69 c50
 

I posted this over a month ago apparently in the wrong section.
I'm looking at buying a 69 C50 with a small block 350, manual trans (not sure which one) and a 2 speed rear end. I have 0 interest in keeping the 350 in it. I was thinking of swapping a for a carburated big block and a 4L80E with a stand alone controller. My problem in doing this is the 2 speed rear end. The more I think about it the more I'm talking myself out of it. I would have much more torque then the 350 would dream of having but I'm not sure it would be enough to make up the gears to just run it in high. Another option would be to make the 4L80E completely manual and use low 1,2,3,4 then pop it into 4hi once I got some speed going. That sounds like a pain to me since I would be stuck in hi gear until I came to a complete stop again. Swapping rear ends is also something that is on the table too for something with a fixed gear instead of the 2 speed if there is a fezable option please let me know. Most of this truck will be one off when I'm done with it and disc brakes would be nice anyways.

I'm open for opinions on the best way to drop a big block into it with an od trans. If I do get it (I'm certain I will). It will be used to pull my wife's 72 Chevy mega truck around to local bogs and later will be used to pull a 40' trailer with 2 mega trucks (when I get time to build myself one) plus gear so 20k pound load give or take.

I've been doing a lot of searching here and fortunately the truck does have the 10 bolt lug pattern.

I'm debating an axle swap from a 4500 or 5500 truck so I would have disc brakes all the way around.

The truck currently needs a booster/master cylinder. Since they're only $500 I'm just going to replace the whole set up so I can drive it around. I will be upgrading that also down the road.

Re: 69 c50
 

ok - surprised no replies yet, so here's my perspective. I have a '70 C60 with the 366, 4spd and 2spd rear. While I thoroughly enjoy driving it, it is quite slow and tops out at around 52 mph empty. Fuel mileage really isn't worth calculating as there aren't many fuel stations that I pass by. The original brake set up works - certainly isn't like today's brake systems, but they do work. When I bought my truck I had planned to repower it with a Detroit Diesel, update the brake system to something more modern and basically feed my hot rod desires. However, after going through the truck, (it was all original ex-firetruck) I decided to pay homage to American History and leave it original and just enjoy the simplicity of it and the way things were in my childhood days. :5150: It is my go to vehicle when I just want to drive and not when I have to drive.

I know that doesn't even come close to providing any answers to your thoughts, but maybe it'll get some conversations started.

Re: 69 c50
 

I figured I'll put less then 1000 miles on it a year so mileage isn't much of a concern. It's more truck then I currently need. I could wasily buy a 1 ton truck and be ready to go but whays the fun in that. I'm thinking future plans and I love the look of it plus we already have a 72 K10 and a pull truck from the same era would be pretty cool looking driving down the road. Once I can narrow down a few things like what engine/trans I want to use which I'm leaning toward a p pump 12 valve and a G56. After having a 600 hp Cummins before they're hard to beat in my opinion.

I would really like disc brakes all the way around since I'll be pulling semi heavy for this truck later down the road. It will only be pulling around 10k pounds for the next few years. Most of which will be on the highway. Getting it capable of hitting 60-65 mph would be plenty fast enough for me.

Re: 69 c50
 

I know what you mean. As an old Hot-Rodder, some of my best cruises were in my all original 2-Ton and 3-Ton trucks.

Re: 69 c50
 

Back in 70/71 I worked at a Sunoco station in Charlotte NC and we were the maintenance center for EZ Haul truck rentals. They were all 69/70 C30 350 400turbo automatics and C50 4 speeds single speed rear ends. The C50's all had governors on them. I had to go all over the south to bring them in to work on. I always disconnected the governor and those trucks ran at 65 no problem. So it's all gearing. Two speed rears are great if you really are gonna haul stuff. Plus they are fun to drive. It takes a little skill to master them. I also owned a 54 6400 Chevy 5 window that was originally a oil truck and I put a dump body on it. It had a vacuum 2 speed rear. That was even more fun as you need to work the gas pedal to make sure you had enough vacuum for it to shift. One year I had a reason to it run from southern MA to outside of Augusta ME about 10 times. Me and my 125 pound mutt. I enjoyed the crap out it!

