Picked up a 72 Challenger w/440. Having some plug difficulty.

[johnnycharger]

 
Hi all,
I purchased a 72 Challenger with a 440 in it. It was originally a 318 car. I do not know where they sourced the 440. I researched what NGK plugs to buy and  everything I saw said to use the XR5 332. I bought them and installed them on the driver's side just fine. On the passenger side none of them want to start in. I notice the AC delcos that I removed are R43TS seem to be quite skinnier. This is my first 440 and need some help getting this sorted.
Thanks!
John

[70 sublime]

Are there two different heads on the engine ??

[johnnycharger]

I hope not. They look like old stock iron heads that have been painted.

[johnnycharger]

Pics

[johnnycharger]

Pics 2

[johnnycharger]

They won't even begin to thread even though the threads look the same as what came out. The Delco plugs are definitely skinnier.

[johnnycharger]

The NGKs went in fine on the drivers side but not the passenger side.

[metallicareload99]

Are there two different heads on the engine ??

Wow, looks like you got two different heads on one engine. I've heard that some cylinder heads did take the tapered seat plugs like you got on the left, but this is the first time I've seen em

[johnnycharger]

In my opinion,  the heads look the same.  Am I missing something?

[metallicareload99]

In my opinion,  the heads look the same.  Am I missing something?

Be that as it may, there are two different sealing methods going between your two heads The spark plugs themselfs give that away

[johnnycharger]

The delcos on the left were installed on both sides. The ngks on the right are what I am trying to install. 

[Nacho-RT74]

Casting number is visible just removing the valve covers.

[johnnycharger]

Ok. Thank you. I will order some valve cover gaskets and then pull the valve covers in a few days and provide an update.
Any recommendations for good rubber gaskets that don't leak?

[DownZero]

You can not replace a "taper" seal spark plug with a "washer" seal one. Realy should be using Champion plugs on a mopar anyway.

[John_Kunkel]

Compare your taper seat spark plug holes to the pic below for plugs with gaskets. Notice the flat surface around the holes for the gasket to seat on.

Taper seat plugs will go into gasket seat holes but not necessarily vice-versa because the gasket will contact the head before the plug threads meet the threads in the hole.

[Nacho-RT74]

hence would be nice to find out the heads casting numbers... if any. I never have seen an oldy V8 Mopar using 5/8" socket spark plugs from factory, but 13/16" socket spark plugs

[Nacho-RT74]

just found this... 452 taking tappered plugs are for RV and industrial heads.

https://www.forbbodiesonly.com/moparforum/threads/440-spark-plug-type.161006/

https://www.forabodiesonly.com/mopar/threads/rv-452-heads-spark-plugs.342712/

https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1110684/re-weird-cylinder-heads-on-440-spark-plug-wont-fit.html

Passenger 452s use the regular washer plugs.

Mostly sure the full engine came out from some RV/industrial donor

[ACUDANUT]

I would pull the heads and really look at them. Chances are you have one RV head.

Would also be a good chance to see the pistons and bore condition. Just do it !!

[johnnycharger]

hence would be nice to find out the heads casting numbers... if any. I never have seen an oldy V8 Mopar using 5/8" socket spark plugs from factory, but 13/16" socket spark plugs

Driver's side valve cover is off. I believe this is the casting number I am looking for.

[johnnycharger]

On the passenger side it is the same stamping.

[Nacho-RT74]

well.... it doesn't say is for RV...

https://www.mopar1.us/headcastnumber.html

however...

and to add more mistery... these with same CN are machined to spark plugs with washers:

https://www.ebay.com/itm/284684491767?_trkparms=ispr%3D1&hash=item4248849bf7:g:uZIAAOSwqQtiI7lG&amdata=enc%3AAQAGAAAA4NIQ0UYg%2FppJRqMwypxaJXAVVjPKdfMcoj16Dc1qgqbkKzyRnPV%2BKpBdSNq6EpVC08OPaTj1nvme3U9wVNrhVp6LbHrmUtAjsf9WLYwzXdU7%2FGt22DCi7owCIuUzxECDCRidZolYNfzfIu3q3FXMi3pYOCm%2BTtduXPdYcrMkTWKAVAUiQoWXq5Rs5Q7e1Q64pfCpDAGrBWtiTvd0YVoKyMsGYNYpnPwuhwaSS1Rf0KRwVr8U5Qb9Eqdc6sNMxcD2HLuQBeh0EqFcN5xEcI%2BKjq%2BBZ5c%2BAep7cOo9exVWxl9m%7Ctkp%3ABFBMjIeihYlg

and I even think the original heads on my 74 are also 902... and they take RJ ( champion code ) spark plugs

[johnnycharger]

Thank you all for the help with this. This one is a bit of a mystery!

[johnnycharger]

Got the Moroso silicon gaskets. Now I just need to determine the best ngk non washer plugs for this.

[ACUDANUT]

Not sure, but i Never heard of heads ever stamped RV

[Nacho-RT74]

I remember reading on some heads the word TRUCK on them, but can't recall if they were BB or SB. It was at an old Mopar parts dealer.