71 350 running hot coolant backup up problem

[Gregski]

OK, so back to the Timing thing, I did some more testing and I found that the vacuum can on the distributor was kaput, did not respond to my vacuum pump at all, so I decided to replace it with a Crane Cams adjustable one just because that's what I had in my pesky inventory of junk

It appears that the new can is good for an additional 14 degrees of timing so 12 degrees initial plus 14 vacuum advance (since I am hooked up to manifold vacuum) gives us 26 degrees, so where is the other 10 coming from? (edited 2/9/2017)

whoa additional 14 degrees for a total of 36* at idle that's allot! or that's too much? remember this can is adjustable so we can adjust it, and we need to start somewhere, so this is a start

now before we start WWW III arguing over weather to use Ported Vacuum or Manifold Vacuum or Vacuum at all, LOL I will take the truck for a test spin

[Gregski]

ok, guys here are the results of the first test drive

195 Thermostat, running water only, 12 degrees initial timing

as you can see we were averaging over 200 still, here I caught it at 201* F degrees close but a bit hot for my taste

[Gregski]

ok, guys here are the results of the second test drive, this is for everyone insisting I run Coolant

195 Thermostat, running 50/50 water coolant mix, still 12 degrees initial timing

as you can see we were averaging over 200 still, here I caught it at 206* F degrees so technically it was running even hotter with the 50/50 mix, but I did not expect any improvement with coolant since it does nothing for the operating temperature it just shifts the freezing/boiling points, but that's a common misconception

[GASoline71]

Originally Posted by 54blackhornet

Gary, how’s those scars doing ?

Scarred for life!

Originally Posted by Gregski

195 Thermostat, running 50/50 water coolant mix, still 12 degrees initial timing

Try a different gauge.

Try a different radiator.

Gary

[Andy4639]

Have you checked the cap?

[Gregski]

Originally Posted by Andy4639

Have you checked the cap?

yes and it is a brand new cap

[Gromit]

Not sure how much I can quote Mr. Ray and stay within fair use but here are a few of his good thoughts on this topic and hopefully this is enough to help:

"Notice that the OEM GM advance has an addition to the pull pin that passes through the advance mounting bracket, a section of rubber hose is covering the pin, through the mounting plate. This rubber tube (stop bushing) is there to both cushion the advance at full degrees stop, and LIMITS STOP degrees down to the correct specification for that advance/engine application.
These rubber stops usually degrade over the years an engine goes through running the bushing against the stop slot, and engine heat cycles, chemicals that get under the distributor cap, and can disintegrate, and/or fall off the pull pin, eliminating correct degree stop.
The after-market advance shown does not have any stop on the pin, as they are NOT supplied with the advance, and, when used thus, gives far, far too many degrees of vacuum advance for the application."


All I can say is I've researched this enough to satisfy myself anyway - not trying to convince anyone here. I agree with you about starting world war three on manifold verses ported.. LOL I just liked the way Dave Ray thinks on this topic and his advice has worked for me.

[Steeveedee]

There are a myriad of advance chambers, with different strokes and vacuum actuation requirements. I disagree with Mr Ray.

[Gregski]

Originally Posted by Gromit

Not sure how much I can quote Mr. Ray and stay within fair use but here are a few of his good thoughts on this topic and hopefully this is enough to help:

"Notice that the OEM GM advance has an addition to the pull pin that passes through the advance mounting bracket, a section of rubber hose is covering the pin, through the mounting plate. This rubber tube (stop bushing) is there to both cushion the advance at full degrees stop, and LIMITS STOP degrees down to the correct specification for that advance/engine application.
These rubber stops usually degrade over the years an engine goes through running the bushing against the stop slot, and engine heat cycles, chemicals that get under the distributor cap, and can disintegrate, and/or fall off the pull pin, eliminating correct degree stop.
The after-market advance shown does not have any stop on the pin, as they are NOT supplied with the advance, and, when used thus, gives far, far too many degrees of vacuum advance for the application."


