Thread: 350 Winnie 20' 1981 motor home

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I am not working on this currently,but I do want to map out a plan for it with Pat,Jerry,Dave's and everyones input.

The known details are it is a 1981 motor home that is 20' long and it's weight is wet 8,000 lbs.It has a 350 with a four barrel Quadajet,400 tranny with a external tranny cooler ,4.10 rear end gears with a Salisbury rear end.The build sheet I got from GM archives says it is 160 net hp@ 3800 rpm and 250lbs of torque@2800rpm.The miles on it which I do believe to be true is slightly over 40,000 miles.I do not have the casting numbers,but I do think it is a four bolt main given what it is in.For the life of me,I don't know what GM was thinking putting in this engine with those ratings.It gets from 9mpg to 6mpg and that is with a fresh tune-up.The intent is to tow a dual axles enclosed trailer over the road.I am told these M/H's are not intended for driving over 55 for long periods of time.Yeah that is kind of a kick in the butt........But it hafts the gas mileage.The build sheet from GM said it did come with a 454 as a option,but that makes gas mileage even worse and those ratings for that is 210hp@3800 and torque is 340@2800 rpm.

I want better gas mileage.I have been looking into a swap for a 5.9 turbo Cummins and dodge 47 tranny.Tons of fab work involved there.The 5.9's is about 1,100lbs too,but the 350 is about 550lbs with the M/H having a front end rating rating of 1,400lbs with a option of a heavy duty front end of 1,550lbs.My point is that if anyone is thinking of the wt being a problem,I think it could be handled.The best yrs for this swap is 1994 to 1998.5.

So I am posting this here because of the 350.Before I start a huge project shoe horning in a 5.9,I an asking for feedback/input about the 350.

I am first of all for reliability well beyond the life of the M/H,gas mileage(would be a blessing if that was between 12 to 14mpg),more power,and a engine that does not require high test gas.I am not in the mind frame to the purchase of a Gear Vendors O/D.It just doesn't seem to be a quick return on investment and it's costs is something I don't think is in my price range.If anything a stand alone 4l60E or 4l80E donor O/D tranny.

So guys,I'll await you input and advise.

Please and Thank You,

Gary

The Cummins is the only thing that makes sense to me. How did you arrive at the years '94-'98.5 as being the best candidates?

I'm interested in this because I have been eyeing a '47 Chevy COE in Tucson for $1800. Rust-free, no drivetrain.

well i think the 10.200 tall deck for a big tq monster with a 400 with a O/D may be cheaper and fab work? then the cummins would be hard to beat but the big chevy can be turbo too .525 cid small port heads nice hi TQ roller cam with a turbo = stump puller

the cummings 94-98 is th most powerful of the 12 valve non electronic engines It would be a good combo but a job to put in. Might be pretty loud inside you probably will have to do something with rear gearing
I have a 76 18 ft m/h with a stock 454 400 combo i get about 10 mpg when hauling my 18 ft trailer and car 55 mph max. can always want more power but works ok. they are a brick with wheels

Heres a suggestion keep it simple pull the 350 stroke it as big as you can go , vortec heads good towing torque cam headers etc . maybe an extra 100 hp out of your original if your lucky dont have to change any gears or anything else keep it cool and run good oil and it should go a long time. a cummings or built big block it wont be but it should do the job. My preference would be a hd 5 spd manual but not practical in a m/h.
just my 2 cents and suggestion

I have a 2000 37 foot motor home with a 320hp turbo cat and a allison 6 speed transmission..rig is about 25,000 pounds and get consistent 11 mpg pulling a car trailer with a 5,000 pound truck on it, turning less than 2,000 rpm.

I think for longevity you could use a diesel and get the best possible fuel mileage and reliability.

I would use the one that fit the best, there are many good diesel engines out there.

The simplest and cheapest would be to build that 350 for low end torque,calculate rpms at drive speed and match that to the largest torque numbers you can at that rpm....no reason to have it do much past the rpm you will be cruisin at anyway...when you hit a hill it will slow down and down shift anyway.

I dont see why you could not get very close to 400ftlbs out of that engine and that would be plenty....

Any gas engine will get less mileage than diesel, but between the more expensive fuel and the greatly increased cost of a diesel engine.....

It`s a hard choice.........for about 2,000 bucks you should be able to get 50,000 trouble free miles out of the gas one....or more miles....since you have a good running base to start with anyway.

I would not worry about the rpms much.......my 460 with 4.11s and a c-6 went 250,000 miles with no problem and at 65 was at about 3,200 to 3,300 rpm all the time and at about 9 to 10 mpg no matter what.


