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Old 05-16-2022, 07:48 AM
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One thing to remember is that early GTO's have a significantly smaller radiator vs. later years. The early core area is roughly 401 square inches and later core is roughly 476 square inches. That's 16% more frontal core area alone.

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Old 05-16-2022, 08:34 AM
alanmay0 alanmay0 is offline
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what should the in the hole clearance be ? I am using vacuum advance. It was plugged when i was setting the total timing at 31 "per butler" after setting the total at 31 I plugged in the vacuum. I am using a quadrajet carb.

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Old 05-16-2022, 08:37 AM
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I will get the ac car rubber flaps etc that come on a ac car. keep in mind that i have not used the ac yet, only to test it, because the car runs too hot to dare turn on the ac.

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Old 05-16-2022, 08:51 AM
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I have vacuum advance and it works off of manifold vacuum. total timing was set wtih initial + centrifugal after setting total i connected the vacuum advance to manifold vacuum. so i first set the initial timing at say 12 the zero out the timing light and then add 35 degrees advance to the car and then connect the manifold vacuum advance . just trying to understand the process. yes the fans are 2800 cfm each. i do not recall the rubber flaps on the fan shroud but i will check to see. I do plan on going back to the 7 blade clutch fan with the shroud when i get this overheating problem figured out. problem is i am out of things to try. I had another GTO that had factory ac so I am aware of what and how I need to get all the air flow through the radiator and not around it. Even that GTO ran somewhat hot but nothing nothing like this one. I will try the valve at tdc thing to see if my cam timing is where it should be. thanks for all of your suggestions and help. one more thing what about the guy who posted that i needed a water restrictor in the water heater line to slow the flow of hot water back to the water pump inlet??

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Old 05-16-2022, 09:29 AM
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Alan,

At what rpm did you get 35° total?

And where did initial end up after setting total?

Need to use a piston stop and verify TDC mark on the damper. If its off/slipped, your timing specs don't count.

Clay

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Old 05-16-2022, 10:05 AM
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Let me clarify. Just as everyone else who is trying to help with tips regarding timing, divider clearance etc.. I was trying to help too. I’m not saying that the lack of the restrictive heater hose fitting in the head is THE problem but could be a contributing factor to the rising temperature. Whatever is causing the coolant to be 240 in Alan”s case isn’t being helped by a higher volume of already heated coolant (through passenger side of block then head) being returned to the pump (timing cover 3/4” port) which does not go through the radiator but instead gets fed right back into the block again. Alan may even have the OEM fitting in the head for all I know so my “tip” is moot.

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Old 05-16-2022, 10:10 AM
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Originally Posted by alanmay0 View Post
I have vacuum advance and it works off of manifold vacuum. total timing was set wtih initial + centrifugal after setting total i connected the vacuum advance to manifold vacuum. so i first set the initial timing at say 12 the zero out the timing light and then add 35 degrees advance to the car and then connect the manifold vacuum advance . just trying to understand the process. yes the fans are 2800 cfm each. i do not recall the rubber flaps on the fan shroud but i will check to see. I do plan on going back to the 7 blade clutch fan with the shroud when i get this overheating problem figured out. problem is i am out of things to try. I had another GTO that had factory ac so I am aware of what and how I need to get all the air flow through the radiator and not around it. Even that GTO ran somewhat hot but nothing nothing like this one. I will try the valve at tdc thing to see if my cam timing is where it should be. thanks for all of your suggestions and help. one more thing what about the guy who posted that i needed a water restrictor in the water heater line to slow the flow of hot water back to the water pump inlet??
x2 on not needing a restriction in the heater core lines, with or without one it shouldnt change the temp the engine runs at. im not sure on older cars but for 2nd gen 70-81 firebirds there is no control of coolant flow to the heater core, the heat from the heater core is controlled by a flap in the heater core housing that controls how much heat is sent into the car.

looks like youre getting some good suggestions on this thread & the other one you started, hope you can get it figured out out.

a suggestion for you on these threads to keep the questions & answers more efficient & easier to keep track of, is to use the "quote" button when you reply to a specific question.

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Old 05-16-2022, 10:29 AM
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My dad told me, when I was very young, that you can run the heater to help out if your car is overheating in traffic. Might make you a little miserable. You could see if that makes a difference when it's running hot. Might give you an indication of if you are bypassing too much coolant.

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Old 05-16-2022, 10:52 AM
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Quote:
Originally Posted by Cliff R View Post
"Butler is old school, and I believe we had a discussion on here where it was mentioned he's not a fan of vacuum advance"

Per Rodney Butler last time I sent a carb down there and they called up wanting me to send bigger jets because it was too lean on the dyno when they were running in the engine:

"we don't use it".

If you are NOT using vacuum advance then you don't understand it. Last time I looked it was 2022 and we should be a LOT smarter at this point. Even so there are a butt-ton of folks stuck in the 60's that still think than putting light springs in a distributor to get ALL the timing in right off idle makes up for not having vacuum advance.

You are still MISSING a lot of timing with these mechanical advance only distributors, so loosing a LOT of combustion efficiency and you are going to have to burn a richer mixture to keep things happy.......FWIW.