Re: 69 c50
 

I've done a lot of searching and reading all over the net. It seems like most don't take their trucks to the level I'm thinking. I figure this would be my forever pull truck. One thing upgraded at a time but I'm still looking for ideas and coming up with a plan. I do have the skills and the tools to do just about anything. If I don't have them then I know someone who does. I appreciate the responses so far.

I currently have a 366 at my disposal, it's in one of my wife's mega truck and that truck needs more power! That truck will be getting something a little special one day. Looking at the rated torque numbers of the 350 which is 325 and the 366 which is at 345 it's not worth it to me to do that swap for 20 ft lbs.

I'm glad to hear these things will run higher speeds but does that include the 2 speed rear end? You specified fixed gears. What rpm would the little 350 be turning at at 65 mph? I only ask because an engine swap and rear end swap would probably be the very last thing I do to it.

I assume it rides like a mule so I've been pondering weather or not to do a parallel 4 link with pan hard bar with 1-1/4" heims and air bags. I've built a few different suspensions. This would be the first parallel one since i believe it would be the best fit for the application. I'll do it to the stock rear end if I know it'll do what I want it to. Anyone done that?

I've decided I do want to stick with a manual transmission for sure. I like having control of rpms while towing.

Dumb question now... when shifting. I've driven split rear ends where the pattern is 1L, 2L, 3L, 4L, 5H shift to high 1H, 2H, 3H, 4H, 5H. That was much newer truck with a diesel. Is that the way to shift this C50 or is it 1L/1H, 2L/2H etc...?

Re: 69 c50
 

Depending on your Trans, but I would say what you have would be the 1L/1H, 2L/2H, etc as you have mentioned.

My Clark 5-Speeds with the 2-Speed Rears had the more unusual pattern:

1L
1H
2L
2H
3L
3H
4L
5L
4H
5H

On the 2-Speed Rear, your Last Gear in the Trans and Hi Range on the Rear will give you 1 to 1.

Re: 69 c50
 

Thanks for the info! Much appreciated. I would love to have an OD 5-speed. There's not too many options for it out there. A trans swap would be quick and easy. I need to do some more home work on what would be a good trans to swap into it. My transmission knowledge is very limited

Re: 69 c50
 

Those EZHaul trucks didn't have a tach so I don't know what rpm they were turning but they were fine at 65.I can't imagine it can be hard to find a ring an pinion for that. That is the trouble with old Fire Trucks. Most were geared very low. They usually are great trucks to buy. I missed buying my towns 56 FWD 1 1/2 ton forest fire truck because I had two kids in college. Some guy in the midwest bought it.
C90 Bill is right. You split each gear. Very hard to split first. Also it shifts much easier when you keep in in the mid rpm range. Don't rev it close to it's limit, it just makes it harder to shift it. When you up shift, you pull the button up while it's still under a load then just let off the gas for about 2 seconds and then apply the gas gently until you know it is engaged. When you go from say 3rd hi to 4th low, do the same but use the clutch until you get your timing down. the gears in the diff just have to be going the same speed to engage, Just takes practice.
One of my Ryder Car Carriers had an air two speed rear end behind a non synchro 5 speed. I enjoyed it.

Re: 69 c50
 

I actually looked up a YouTube video on shifting it. It is a bit different but nothing I'm concerned about not being able to figure out. Last shifting question... Is it geared too high to keep in high while driving empty? This truck I'm looking at someone has already pulled the dump bed off of, made a steel flat bed and threw a cab on the back so it's now an extended cab. That's the reason I want this particular one. I have my wife, daughter and niece who will be with me a lot of the time driving so the extended cab on it is a real selling point for me.

Re: 69 c50
 

I only run high when empty. I also start in 2nd most of the time. I can be in 3rd before pulling through an intersection at times.

