Daily Driver Tips

[Noah96]

Hey Guys I am currently building a 1969 GMC C2500 with 4spd 350. I know these trucks aren't built for mpg, but this summer I plan on driving 80 miles a day just want to make it reliable and stay cool and keep it from overheating. Any tips?

[Barnfind46]

I have been driving my '68 C-20 every day since last November. Mine sat for seven years so it has had a lot of growing pains.If you are building it with mostly good quality new parts you should be fine. There will be a period where you are getting the bugs worked out. Mine has a 327/TH350 with 3.73 gears and gets 10 to 13 MPG.

[Coley]

I would seriously consider putting a newer 5 speed transmission in place of the 4 speed to get the extra top gear (overdrive) on it for the highway.
I know this has been done in the past...and you can always make the set up look like the original 4 speed system....no one has to know except the gas pumps.

Coley

[Benjamin]

I've been scheming something similar for a while now. Are you planning to use a 4 speed with granny low or a 4 speed close-ratio muscle car transmission?

[Stocker]

Originally Posted by Noah96

want to make it reliable and stay cool and keep it from overheating.

Make sure all the basics are covered.... cooling system needs to be in top condition.

Unless you know the radiator is excellent, have a rad. shop check it out & rebuild if needed. Install new hoses and a new water pump (unless you're sure it's good). A coolant recovery tank (and rad. cap for a sealed system) will help by keeping the radiator full at all times. Have a fan shroud and a heavy duty fan clutch, and a 7-blade oem-type fan.

[lowbucktrucks]

I would use an nv4500 5 speed if I wanted to retain my towing capacity, or you could change to a 700r4. lot to be said for an auto on a daily driver, but you would probably lose a little durability.If you have a standard 3.73, it would be like a 2.6 final drive
If you wanted a tough auto and overdrive there's always a TH400 and gear vendors overdrive, but very pricey.
Lots of options on these old trucks, and all have pros & cons.
Also, on a daily driver, HEI is awesome.
Do you have power steering and /or brakes??
Are you going to upgrade to disc (going fast is fun, but stopping is cool)
Have you considered a seat upgrade?? JY 88-97?? bench seats are much more comfy.
I love to build a good driver and so many things make a good one. Good luck!!

[Benjamin]

I agree with Stocker on the cooling system.

I drive my 1972 K10 to work everyday, but it’s only a 15 mile round trip. I also take it on a road trip about 3 or 4 times a year, the most recent from New Orleans to Houston, round trip 892 miles.

My advice would be to drive it as often as possible, that way you are more familiar with the truck and you will expose any problems and can fix them. If nothing is breaking do some preventative maintenance. If something doesn’t look right or is raggedy, fix it or replace it. Stay ahead of your repairs.

I have had my truck for 6 years now and I have replaced the following items:

starter
battery (optima Red Top)
battery cables
distributor (HEI upgrade)
thermostat
water pump
radiator hoses
fan belt
alternator (upgrade)
fuel pump (stayed with mechanical)
front wheel bearings
brakes all around
all rubber brake lines
master cylinder & booster

The fuel pump was the only thing that was broken when I replaced it. Everything else was OK, but maybe showing signs of needing to be replaced.

Overdrive is great, and I want it on my truck, but unless you are cruising at 70-75 mph a lot, you may not need it. It seems like all the guys complaining about not having overdrive are the ones doing a lot of interstate driving.

We can go on an overdrive tangent in this thread if you want to, just say the word.

[68Stepbed]

HEI ignition swap along with new plugs and wires. Set initial timing at either 10 or 12 degrees BTDC. You could spring the extra money for an HEI with adjustable vacuum advance to fine tune total timing. Between 34-36 degrees at about 2800 is what 350's tend to like. Also a spring and weight kit for the distributor so the mechanical advance opens at the proper rate to match the gearing.

A properly built Q-jet will give you the best overall driveability and mpg, even though I've personally never had one that worked properly. If you're dead set on aftermarket carburetor, my recommendation would be a 500 cfm Holley 2 barrel.

Headers wouldn't be necessary, but a decent exhaust system with either a single 3" or dual 2 1/4" will help it exhale a bit better. An H-pipe will help with torque and exhaust scavenging. Mufflers will be personal preference as far as tone and volume level, but on a stock 350, HP and torque gains between different mufflers will be minimal.

