'75 C30 Dump Truck "Betsy" needs new engine for hauling

[JoeK]

Hi everyone,  I'm an amateur driveway mechanic and I love my old work trucks because I can actually work on them myself and they don't have a bunch of electronic crapola to frazz out on me.   

So here's the story on my '75 C30 Dump Truck, I won't bother keeping it brief, cause that's not why your reading this is it?  Sorry if I ramble I'm trying to get this post up not make it perfectly organized.

Been my daily work truck since last year, though I've owned her (Betsy) for a few years now she spent her early years hauling a load of manure every week or two when I was making compost for my veggie farm.  I made the dump box myself(8Wx12Lx4H) when I bought her from a construction background there were short, wooden stakesides. I've replaced the brakes all around and various accessories in the engine bay, fuel pump, power steering, hydrobooster, fuel tank etc.  Truck has a "3" spd manual (3+granny) and a PTO gear for the hydraulic dump cylinders.


Now I'm operating a Tree Service and this beauty is working hard for me on the daily.  I added a big tool box on top of the cab, another panel to the sides so they are now 6'H in front. Hauling a lot of wood around, loads of chips, a 5K lb chipper, crap ton of tools, etc.  This truck weighs 8k lb empty when I leave the dump.  My job tomorrow will be hauling ~4-6 ton of cactus to the dump. I normally will haul 2 tons in the box at a time and she seems just fine with that.  First I need to haul the 12k lb tractor to the job site, only ~3 miles.  Moving the tractor is pushing her I think, I don't take it far from home, or very often, but it pays well to drive the tractor so why say no to work close to home if I can get it there?

Now for the bad part.  Bad Compression in two cylinders as tested by my real mechanic who works on lots of equipment.  He thinks rings, said he sprayed a little oil in the bad cylinders and it improved compression temporarily as if it sealed up around the rings for a few strokes.  One cylinder is especially bad. Failed emissions first try in January and I had a nasty fouled plug, replaced the plug and then passed emissions.  Engine is a 350 SBC i think. no idea if it's original or not but that is what she came off the line with. I do know the Rochester Carb is out of a mid 80's G20 van. I've rebuilt the carb and ran the numbers off it.

She usually gets ~8-10 MPG I think.  the 350 generally has enough power for my taste, even with the bad cylinder(s) except when I pull the tractor. Like I said hauling the tractor(12k lb) is about all she can do, if I have to start on any slope it SUCKS, other wise its not too bad starting off on flat ground, just slow going.
So I'm on the lookout for a replacement engine and I'm thinking about upsizing since I am doing a lot of hauling and I also have a property my sister bought that needs tractor work done ~50 miles down the highway so I'll be hauling the tractor back and forth occasionally and there are hills involved.
This is is Southern AZ too so it gets hot, I'll only make that trip when it's cool out early mornings though.

What do you all think I should put in this baby? I've been thinking maybe I should find/rebuild a 454 from the era.  I know that swap has been done to thousands of trucks so I can find out what details need to be adjusted for bolting it up.

Then recently I came across a possible local deal on one of these newer 8L 488's https://gmpowertrain.com/engines/8l-lfi.html
That seems like it could be an awesome engine, but how hard would it be to swap it into Betsy?

Any other good ideas?  Should I just rebuild the 350? I can find one already built and swap it out without taking the truck out of commission more than a couple days, which is nice since she's my money maker.

Can I swap in a 350 from an '87 G20 van? I think it should have TBI in '87? don't know much about TBI I know my way around a carb OK.  I WOULD love the efficiency of EFI if I could make it happen somehow I'd probably put up with the extra electronics...

I'll hit post on this and then see if I can get some pics up real quick before I get to work. sun is up and we're headed for *101 today...

[JoeK]

Hopefully I can get these pics to show up....
Thanks in advance for any input.


Joe

[JoeK]

ok I think I got the pics

[JAH]

Where to begin(?)…


Man, first, I wanna' say that I'm MADLY in love with Square Body duallies.  So, posts like yours automatically give me a warm-fuzzy.  Goodonya' for still working with that classic beast!  That truck was MADE for that.  And, I bet the 70's and 80's Engineers at GM would be proud of you.

Second...being the grandson of a Farmer, and the son of a late-in-life Rancher...I've been towing and hauling most of my adult life (and much of my childhood).  So, I definitely have some opinions on the matter (albeit mostly "anecdotal").  If my post seems a bit condescending, forgive me.  I'm just thinking out loud. 

