Plug Wire Routing

[NC_John]

It is my understanding that the factory ran the spark plug wires behind the exhaust manifolds and then up to the distributor and my truck seems to still have the looms to route them that way. Does anybody have theirs still routed that way that can post a few pics? I'm curious how to keep them off the backsides of the exhaust manifolds.

I've got buying a set of plugs and wires on my short list for the truck to see if I can lose what feels like a slight misfire under medium engine load (idle and full rpm are great) and if I can run them correctly, I'd like to as it would tidy up the engine bay.

Muchos thankos.

[kwmech]

When I had a small block in my 71 I ran the wires across the top of the valve covers and around to the front plugs

[Tx Firefighter]

I always route them like original. Pictures are anti-climatic though since there nothing to see when they're routed that way.

327 I built a couple of years ago.





The "bare metal" 350 in my 72




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[Mister-B]

You can also try these wire keepers, and then let it drape across the valve covers. Mine runs great this way


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[NC_John]

Originally Posted by kwmech

When I had a small block in my 71 I ran the wires across the top of the valve covers and around to the front plugs

Nah, I'm going to get the Chevrolet scripted valve covers and I sure don't want anything over top them.

[NC_John]

Originally Posted by Mister-B

You can also try these wire keepers, and then let it drape across the valve covers. Mine runs great this way

That looks OK, especially since you have some hop-up stuff on there, but Tx Firefighter has got it exactly like I want. Especially if I keep factory manifolds on after the rebuild.

[NC_John]

Originally Posted by Tx Firefighter

I always route them like original. Pictures are anti-climatic though since there nothing to see when they're routed that way.

That looks perfect. I guess it might make more sense when I run the wires but what keeps them off the manifold when they are behind it?

[Tx Firefighter]

I usually wind up making looms since the originals are usually long gone. Basically, you want something to bolt to the holes in the back of the cylinder heads. I usually wind up taking a piece of 1/8 inch welding rod and bending it to shape them weld it onto a flat washer. Then bolt the flat washer down to one of the empty holes in the head and use zip ties to hold the wires to the welding rod.

This is how I organize my plug wires and keep them nice and in line. It's a neat trick I learned years ago from a celebrity (seriously). All the NASCAR guys do it this way too apparently.
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[Bigdav160]

[ray_mcavoy]

Here are some scans of the factory assembly manual that show the factory wire routing and plug wire holder brackets:





I believe many of the parts are available as reproductions if you can't find good used originals.

[Tx Firefighter]

Originally Posted by NC_John

That looks perfect. I guess it might make more sense when I run the wires but what keeps them off the manifold when they are behind it?

I just figured out what you mean by behind the manifold. I think you mean on the sides of the block where the down pipes are.

I zip tie the front two wires on each side to the engine mount where it bolts to the raised boss on the block. Do it loosely. That holds them up snug enough to the block that they don't sag down against the pipe nearby.
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[NC_John]

Originally Posted by Tx Firefighter

I just figured out what you mean by behind the manifold. I think you mean on the sides of the block where the down pipes are.

I zip tie the front two wires on each side to the engine mount where it bolts to the raised boss on the block. Do it loosely. That holds them up snug enough to the block that they don't sag down against the pipe nearby.
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That's what I get getting after. Sounds like a project done better when the engine is cool, eh?

[NC_John]

Great drawings Ray- thanks. I have the factory service manual but I need to add the assembly book too.

[Acorn]

I love this forum! I was just trying to find this info on my ' 70 with a 350. PO has them looking like spaghetti. What wires are you guys running with hei and ramhorn manifolds? I read somewhere on here about using corvette wires but can't confirm what year.
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[OhioDan]

I just told them I needed a set of plugwires for a '75 vette 350, w/ramshorn exhaust. Should get ya what ya want?

[NC_John]

Did the plugs and wires today. Got the recommended '75 350 vette wires (Bosch kit 9661). Didn't fit perfect, some a little too short, some a little too long, but I made it work. Running the wires behind the manifolds was a huge PITA but worth the effort. I had to jack up the truck to get underneath and even removed the starter. I was tempted to pull the inner fenders too.

Did the tywrap trick for looms...

Thanks guys- I think it looks great. Nice and clean.

[Tx Firefighter]

Keep in mind that if your truck was bone stock and you bought the exact stock wires they sell, some would be a bit long and some short. Never found a set of pre assembled wires that fit as good as the orignials.
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[NC_John]

Originally Posted by Tx Firefighter

Keep in mind that if your truck was bone stock and you bought the exact stock wires they sell, some would be a bit long and some short. Never found a set of pre assembled wires that fit as good as the orignials.
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Yep. I'm tempted to get a cut-to-fit set when I do the new engine. I love that look though- the plug wires pretty much vanish.

[TxTan]

I had this same problem last weekend while replacing the plugs and wires. I have a 72 with a stock 350, and the two front wires on each side were routed up through the engine mounts. There are two wire looms just above each engine mount. If this is what your dealing with I'll try to post some pics. I used some AC Delco wires from O'reillys ($36), and they fit perfectly with no alterations needing to be made.

[NC_John]

Originally Posted by TxTan

I had this same problem last weekend while replacing the plugs and wires. I have a 72 with a stock 350, and the two front wires on each side were routed up through the engine mounts. There are two wire looms just above each engine mount. If this is what your dealing with I'll try to post some pics. I used some AC Delco wires from O'reillys ($36), and they fit perfectly with no alterations needing to be made.

Did you actually get the plug wires through the engine mount? I didn't think there was any way to get mine through and I didn't want to screw up new wires by tearing a plug boot off.

I'd like to see yours... What was the PN for the AC Delco wires?

[TxTan]

Slide the boot away from the distributor end, and the stick the distributor end through the engine mount, and then squeeze the boot through the mount. When it's all through, slide the boot back towards the end. You shouldn't even have to remove the loom.

The part number should be: AC Delco - Spark Plug Wire Set Part # 9508N