Replacing 1979 440 with 1972

[Ken]

I have a 1979 Winnebago 26ft with a tired 440-3 running on propane. (cast crank). I have an opportunity to buy a 1972 newly rebuilt 440 ( with forged crank) with compression bumped to 10.5:1 with hardened valve seats. This motor however is apparently out of a car. I am aware that I will probably need a different flex plate to correct engine balance. I also am aware of the added cooling passages in the motorhome heads that the car motor does not have. I am also told  that some motorhomes have these special heads and some do not. Has anyone ever made a similar swap and have any advice to offer?

[Elandan2]

Sounds like a pretty good replacement other than the compression ratio.  10.5 to 1 will require premium fuel and will certainly increase your operating costs.  Then again, there used to be "thicker" head gaskets available to lower the compression ratio.  I don't know if you could still get them.  We replaced the 440 in ours with one out of a 1973 Chrysler.  Before installing it, it was completely rebuilt except for hardened seats.  That was in 1985, and it wasn't until this year that I had to take the heads off and get hardened valve seats put in and the heads reworked.  We put about 60k miles on it before needing that work and have never had overheating problems, even with burnt valves.  Rick

[Ken]

Thanks for reply. The compression ratio is actually the reason I am considering this engine, I run on straight propane so will gain some wanted power. Original engine is a dog on hills of British Columbia, I do not burn gas at all so premium is not an issue. My concern is that the car engine may have less cooling capacity than the original motorhome heads and wondering if anyone had any issues with that.  Thanks for your info, Ken

[Elandan2]

Like I said previously, we have no problem with cooling with the car heads on our rig and seeing that we live in BC, the mountains are no problem.  I lived in Ashcroft for 10 years and the hill going south out of there is 11% for 10 miles, a good test for any vehicle.  Although it was pretty slow by the top, it never overheated, and when I had the heads redone this year, there was no damage to them other than the valve seats.  Rick

[Ken]

That is reassuring. I live in Radium Hot Springs. Another question for you seeing as our original and replacement engines are very close to same year. Assuming that your original 440 was a cast crank (external balance), was your replacement also a cast crank thus resulting in no balance issues, Or if it was a forged crank (internal balance) how did you correct?  Thanks
Ken

[PwrWgnWalt]

Hi Ken!
I'm new to the RV world, but have worked on Mopar engines for more years than I want to count.
The '72 440 can have many different parts, but being from a car - and since the seller hasn't mentioned anything differently - I will assume it is a standard 440 with forged crank (but Mopar began cast cranks in some big blocks in '72, so beware).  I rebuilt a forged crank 440, just like the one you are buying, for my pickup. It was a '72 car engine... I upgraded to forged pistons, later-year heads (for hardened valve seats & added cooling), and electronic ignition during the rebuild. Such a change is easily done; "most" everything from your '79 440-3 should transfer over to a '72 440-1 just fine, but here are some things to be aware of:

Harmonic Balancer - at the front of engine, on the crankshaft.  It is imperative that you use the correct balancer, or you will know it right away (the engine will shake very badly). The 440 forged crank (internally balanced) balancer will appear symmetrically rounded, while the 440 cast crank (externally balanced) will have a definite non-symmetrical portion. There are differing bolt patterns on some of these, where the pulley bolts on. Good pictures of both balancer styles are here: http://www.moparts.org/Tech/Archive/bb/22.html

Flex Plate - on the flange at the rear of the crankshaft, there were some variations on bolt pattern here, too.  Be sure to check the '72s forged crank pattern before ordering a new flex plate.

Torque Converter - this is where you also want to be extra careful. Like the Harmonic Balancers, there is a difference in these (added weight on the cast crank torque converters). Your engine will shake violently if the wrong one is used.

The oil pan & oil pickup tube - these were different depending on car/truck and where the front axle or frame component was. Compare the one from your 440-3 to the '72; interchange is straightforward if needed. If your 440-3 has a windage tray, you might consider using it in the '72 (I use one).

The water pump housing - some of these had a bottom inlet that pointed in different directions, but just compare them. Again, interchange should be easy and no-fuss, if needed. I would encourage the use of the best water pump you can get (the A/C type flows more water than the std non-A/C style). There's a good picture of one here (& other stuff, too): http://store.440source.com/

One more thing to be careful of - the other Mopar big blocks of the 70's (383 and 400) were "B " blocks, and some of their parts do not interchange with the "RB" block (440).  Mainly the intake manifold and distributor, for external parts.  Just be careful.

Here's an excellent listing of part/casting numbers for engine components & overall discussion: http://www.moparts.org/Tech/Archive/motor/36.html

Best of luck with the replacement!  Should be a good runner.   
- Walt

[Ken]

Thank you for the useful info. Ken

[Ken]

Thank everyone for their input but decided to go with another engine. Found a better deal on a rebuilt 1977 440-1 with cast crank and RV cam. Only 5000K on it since rebuild and excellent price. Compression ratio not quite so high 9.2 : 1 but still up from old 440-3. Bought last week but not going to start swap until March when snow gone.