440 Motorhome head swap

I have regular 76 440 out of a truck I believe. No extra cooling holes on the block deck. For my purposes, I would like to run some motorhome(whatever you want to call them) 452 heads. The heads have the extra cooling holes near the spark plugs. Has anyone ran these heads on a non-drilled block 440? I am intending to use steel shim gaskets etc.

I'd really rather not drill the block as I am eventually going to do something a little more normal once the car is done.

Thoughts? I don't want things running hot. I personally think it will be fine, but I am just asking before I invest in the heads.

I’ve used the MH block with 906 heads and that ran hot on two different engines. Never gone the other way. I would think it should work ok. The 452MH heads are the same casting just machined a little different

In my own limited experience: I ran a '73 Motorhome 440 with steam holes in the deck & heads, however, my Fel-Pro head gaskets blocked off the holes. I had no noticeable problems with cooling.

My particular motorhome heads took a different style of spark plug compared to a "car" head. Tapered seat with no gasket as opposed to a flat seat with a crush washer. Not sure if its a similar situation with your later 452's but thought I'd mention it anyway.

If you have plans to deck the head surface at all and you are concerned about the holes, it would be easy to tap them for a pipe thread and run crack-repair pins into the holes, then cut off the excess and deck it flat. I've also seen small set screws used to plug steam holes.

RV also have a different water pump housing to plumb to the heads....

You’ve seen that pump housing on a 440? I’ve only seen it on a 413 and supposedly on a 361 industrial motor

Ok. I think the engine that has the "special" heads is likely motorhome, but not industrial. Other than the heads and the corresponding deck holes, it is largely identical to the other engine. It has a cast crank, but a windage tray and roller chain etc. I am saving it for the next build after this one. It has zero ridge etc. so it will be a good builder for later.

452 casting number, but I think there was an additional symbol on them or something. I will look later this weekend.


I have seen the "industrial" 440 engine, which I suspect came out of a really large motorhome. It was somewhat challenging to even identify as a Mopar with the external differences. Water pump, it seems like distributor, etc. Looked strange and it was partially hidden.

And you are correct on the plugs etc. they are different.

I am using these "holey" heads on the first build with the car. Going to do some bowl work etc. as they are pretty tight and use them while I gather parts for the next round next winter etc.

The usage on both of my MH blocks that ran hot were in Texas. That might have something to do with it. Never had any trouble with excess heat except for those two blocks.

On a side note for this app (heads/decks not milled flat) I would consider a composition gasket (or at least copper koat on the steel shims).

Definitely the copper coat for sure. The thing has such low-compression that I don't want to lose any.

I bought the shim gaskets in addition to the regular Fel-Pro ones so I can run either if need to.

Don't want leaks but I do want compression.

Your good on using those heads on your short block without adding the extra holes
Mopar added the extra holes for exhaust valve cooling in the 440-3 motor home motors only, none of the other H.D. motors had them

What I would do is measure how far in the hole they are & a righteous guesstimate on the head CC's to see what you have now & also to see the diff between the 2 gasket types just for fun. United machine and Wallace racing have user friendly CR calculators. Post how it turns out.

I believe that they were .170 in the hole. I don't have the engine here now. Whatever it is, it is the typical 7:2.1 compression scene or close to it.

My whole purpose for using the heads is that they are better than the regular heads I have on hand.

That and practice porting the bowls on and playing with my guide tools etc. Learning....

As an aside, how common are leaks with the steel shim gaskets? Just OEM parts cleaned, copper coated and torqued? Are leaks generally an issue?

I have never had a problem with leaks using the steel gaskets on an iron head. Plus, I usually don't coat my gaskets. My thoughts were that Chrysler made millions of big blocks and used stamped steel gaskets on them. If it was good enough for Ma Mopar, it's good enough for me.

I use two or three coats of silver or aluminum rattle can paint to seal steel shim head gaskets on non decked and or smooth surface heads

I ran 213 motorhome heads on my 470 without issue for what it's worth.