Re: 69 c50
 

That's what I figured and was hoping to hear.

It'll probably be a month or so until I can get the truck home. I'm probably just going to have it hauled. A friend of mine has a semi and trailer. I appreciate all the responses guys. I'll let you know when she's sitting in my driveway!

Re: 69 c50
 

Don't forget the pictures.

Re: 69 c50
 

I have a 1979 C70 Chevrolet with 4-53T Detroit Diesel, Clark 5 speed and Eaton 2 speed rear end. Its a blast to drive, tops out at 71 MPH, however I like cruising at 65 MPH. The hydraulic brakes (OEM equipment) are fantastic, not sure why anyone would upgrade them. I think they are powerful enough to stop a train! No issues with the rotors rusting when they sit idle. The brakes are so powerful you cannot get on them long enough to see any fade. I am sure if you were coming down Pikes Peak with a load it could be a problem. I would try the brakes before deciding they need to be changed. I usually shift all five gears then pop the rear end into high. Normally I just drop the rear end into low and I can top all the hills in my area. I think spitting each gear is just unnecessary wear and tear on the the rear. I used to drive a C50 (1972) with a 350, 4sp and 2 sp rear. The 350 was a great motor and I found it had plenty of power for 200 bushels of grain (11,000 to 12,000 lbs). It was a very long life motor and got good mileage.

Re: 69 c50
 

It's my understanding that after 72 the C class medium duty trucks came standard with disc brakes at all 4 corners. Correct me if I'm wrong please. My thought was if I upgraded it would be to disc brakes. I also want to upgrade the master cylinder just for the simple fact it is a single and if I were to loose a brake like then I would loose all brakes completely. It basically gives me the warm and fuzzies to know that there is always a backup.

I will have plenty of pictures for sure.

Re: 69 c50
 

I understand regarding the single brake master cylinder. That is my only concern with my C70. I did rebuild the parking brake and use that as my emergency brake. I have tested it and it appears to be able to stop the truck. I am sure it would fade quickly, however it is an emergency backup. The 1972 I drove had drum brakes all the way around.

Re: 69 c50
 

Making sure the parking brake is high priority on my list prior to the upgrading. That way there is always a fail safe. Fortunately the truck will not be driven without a trailer with trailer brakes hooked to it often at all.

I had back surgery less then 2 months ago and it's delaying me a lot with this truck.

Once I figure out how to upload pictures I can post some of the previous trucks I built. The last one was a 53 Willys pickup that wasn't intended to be pretty at all. I ended up doing a body swap from an 89 econoline that had a 460 in it. It was supposed to be my mega truck but someone came along and fell in love with it and money poured out of their wallet... I never got the chance to finish it.

Re: 69 c50
 

He is right about not splitting each gear. I doubt you will ever have a load so heavy that you would NEED to do that. Start off in low axle and that kind of saves your clutch. Splitting the top gear is usually all you need to do. The most you should have to do is split the top two gears. Most of the time you will only need to down shift the axle to keep your speed up. I have driven these trucks with 292 6 cylinders and you have to shift more but that 2 speed can keep you in your power band much better.
As far as the brakes go, I can't ever remember thinking they were not enough. Just make sure that they are adjusted correctly. Same for the parking brake. The lever that you set the brake with, the end of it twists to adjust it. When you get to work on it, back off the the handle in the cab all the way, then go under the truck and adjust it underneath so it's tight but not dragging, then you'll have plenty of adjustment from within the cab. The parking brake is located behind the transmission, on the drive shaft. You'll see that they too are a simple form of drum/shoe setup. When adjusted properly, they work great.

Re: 69 c50
 

Thanks that's good to know! I'll take any tips and tricks anyone wants to offer. I'm trying to learn as much as possible and get a solid plan on what I'm going to do now and down the road. I know I will definatly be putting in a 5 speed trans once everything is ironed out with what I have.