As for the overheating issue here, I covered it in the last thread when I ran into the SAME thing with a 400 build decades ago. It had those POS 8 valve relief pistons on it, they were nearly .050" in the holes at TDC. That is NOT a friendly set-up when it comes to running hot/overheating.........FWIW......
So true. I've had so many people through here that aren't using it, and complain about all the classic things. "Oh it gets horrible mileage so I don't drive it much" "It runs hot so I can't go far in it"

I take one look and there is a vacuum can just sitting there with no hose, or in some cases they don't even have a vacuum advance can.

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Old 05-16-2022, 11:03 AM
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This discussion has me thinking about heater control valves. This one is cheap. I wonder if it can be used to control flow like a ball valve. Or is it only designed for open or closed.

https://www.summitracing.com/parts/fss-84706

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Old 05-16-2022, 11:08 AM
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I really don't think there is anything there to be found.

I mean if the OP really wanted to test it really quick, just take a pair of channel locks and pinch the heater hose closed and see what difference it makes.
I know where my money would be.....

If heater core water flow were really an issue, then all my junk here should be overheating

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Old 05-16-2022, 11:11 AM
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Quote:
Originally Posted by JSchmitz View Post
This discussion has me thinking about heater control valves. This one is cheap. I wonder if it can be used to control flow like a ball valve. Or is it only designed for open or closed.

https://www.summitracing.com/parts/fss-84706
says its just a shut off valve to stop the flow of hot water to the heater core for improved A/C function. but im sure if it was only closed half way it would restrict coolant flow. not sure how this would change the temp of an overheating engine though?

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Old 05-16-2022, 11:23 AM
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Quote:
Originally Posted by Formulajones View Post
I really don't think there is anything there to be found.

I mean if the OP really wanted to test it really quick, just take a pair of channel locks and pinch the heater hose closed and see what difference it makes.
I know where my money would be.....

If heater core water flow were really an issue, then all my junk here should be overheating
I agree. Just kinda thinking out loud and throwing it out there as general FYI on the subject. I might add one. I like the idea of keeping the heater box cool during the summer. My car doesn't have A/C

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Old 05-16-2022, 11:27 AM
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Having my heater core hooked up to use as a additional small rad has save me at least twice from having a full boil over when a thermostat was sticking!

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Old 05-16-2022, 11:29 AM
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Quote:
Originally Posted by 78w72 View Post
says its just a shut off valve to stop the flow of hot water to the heater core for improved A/C function. but im sure if it was only closed half way it would restrict coolant flow. not sure how this would change the temp of an overheating engine though?
I was looking at the threaded stem. Thought it might be a double seating plunger or gate that would need to be fully closed or open. It looks like there is a packing nut on it. So should be able to be in the middle.

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Old 05-16-2022, 11:44 AM
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Never had a car withA/C, so no valve.

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  #57  
Old 05-16-2022, 12:41 PM
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one of these was on my car when i bought it. I thought it was some sort of aftermarket flow restrictor so i took it off. when i was younger us kids would use these to cut off water to the heater to stop heater cores from leaking. could not afford to replace the heater core then.

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Old 05-16-2022, 12:43 PM
alanmay0 alanmay0 is offline
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yes i have done this each time i have taken the car out. the temp coming from the heater is well 200 degrees. hot hot hot

  #59  
Old 05-16-2022, 02:03 PM
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A cooling system isn't that complicated, and besides the e-fan (and that's a maybe), it sounds like your's is up to the task. I can't understand some of the complicated and McGuyver-esque measures some people take to keep their motors cool, even with the higher horsepower.

I'm with everyone else in that this is probably a tuning issue, and agree 100% that you should use your vacuum advance. If your total timing all in is at 31 and you're not running vac advance, that's a major issue when you are at cruising RPMs. Adding in a vacuum advance is one of the simplest things you can do that will probably either resolve or dramatically improve this issue, and they make pre-calibrated vacuum advance cans or adjustable ones to give you the exact amount of vacuum advance you want, when you want it. Lars Ulrich from the Corvette community even made a table outlining all of the exact specs of the aftermarket vac advance cans so you know exactly which one to buy, since the statically-calibrated ones are usually more reliable than the adjustable ones. Bottom line is, if you're running a street motor, you're leaving many driveability aspects on the table by not using vacuum advance, including engine temp.

And I'm betting going back to the stock shroud and upgrading to an HD fan clutch will help your low speed or idle overheating issues. A Cold Case radiator should have been *PLENTY* of radiator to cool your engine.

If the above measures don't correct your issue, that's when I'd start suspecting internal build problems such as cam timing, a cavernous piston quench, or maybe compromised cooling pressure. Who built your engine? And do they have experience with Pontiacs? Did you personally witness or oversee them putting in the water pump? I'm aware that the divider plate situation with the pre 1969 engines is a little more complicated than like on an 11-bolt. I can see how somebody inexperienced with Ponchos may mess up on that.

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Old 05-16-2022, 03:07 PM
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Originally Posted by nUcLeArEnVoY View Post
and agree 100% that you should use your vacuum advance. If your total timing all in is at 31 and you're not running vac advance, that's a major issue when you are at cruising RPMs. Adding in a vacuum advance is one of the simplest things you can do that will probably either resolve or dramatically improve this issue, you're leaving many driveability aspects on the table by not using vacuum advance, including engine temp.
Quote:
Originally Posted by alanmay0 View Post
I have vacuum advance and it works off of manifold vacuum. total timing was set wtih initial + centrifugal after setting total i connected the vacuum advance to manifold vacuum.
he is using vac adv.

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