1978 Chevy 30 motorhome

[Tannerwilliams]

Hey everyone,

I'm looking at an 18 foot Chevy motorhome with a 350 big block, I can't find any specs on the motor or chassis but does anyone know if it would be possible to dinghy tow my Jeep Wrangler?

[SoCalDesertRid1]

tatest wrote:

SoCalDesertRider wrote:

tatest wrote:
Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

I see someone far more knowledgeable has already responded! 😛

I don't remember the 366 and 572 big blocks. I'm guessing they were used in the big trucks, like the C50, C60?

366 was a truck engine, the 572 was GM Performance Parts and possibly OEM to some boat builders.

Thanks, Tatest.

I've seen the Chevy big block built out to beyond 600 cu in, by race engine builders like Kieth Black and Rodeck.

[Jarlaxle]

SoCalDesertRider wrote:

tatest wrote:
Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

I see someone far more knowledgeable has already responded! 😛

I don't remember the 366 and 572 big blocks. I'm guessing they were used in the big trucks, like the C50, C60?

The 366 (and tall-deck 427) were used in medium-duty (C50 and C5500 and up) trucks and school buses (thousands of Blue Birds were built on GMC C5500 chassis with propane-burning 366s)...I think the 427s also went into boats. The 572 is only sold as a crate engine.

[tatest]

SoCalDesertRider wrote:

tatest wrote:
Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

I see someone far more knowledgeable has already responded! 😛

I don't remember the 366 and 572 big blocks. I'm guessing they were used in the big trucks, like the C50, C60?

366 was a truck engine, the 572 was GM Performance Parts and possibly OEM to some boat builders.

[Tal_IL]

I had a 1976 26ft Class C on the Chevy Van 30 chassis. It did have the 350 engine. The previous owner towed a large boat with it and claimed it towed it fine. But, I never did any towing with it. It was very reliable. Over the 5 seasons I used it, I tracked my fuel usage and averaged 9 MPG.

[SoCalDesertRid1]

tatest wrote:
Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

I see someone far more knowledgeable has already responded! 😛

I don't remember the 366 and 572 big blocks. I'm guessing they were used in the big trucks, like the C50, C60?

[SoCalDesertRid1]

If you can find a Ford E350/450 chassis with the '95-'03 7.3 diesel, that would be a good choice to tow with.

[SoCalDesertRid1]

Chevy small block V8's-

-265
-283
-302 (used in Trans-Am racing only, not a normal production car displacement)
-305
-307
-327
-350
-383 (not a factory displacement, comes from using a turned down 400 crank and rods in a bored 350 block)
-400 (has siamese cylinders, and cooling issues from lack of water jackets between cylinders)

Chevy big block V8's-

-396
-402
-409
-427
-454
-496
-502

*I may be missing some early displacements from the 50's and early 60's, smaller than the 283. My mind is always foggy on those.

Big blocks are easy to identify. The exhaust ports are evenly spaced along the head. Small blocks have the middle 2 exhaust ports next to each other and the front/rear ports farther away from the center 2.

[Mile_High]

tatest wrote:
Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

from a sideline - thanks for that. I learned a bit.

[wolfe10]

Not sure the seller really knows what engine it has. There will be an emission sticker under the hood and you can also tell by the VIN.

Certainly, the seller can tell you the 17 digit VIN.

And, agree with advice so far-- you will not be towing anything significant with a 350 (Chevy small block).

[tatest]

Chevrolet's first "big block," the W-series truck engine, was originally as small as 348 (grew to 409 and the Z-11 427) but that won't be in a 1978, GM stopped using it when Chevrolet introduced the Mark IV (366, 396, 402, 427, 454, 502, 572) in 1966.

So the 350 is a version of the original small-block V8 (262, 265, 267, 283, 302, 305, 307, 327, 350, 400 working with combinations of six different cylinder bores and five stroke lengths). Most likely it is an LT-9 "heavy emissions" build, available only in 3/4 or larger chassis. Rated 160 HP at 3800 RPM, 250 lb-ft at 2800. Not a screamer, but design to run at full load all day. Engine code will be "M" on the VIN.