From my experiance driving a huge motor home and now having more than enuff power 1,000 ftlbs or so ...I can honestly say it really only comes into play on the long steep grades and then I just mostly slow down to 45 with the big rigs and take it easy to prolong the engine anyway.

On the flats, guys with the same size or bigger motor homes and the gas engines...454,460,v10s etc maintain the same speed or pass me.....I usually keep her at 70 or less even when the speed limit is 75...even though it has no problem at all going way way faster than that...

I am sure your rig would do fine with a 350/383 towing build.....no wheel stands or passing everything on the road going up a steep grade, but will still be just fine in a 20 footer with a trailer behind it and be the cheapest easiest option..the 383 being more expensive of course than a 2,000 dollar tow build on the 350.......

Hope this helps some in making your descision......

there isn't any thing about that vehicle that makes sense---just stay at home-----

An idea that is worth considering is look for a Ford E350 van with the 7.3 diesel and fix it up some---it would have what you need for towing and between the van and trailer you could get by----

Originally Posted by jerry clayton

there isn't any thing about that vehicle that makes sense---just stay at home-----

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now what there is funny

Originally Posted by jerry clayton

there isn't any thing about that vehicle that makes sense---just stay at home-----

So Jerry, ya' think there's a reason the whale only has 40k miles in 30+ years??

Yep---gas got over $.50 gallon and people quit driving

Seriously--these vehicles were put together at the minimun of every thing--they were loaded to gross figures with the M/H stuff and there was no extra capicity in weight carrying, towing or braking capibility---

They were wind hogs at anything above 5 mph and were quite often banned from limited access highways because of winds

It is the wrong vehicle for anything but occasional short trips to keep the battery charged and the rear end gears lubed

Jerry, why don't you tell us how you really feel about these land barges?

It isn't about these land barges---its about taking something that is grossly under what weight carrying/towing /braking ability that he needs and then completely re-engineering it still another level of power/fuel economy that will still be inadaquate----

about all on that vehicle that is up to the task are the headlights and wiper blades--maybe the steering column----

the change to a heavier engine will require heavier front end components---brakes, rotors, springs/shocks, tires and wheels

the change to the rear the same plus a different housing, wheels/tires---

and after all that , it won't have a frame strong enough to pull his trailer, plus the balance front to back would be a night mare

Back in the 70's I usta' build those things. Jerry is right. In a wreck they pretty much disintegrate. My first job at 'Bago was running the drill press drilling holes in the 1'' X 2'' thin wall tubing used to build the "box" that is the motor home. A little stamped aluminum skin on the outside, foam insulation between the tubes & paneling on the inside and there you have it.

insulation????? how about making an ice cream truck???

I think the insulation was just to muffle road noise and the creaking sound the 1''x2'' frame made going down the road.

Jerry not to take a stand about M/H's.I set the scene for you.We're running 9.90 at the Empire Nationals.The rig we got is a M/H and a 24' enclosed trailer.You know what it is like at a national event for the "sportman" classes.It's a wk taken up and you hurry up and run a round,then you wait and wait and wait some more for the next round.At that track is always rains once during a event like that.So we are looking like it is going to rain and we put the car in the trailer.We're setting in the M/H to watch what looks like Curie,Larry and Moe with a open trailer and a Ford truck.(don't know their names,so the three stooges names works for me.)There out there in the rain trying to put on a car cover.We watch this for about 20 minutes is a real down pour.They then crowd themself soaked to the skin in the Ford truck looking like they aren't having too much fun.They are sleeping in a tent too.Looked really bad the next day.All this is going on while we are eating our hot lunch and drinking our hot coffee at less than they paid for track food.The next day my partner tells me we are going to race those guys next.I turn to him and tell him lets take them out of their pain.My partner saids you read my mind.Yes we sent them home winning another round.

We over all the yrs have had M/H's Jerry and as long as we used the load leveling bars we have kept for the whole time,we haven't had a issue towing up to a 28' trailer.We do travel abit too.Currently M/H less for that,but never excluded that for the future.

I would really like to get back to the posts about the 350 that is there and what I could do for that.I am busy moving into a new rented 1/2 pole barn.I'll try to posts some ideas for that maybe tomorrow.I want to also explain a bit more about the diesel.Like there is a heavy duty front spring option for this chassis.I have considered that.


Jerry,hands down I respect the heck out of you.So I am asking you for your help as well.Thanks Bud.

Jerry-I am going to tow a dual axle 12' trailer that at most would be 5,000lbs.