Plug Wire Lengths

[eric8]

This might be a dumb question, but I ordered a new set of exact fit Denso plug wires for my 77 (350 with HEI distributor). As you can see, the lengths are all over the place. One wire is extra long, 3 are long, 1 kind of medium sized, and 3 are short. Is there a specific cylinder these are assigned to, or is just a "wing it" or trial and error kind of deal?

[sweetk30]

i tend to do cut to fit and crimp them my self anymore .

it seems every few years DIRECT fit wire sets grow a few inches . . . there almost always to dam long .

[Dead Parrot]

I usually start with the shortest wire and find the best fit. Repeat until you have all 8 done. Last couple usually wind up being a little long. Better a couple inches too long then a couple inches too short. Yes, 'wing it and trial and error'.

[eric8]

Well for what it's worth, I did some digging and found a post on another site that said for a sbc, the plug wire lengths generally go in the following order (from longest wire to shortest wire): cylinder #'s 3,2,1,4,5,7,6,8

I used this method and the wires look good.

[Katrina/10]

Originally Posted by eric8

Well for what it's worth, I did some digging and found a post on another site that said for a sbc, the plug wire lengths generally go in the following order (from longest wire to shortest wire): cylinder #'s 3,2,1,4,5,7,6,8

I used this method and the wires look good.

I put some wires on my truck just a couple days ago, and ran into the same thing. Always a box full of unmarked wires, no indication where they go. I didn't think to look on the internet to see if there was a recommended sequence for length, that was a good idea!

I tried to guess which ones would go where by laying them out on the floor by cylinder location, it didn't work perfectly, but helped. I did find that the longest one worked best for number 3.

[rpmerf]

Originally Posted by eric8

Well for what it's worth, I did some digging and found a post on another site that said for a sbc, the plug wire lengths generally go in the following order (from longest wire to shortest wire): cylinder #'s 3,2,1,4,5,7,6,8

I used this method and the wires look good.

Interesting. Not what I would had guessed. When you look at a picture of it, it makes a bit more sense.

[SunSoaked]

This is why God invented the LS.

[1976gmc20]

When you look at a picture of it, it makes a bit more sense.

Except the distributor is nowhere near that large compared to the rest of the engine.

I always start with the longest one(s) on 1 or 2, then work down and hope.

And yeah most wire sets are hopelessly too long. I think I have some plug wires zip tied to the brake vacuum hose (anything non metallic), and maybe to a heater hose on the other side.

I had a rough running problem and replaced cap, rotor, wires, and plugs as a matter of course. Just kept getting worse and turned out it was a blown head gasket between 3 and 5. So I had a shop do that and a few weeks later it started running rough again! Then I discovered one of the plug wires dang near burned through on the exhaust manifold on that side. Obviously the shop didn't taking much care putting the plug wires back on