Dmulally's Chev C20

[dmulally]

1966 C20. Got it on the road a few years ago but have never really liked it. Changed engines a few times and gearboxes too. But even if I baby the throttle it gets 23l/100kms and anything resembling a warm day sees it overheat at idle and the gearbox hate life. So out come the 350 small block and 700r4. 

It is still a fun rig in spite of the flaws and apart from wof sheets being in the pages long for stuff considered fine six months ago let alone things considered fine 50 years ago, I do enjoy using it. Being the C20 it is a 3/4 ton (a few kgs under the COF limit) and has long trailing arms in the rear with coils and over rider leaf springs for when it is carrying a load. Of which it does often. 

 

I nearly went for an Isuzu 4BE1 mainly because it had similar torque specs to the chev and one wire hookup. But I have since decided that I need to man up and put in something cooler. Seeing as I haven't been about to find a Detroit 353t, I'm going outside of my comfort zone and putting in a BMW M57 3l straight 6 turbo diesel. 

[dmulally]

Prior to the swap taking place, I had the diff fail a wof due to an oil leak onto the drum. Brakes were fine but only a matter of time before that was an issue and being a full floater, it was a pain to work on. The 4.56:1 ratio on the eaton sucked balls so out it came for a 14 bolt from a square body. It has a much more desirable 3.4:1 ratio and as it is noisy, I can give it a birthday and at the same time put in 3.2 gears. It's only a semi floater but for what I use it for I doubt that'll be an issue. 

 

I set up the Eaton on some wood blocks and used some scrap wood to set the pinion angle and the placement of the trailing arm mounts. 

 

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Then it was just a matter of screwing down the mounts onto the wood and sliding the diff left to right to get it equal. 

Then it was a matter of rebuilding the brakes with new parts and setting the panhard rod bracket. There was a bit of farting about with the the tail shaft universal joint clamps as I didn't quite know the exact year ute I got the diff from, but it's all sorted and it made driving the speed limit so much more relaxing. 

[dmulally]

So the diff was the first phase. That's all done and I'm happy with that for now. The brakes are all good as every wof place get excited about failing it for brakes only to have to find something more nefarious. Such as having to change the timber in the bed as it was too old was a new one but I did what I was told and it looks a lot better now. Plus I was able to clean up the chassis from the top and paint it with some POR15 so I shouldn't have to worry about rust there for a while.

I didn't go back to that wof shop again. 

 

 

 

[dmulally]

So that brings us up to this weekend. The fuel tank still had a bit of fuel in it and as the gauge doesn't work, I just decided to run around doing odd jobs but not before going to the local servo to fill up the jerry can in case I ran out before getting home. I gave shit to the Dodge owner that he needs to stop driving modern stuff. 

Now she sits in the unfinished workshop after having drained the radiator water onto the gravel outside. 

Bonnet is now in the up position to get out of the way and the radiator is now out and on the bench. During the week after work I'll be starting to unbolt things in order to hoist the running gear out. Not before setting the tyres to the same PSI and taking the pinion angle off the gearbox so I can use it to set the engine and box height for the new one. 

[dmulally]

So making a list of what I need to remind myself later. 

Need:

Engine
Box
Yoke with 100mm or so of tailshaft
Loom (will need to have it trimmed for standalone)
Pedal assembly with pedal position sensor
Electric fuel pump and any filters
Fuel line/s from electric pump to engine
Gearbox shifter and wiring (will likely change out)
Gearbox cooler lines
Radiator
Radiator hoses
Heater hoses (just part of them and a label so I know which ones they are)
Coolant overflow/fill reservoir
Engine mount blank plates
Stock mount brackets and mounts
Gearbox mounts and crossmember if it's easy to get out
Exhaust manifold and a few inches of the stock exhaust
Intercooler and hoses

Don't need:

Power steer pump
AC compressor
Plastic engine cover over the top of engine
AC condenser and fans

This is the car that the engine I bought came from. Heading up north this coming weekend to pick it up. 

[dmulally]

Note to self. 

 

[dmulally]

So the engine and box got picked up over the weekend from Te Awamutu. Nice town. Don't think I have ever been there before. 

The tailshaft rubber coupling looked the same as what I have in there now being commodore but sadly it's about 10mm off. Being so close, I might look at plug welding the yoke and redrilling it to suit. That is a shitload easier than having a custom tailshaft made. When I take the engine out Ill line it all up proper for a look see. 

 

[dmulally]

Evicted the 350/700r4. Can't say I'll miss it much. Sounded great and always started first kick but that's where the fun stops. Absolute slug. 

To get it out easier I take off the front wheels to have a slight rake at the front end. I'd never be able to do it and have it keep being a farm truck but lowered utes look pretty cool to me. 

Luckily the yoke only fell out once so I have a moderate size pool of ATF on the new concrete floor. Nice to see it christened. 

There is always one wire left forgotten and in this case it was the temp sender from the gearbox. Yellow wire above the shift linkage. Which was a dumb place for me to put a sensor as all it measured was the case temp. 

[dmulally]

Ready to go to it's new owner which is another 60-66 chev but a C10 instead. 

[dmulally]

She's a large engine. Bigger than the small block chev. 

Imp for scale. 

[dmulally]

Still waiting on some parts. Namely the bellhousing bolts, engine mount blank plates, and the custom loom. 

In the meantime I dropped the tailshaft off to the engineering shop I like to see what they thought. They made up a nifty pcd adapter for the coupling. I'll have a faff about with the tape measure to see where the engine will sit. 

Also whilst there I grabbed some 10mm flat bar to make the engine mounts. One side is quite offset towards the middle of the block so will need to travel forward with gussets. 

 

[dmulally]

On 21/04/2025 at 16:10, dmulally said:

So the diff was the first phase. That's all done and I'm happy with that for now. The brakes are all good as every wof place get excited about failing it for brakes only to have to find something more nefarious. Such as having to change the timber in the bed as it was too old was a new one but I did what I was told and it looks a lot better now. Plus I was able to clean up the chassis from the top and paint it with some POR15 so I shouldn't have to worry about rust there for a while.

I didn't go back to that wof shop again. 

 

 

 

Hmm some of my pics remain and some die. That's frustrating. I clearly did something wrong but not sure what as it worked for a while.