First off...Gearing.  Gassers need cogs to keep 'em in the "meat".  And, the deeper the better.  That's just the nature of the beast.  If you're not in the 4.10 to 4.56 range, that should be one of your first issues.  Being that your truck looks like an 84" cab-to-axle chassis (to my eyes), you're probably already there.  I think the early trucks ('73-'80) have the RPO info under the seat.  If you can't find the info there, a simple removal of the rear diff cover will reveal the tooth stampings on the ring and pinion. (*This would also be the time to put some good 75W140 full syn gear juice in the rear diff...especially important when you're dealing with the possibility of 101* heat in April.)

It seems to me that you're already operating well above the Manufacturer's suggested GVWR and GCWR.  The good news is that you're not the first, and that I honestly believe that these trucks were horribly under-rated, and wayyy before their manufacture date.  My main concern wouldn't be getting the load moving, but getting it STOPPED.  If you're getting it stopped with no issues, you should be good (*Read- "Safe").

As far as the engine, I can tell you that "torque is torque".  The difference (in my humble opinion) is how it's produced.  For the most part, the big blocks make their torque right off the bottom (a lot like a diesel).  Therefore, you don't have to wring 'em out to get to the meat.  Imagine two rock-crawling vehicles engaging an obstacle.  The one with the small block will have to build the revs and dump the clutch, whereas the big block equipped vehicle will just have to lightly engage the power to address the same obstacle.  Why does this matter?  Well, every piece of hardware on the small block vehicle (clutch, diffs, u-joints, etc.) will have to absorb the added revs of the small block.  Advantage...Big Block. (*In my humble opinion)

The period-correct GM big block (LE8/454) is a great engine.  It was rated at 360 pounds of twist. (*For comparison, the venerable [and often-overloaded] 1st Gen, VE-pumped, 12V Cummins was rated at 400)  The LE8 had the Cummins on horsepower, though...230 vs 160.  A double-roller timing chain, and "RV cam", really make the LE8 a formidable powerplant.  In my humble opinion, I think it would make you smile.

If my two LE8s should ever give-up-the-ghost, I hope to have the $$$ to replace 'em with a "roller" big block GM crate engine (HT502 for me).  But, being that that the HT502 is a $7K engine, I wouldn't think twice about another LE8 (or L19, if I could figure how to make a "fuelly" work for me, a lot like you). 

Lastly, I have two friends who build (and rebuild) big block General engines to pay their mortgages.  And, neither are fans of the 8.1L General.  Because I'm not versed in engine-speak, I will not even TRY to attempt to articulate their disdain.  But, suffice it to say to say that I trust their opinions.


Happy hunting, Chief. 

[Mr Diesel]

Good advice in the post above., especially about the brakes. All the power in the world is no good to you if you don't have enough brake power to stop it quickly. If your brakes are working properly they should be adequate, and there isn't much you can do to improve that anyway (except for having trailer brakes).
If fuel mileage isn't a huge concern the 454 is a great engine. It would drop in with no modifications. A GM crate 350 is also a great option and reasonably priced drop in.
Thanks for the truck pics. I too am a huge fan of these old duallys and love seeing them still used for work.

[JoeK]

Thanks for the replies fellas.

Brakes are obviously of utmost importance, and I've replaced almost the entire system in the last couple years, excepting some of the hard lines. New Master, wheel cylinders, shoes, pads, calipers, almost everything and they're working properly.  And while the truck will stop even pulling the tractor it won't stop it fast, and trailer brakes are definitely a must as well. 

The GVWR is 10k on this truck, it's a "heavy duty" model or whatever they call it.  and it did come off the line as a cab n chassis.  I think it has a bit longer wheelbase than lighter models too. I know it has the larger brake setup, thank goodness.
I went over the scales twice today at just a hair over 10k with 1.1ton of cactus in the back, and when she's up at 12k (20% over GVWR) still feels very comfortable, albeit a little slower both stopping and going.
 I was never able to find an GCWR but I doubt it's over 20k, and I'm surely a little over 20 maybe even 22-23k when I pull the tractor. I'd guess maybe 15-18k GCWR for this model?  I plead the 5th.

The gears are probably in a good place already though I couldn't tell you any numbers, she was certainly made for this kind of duty and not for speed.  With the 3spd I hit third gear between 35-40mph and while she cruises comfortable at 50-55mph I need a good tailwind or a downhill to reach 60.
I topped up the diff, and tranny with regular ol' 80w90 gear oil and about 25% or so of Lucas.  I do want to pop the case off just to have a look in there for curiosity sake, and do a full fluid change.

