Restoring Rusty

[Gregski]

here I'm just trying to show you that the water reaches to the very top of the thermostat hole, so it really don't matter how deep by stat is, but the point is that there is / was no air pocket

[Gregski]

as I said earlier, the rubber seal that came with the thermostat would not allow it to seat properly in its little hole/opening so I had to reluctantly revert back to my "Poser" chrome water outlet as they call them, it comes with a recessed rubber ring and requires no gasket, that part I like

[Gregski]

well with the new thermostat it was more of the same the truck ran hot, after 30 minutes we were in the red (or what would have been red if the gauge hadn't faded, lol)

[Gregski]

so I peeled off the Magnaflow sticker off the back window my buddy Mike put on to prank me, and that Welders one as well, that one was on there for 40 years and it took me 2 years to finally get rid of it, then I washed that glass, and had a few beers...

ah a clean canvas, that's more like it

[Gregski]

then I had a few more beers while Rusty sun bathed

[Gregski]

folks, sometimes you have to walk away from the problem to have that Eureka moment

so I got to thinkin', why does my truck overheat now when it didn't overheat before this project, I mean I know the heads are different, I know the intake manifold is different, but what else

hmmm, remember we used to run the heater core and now we don't?

Well, we are blocking off the port on the intake manifold and we are blocking off the port on the water pump, what if we STOP blocking them off and run a bypass hose as a happy compromise?

and so we did just that

Note: we had to run the hose 5 foot high to prevent it from kinking, hey its a temporary solution to test a hypothesis, the zip ties don't hurt either

[Gregski]

now running the bypass hose was harder than I made it sound, first of all the hoses are of two different sizes, the smaller one is 1/2 inch I think the larger is 3/4, which means the nipple fittings are different, the one in the intake manifold is smaller than the one in the water pump which is bigger

so I had to go to the parts house and get another 3/4 aka bigger fitting figure I better run a larger hose than a smaller one

but the two fitting sizes were only my first problem

Where do I put the water temp sensor if I have to dedicate its current hole/port to the bypass hose fitting?

Well aint there another port on the other side of the intake manifold? Why yes there is, it is directly under the upper radiator hose and the sensor won't fit

So I considered getting another "Poser" chrome water outlet, one that points straight forward rather than to the driver side, but that would mean getting an upper radiator hose pre bent the same way, etc

So I found that the 1972 water outlet has a port right in it for the water sensor, but they were out of stock, ok how about the 1981 water outlet ($7 bucks) it has not one but two ports right in it, AWESOME, we can screw in our water sending unit right into the thermostat housing, how interesting, problem solved

Note: Eventually if I get super geeky I will run both the old and the new sending units off of this water outlet and into two separate gauges and stare and compare their readings, should be fun.

[Gregski]

well Good News with the heater bypass hose the truck no longer overheats, the gauge sits just barely to the right of center (wish those notches had some numbers like 180*F or 220*F, etc.)

here it is after 10 minutes and again after 30, which would have overheated by then without the bypass hose, I kept driving hard for an hour (twice the normal overheating time ie 30 mins) and no problem the needle did not move

after the truck cools I wills see if it needs to be topped off with water as there was some water loss during the bypass hose installation

Remember: Key to proper troubleshooting is making one change at a time and one change only, no matter how tempting to do other things. Then reading the results and deciding on whether to make another change, etc.

[hatzie]

Originally Posted by Gregski

folks, sometimes you have to walk away from the problem to have that Eureka moment

so I got to thinkin', why does my truck overheat now when it didn't overheat before this project, I mean I know the heads are different, I know the intake manifold is different, but what else

hmmm, remember we used to run the heater core and now we don't?

Well, we are blocking off the port on the intake manifold and we are blocking off the port on the water pump, what if we STOP blocking them off and run a bypass hose as a happy compromise?

and so we did just that

Note: we had to run the hose 5 foot high to prevent it from kinking, hey its a temporary solution to test a hypothesis, the zip ties don't hurt either

I would put the temp sender in the intake manifold not the water neck. If the thermostat doesn't open you could overheat before you get a trouble indication.
The threaded hole you plugged directly under the radiator hose on the LH front side of the intake is a good location or you could drill and tap the unthreaded boss next to the heater hose.

[Troy Sr]

Originally Posted by hatzie

I would put the temp sender in the intake manifold not the water neck. If the thermostat doesn't open you could overheat before you get a trouble indication.
The threaded hole you plugged directly under the radiator hose on the LH front side of the intake is a good location or you could drill and tap the unthreaded boss next to the heater hose.

What he said. This is a good spot for the sensor.

