. I looked all over for TPi engine pics too. Hard to believe there's nothing out there.

 

Looks like all the drives side might be 90s

 

Thanks Tuned Performance. Looks like the 2nd boot from the left could be a straight boot but hard to tell definitively. I know the rightmost wire in the pic (rear of eng) gets the heat shield (#26) and the heat shield is shaped to accommodate a 90. I believe that much is the same on the RH side. Still stumped.

 

#5 and #6 or #8, IIRC. With a 90* boot, the cable has to have a big loop put in to double back to those plugs, or the cable will be against the manifold.

 

Funny... 1986 Assembly Manual shows #3 with a straight boot, but nothing on the even bank.

The 87 and 91 Service Manuals show straight boots on #5, #6, and #8. The 91 Manual says "typical V8" while the 87 calls out specifically LG4, LB9, and L98. Both diagrams are similar, but they show specific details like the emissions piping routed correctly (differently) for their years.

I know that from 86-87 GM switched from 8mm wires and the large coil-in-cap distributor to the divorced coil distributor and 7mm wires. Looks like the plug wire clips and maybe the heat shields changed too. I don't really feel up to digging into it further, at the moment. When you lay them in place, you'll know if you need a straight or 90* boot depending how they clear the manifold and heat shields.

Edit: Forgot to mention, 86-earlier spark plug wire sets have 2 straight boots, 87-92 sets have three. Which explains the diagrams.

 

Thanks again Drew. Should be enough to get me through. Appreciate it!

 

... I found an '85 service manual with this pic. Looks like both straight boots go on the passenger side - cylinders 4 & 2. Again, this is 305 TPI engine (LB9). Hopefully it will be helpful for future visitors to this thread!