Re: 69 c50
 

I never use low gear in my 5 speed. I guess If I needed to pull down a building or remove a tree it might come in handy. The C50 I drove had a 4 speed which was perfect. I never wanted more or less gears.

Re: 69 c50
 

Later I'll be moving to the mountains and pulling 20+k pounds so the extra 2 gears in a 5 speed I'm sure will make a big difference. I just have to narrow down what 5 speed it is that I will want to use.

The body on the truck is in great shape so it will be mostly a mechanical build instead of cosmetic. I do plan on putting a lot of lights on it since we do get stuck loading or unloading at night a lot.

Once it's in my driveway I will get it going and drive it around once in a while and see what I feel it needs to make exactly what I will be using it for a little better.

Re: 69 c50
 

I'm a little different.

If it has a gear, I'm using it, lol.

Although I never split the Granny gear.

Re: 69 c50
 

I would usually use all the gears also but it's depending on how everything is geared and what I was doing. I had a 91 Dakota over 10 years ago with a 5 speed no OD and a 3.9 V6 most of the time 1st, 3rd and 5th was how I shifted it. I really only use the clutch when I took off with most of the manual transmissions I have owned. I haven't owned a manual trans in a few years and I do miss it.

I do not have any pictures of the engine on the C50 but what I've been reading is that on the hood there are 2 vents for the 427, 1 vent on the drivers side and no hood vents on the small block or straight 6. I find it fishy because this truck has 1 vent on the drivers side. Either what I have read is wrong, someone put it in it or the current owner doesn't know what they're looking at. I'm trying not to bug them anymore then I have to before I can actually get down there to get eyes on it. It's 2 and a half hours from me and I'm not sure I can sit for a 5 hour round trip with my back yet. It's been almost 8 weeks since I had back surgery and I feel pretty good until I can't get up and move around when I need to.

Re: 69 c50
 

Starting in a Low Gear (not necessarily the Granny gear) is also easier on the Clutch as NewBayColony has mentioned above. The truck manuals also recommend starting in Low Range with a 2-Speed Rear, but I agree that it won't ruin your truck if you don't. Some Transmissions like the SM 420 and SM 465 4-Speeds, I always start in Granny 1st. To me 3-Speed shifting is for Manual Shift cars, lol. Seems to work, I never wore out a Clutch yet.

Re: 69 c50
 

The trucks that had a vent on each side of the hood came with the 427. The ones with a hood vent only on the drivers side came with the 366. No vents were small blocks or 6 cylinders

Re: 69 c50
 

Thanks for the replys guys! So as I learn more and more about these trucks I'm liking them more and more!

If it turns out to have a 366 vs a 350 to me really doesn't matter. I just found it odd that someone potentially can't tell the difference between a small block or a big block and wanted to confirm what I have been learning. I'll keep you guys posted on what it turns out to be.

Re: 69 c50
 

valve cover = 4 bolts on small block chevy

valve cover = 7 bolts on big block chevy

exhaust manifold = 1-23-4 ports like this on small block chevy

exhaust manifold = 1-2-3-4 ports like this on big block chevy

Re: 69 c50
 

I can tell the difference. It just poses more questions I have for the current owner. My wife's truck has a 366 in it right now so we're quite familiar with it and who hasn't owned at least one 350 :lol:

Re: 69 c50
 

Alright guys I'm still waiting on some pictures of the tires and the engine to verify that it is or isn't a 350. It is definatly a 4 speed.

Couple questions. With this setup the way it currently sits what should I expect for mph with it being nine stock?

Apparently there was a vacuum leak at some point in time so the rear is stuck in high. If I assume it's worse case and I can't fix it for a decent price right away how should I assume it will pull 10k pounds without having low in the rear end?

Re: 69 c50
 

Make sure it is vacuum 2 speed; I haven't seen vacuum switches in those years, all I've see nc are electric switched.
As for towing, I think you'll be fine, but expect slow starts.