Your comments RE: torque are pretty much what makes me lean towards the big block, more lower end torque would be nice when I get on a slope under load I have to downshift pretty soon to stay "in the meat" as you say. 
  I've seen a couple early 80's chevy RV's on craigslist with low mileage 454's and rough body shape for darn cheap and I think if another one comes around soon I may just go for it, could use a cheap camper out on the new property too so that would make a pretty nice two birds deal. Especially if I can just drop in the 454 as you say Mr. Diesel.  I'm not worried much about MPG, and I'm not so sure I'd even be losing much there compared to my 6.5/8 cylinder 350.  Met a guy while back with a nice c30 from early 80's and he said his 454 would get 10MPG or even a little more, although his truck was probably lighter by a thousand lbs or two without the dump body and I don't think he was hauling weight as regular as I do.

Either someone just bought up that 488 or the post finally got deleted.  Was only $2K OR MUST GO MAKE OFFER! so I didn't think it'd last. looked brand new!  Just a good excuse for me to finally ask for advice and get more serious about finding Betsy a new engine, she sure deserves it.

I know a sawyer who LOVES his 502 and he hauls some seriously heavy logs around.  "no replacement for displacement" eh?

[JAH]

Hey Joe,


I hope you don't mind me posting some more.  But, I really want to help you.  I wasn't bad at math, in High School, but wasn't exactly a Scholar.  However, when it comes to "cheating" the GVWR of trucks and goosenecks, I could be a Fields Medal winner. 

I don't know about your cab-&-chassis.  But, my '86 K30s have Dana 70HDs in the rear.  From what I've found, most "truck" guys (far smarter than I) agree that both the Dana 70HD and Dana 80 were stupidly underrated by the OEMs.  Some argue that the 70HD and 80 had true GAWRs in the 10K and 11K range, respectively. (*I do know that the 80 was offered in medium duty trucks.)  My point?  If your truck has a 70HD, it's a hoss.  If it has a 14-bolt corporate, keep in mind that that axle is no slouch, either.  It was the preferred rear axle for MANY big-power off-roaders, for many-many years.  Either way, I think you're G2G. (*My '92 W350 chassis [also equipped with a 70HD] has a GVWR of 11K, if I'm not mistaken)

Being that your truck is a chassis, I'd bet that you're probably somewhere in the 4.10 to 4.56 range, already.  If you're somewhat curious, crawl under the truck with some WD-40 and scrub any axle tag you might find.  If you're really curious, jack-up the rear tires, pop the cover, dump the axle juice in a clean container (for re-use), and mark & count the teeth on both the ring and pinion.  Just from what you've posted about speeds, it sounds to me like you have 4.56s.  Unless the 350 is having trouble maintaining the speeds, the 4.56s would be the penultimate for towing and hauling. 

Both my 454s (mated to 3.73s and 4.10s, respectively) get about 6 MPG with mix driving (city and highway).  What would you expect with a flat-tappet big block?  To me, that serves as proof that there really aren't any noticeable gains from shallow gears.  As I posted, "The deeper the better."

The "1986 Chevy Recreation & Trailer Guide" shows the following GCWRs for the 350 (5.7L)...

13.5K for 4.10s and 15K for the 4.56s

This can't be much different for your ride.  And, as I already mentioned, you're WAYYY over GCWR...especially for a clapped-out 5.7L. 

For comparison's-sake, the same numbers are 16K and 18K (on the 7.4L), for the 4.10s and 4.56s, respectively.


So...YES..."There is no displacement for displacement." (*A statement I almost included in my last post)   Getcha' a 7.4L in that truck, post haste. 



Happy hunting, Big Un'. 

[JohnnyPopper]

Nice truck, ol Betsy!

I have little to add to the foregoing except to say that for the work you're doing, a 350 is taxed pretty hard.

My '73 3+3 came with a 454 that I had to rebuild. Hydro lock, long story.

While I had her out, I installed a 'mileage cam' and buddy, between 25-3500 RPM it felt like the loaded toy house wasn't even behind me.

I did have a water injection system from the '80s so that was a factor. Used to juice up the mixture with H2O2 and Rubbing Alcohol... What a burn! 

[JoeK]

Thanks for posting Jah I don't mind at all rather I appreciate the input.  Especially glad to hear the GCWR info which is probably very similar indeed, albeit perhaps underrated.  18k seems pretty reasonable though, and yea at ~22k or so its sluggish to say the least.  had to go on some very slight slopes on the way back home last week and it was compelling me to find a big block...got a couple prospects on the radar, may go check out a 30' winnebago from '83 a few hrs away.
I'll update here when I finally get to look at the diff gears. 
Had to swap the starter out on my chipper monday morning (3.9L Cummins), shorted out and MELTED my Neg battery post.  Thought hmmm, I hear the solenoid click and a slight humm, but doesn't even try to turn over.  Either my battery is done or my starter is.  went and looked and found this... so it was both.