I would say you can tow with this engine, and the TurboHydramatic 400 it is most likely paired with. It is just not going to accelerate quickly, nor go up hills very fast, but should be able to handle any Interstate grades in second gear, and any grade on which you can get enough traction in first. One of the guys in our RV club pulls his 30 foot trailer behind an old G20 van with the LT-9 and TH-400, but he doesn't go very fast, usually limiting his speed to 55-60. Only problem he ever had was losing power when the rear fuel pump started failing.

Most likely limitation will be the hitch, which can be changed out, if the OEM frame rails extend to the rear of the vehicle. This is not always the case with RVs, some manufacturers extended frames, I've seen others hang the house over the back of the chassis to make some nice big storage space. But probably not in 1978.

In that vintage of motorhome, I would be looking for P30 chassis with the 454, or the Dodge chassis with the 440. While not rated for much more than 30-40% more HP than the Chevy 350 or Chrysler 360 small blocks, these big block engines were rated with at least 100 lb-ft more torque, and they got that at engine speeds about 1000 RPM lower. Won't be climbing hills faster, but engine doesn't have to scream to do it.

[Mile_High]

Might mean floating the valves, and he is probably right. Not a lot of gear selections on that old Chev, so you pretty much would have to try to keep the rpms down in 1st while still actually getting up the hill.

If its got any Carbon buildup, you'll probably be burning premium octane to keep from burning through the piston tops from pre-ignition.

I bought a 78 350 3/4 ton pickup with auto and 4.10 gears to pull my boat to Nebraska years ago. Not only could it not get over 55, it couldn't accelerate without pinging. it was just not a truck for towing, not with the big block camper specials available out there in the day. I thought I was being wise because the big blocks didn't do well on fuel, but towing that little 350 was getting 4 mpg, so it backfired.

[hipower]

rockhillmanor wrote:
You can weld whatever to a chassis to whatever weight capability. But it won't help the coach pull it! :W

I 'know' that my toad is back there when pulling the grades or even small hills. You can drive on the straight away pulling just about anything with any size engine but you'll never make it up a steep hill without it floating out with an underrated motor for what you are towing.

I don't know what you are are describing when you say "floating out", but your claim of never making it to the top of a hill is certainly not factual. Back in my youth I hauled coal with a tractor trailer rig powered by a six cylinder International engine that developed about 165 horsepower and climbed some fairly big hills quite successfully. Those loads grossed about 75,000 pounds so what we are talking about here is nothing in comparison. Granted you won't go up hills breaking the speeed limit, but to say you will never make is flat wrong.

[rockhillmanor]

You can weld whatever to a chassis to whatever weight capability. But it won't help the coach pull it! :W

I 'know' that my toad is back there when pulling the grades or even small hills. You can drive on the straight away pulling just about anything with any size engine but you'll never make it up a steep hill without it floating out with an underrated motor for what you are towing.

[hipower]

First we don't know if this unit has a single rear wheel chassis or a dual rear wheel one. Either way GM rated the chassis as a one ton chassis, just with a slightly lower load capacity.

The engine is capable of the load carrying as well as the towing, it just won't go up hills or pull away from a stoplight like a passenger car. The transmission and rear end might be the weaker links, but have certainly been used in more difficult environments successfully.

The real dilema with this situation for any smaller coach/chassis is the hitch rating and how much someone is willing to trust it. Where the dilema begins is the frame extensions added to the chassis by the coach builder. Under the best of circumstances it is subject to how well engineered it is and how good the welder was that day.

If I was serious about a unit like the one being looked at and I could connect an appropriate hitch to the original frame rails of the chassis I would not be deterred by anything else about the drivetrain assuming a supplemental brake system is used.

Opinions will vary on this, of course, but I base my opinion on a career in the welding industry and dealing with welding engineering on a daily basis.