Proper gearing and tire size. As long as you keep the tire size reasonable, a 3.73ish gear would work well with about a 30-33" tire. If you plan to run 35's or bigger, 4.10s or deeper will be beneficial to offset the larger diameter tire.

Obviously, the largest radiator you can get is what you will want. Most came with a 2 core radiator, but 3 cores are available. Keep in mind the 3 core versions require different "hold downs" and rubber cushions. Make sure what you currently have before ordering any parts. Next item will be fan and shroud. No need for exotic electric fans. Just get a stock fan shroud and install a clutch fan, properly positioned with the front of the blades about an inch inside the opening of the shroud.

The only other item off the top of my head would be a power steering cooler, but that mainly depends on the type of driving or hauling you plan to do.

[Stocker]

Originally Posted by 68Stepbed

HEI ignition swap along with new plugs and wires.

Great suggestion, I hadn't even thought of that. With HEI you need larger plug wires, and stock plugs gapped at .045". Not a bad idea to carry a spare module just in case, though I have never needed it (yet!).

[demian5]

Spend money on a good, large, brass and copper radiator.

[sick472]

If you do a good job of building and breaking in your drivetrain, then all you have to do is put a big tool box loaded with tools in the truck and you won't need them.

Seriously though, extra fluids and simple parts are great to have on hand as freshly built vehicles tend to show the weak spots pretty soon after hitting the road. Mostly bolts that loosen up, leaks, hose clamps that need tightening, funky wire connections (read - extra fuses in the glove box), etc.

+1 on the cooling system being top notch and drive it a lot before committing to the daily commute.

[Noah96]

Thanks yall. I have intentions on adding power steering have a box just need a pump. It came with a HD radiator havent flushed the system but drained it and replaced it with the green fluid. Have intentions to replace plugs/wires and rearend is dana 60 max traction not sure of ratio. And going to get some tires soon hopefully. replaced hoses a few weeks ago.

[Myoldtruck]

I have the same truck as you. This is my everyday driver. Here is the short list: Gm Hei, a/c delco fuel pump, front sway bar, Stock fan shroud, 7 blade g/m fan blade on a new clutch, internal regulated alternator. I added power steering and power brake booster. What I would like to have with my 3.73 rear is a overdrive unit or switch to a 5speed with overdrive.

If your going to drive 80 miles a day, go buy a beater 4cylinder s/10 pickup, it will be your parts runner for the c/10 and pay for itself in fuel savings in no time. I drive my motorcycle on most dry days, 40+mpg.

[HO455]

One cheap MPG tip is to install a air dam/spoiler under the front bumper. If your lowered the gains will be more noticeable. Plus it generally helps with cooling by creating a low pressure area behind it. That's why virtually ever car and truck in the last 20 years has one. It was worth 3 mpg on my S10.

[Noah96]

Well I plan on driving it on a 55mph-65mph road so shouldnt be running it too hard but done some research and either have a 3.54 rearend or 4.10 because BB trucks came with 3.54 from my research. My truck orignally had 396 then owner sold engine and put a 350 in it.

[mike16]

80 miles a day? you'll go broke. better to park it and throw that money into fixin it up.

[Jrainman]

Ok My friend I have been driving my 68 everyday next month will be 2 years and I drive double that about 170 miles a day, 5 days a week , the first year I put 52k on the engine it came with. unknown 1980s 4 bolt main engine, and the only falure I had was my alt regulator,The 68had the external type regulator , I put a 308 rear in it to help keep the rpms down,if I kept my foot out of it I can get 16-17 mpg,but when you travel on interstates every Dodge Hemi truck wants to race you . a little after one year I pulled the tired unknown 350 out that never let me down and kept those hemi rams in the rearview , and I bought GM L31 crate engine bolted a fitech efi and mated that to a 200 4r and 47,000 miles later she runs like the day I installed it but never was able to get over 15 mpg but then again instead of 65 75 MPH i travel at 75-85 with that 2004r in full lock up on the interstates. Good luck and have fun

[Noah96]

Thanks Jrainman, When I go home for break from college imma check the gear tag ratio. Its either a 4.10 or 3.54 plan on finding a 3.54 to swap in if not and I have a '04 tahoe that gets around 14-17 mpg. On a few vactions when my dad had it, its got up to 20 if I remember right. I really want to drive my truck this summer so I intend on driving it easy so I can get the most mpg.