Took me the whole morning to find the right part and get it changed out but was back in business at noon and still managed to get my scheduled job 90% done before dark.

[JAH]

3.9L Cummins, huh?

Tonight, I'm staring at '92 12-valve 1st Gen, in my driveway, with less than 50K original miles on it.  I went and got him out of the barn today, and left my towing rig (4th Gen Ram 3500 C&C) there.

I needed to run some diesel through the pump of this ol' 12-valve...

[JoeK]

well its a bit dark but that's a beaut you've got there JAH.  Got a pal who pulls his bobcat around town with a '91 first gen w350. I think it's pretty low miles, but low like 100k or 150k.  50k original is amazing!  he gets offers on his out of the blue even though its a work truck and it looks like it.  He did offer to haul my tractor out to the new farm plot a time or two if I need the help.  Just need to buy him pintle hook and owe him a favor in return.

The Chipper is a 1987 Morbark model 200 (12" chute).  Great machine and they still stock parts for it cause apparently I'm not the only one still running one.  Just don't try to find parts at the auto store without doing your own research and cross reference part #'s. The cummins part numbers won't get you anywhere. I finally took the starter in to a starter/alternator shop after I spent over an hour calling morbark and cummins trying to get a number that AutoZone or O'reilly could make sense of.  My job was only 1/2 mile from either autostore but had to drive like 10miles to the alternator shop. Oh well it got me what I needed up and running again.

Just for kicks Here's a peek at Betsy's younger sister Sophie...She was born in '82, spent a few years at ADOT before becoming a municipal welding rig.  I bought her off the city mechanic that used to maintain her and scooped her up at the auction after she aged out of the fleet. that 8x12 flat bed makes a real sweet mobile welding and fab table. not street legal though due to missing smog pump. hydrocarbon emissions are real high too. Stock 350 and 3spd manual in her too.

[JAH]

Thanks, Joe.


Sophie is pretty sexy, too. 

I'm a sucker for a flatbed.  And, a Square Body flatbed?...fuggedaboutit. 


"Bubba" (my '92 W350) was pretty rough when I got him.  He was a brush truck...ahem, a "Fast Attack", as they call 'em up North...for the Montana "Department of Natural Resources and Conservration" (DNRC).  I paid wayyy too many $$$ for him, but thought that I could recoup my money, if I ever decided to turn him.  Afterall, he's a '92 1st Gen Cummins, with an unmolested injector pump.

Since acquiring him, I've put an "industrial" paint job on him. (*My Buddy paints for the "oil patch", and blasted and sprayed him and the flatbed in two shades of industrial enamel for me)  You can't tell from the pic, but he was about 20 shades of white/peeling paint when I got him.

I'll try to get another pic, tomorrow, in the driveway.  But, for now, here's a "teaser" pic of him getting prepared to tow the 38-horse Massey (from the Farm to the Ranch), for "sendero cleaning" duties...

[JAH]

...and I'm glad you were able to find a decent place to rebuild your 4BT starter. 

[JoeK]

Nice looking rig Jah!
I used to have a way fun little truck named Bubba. He was a suzuki sidekick 4dr, hillbilly converted into a 2dr truck with a 4x4 utility bed made out of a luggage trailer with a removable teardrop cover.  Fenders chopped off to fit 31" mudders, a real piece of work. Had the same 4wd transfer case as the sought after Samurai rock crawlers. Tons of fun to drive around the snowy roads of Colorado doing my old shoveling route.  sweet mileage too with the little 4banger.
Been all flatbeds and the dump box since then.  both these trucks could REALLY use a paint job.

So I may have a deal lined up a few hrs away for an '83 winnebago with 44k miles and a solid 454.  Hopefully it pans out. Drove a 5hr round trip with my pops last weekend to look at an '85 Honey motorhome that "fired right up" with 28k miles and when we got there it fired right up for about 1 second flat before it ran out of fuel and wouldn't pump a drop. Guy had already bypassed the mechanical pump off the motor and said he ran it two weeks before and it purred with just the electric pump at the tank but that sucker was not up to the task anymore the day we went.  Total bust. thing had been sitting for ten yrs in an rv park and was dry rot city on hoses, belts, tires etc... glad I didn't try to drive it home.