1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

How’s it goin guys? I just picked up this 1970 C10 in pieces, and am lookin for a little- hell a lot of help. I went to retard the timing because it was dieseling when I would shut it off even when cold. The problem is the timing mark doesn’t look like it’s in the right spot or somethin. I gave up on the timing light, and decided to do it by ear. I got it to stop dieseling when cold, but now it’s over heating. The timing mark is about an inch or more before the tape/ readings on the crank/ pulley. So running at it’s best it’s not even within the measurement marks. Is my distributor in backwards? I’ve been reading and reading, and have found that timing, and clutch adjustment have direct effects on engin temp. As well as radiator size, and I’m pretty sure I’ve have the origanel radiator. Also, it looks as if the thermostat is open because the upper radiator hose is hot, but I can’t ever see it come into effect with the temp sensor. I don’t know how to adjust a clutch’s free travel, but I’ve been watching youtube videos so I’m going to give it a shot in a little bit. Actually, this is my first time trying to do the timing too, but I’ve watched a couple videos and read the instructions that came with the light.

O and I wanted to add that I read about air pockets in the coolant systems of new engines, so I tried leaving the radiator cap off and bringing the temp up to 215 to 220, but it never blew the air out so I shut her down. Does this actually work? Is there a better method?

The truck doesn’t like going into first or second, and kinda grinds when going into first sometimes. The transmission was recently rebuilt and a ten inch clutch was dropped in too.

Here’s a couple pictures or the truck how I got here, and now that she's back to gether with new wheels, tires, and windshild. I can take more if it helps out. I was thinkin about taking some video with the timing light going so I could show how off it is. She has the 1969, 350 4 bolt main.

Any ideas!?!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

I can probally help you out on your shifting proplems as my truck is also a 4 speed...check your clutch pedal bushings for wear... also you should have aprox 1 inch of clutch pedal free travel....check your clutch pedal stop bumper should be around 3/8 of a inch thick.....after all the years of owning my truck it has always been a bit tight to getting into first.....how is yours going into reverse!! lot of times mine will not go in so I let the clutch out then in again and it goes into reverse....with a slight grind....same with first....get a buddy to check out under the hood at the cross shaft lever... while the clutch pedal is depressed...check for play...I would check these all first before adjusting the travel on the push rod....hope this helps.....nice truck you got there!!!!!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Thanks for the reply man. I don’t have a clutch pedal stop inside the cab, and right now I a little over two and a half inches of travel. I could only see one bushing and it could probably use replacing. I did notice that the bar/shaft connecting to the engine is off it’s rest/ bushing which is probably because the nut on the other side of the arm closest to the frame/fender was put back on without a washer. That’s the spot that has the bushing for sure. Here are a couple pics. In the last pic it looks like there’s two marks were it had been adjusted before. Should I just put it back?

My revers is decent, but I have a habit of throwing it in to 5th (in my 91 mustang) because it doesn’t have a sincro for revers. Still it’s better than 1st and 2nd. Sometimes it plane wont go into second so I have to clutch it in third. I don’t have a buddy around today, but I will check as soon as I can.

Thanks again, and back at yea about the truck!!

Also, I picked up a new 160F thermostat and installed it. Then picked up vacuum tester to try and adjust my timing as a buddy told me a timing light wouldn’t work for a performance cam that I don’t know the specs of. I adjusted my distributer to the middle of the green on the gauge, loosened my throttle linkage to lower the ideal, and it’s still over heating. I think I’m done for the day!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Are you not running a fan shroud? In a 4 wd the engine sites back further and that flexfan ain't gonna cut it sitting still.
Does it cool better running down the highway?

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Here is a pic...and yes you are missing the lock washer...and this places it in the correct location back in the slot and stops the stud...frame side... from turning as you tighten the 3/8 coarse thread nut...it has two tabs you bend over once the nut is tight to lock it

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

I couldn’t put it down.... I re-adjusted the timing with the vacuum tester, and now my idle is a little better.

