Chieftain Motorhome 440

There's a 73,000mi 1976 440 4bbl in a Chieftain motorhome we found.

If this were theoretically going in a theoretical '69 Dart (727, 9 1/4 rear) and you were on a theoretical budget, what would be the theoretical minimum build/rebuild you'd want? Are the heads worth keeping? Bump up compression? Small overbore? Theoretically speaking that is...

End result/use would be a nice cruiser that could hold its own on the street (no illegal racing). 350-400hp, is that not possible with a conservative-ish budget?

1976 means new heads and camshaft at the very least, from a performance standpoint. 75,000 miles in a motorhome will have me questioning overbore, just based on time and severity of service.

Or, throw the bugger in with nothing done and appraise it later. Collect parts while enjoying a low revving torque monster.

In reply to Streetwiseguy:

Now I'm wondering if a better cam and heads can make 350+ hp from the stock 200-205hp

heads, cam, and don't forget compression. I doubt that the engine in a motorhome is designed for anything better than bottom of the barrel swill. I would also consider megasquirting it for more control, economy, and power

In reply to mad_machine:

I Googled the compression ration yesterday at the junkyard and was surprised it said as high as 8.5.

It will rev up with these heads!

CNC MOPAR heads

Odds are the transmission won't work in the car. The trucks had either the short tailshaft or the middle length one with the parking brake on it, and cars need the long one with a slip yoke. Out of an RV there is also the chance it will have the cable operated shifter, which looks on the transmission end like a push button automatic but doesn't quite work right with the push button dash.

As long as it has regular heads and not the commercial/RV ones changing the heads isn't going to get you a lot. The lower compression on the truck was usually done with pistons. For big blocks the question of heads is more based on year: Old enough for performance or new enough for unleaded gas.

How fast do you want to go? HP is just a number. If you're trying to go 13s forget about aftermarket heads, just put a cam intake and headers on it and go. If you're trying to run 14s just put an intake on it and go.

In reply to Vigo:

I think he'd be happy with 13's and later down the road? Mid-12's

I think with just and intake and cam you'll get there. You may have to do valvesprings right away, not sure what motorhome valve springs are like. It should only take like 270-300hp to crack a 13.9 with good traction.

Car craft and hot rod have done this same build a few times. Box stpck, low options dart that hooks with good gears is 13s out of the box.

I actually had a late motorhome 440 and a 4 speed in my duster fpr a little while in college. 3.91 gears, borrowd slicks and i was running 13.teens. never got a clean run on the bottle before i grenaded it.

Dusterbd13 wrote: Car craft and hot rod have done this same build a few times.

There's an episode of Roadkill on Youtube where they did it as well.

Call me crazy, but I'd be thinking twin turbos.

https://www.youtube.com/watch?v=N16Kwoezs8k

stuart in mn wrote:

Dusterbd13 wrote: Car craft and hot rod have done this same build a few times.

There's an episode of Roadkill on Youtube where they did it as well.

That's the episode where they build the General Mayhem. And, no, the trans was unusable.

In reply to Appleseed:

They used the LeMons Fury trans then junked the car (after stripping it of everything else they might need) if I remember correctly.

One thing with Mopar of that era is advertised compression ratio vs actual compression ratio is usually pretty large. I'd be really surprised if it's over 8.0 to 1. By just an average rebuild, you should get those performance goals.

You can get into the 12's just as easy with a 360 if you don't want the weight of the BB up front.

In reply to bmw88rider:

Funny, he's got a 360 in it now! I think there's something alluring about having big-block especially if it's your first.

Maybe that's a shallow reason for wanting one but who ever said performance cars are logical?

The other Roadkill episode to look at is the Crop Duster episode. The duster gets the General Mayhem's 440, with upgrades. I don't know how fast it ended up being, but it sounds wicked.

I notice everything was theoretical except for the 440. I assume this means he/they/you already own it. Which is the correct choice.

It was cool having a big block a body, but i learned that im a small block guy.

Funny, when I hit 50 I was dumping my Smallblocks and now it's all Big Blocks.

Have you googled all the cutting, welding, beating and bashing involved in getting a big Dodge into an A-body? I seem to recall some pretty weird headers on the ones I've seen, plus any significant torque will tear the k-member out of the tinfoil that Mother Mopar used for the front frame rails.

Not saying it isn't a fabulous idea...

Headers are a nightmare. If you have money, tti and schmacker and dougs all make headers that fit without too much hackery. The weak spit on tbe kframe stuff is the 68-72 mounts. Spool type from 73 up are the cats pajamas.

This info is now at least 15 years old. I would reccomend to go to www.bigblockdart.com or www.forabodiesonly.com for the current information on it. Im sure that more, better, or cheaper stuff has been made or found by now. Only reason I was able to afford it in college was a buddy of mine had a big block swapped dart that rotted out. We pulled Ll tbe swap stuff, bellhousing and flywheel, i bought a junkyard motor form over in Knoxville, and we got drun and hacked it together. I dont remember anything major done to the shell, except for maybe a little hammer work that has long since been painted iver and forgotten about.

https://www.youtube.com/embed/juGNz1DJ4xw

So yeah if you put aluminum heads, cam, intake, headers, full exhaust, 4.10s, limited slip, and slicks on it you could run 12.4....

Call me crazy but that sounds like a lot less of a value proposition than just riding the abundant torque into the 13s with very few mods to the engine or chassis.