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Author Topic: Running Hot?  (Read 1909 times)
JohnZ
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« Reply #15 on: July 30, 2014, 10:00:35 AM »

<< Well I was finally able to do some checking on the underhood temps.  I drove the Z for between 2-3 miles to get the engine up to temp.  The outside air temp was in the mid 80's.  While driving the temp gauge stayed right around the first quarter marking, maybe one mark up toward the half marking.  While idling in my driveway the gauge read right at the one half marking.  The engine would not hold a steady idle but slowly had the idle decrease until the engine died.  This happened 3-4 times.  While the engine was not running the temp gauge would increase until it was between the one half marking and the three quarter marking.  This I take to be normal due to heat soak.  
Here are the temps I recorded with an infrared gun:  

radiator hose at thermostat- 183, bottom radiator hose- 164  >>

The last line above are the only temps that mean anything, and they're normal - don't agonize over all the other external temps - they are what they are, and you can't change them. You don't have a cooling problem, you have a typical fuel percolation problem, aggravated by low E10 fuel boiling points. Insulating your fuel line from the frame to the carb will help, as will an aluminum heat shield that extends under both fuel bowls. E10 fuel boils at 150*F, and at extended idle, the fuel bowls get hotter than that.

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Stingr69
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« Reply #16 on: July 30, 2014, 11:28:54 AM »

Yep - the only thing else to do is slide a stainless steel shim in between the intake and the head on the drivers side right in the middle of the manifold to block that passage.  It will help to reduce the cooking of the carburetor and fuel percolation. Only do this if you have eliminated the heat riser function.

Just go to the kitchen when your wife is not around and find a flat bottomed stanless bowl.  Cut out a flat piece of material with tin snips just wide enough to fit between the manifold bolts in the center of the drivers side. Bend a small tab over to help you push it in.  Loosten the manifold bolts just a little and see if you can slide that metal down in there between the gasket and the intake. Try not to disturb the gasket too much.  Tighten the bolts back up and see if that helps.  It worked for me when I had the percolation issue.

PS - if you go snatch the bowl when the wife is watching, you are a BOSS!  Cheesy

Good luck!

-Mark.
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z28z11
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« Reply #17 on: July 30, 2014, 09:57:55 PM »


You don't have a cooling problem, you have a typical fuel percolation problem, aggravated by low E10 fuel boiling points.


Since John brought it up, let's discuss fuel for a second - any local station carry straight (non-ethanol) gas, and/or what are you running through the motor ? I would not recommend any E10 gas for any early engine, especially one that uses neoprene tipped needles in the carb, or rubber fuel lines. Like John indicates, the percolation is a problem, plus the stuff eats everything else, and has an affinity for moisture build up in the tank. Nothing draws a vacuum worse than ethanol in my opinion. Find a race gas distributor and run 100+ octane unleaded, or blend it with non-ethanol regular to stretch it.

I would, regardless, clean the cooling system completely, especially if the motor sits for a decent while without running up to operation temps regularly. Buildups are inevitable internally to the block, heads and radiator - keep them clean and they'll function accordingly.

2 cents -
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
Vince
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« Reply #18 on: July 31, 2014, 12:46:41 PM »

Really does begin to sound more like a flow problem. Flush the system with the best product you can find, change the water pump and the thermostat. Check and/or change the cap - you need to run about 12-15 psi in the system to make it work properly. If no big improvement, I'd take the radiator out and replace with another known used clear radiator, or a cheap repop just to isolate the problem. Or, just core the old one like most of us are having to experience.

What does the coolant look like ? Dark colored, any foam in it ? Leaking head gaskets can cause hot spots/steam pockets like this. Oil clean ? Any coolant contamination ? Hoses collapsing ?

Bad flow across the radiator could also be a culprit, as we conjectured before. Bet the lower half is plugged - that's why the temp is so low in the bottom half.

