What 440 heads use a 3/8th Spark plug?

[RedShadow30]

If someone can tell me if there are any 440 heads that use a 3/8th socket spark plug or what specific type i need to have, reach, thread ect. Ill explain.

When prepping the engine after it had sat 5+ years I made shure to replace everything, The plugs that were in it fit a 3/8th sparkplug socket, I didint think anything of it and just tossed them, Stupid rookie mistake on my part. Well all the "OEM" plugs were a 13/16th socket. They both were a 14mm thread but the 13/16th would not fit, so I put some extra 3/8th plugs from my chevy in it, Is this common at all?

I have not checked the head casting number yet because I dont want to break the perfect seal on the valve cover gaskets if I dont have to, I have 0 leaks so far and I dont want to curse myself. I am told that they are probably not aluminum since they are painted, and the block is a 77 RV block originaly.

 

[Budnicks]

I don't know of any with a 3/8" spark plug, there are 5/8" spark plugs available, for long & short reach 14mm threads, go to Summit or Jegs...

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They are no doubt probably Cast Iron Heads, especially if they are from an 77 RV, not usually a performance head either, make sure you use the proper "gasket" type plug, not the Chevy Tapered seat style...

 

[benno440]

i bought a set of these for my stealth aluminium heads
NGK Spark Plugs XR5IX Iridium IX Spark Plug
Iridium IX Spark Plug 14mm x 3/8" Reach
13/16" Hex
Projected Gasket seat
but the hex on the plug was too big for the heads and the spark plug length was too short, i later found out these are for stock 440 heads.
i had to buy ngk BCPR6EIX11. for the stealth heads reach 19mm
hope this helps a bit

 

[IQ52]

I'm pretty sure the motorhome heads with the 5/8 socket plugs used the NON-gasketed, tapered seal plugs like the Chevy's do. Your Chevy plugs should work just fine. Use the 14mm thread, .460" reach, tapered seat, 5/8 socket, el'cheapo $1.50 Autolite 25 or 26.

 

[RedShadow30]

Yea 5/8ths sorry, didint even notice i put 3/8th. I dont think the heads are stock to the block though, even though its a 77 rv block, its cammed, and at least mildly built, and whoever built it put the exhaust on so well there is no noise up front and all the sound in back, so they knew what they were doing. The size of the hex was what was causing it to not fit. Dont worry the chevy plugs were only temp to fire it up, they will be replaced before i start driving. I got stupidly lucky with it so i dont want to ruin it.

 

[benno440]

is it externally balanced motor? (cast Crank) (you can tell by the harmonic balancer) or has someone put a forged crank in etc.?

 

[Budnicks]

I'm pretty sure the motorhome heads with the 5/8 socket plugs used the NON-gasketed, tapered seal plugs like the Chevy's do. Your Chevy plugs should work just fine.

I didn't remember that, thanks IQ52 buddy... Still a crappy head choice

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Yea 5/8ths sorry, didint even notice i put 3/8th. I dont think the heads are stock to the block though, even though its a 77 rv block, its cammed, and at least mildly built, and whoever built it put the exhaust on so well there is no noise up front and all the sound in back, so they knew what they were doing. The size of the hex was what was causing it to not fit. Dont worry the chevy plugs were only temp to fire it up, they will be replaced before i start driving. I got stupidly lucky with it so i dont want to ruin it.

You realy need to pull a valve covers & write down the casting numbers to actually get a good knowledgeable well informed recommendation, on what you actually have installed, instead of guessing what you have, on a modified 77 RV RB Wedge engine...

 

[IQ52]

I think he'll find they are just the 452 heads drilled for extra water around the spark plugs and of course drilled for the tapered spark plugs.

 

[RedShadow30]

I guess im gonna have to take the valve covers off then. The car is pretty much parts from 68-77 anyway, but not in a bad way. This weekend i think im gonna take alot of pics and play "guess this part". I could care less, its a Mopar that hauls a pair and looks nice too. I hate matching numbers because you cant make the car what you want.