Hey all. Short time lurker and newb here.

Two weeks ago, I spent 4 days wrenching on my 454 for a 4 day weekend trip...And another half day working on it at the camp site!

I would LOVE to drop a diesel (overdrive mandatory!) in it but I was also thinking about a SBC and overdrive tranny swap.

Right now, the powertrain is the 454 big block, a TH400 and 14 bolt corporate with :4.56 gears. Cruising speed is about 45mph. At 55, she's singin'. At 65, she's a screamin"!

The 454 is being over spun like 80% of the time.

The manifolds were cracked when I bought it so I replaced them with headers. I KNOW they're glowing at highway speed. I haven't melted any wires or caught on fire yet!

I have the timing advanced to the threshold of audible ping and the starter binds a little on start up. It does run cooler then it did but the temp still climbs while in the mountains.

I think my RV weighs about 7300 dry.

I thought about swapping out the rear for a :3.73.

I do have a 6BT in an old Econoline bus that ran through a Ford C6. (Very nice adapter kit) I could bolt that to an E4OD with the plate already on it.

I have a 6.9L Hino 6cyl bolted to an AT545 (no overdrive!)

I thought about finding a wrecked diesel G2500 or something, with the 6.5.

Since I don't have the time or money to do any of the engine swaps I really want, I was also thinking about a (4bbl headers and cam) 305 or 350 with a 4L60/80 through that :4.56 rear.

Is anyone running a ~8000Lb RV with a small block?

I had a K30 mason dump that weighed about 6800 and the 350 with headers moved it right along...power to spare. I hauled a 6 ton track hoe on a 9 ton trailer for two years with that truck.

I think the only time I would kick myself with the small block (if at all) is if I were towing a pickup truck.

I could buy a 2WD 1990 Silverado tomorrow for $500...OBO. Engine (supposedly) rebuilt 50k ago.

Anyone have any thoughts?

Don't worry about hurting my feelings ;-)

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What rpm are you running at @ 65 mph? It shouldn't be screaming and if it is and the tranny is shifting properly then a gear swap could be interesting; these monsters sure have more than enough power and torque. The way we have fixed our 454 overheating problems is:

-headers ... you've done that. With home built heat shield for starter motor.

-checked the heads for cracks... magnfluxed.

- New radiator cap, thermostate and hoses, upper and lower. totally cured the overheating problem on one of our old classA's on a p30 chassis.

- Pulled the radiator and had it rebuilt with 30 percent more cooling capacity... a HUGE improvement on another chevy powered rig.

- Made sure it got LOTS of air into the engine compartment.


When doing an engine swap, which is fun, you gotta ask yourself is it worth it? In almost all cases if the engine runs the answer is no, but then some of us just like tinkering with big those big chuncks of steel. LOL


The 454 is a work horse, BUT,, I have written on my page the over heating problem DUE to small water jackets, and under powered waterpump. Check with Edlebrock corp, on there HIGH volume low pressure water pumps,, (i.e. 13 lbs at radiator cap). go with Industrial 4 plus core radiator, its actually a 6 ribbed core dump truck radiator, Huge ventlilation grooves. As for the 1990 silverado engine,, dont waste your time, there known for underpowered and blowing injectors out. (1990 thru 1992 had that problem till chevy figured it out).

I went all crazy on my winnie chieften on my page,, 327 w/ 4 bbl, headers and standard trans. The standard over the automatic was I could hold a lower gear longer for an incline and still hold the power band on the engine.

As far as your gear ratio, 3:73 are ok, UNTILL you hit a steep upgrade, your trans will want to jump between gears, because the 454 power bands out around 3200 rpm's give or take a couple rpm's due to age and disposition and temperment of your engine, (each one has there own quirks). If you advance your timming to much IT WILL RUN HOT. drop to next colder plug, Put heat shields on your headers,, cooking your wires decreases the electrical flow to the plugs, (a.k.a. prefire or no fire at high rpm). Back rinse your radiator often,, use hose and spray the crusted bugs between the fins from inside out. 

I would guess around 3600 at 65.
The headers start rapping pretty nice at 60-65mph.
They are race headers for a 55 Chevy. Big primaries.
I had to offset the shifter linkage to go around the collector.

Funny story really.
I won them off eBay for $20. I had forgot I put them on my snipe list and was surprised when I got an email on my phone.
They were hanging on the wall in a barn, where they'd been for the last 40 years.

The farmer and his brother had an old gasser that they would hustle people with. They had someone talked into running for pinks...something fancy, like a corvette. They lined them up and off they went.
When his brother grabbed 2nd gear, BANG! The shifter yanked right out of his hand and went right down through the floor!
The clutch exploded and took out the bellhousing and, on those old cars, there is no cross member after the motor. Just three motor mounts and the trany hangs off the back.
The whole running gear went right out the back and landed in the road. The guy in the other car turned around to see his new Chevy and decided he didn't want it any more. They towed it home and parted it out.
The headers were never installed and hung on the wall until I pulled them down.

Lucky neither lost some toes or a foot!
Any more details on the 327 and the rv it motivates?
What tranny did you use? Not a W85 I hope. ;-)

The 305 gets a bad rap. With a couple hundred bucks worth of boltons and an hour or so with the carbide burr, they make as much power and torque as a 454 smogger. Just higher up the tach. I could drive to Chester right now and pick up a 305 with engine stand for probably $75 to $100 off Craigslist.