One other thing - I witnessed a big block Chevelle do this once upon a time - turns out it was spun bearing (main), causing the engine to not only run hot, but choke down and die when it warmed up enough to start galling on the crank. Check your oil pressure with a mechanical gauge, and a mechanical temp gauge if you can. Just to make sure -

Regards, and good luck -

Thank you for your response.  I had the current radiator recored and a new thermostat put in 14 years ago.  The coolant looks fine, the correct color green and no foam.  The oil is very clean.  I have noticed no hose collapsing.  I have the coolant replaced every 2 years.  I'll have the shop were I usually take my Z check the radiator functioning, etc.  Sure hope it is no spun bearing or any internal engine problem. 
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Vince
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« Reply #19 on: July 31, 2014, 12:52:50 PM »

<< Well I was finally able to do some checking on the underhood temps.  I drove the Z for between 2-3 miles to get the engine up to temp.  The outside air temp was in the mid 80's.  While driving the temp gauge stayed right around the first quarter marking, maybe one mark up toward the half marking.  While idling in my driveway the gauge read right at the one half marking.  The engine would not hold a steady idle but slowly had the idle decrease until the engine died.  This happened 3-4 times.  While the engine was not running the temp gauge would increase until it was between the one half marking and the three quarter marking.  This I take to be normal due to heat soak. 
Here are the temps I recorded with an infrared gun: 

radiator hose at thermostat- 183, bottom radiator hose- 164  >>

The last line above are the only temps that mean anything, and they're normal - don't agonize over all the other external temps - they are what they are, and you can't change them. You don't have a cooling problem, you have a typical fuel percolation problem, aggravated by low E10 fuel boiling points. Insulating your fuel line from the frame to the carb will help, as will an aluminum heat shield that extends under both fuel bowls. E10 fuel boils at 150*F, and at extended idle, the fuel bowls get hotter than that.



Thanks JohnZ for your insight.  My car already had the aluminum heat shield installed when I bought it from the previous owner 18 yrs. ago.  I'll try insulating the fuel line as you suggested. 
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Vince
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« Reply #20 on: July 31, 2014, 01:00:54 PM »

Yep - the only thing else to do is slide a stainless steel shim in between the intake and the head on the drivers side right in the middle of the manifold to block that passage.  It will help to reduce the cooking of the carburetor and fuel percolation. Only do this if you have eliminated the heat riser function.

Just go to the kitchen when your wife is not around and find a flat bottomed stanless bowl.  Cut out a flat piece of material with tin snips just wide enough to fit between the manifold bolts in the center of the drivers side. Bend a small tab over to help you push it in.  Loosten the manifold bolts just a little and see if you can slide that metal down in there between the gasket and the intake. Try not to disturb the gasket too much.  Tighten the bolts back up and see if that helps.  It worked for me when I had the percolation issue.

PS - if you go snatch the bowl when the wife is watching, you are a BOSS!  Cheesy

Good luck!

-Mark.

I definitely will install the blocking shims on the driver's side intake manifold.  I know that my heat riser function has been disabled.  I am not going to take the chance of cutting the shim as you described whether the wife is around or not. She would miss the bowl even if she didn't actually see me take it.  Smiley
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Vince
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« Reply #21 on: July 31, 2014, 01:10:31 PM »


You don't have a cooling problem, you have a typical fuel percolation problem, aggravated by low E10 fuel boiling points.


Since John brought it up, let's discuss fuel for a second - any local station carry straight (non-ethanol) gas, and/or what are you running through the motor ? I would not recommend any E10 gas for any early engine, especially one that uses neoprene tipped needles in the carb, or rubber fuel lines. Like John indicates, the percolation is a problem, plus the stuff eats everything else, and has an affinity for moisture build up in the tank. Nothing draws a vacuum worse than ethanol in my opinion. Find a race gas distributor and run 100+ octane unleaded, or blend it with non-ethanol regular to stretch it.

I would, regardless, clean the cooling system completely, especially if the motor sits for a decent while without running up to operation temps regularly. Buildups are inevitable internally to the block, heads and radiator - keep them clean and they'll function accordingly.

2 cents -

I live in a small town in the Sierra Foothills in California.  There are no stations around here that I am aware of that sell non-ethanol gas.  I use premium Chevron, Shell, or 76 in it.  I'll do some research to see if I can obtain unleaded racing gas in my local area.  My car does sit every so often, sometimes up to 2 months between my taking it out for a spin.  I plan on having the radiator and engine gone completely over to check for gunk build-up.  Thanks for your info. 
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Vince
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« Reply #22 on: August 06, 2014, 12:51:10 PM »

I plan to have my smog pump deveined and the screws put into the exhaust manifolds in place of the extension tubes.  I have 2 questions:

What is the easiest or best way to completely degut the smog pump?  What do I take out and what do I leave?  I am guessing when done it will just have a rotating pulley on the outside, but what is left on the inside if anything; is there still something rotating on the inside? 