Re: 69 c50
 

His wife did tell me "all that is there is 2 wires so the speedometer is correct".
I'm not knowledgeable enough to tell the difference between the two. Can you or anyone enlighten me. I'll be doing a lot of research on all of this over the next few days. I'm going to get eyes on it this weekend as long as our schedules work out.

Any ideas on top speed?

Re: 69 c50
 

If it is electric, there are 2 wires running to the switch on the rear end. You can ohm the wires to determine which is high and which is low. Then make sure your switch on the shifter is aligned to the right wire. Pretty simple.

I took mine out today, is a 1970 c60 with 366 and 4 speed. I topped out at 55. Possibly could have gotten more but I was happy with that.

Re: 69 c50
 

That sounds simple enough to figure out. If it's claimed a vacuum leak on an electric setup what could be the issue? More important what's a round about price to fix it? I know it's a loaded question.

55 might just work for me. Lots in question now. Thanks

Re: 69 c50
 

I've never messed with the vacuum switches. On the electric, if the wiring is good, you can probably just take it apart and clean it. I have no details on how to do it, but I've been told it is easy.

Re: 69 c50
 

Any idea what rpm you were turning while you were doing 55?

Since I have a red flag or two so far I'm starting to reconsider. If the tires are bald I'm not even going to bother is what I'm telling myself right now

Re: 69 c50
 

A little over 3k rpm. Tires aren't cheap. 20" are hard to find. Changing over to 22.5 is best, but still not cheap. A little easier if it has Dayton wheels.

Re: 69 c50
 

I believe they are dayton rims since they're 10 lug but I'm not completely sure either. A set of tires would be more then what I may be spending on the truck.

3k at 55. I don't mind cruising at 3500 or so at all so 60 might just be within reach.

Once I get the few pictures I'm still waiting for (it's cold and dark here so I don't expect pictures until tomorrow). I'll do some more searching around and learning about the rear end. From there I'll decide if I still want to take the trip to check it out. I'm starting to think it'll be a money pit. I'm ok with money pits as long as it does everything I want from the get go. From there I can upgrade over time. If it doesnt make sense it doesn't make sense. Thanks for all your input guys.

Re: 69 c50
 

The 2-Speed Rear should be Electric as a few have mentioned. Always check the simple things first. Could be just a broken wire somewhere.

I haven't fooled with tires for years, but years ago buying used school bus tires used to be a good option. They take them off pretty early. If the sizes are right.

Re: 69 c50
 

Two speed rears are usually either electric or vacuum. The old Chevrolet rears were shifted by a vacuum cylinder. The vacuum cylinder was controlled by a mechanical cable to a vacuum valve. The cable was like a choke cable attached to the shifter which you would pull up or push down. In addition they had a small link between the vacuum valve and a two speed box on the speedometer cable. This allowed the speedometer to be adjusted for hi and low rear gearing. Some had a vacuum valve mounted under the dash that you would shift left to right for low to hi.

Most of the vintage you are talking about were vacuum. The vacuum was generated by the intake of the engine. Easy to trace and fix, usually a broken vacuum hose. Worse case would be the cylinder diaphragm is busted. Either way it should be easy to fix.

Later years they switched to electric. My 1979 is electric. It has a dc electric motor that moves the rear between high and low just like the vacuum cylinder above. The motor is controlled by two wires, red and black. The two speed selector switch receives power via a green wire. It applies power to the black wire for low speed, and the red wire for hi speed. The black wire also feeds power to an electric speedometer adapter unit, in line with the speedometer cable, to adjust the speedometer gearing when in low. The motor and speedometer adapter both must be grounded. Do not apply power to both the black and red wires at the same time or you will let the smoke out of the motor and it will cease to operate.

On the electric unit, the first place to start would be the fuse panel, looking for a blown fuse.

Here is a link to my two speed rear end. I upgraded the gear ratio by changing the ring and pinion.

http://67-72chevytrucks.com/vboard/s...d.php?t=729084

Re: 69 c50
 

GM was doing electric as early as 1970