[Keystone_Hate]

If you plan on driving it easy go with a 3.07 rearend. I just had mine swapped from 3.73 to 3.07 and it's much better for cruising. Don't worry about losing bottom end torque because the 4 speed is geared so low that 1st and 2nd gear still have plenty of get up and go. I can still break the tires loose in 2nd.

As far as cooling, I run a two core Champion aluminum radiator and it runs nice and cool all the time. right around 180 in traffic or on the highway. Like mentioned above, get a quality steel clutch fan and proper shroud.

This is all in a 72 LWB with a 350 and 4 speed trans. manual steering and manual brakes, no AC.

[Benjamin]

I have 35 inch tires and at 65 mph I'm turning about 2000 rpm. I did a little math and that tells me I have 3.07 gears.

If you have a 3.54 gears, and assuming you run a 31 inch tire, you will be turning about 2500 rpm at 65 mph.

I think 3.54 is the highest gear you can get for a Dana 60
(higher gear = numerically lower = higher top speed & lower engine RPM)

This chart assumes no overdrive in your transmission.

[Noah96]

That helps me alot Benjamin, I have to get new tires for my tahoe so when I go to the tire shop Ill see what I can come up with.

Do you think Ill have any trouble stuffing 31s under the truck? Or turning and rubbing on the fenderwells?

[superhondaz50]

Originally Posted by Noah96

That helps me alot Benjamin, I have to get new tires for my tahoe so when I go to the tire shop Ill see what I can come up with.

Do you think Ill have any trouble stuffing 31s under the truck? Or turning and rubbing on the fenderwells?

My old tires were 31's, at stock height they fit fine. Now on 35's. Check out the first pics in my build thread to see the 31's. They were BFG copies and looked really nice.

[toolboxchev]

Originally Posted by Noah96

Hey Guys I am currently building a 1969 GMC C2500 with 4spd 350. I know these trucks aren't built for mpg, but this summer I plan on driving 80 miles a day just want to make it reliable and stay cool and keep it from overheating. Any tips?

The Full Meal Deal.

New Copper and Brass 4 Core Radiator
New Water Pump with stamped steel impeller
New Heater Core, preferably Copper and Brass, the common aluminum ones do not fit right.

Completely flush the entire block and cooling system prior to to install new components. That includes the 2 plugs on the bottom of engine block.

Watch out for the cheap products that do not work, EPA has forced the chemical companies to use Sodium Citrate as the main cleaning agent in Radiator Flush systems. It does not do a good job at all. ( Been there, done that ).

Install a Schrader Air Valve into your cooling system, yup just like the one on tires they make them in brass. Use pressurized air with the Radiator cap off, so you do not blow out gaskets and other high pressure sensitive areas, to force rust and contaminants out of your cooling system.

Do all this with those bottom 2 engine block plugs out and your will see the crap and corrosion on the driveway when done.

[demian5]

Make sure your heater works and can defrost the windows.

[Benjamin]

Me and all my buddies ran 31 x 10.50 on the rear of our 67-72 C10s in high school, no problem, but I had 235/75/r15 on the front. For comparison that is approximately 29" tall and 9.25 tread width. Can't remember if the 31 x 10.50 wouldn't fit on the front or it was an issue of not being able to afford them for front and rear.

The C20 is a different story, I feel like they ride a littler higher. I would ask around and take some measurements, but I would think MAYBE, just maybe, if you aren't lowering the truck you might be able to fit 31 x 10.50 on the front and (gasp) 33 x 12.50 or 33 x 10.50 on the rear. Also, I'm guessing you have a 16 inch wheel on the C20, so you may need to figure out metric equivalents.

Just like carpentry, measure twice cut once. The best thing to do is lurk on the forum and Instagram until you see a C20 with a stance you like, then get the wheel-tire combo specs from the owner.

Board member cheyenne shortstep (aka tremaynes_trucks on instagram) has a few C20s, he might be able to tell you what wheel-tire combos he is running.