All I can say is I've researched this enough to satisfy myself anyway - not trying to convince anyone here. I agree with you about starting world war three on manifold verses ported.. LOL I just liked the way Dave Ray thinks on this topic and his advice has worked for me.

I hear you, thanks for sharing but aint that what the tiny alan wrench is for to twist and turn the adjustable vacuum pod to adjust the vacuum to your liking, as opposed to the non adjustable OEM can which lacked that feature?

[Gromit]

Originally Posted by Gregski

I hear you, thanks for sharing but aint that what the tiny alan wrench is for to twist and turn the adjustable vacuum pod to adjust the vacuum to your liking, as opposed to the non adjustable OEM can which lacked that feature?

Yes but remember you are only affecting the rate of the vacuum advance portion of your total advance with that Allen trim screw. So let's say your vacuum advance will deliver up to 20 crankshaft degrees of ignition advance. You have set 12 crankshaft degrees of initial advance; so now you're POTENTIALLY up to 32 crankshaft degrees; and then your centrifugal or mechanical gives you another 24 crankshaft degrees beyond that, if you don't limit the vacuum actuator that would potentially be a total of 56 crankshaft degrees ignition advance.. way too much.

(note I have zero experience with the HEI)

I know what you are thinking and it does make sense that if you turn the Allen screw of the vacuum pot so that at your max idle 21 Hg it is only giving you a known amount of advance - but I think it is not recommended to depend on that - and I think that is why Crane also makes the adjustable stop plate and the stop plate and adjustable pot are meant to work together.

I feel bad bringing up timing if it hijacks your original overheating problem and there are such good posts already on this forum from people far more qualified than me. For example Bruce88 did a whole series on timing in his build post - starting with post #712 and it is just a masterpiece of logic.

I think if you have your initial at 12 BTDC and you are sure of your TDC and balancer mark and you set it with the vacuum advance disconnected and you know there was no centrifugal advance coming in at your 850 RPM idle that should be enough to eliminate insufficiently advanced timing as the cause of your overheating.

I guess if that is all the case and it were me I might then check to see if the heat is coming from your automatic transmission rather than the motor... assuming of course you are running the trans fluid through the factory heat exchanger in the radiator

[Gregski]

the fun continues, whilst pickup up a 180* thermostat I procured a brand new filler neck jobbie since my old one was pitted, the new one not only is it chrome (joke) comes with a reusable rubber O-ring, so lets see if this one seals more better

baby steps people, baby steps

[demian5]

Originally Posted by Gregski

the fun continues, whilst pickup up a 180* thermostat I procured a brand new filler neck jobbie since my old one was pitted, the new one not only is it chrome (joke) comes with a reusable rubber O-ring, so lets see if this one seals more better

baby steps people, baby steps

Confirm the actual temp with a temp gun or mechanical gauge instead of spending all of this money on guesses.

[demian5]

Confirm the actual temp with a temp gun or mechanical gauge instead of spending all of this money on guesses.

[toolboxchev]

Check my thread on Oxalic Acid then flush with Washing Soda.

[Andy4639]

Originally Posted by Gregski

the fun continues, whilst pickup up a 180* thermostat I procured a brand new filler neck jobbie since my old one was pitted, the new one not only is it chrome (joke) comes with a reusable rubber O-ring, so lets see if this one seals more better

baby steps people, baby steps

They look good but it's not what most would prefer. The differences in metal will cause it to eat away faster in the long run.

180-195 t doesn't mean your truck will run at that temp. It's when it opens and lets the water flow. It's a good starting point but some of the cheaper ones may not fully open at stated temp it may not open til 200*
If it's a 195* stat it will see 200* easy and even more maybe before it opens fully.

180* should open a little cooler but again it's a estimate.

[demian5]

Do not care about the t stat temp, its going to run at 195 ish or 180 ish, it won't make it run hotter.

What matters if the t stat works. Looks like it does. Confirm the actual temp with a temp gun or mechanical gauge.