I think the 454 is wasted in my rv. It would be better in a street rod with dual quads and chrome. BBCs LOOK kool.
If I sold it and the TH 400, I could probably buy a tight fuel injected small block and have OVERDRIVE!

The standard tranny was out of a 97 chevy commercial 3/4 ton pickup, as far as the number, havent a clue, standard 4 speed with overdrive, (just a 5th gear actually). The low gear is perfect for a gentle take off without burning the clutch to get her rolling. i will ask buddy of mine what tranny it is and pass that on.

 if you can find a chevy or even a ford diesel engine with trans out of a nice 3/4 to 1 tone van, then your all set, which includes the nessarry wiring you will need, and government auctions are where alot of them are at. 

The W85 is the old "granny gear" 4 speed (or; 3 speed with low).

That's what you'd expect to find after a 327 from an old 3/4 or one ton Chevy, back in the day.

Great tranny but exhausting to drive. :-0

As (bad) luck would have it, my mason dump went down on Labor Day.

I was towing the red truck home on my 5 ton trailer.

The torque converter in the white truck was slipping badly and I just need one more trip out of it to get the parts truck home.

Didn't make it! DOH!!!

Anyway, the white truck has an E4OD and 7.3.

The red one has a ZF5 and 7.3

After doing the 5 speed swap on my mason dump, I'll be left with an extra 7.3 and E4OD that needs a torque converter and some fixing (which I am totally capable of doing....given the time!)

MY 7.3 IDI no turbo will walk away from the 454 in my Itasca, even in a 9000lb truck.

Also, I know the 6.9 7.3 IDI pretty much inside and out. There was a time when you could show me a bolt and I'd tell you where it went.

Something for me to think about.

No one was going to tell me out the most obvious repower option?
P30 delivery van already equiped with diesel engine? They came with Cummins, Gm and even Detroit and other engines, apparently.
Looks like the 454 will be going on Craigslist. :-)
I have a 1984 Winnebago Chieftain with the 454/TH400 combo and the 4.56 rear end. I average about 8mpg and have pulled 8% grades on 100 degree days with no overheating. I think that the 454/TH400 are a work horse combo. I have debated swapping to something else, but in the end why fix it if it ain't broke. Beside you will never recover the cost of the swap. I would enjoy it the way it is, save your money for the journey!
I have also followed some threads on various forums about different swaps and in the end they all end up with the same mpg and a way lighter wallet. Most complaints on a diesel swap was that you can not gear the rear end high enough to take advantage of the diesels fuel economy.

Thanks and your opinions are noted!

I am on the fence with this because of the time commitment. The cost in bucks would be minimal because...I don't have any money! ;-)

My mason dump has a 7.3 IDI non turbo with E4OD, 5.13:1 gears and 16" wheels.

At 60mph in OD, it's cruising at 2400rpm...and I mean cruising. I can maintain 70mph, all day, without the engine trying to come through the hood.

65mph is effortless.

If my Ford had a 4.56 rear, it would be a highway cruiser.

Big difference between a 454 at 3000rpm and a 7.3 at 3000rpm.

65mph in the Itasca is too much for the 454 and TH400. A4L80E swap would be sweet but almost as much work/$$$ as a total re power.

I'm getting between 9.5 and 10.5 MPG with the 454.

My RV weighs about 7300 and I rarely take it over 55mph. It's the stubby Sunflyer model and is only 22'.

I would hope to get at very least 12-14MPG with a diesel and OD.

I think a small block would do about that, just with a lot less power.

As for the pay off, I hate the way it drives. Like a deuce and a half on I-95. Noisy and slow.
Not that it doesn't have the power, it just needs one more gear.

Interesting comments on this thread. I have a 69 Dodge Glastron with a 318 -3 small block and a two barrel with the 727 Torqueflyte transmission ad I believe 4:56 rear Dana. I run well about 55-60 mph on the freeway and it is a dog to get up to speed but does well on hills, (havent tried mountains). My rig is all hand laid fiberglass and so weighs at least 10,000 Lbs. I dont know about mileage yet as I havent taken any long trips since I finished the restoration. Just for some comparison, I would like a little more power too. but $$ has run short for parts. Jim

Thanks Jimmy. Good info.

I have owned a few 318's and I remember them being around 120-130hp. Not torquey but nice mid range, even if it wasn't very much.

A 360 would be a big jump from a 318. Especially a Magnum with headers and cam.

That's why I'm thinking about a small block for my rig. I could probably fund a really clean swap by selling the big block and TH400.

I finished the 5 speed conversion on my dump truck yesterday.

I have a pile of parts left over. The E4OD would need to be freshened up but the failiure was the torque converter clutch which overheated the TC took out the front seal.

Side note:

My truck is a bit slower now. In fifth, I'm turning 1500rpm at 35mph and 2400 at 55.

No more cruising down the highway at 75mph!

So I have a 7.3 ID no turbo and an E4OD for a possible swap.

The only problem is the 1300Lb and change. It's pretty heavy.

Also, diesel is a little harder to get.

Back to thinking about a small block and OD tranny. ;-0




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