[Gregski]

Originally Posted by hatzie

I would put the temp sender in the intake manifold not the water neck. If the thermostat doesn't open you could overheat before you get a trouble indication.

Yes I concur, I am not a big fan of where the sending unit sits now.

Originally Posted by hatzie

The threaded hole you plugged directly under the radiator hose on the LH front side of the intake is a good location or you could drill and tap the unthreaded boss next to the heater hose.

I plan on getting a forward facing water outlet so that I can install the sending unit on the driver side and clear the upper radiator hose. Not a fan of putting any more holes in that intake. ha ha

[Jaysonb]

Why not put the water temp sending unit in the head? I noticed that the temp sending unit on my 80 4.1 was 3/8 npt.

[y5mgisi]

I dig the new look.

[68Timber]

Originally Posted by rich weyand

I *added* a second high-beam switch to the left of the original, but this one is momentary. I connected it to the contacts on the windshield wiper cam. When you push the switch, the wipers run. When you let off on it, they finish the current swipe and park. No more rooching around on the dark dash looking for the wiper switch while driving one handed in the rain.

I love home spun upgrades like that.

[hatzie]

Originally Posted by Jaysonb

Why not put the water temp sending unit in the head? I noticed that the temp sending unit on my 80 4.1 was 3/8 npt.

Not as simple as you think.

The 3/8" NPT tang senders have a different resistance range than the 1/2" NPT Nail Head senders.
You could swap in a matching 1979/1980 or later temp gauge along with the 3/8" NPT tang sender.

[hatzie]

Originally Posted by Gregski

Yes I concur, I am not a big fan of where the sending unit sits now.



I plan on getting a forward facing water outlet so that I can install the sending unit on the driver side and clear the upper radiator hose. Not a fan of putting any more holes in that intake. ha ha

Looks like there's enough clearance right now.

[Gregski]

Originally Posted by hatzie

Not as simple as you think.

The 3/8" NPT tang senders have a different resistance range than the 1/2" NPT Nail Head senders.
You could swap in a matching 1979/1980 or later temp gauge along with the 3/8" NPT tang sender.

Exactly

[Gregski]

Originally Posted by hatzie

Looks like there's enough clearance right now.

not really, that pic is deceiving

[Gregski]

New Clue: truck will not idle below 750 RPM, even with the idle speed screw all the way out, timing set at 12* BTDC

[Gregski]

OK, back to basics

went out and bought a Vacuum gauge at NAPA for $25 bucks this should help set the idle mixture screw on the Holley 4160 carb

so following a Super Chevy article (love that magazine) we set the idle to 850 RPMs that should give us a stable vacuum reading

[SkinnyG]

That sucks.

(gufaw, gufaw, gufaw, hyuck, hyuck, hyuck)

[Gregski]

so we hook the timing light up and the vacuum gauge to a non ported manifold vacuum off the base of the 4160 carb and the needle won't sit still, it jumps spastically between 15 and 20 PSI, see video

we bottom out the idle mixture screws one on each side of this carb (it only has two) and then turn them out 1.5 turns as per Holley's instructions

than we play with them screwing them all the way in slowly then backing them out to about 2.5 turns, and that pesky needle keeps dancing and won't stabalize

https://www.youtube.com/watch?v=ry9ShldWpUg

[Gregski]

so at this point I am thinking vacuum leak, so I disconnect anything that may be sucking vacuum, brake booster, PVC, etc. and plug those ports up with some spare hoses and bolts in them to clog them up, still no change, needle keeps dancing

so I remove the carb and notice I got a 1/4" spacer but it ain't sandwiched between base gaskets, (not sure if it must be, but something tells me it ought to should) so I shoot over to the parts house and buy 3 different types of gaskets (two of each)

a 54

a 55

and a 57

hey, who knew? right?

[Gregski]

Now Silver-hair was by this time very tired, and he went downstairs to the garage, and there he found three Holley carb gaskets. He tried the largest one, which belonged to the Big Bear, and found it too big; then he tried the middle-sized gasket, which belonged to the Middle-sized Bear, and he found it too small; then he tried the smallest one, which belonged to the Little Bear, and found it just right, so he laid it down upon the intake manifold, and put the carboretor on it

[Gregski]

well Donkey Kong, even with a single brand new base gasket between the intake and the carb (no spacer for now, keeping it simple) we got pretty much the same results

so then we found this Holley video - it claims an ignition problem, check spark plugs, plug wires, distributor, and coil



How To Diagnose Common Engine Problems With A Vacuum Gauge

https://www.youtube.com/watch?v=NrnzD7PgoHI