What screws exactly do I need for the exhaust manifolds?  I have read on other posts here on CRG that they should be stainless (I am guessing steel), #10 x 1/2 in., flat top.  Where is the best place to get them, hardware store or auto parts place? 

Thank you.  I really appreciate all the help from all you guys on this website.  I wish I knew more about first gen Camaros, especially mechanical wise. 
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z28z11
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« Reply #23 on: August 06, 2014, 09:49:03 PM »

De-vane the pump - the rotor spins, but doesn't pump air, obviously. Block the vacuum tube for the divertor valve.

You can use roofing nails (galvanized) in the extension tubes - seals off the extension tubes, flat surface to seal on. Drop them in, tighten the tube fitting and you're all set.

My opinion - others ?

Regards -

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1969 X66 L78 Cortez/BVT
1969 Z11 L48
JohnZ
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« Reply #24 on: August 07, 2014, 09:35:40 AM »

You can use roofing nails (galvanized) in the extension tubes - seals off the extension tubes, flat surface to seal on. Drop them in, tighten the tube fitting and you're all set.

My opinion - others ?

Regards -



That leaves both the extension tubes AND the roofing nails in the exhaust stream - I prefer to knock out the extension tubes and use the #10 x 1/2" flat head machine screws to plug the holes; leaves nothing at all in the exhaust stream.
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z28z11
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« Reply #25 on: August 07, 2014, 09:54:51 AM »

My only reason for leaving the tubes in place is the 30 degree countersink under the tube - the tube seat seals that, then the flat nail head seals the top of the tube. You could always cut the tubes/nail short if you don't want to obstruct exhaust gas flow. On the other hand, as fragile as the manifold is to work with, I would not alter the tube hole itself for the risk of either damaging the manifold or not being able to reverse the alteration (like I experienced with my originals when trying to extract tapered pipe plugs from the A.I.R ports). I have worked out a lot of pipe plugs from these things, up to and including drilling out the old plugs/fittings, and lifting leftover materials out 1 thread at a time. Nothing like spending 4-5 hours doing that on an expensive, unobtanium exhaust manifold- great for relaxation and stress relief (LOL !).

Regards -
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1969 X66 L78 Cortez/BVT
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BULLITT65
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« Reply #26 on: August 07, 2014, 02:33:55 PM »

Vince I also live in California, and as far as gasoline goes, I have learned a few things concerning the oxygenated/ethanol gasoline formula used only for California. 1) it has a  very short shelf life. If you don't go through a tank longer than a few months it starts to turn green, and lose its potency. 2) keeping this in mind you also have to observe the station you purchase gasoline from, if it is a slow station and they are not getting tankers dropping off gasoline fairly often, same result gas gets stagnate. 3) Now I cannot prove this, but I have had issues 3 times now with Chevron gasoline in older cars. I just rebuilt my carb on my mustang only to find out the fuel we just got from Chevron starting to separate, and there is like an orange jelly in the gasoline. I knew about Chevron gasoline being inferior already, but my wife thought gas is gas, filled it up there by accident. I know this may cause some people to laugh, but it has happened more than once both previous ties from Chevron in California. I fill up about a half tank at a time from a real busy Shel station here in SoCal, with 91 octane and have never had a problem.
Just my 2 cents from what I have learned the hard way pertaining to California gas. I do miss the midwest's gasoline, both Speedway and Citgo sold 93 and 94 at some stations out there, and for cheaper!
Hope this helps some Smiley
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Charley
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« Reply #27 on: August 07, 2014, 11:01:15 PM »

I would fill the tank with leaded race gas before I spent money anywhere else. Also make sure the race gas doesn't have Ethanol. I know Tognotti's in Sacramento has race gas.
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janobyte
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« Reply #28 on: August 08, 2014, 07:51:49 AM »

I run Marine Sta-bil in the boat to combat effects of ethanol in the fuel. SBC is a SBC. On mine it's fed by a low pressure pick up pump and high pressure feed for the fuel injection. These do not like alcohol. Alcohol also acts as a sponge for moisture.  Seafoam appears another popular product with the boaters.

Also is anybody rejecting their carbs? One could assume a lean condition is being created requiring an increase in jet size.
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janobyte
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« Reply #29 on: August 08, 2014, 09:07:11 AM »

Let me add ,of course having the option I'd run race fuel in the car. Always have. Total agreement.
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