If you plan to deck/re-surface the block, then I suggest you consider drilling the holes into the deck (if you're sure you will be using heads with the extra cooling passages). You would need to find some head gaskets with the extra holes OR possibly drill holes into "regular" head gaskets.

For some more info on the above drilling go to www.moparchat.com then scroll down to & click on "circle track chat" then peruse Sanborns' cooling mods that are in a sticky at the top of the page, A long read but worth the time.

there are 2 sets of BB #452 heads 1 set has extra cooling passages around the spark plug hole and use the 5/8 hex 'peanut" plugs. AKA-#452 motor home heads.

the other set does NOT have extra cooling ports around plug holes and use a 13/16 hex plug. AKA-#452 car heads.

look at the plug hole, the MH #452 head will have a small machine area around plug hole with a small bump in the casting below plug hole. extra cooling port under bump. hence small plug & machine area. (FYI a 13/16 plug will screw in and work as that is what I found in mine at the start, but not ideal fit looking at head on bench)

it also had head gaskets that blocked those ports on block/head so it worked this way either head from what I can tell.

the car #452 head has a larger machine area around the hole and no bump in the casting.

my 77 440 MH engine had the peanut plug heads and I swapped to a fresh set of car 452 heads 13/16 plugs.

I looked into all that when I swapped heads. no cooling issues with mine.

only time it ran hot was with retard timing. stays at 185* now it tuned.

only way to use those IND/MH heads is to use the raised WP housing and exhaust manifolds.

but you can take the IND/MH 413 short block bore & stroke to a 426 wedge as that is the ticket for using one of those IND/MH engines to get a cheap 426 wedge/max wedge clone.

I'm only using these heads because they are in better shape than the other ones. I really am not interested in drilling holes etc. I think it will work with what I have. Kind of practice heads if you will.

There are indeed some differences between these heads and the regular ones. I have to use different plugs etc. but it is mildly inconvenient.

No machining. Just going to run them as is.

that's what I did 20,000 miles ago. but I added the whiplash cam/lifters/springs when I swapped heads out for fresh VJ on the car set. I have the MH#452 with fresh VJ for my 78 new Yorker 440 = I need to look what heads it has now.

use what you got even if it is a 318...LOL!

I'm basically building a mild 440 and doing the rest of the car up pretty well for more HP and I will likely build a better engine later once the car gets sorted.

My recollection is that the old Paul Rossi Street Fighter heads were made from the motor home heads.

So where the Herb McCandless street and strip ported 452 race heads, I think

Steel shim gaskets leak? Not if the heads and block are flat. AFAIK exactly NO B or RB engine came out of the factory with anything but steel shim gaskets. The same with all V8s until maybe the early to mid 80s, when I believe the LA started using composition gaskets, which prompted the reduction in block deck height from 9.600" to 9.577". Shoot, the intake gaskets on my Poly motor were steel shim! As were the exhaust pipe gaskets.

Look in the factory service manual and see if they recommend spraying or brushing any goop on those steel shims. I bet they don't. If they do, copy the page and post it because I want to see it.

To my way of thinking, adding Copper Coat or Hi-Tack or aluminum paint before installing the gasket puts two slippery layers between the gasket and the block or head. The gasket is coated with what the gasket manufacturer wanted to be there.

Back in the day, when Chrysler was forever quitting big block engines, they sold 452 heads for insane prices, like $45 each. The 452 head, like all big block heads since the 346, has an intake port that is easier to work especially when installing larger valves. So people started reworking them. They also had hardened exhaust seat areas and some thought the entire chamber was hardened.
Anyway, the most magical thing about the 452 heads was the fact that they were available brand new by the pallet load for insanely low prices.

If you are looking for a 452 head to port, keep your eyes open for the heads with the numeral "!" cast into the end of the head. These heads were a revision and would have had their own casting number except that Chrysler had already made the decision to quit making big blocks. So the heads got thicker ports and maybe slightly better contours.

R.