Spark Plug Heat Shields

[learyw]

I'm putting in a new crate 350 in my 1978 K20. I was going to switch over the original spark plug heat shields from the old motor onto the new crate but one of the four is too badly damaged to reuse.
1. How important are they? Someone told me new spark plug wires are better and the heat shields are less important. Not sure that sounds right... Anyone run engines without them? I have the original cast iron exhaust headers.
2. The heat shields are also very hard to install since the exhaust manifolds are in the way. I have seen some people that have "two piece" ones that would be way easier. They look like JEGS Part Number: 759-DESPB12 but Jegs said they wouldn't fit my Gen 1 350. Thoughts? Thanks! -Will

[cadillac_al]

I always took them off and threw them away all my life. They got in the way of plug changes and cut my fingers. If I got a truck with them today I might leave them on and rough it on the plug changes. I don't think they are really needed though. When I used to mud bog my K20 the spark plug area would get caked right full of mud and the exhaust manifolds held it in there nicely. The truck still purred like a kitten without a misfire at all. So yeah spark plug wires are a lot better nowadays.

[bhc41051]

reproductions are available I'm all about originality , I use the Corvette vendors for engine detail items.

[tucsonjwt]

As I recall, the spark plug shielding and shielding over the distributor in Corvettes were supposed to be for reduction of radio interference. I think the shielding does more to protect the spark plug wires. Since wires are now of better quality, and some are silicone, that might not be an issue today.

[MJN]

I put them all back on my last rebuild, before that I had to put sleeves on the plug wires to keep them from getting too hot near the manifolds. I also got them from a Corvette parts supplier so they were the correct ones. No issues with the plug boots now.

[learyw]

Originally Posted by MJN

I put them all back on my last rebuild, before that I had to put sleeves on the plug wires to keep them from getting too hot near the manifolds. I also got them from a Corvette parts supplier so they were the correct ones. No issues with the plug boots now.

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[learyw]

Thanks! Im going to go with the reproduction ones. Id like to keep the original look and if they are still important Ill have them.

[sweetk30]

i have them on my 1ton 4x4 work truck . i have seen lots of burnt boots over the years and was not about to have a set of my own .

that little air gap between the manifold and the shield does help drop temps a lot .

[MJN]

Just a couple pictures of the heat shields installed on my 350. I think I got them from Rik's Corvette Parts.

[learyw]

Thanks for the pictures. The key is the front two look like they are in two pieces (held together with that machine screw) so you can install them with the exhaust manifold in the way. The back two are one piece since they are easy to get at. I think the ones I ordered are the same.

[SilverMiner]

Originally Posted by learyw

Thanks for the pictures. The key is the front two look like they are in two pieces (held together with that machine screw) so you can install them with the exhaust manifold in the way. The back two are one piece since they are easy to get at. I think the ones I ordered are the same.

The main thing to note with the heat shields is that not all blocks are set up to accept them. My 1980 Suburban with the original 350 had them installed, but the 1975 small block 400 I replaced it with had neither the cast bosses nor the tapped holes to accept them. I was somewhat surprised, as I seem to remember all of my old trucks having them in the past. Maybe my 400 came from a Caprice?

[sweetk30]

if i recall the older had ear's to pick up the manifold bolts .

and i just installed a 1996-2003 vortec 5.7 engine and it had the 4 bosses drilled and tapped for the newer style .

[MJN]

Originally Posted by learyw

Thanks for the pictures. The key is the front two look like they are in two pieces (held together with that machine screw) so you can install them with the exhaust manifold in the way. The back two are one piece since they are easy to get at. I think the ones I ordered are the same.

These came with a self tapping sheet metal screw that wouldn't keep them tight. I used machine screws and a little loctite on the threads to keep the nuts from backing off. They're very short as there isn't a lot of room for extra threads between the bottom of the shield and the manifold. I installed them on the engine before putting the manifolds on. Not the best way to do it since they needed a little adjusting to fit properly with the manifolds.