Boog,
The guy I bought it from wasn’t using because the fan matches all the hardware. I figured if it worked for him, it would work for me. I was going to try throwing it back on just for the added benefit. And, yea it runs about 185- 190 down the highway now that I just adjusted the timing a little better I think. It didn’t seem to be rising nearly as fast after a messed with it a little more, but it still hit 200 when I parked it. Do you think the fan shroud will help a lot?

My buddy told me to set it right above stall, and then to try it up a hill with some throttle. Then to listen for the soft knocky/chirping and then to advance it a little when I got there. I heard the noise when driving which was good, but I haven’t advanced it yet because the engine was damn hot!! The other noise I heard that I wasn’t expecting was what I think was the belt chirping when I first started her up and gave it some gas. After the initial startup, the belt doesn’t chirp anymore. All in all, the truck ran a lot better and shutoff without running on/ dieseling witch was pretty nice!! Next is the fan shroud that will hopefully help her out a little!!

What’s the normal operating temperature for one of these trucks anyways?

Anybody else have any thoughts?

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Chrisler,
Thanks for the pic! Is the ball inside the shaft there? What should I ask for at the parts store as far as one of those lock washer tab deals? Also, the shaft is supposed to be resting on mount connected to the engine correct?

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Yes the ball inserts into the shaft....here is a pic of a spare unit layed out...left side is the frame side....right side motor side and yes it does mount to a plate attached to the motor ....I would check with your GM dealer for the part....or the wrecking yards....as this is where I got this spare one....good to have!!!! I will try to find a exploded diagram for ya!!!!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Damn man, you're on it!! Thank you!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Boog,
I should have added that this started on my way back from getting a new windshild. In just a little over three miles the temp went up to 250! I didn’t even notice until I got home because I one- wasn’t expecting it to overheat, and two- I was so pumped up on the new exhaust!! I didn’t mention that before.

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Here is the exploded diagram Doublestack....theres a few more parts in the assembly that I did not have time to find in the garage...now you got me going...Ha!!! anyways hope the pic works out...I missed the plastic cup bushings 2 of them,,,retaining wire clip and the felt...which you have.. as seen in your second picture....The reason I know a bit about these parts is one hunting trip....this all fell apart on me....not nice back in the bush...next time you find a standard shift truck in a wrecking yard grab these parts!!!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

NICE!! Stoked on that- thanks again man!! You sound like me- I can’t put things down once I get goin!!
I hear yea on breakin down while hunting, and that would suck!! I’m trying to get this girl ready for bow season at the end of the month, and I think I’ll be able to swing it too. I know where one of these trucks is that I can pull parts from. The only question is, are these still on it.. That would be killer if they were!!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

I installed the fan shroud, and now the truck stays around the 185-190 rang. The clutch fell apart on me before I had a chance to address it. Luckily, it was in my drive way while I was revving the engine. The zbar wouldn’t mount correctly, so I drilled a new hole, and had everything else welded shut.

The only thing is when the clutch linkage fell apart my engine started to die. At that point I didn’t know why, so I started advancing the throttle linkage to keep it alive. Now the best I can get it after messing with it is so it chugs along for two to three seconds and then dies. Me pumping the gas seems to have no effect. Anybody got any ideas?

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

Hey!! Nice talkin to ya!! Looks like you've got a nice elk huntin truck! Hope it gets sorted out soon so that you can pack it full of gear and get out there!

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

I was having the same heat issues and timing issues too. I went ahead and pulled the dizzy and re-stabbed it. It might have been off by a tooth, but its better now. No overheating, but still runs a little hotter than my 71. I'm still not happy about the timing, but like yours, the timing light is useless on it. My timing marks are way the hell out there. I think the next thing I will try is advancing all the plug wires one hole on the dizzy and re-timing it.

Re: 1970 C10, 4x4, 4 speed overheating/ clutch adjustment
 

BMERDOC,
Thanks for all the help! I still haven’t got it going consistently. When I get it started it runs until it warms up and then it dies. I hit it with the timing light again before it died, and it was still way off. Now I can’t get it started again. Stoked you like the tuck though man.

Red71Cheyenne,
It’s cool to know I’m not alone on this, but that sucks you you’ve had problems too. I guess I should fallow your lead and pull my distributer too. This is driving me crazy! I’d like to know how you make out though that’s for sure. Thank you for posting.