[Gregski]

so here are the results of the third test drive, this one is for all of you who suggested swapping to a 180* thermostat

180 Thermostat, running 50/50 water coolant mix, still 12 degrees initial timing

as you can see we were averaging in the high 190s, here I caught it at 199* F degrees this only proves now we are masking the problem instead of fixing it, how do I know that?, well my '74 truck is running a 180* thermostat and it operates at you guessed it 180* degrees year round

[demian5]

Originally Posted by Gregski

so here are the results of the third test drive, this one is for all of you who suggested swapping to a 180* thermostat

180 Thermostat, running 50/50 water coolant mix, still 12 degrees initial timing

as you can see we were averaging in the high 190s, here I caught it at 199* F degrees this only proves now we are masking the problem instead of fixing it, how do I know that?, well my '74 truck is running a 180* thermostat and it operates at you guessed it 180* degrees year round

Confirm the actual temp with a temp gun or mechanical gauge instead of spending all of this money on guesses. Your new fangle gauge and sender may be off.

[Gregski]

So what's next? Well I don't like how deep my flex fan sits in the fan shroud, so I picked up a 1/2 inch spacer to replace the stock spacer and move it back some.

I recon the proper fan/shroud position is 50% of the blades in the shroud the other 50% sticking out.

Here are the pics of what it looks like now, the photos themselves may be old but the fan position hasn't changed since they were taken.

[Stocker]

Originally Posted by Gregski

So what's next? Well I don't like how deep my flex fan sits in the fan shroud, so I picked up a 1/2 inch spacer to replace the stock spacer and move it back some.

I would throw the flex fan as far as possible and get a proper heavy duty fan clutch with a good OEM-type 7-blade fan bolted to it. That's what came on my K20 with a 350 and factory A/C. In 41 years, the only time it ran hot was when a clutch unit failed and I tried a flex fan. Didn't take me long to get rid of it and put the right one back on.

Just my 2 cents...

[Andy4639]

The fan shroud should be blocked off so that all the air pulled with the fan comes through it and not around it. The blades should be about right 50/50 but as stated a good stock fan blade will help you. Those flex fans are not for street driven vehicles and if you have AC your never going to keep it cool.
Again 180* thermastat is reading high 190's is pretty normal. It's not going to run 180* unless you do some work are buy a good aluminium radaitor.It doesn't matter what your other truck is running it has nothing to do with it.
It's a completely different vehicle.

Now if you want to swap the radiator out in both to see then yea go for it.

It wouldn't surprise me if it's the sendor for that gauge.

[demian5]

Originally Posted by Andy4639

It wouldn't surprise me if it's the sendor for that gauge.

See above.

[Gregski]

Originally Posted by Stocker

I would throw the flex fan as far as possible and get a proper heavy duty fan clutch with a good OEM-type 7-blade fan bolted to it. That's what came on my K20 with a 350 and factory A/C. In 41 years, the only time it ran hot was when a clutch unit failed and I tried a flex fan. Didn't take me long to get rid of it and put the right one back on.

Just my 2 cents...

Well finally got to replace the flex fan, not for a clutch fan, but for the good ol' 18" four blader!

Not going against your advice it's just what I had laying around the workshop, and my '74 runs peachy with one.

[demian5]

Originally Posted by Gregski

So what's next?

Confirm the actual temp with a temp gun or mechanical gauge instead of spending all of this money on guesses.

[Gregski]

Originally Posted by demian5

Confirm the actual temp with a temp gun or mechanical gauge instead of spending all of this money on guesses.

These are not guesses, I am proving hypothesis, some people said its because I am running water, well I already had coolant so I tried it with 50/50, others said try a different thermostat, ok, a thermostat was only $7 bucks and a gasket was only $2 bucks, hardly any money. The $15 I spent on a new water neck was because the old one had a leak because it was pitted.

And not trying to argue with you but what exactly is a temp gun going to tell me, it will not match the temp on the gauge anyway. If I point it at the upper radiator hose it will read different, if I point at the driver metal cylinder head it will read different, if I pointed at the lower radiator hose it will read different, and different again for the intake manifold by the thermostat. So honestly and not facetiously what am I going to do with all those numbers when non of them will match my gauge.

And I know something aint right because of the lack of flow in the radiator, that's the first thing I said, it backs up.