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Old 01-28-2018, 04:31 PM   #51
hjewell2
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Re: Overheating issues

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Originally Posted by BigMike View Post
Yes, had a standard thermostat in it before trying the high flow. Thought the high flow would help since I have a high volume water pump. Made no difference.



Once I get all the parts to hook up a regulator I will re-tune and adjust the carb



The few colder days we get in Southern California it runs awesome! As long as the temps stay under 210 it does awesome. When it starts creeping over that then it's no fun anymore. Last time I drove it after having both fans come on at low temps it seemed like over 45 it did fine, but I got in slower traffic and had to drive at 40-45mph and it started getting hot again. The fan controller is set to turn off the fans at 45. It gets hot fairly quickly if I am just sitting in traffic and not moving much (again, result of living in SoCal) Both fans are pullers.

I have nothing but issues if the temps here are 80+ (which is most of the year) no matter what speed I drive



I really wish I knew the answer to this, if I did I wouldn't be here asking for help. I've owned muscle cars and trucks for nearly 40 years and have never had this problem on any other vehicle. Or if I did I was able to fix it easily. I have been fighting this for several years. I built my son a 72 Nova for his 17th birthday. We put a 350 in it & he has nearly the exact same setup as I do with the intake, carb, radiator and fuel pump. We put in a single 15" fan and it never overheats. Why I am having so much trouble with the truck is beyond me.
I hope you find a cure for this, I have the same exact problem on a 1980 Malibu. running a 160* T-stat and new rad new pump, electric fan and shroud and runs at 210 or higher Never had a chevy do this until now, new eddy carb runs just as hot when the quad was on there ETC ETC.
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Old 01-28-2018, 04:52 PM   #52
BigMike
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Re: Overheating issues

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Originally Posted by hjewell2 View Post
I hope you find a cure for this, I have the same exact problem on a 1980 Malibu. running a 160* T-stat and new rad new pump, electric fan and shroud and runs at 210 or higher Never had a chevy do this until now, new eddy carb runs just as hot when the quad was on there ETC ETC.
Take a look at this video I ran across while researching my problem. https://www.youtube.com/watch?v=cadNfSNi_Oc

After I saw this I started looking more & more into vapor lock, heat soak & boiling fuel in the fuel lines, really was an eye opener for me. All of the symptoms were exactly what I was dealing with. May want to take a look and see if this may be your problem as well.

Also, do you have a spacer between your carb & manifold? I had put one under mine a while back, helped it a little but didn't solve the problem. A lot of people have said it had fixed their "hot" carb issues. It's called a phenolic spacer, but don't get an aluminum one, get a plastic or composite one. Aluminum will still allow the heat to transfer from your manifold to carb.

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Old 01-28-2018, 07:13 PM   #53
hjewell2
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Re: Overheating issues

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Originally Posted by BigMike View Post
Take a look at this video I ran across while researching my problem. https://www.youtube.com/watch?v=cadNfSNi_Oc

After I saw this I started looking more & more into vapor lock, heat soak & boiling fuel in the fuel lines, really was an eye opener for me. All of the symptoms were exactly what I was dealing with. May want to take a look and see if this may be your problem as well.

Also, do you have a spacer between your carb & manifold? I had put one under mine a while back, helped it a little but didn't solve the problem. A lot of people have said it had fixed their "hot" carb issues. It's called a phenolic spacer, but don't get an aluminum one, get a plastic or composite one. Aluminum will still allow the heat to transfer from your manifold to carb.

Yes I used a summit brand 1 inch plastic spacer. eddy jetted on rich side and timing is 12* 36 total not including vac advance
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Old 02-17-2018, 07:59 AM   #54
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Re: Overheating issues

So here is my follow up. I initially purchased -6an line and fittings to run the fuel lines. I had a question about the Aeromotive regulator so I called Aeromotive tech support and ran it by him. The first concern he had was that because I would be running an Aeromotive Stealth 340 pump that I might not be able to get the psi down to the 5psi I was after. He suggested going with a bigger -8an line and fittings. So I bought all new -8an lines and fittings (and returned the -6an stuff) and went to work plumbing and wiring it up. After I got it all buttoned up I took it out for a short test run...no problems, no leaks. The next day I took it on a 45 minute run and drove it hard to try and get it to replicate the issues I was having. Not one single problem! Every light & stop sign she purred like a kitten! It ran better than it ever had before. No more idling really low & funny like she wants to die at stop signs. I have already had her out on several longer runs, longest was 1.5 hours and she runs & idles perfect AND she doesn't seem to be running hot anymore either. I can't get it past 194 degrees, granted it's only been in the upper 70's and low 80's here lately, but before the upgrade it really didn't matter the temps before she got hot and ran like crap.

Here is what all I bought.
Aeromotive Stealth 340 in tank pump with Boyd's mount (matches the tank)
Aeromotive universal Regulator
Russell -8an Pro Classic II black braided fuel lines
Russell -8an fittings
Edelbrock fuel pressure gauge
Misc clamps and hardware.

Last picture shows everything hooked up. Nobody makes an Edelbrock carb bracket to mount a fuel regulator (that I could find), only Holley, which didn't fit. So I fabricated something quick, which I will eventually make a better one. Also, need a 90 fitting to tuck in the feed line that's over the valve cover, just haven't done it yet.













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Old 02-17-2018, 08:30 AM   #55
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Re: Overheating issues

Looks good . Got the fuel line away from the heat .

So in the end the fuel was getting very hot and causing the carb to run hot and lean and causing the engine to run hot because of the lean condition and then vapor lock and shut the engine down until it cooled off enough to cool the fuel to restart .

Its always nice to fine the smoking gun .

Time to drive the wheels off that thing .
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Old 02-17-2018, 05:16 PM   #56
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Re: Overheating issues

Interesting, I was begining to think it was a heat soaked distributor or module unit.
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Old 02-19-2018, 09:00 PM   #57
gvw5400
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Re: Overheating issues

I am glad your new fuel lines/ routing has helped the issue!
My .02 cents worth, based on my issues with the same problem is alcohol in the fuel.
My truck had similar issues until I found a source of alcohol free premium fuel.
No hot idle / dieing issues at ALL after changing fuels. This was on a 350, eddy 600, eddy performer RPM intake, no pressure reg, stock chevy fuel pump. Ethanol sucks !!!
All the Best, Dirk
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Old 02-20-2018, 01:11 PM   #58
68gmsee
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Re: Overheating issues

Interesting diagnoses for sure. In the past I've seen and had several overheating issues caused by various failures and I've had vapor lock issues but never vapor lock causing the overheating. That's one for the books.

Thanks for posting solution.
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Old 02-20-2018, 08:35 PM   #59
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Re: Overheating issues

Thanks for the follow up and great write up!

I have a similar issue with a SB in my Nova. I was leaning towards a fuel system upgrade anyhow.
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Old 02-21-2018, 02:30 AM   #60
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Re: Overheating issues

One thing I've learned throughout all this, fuel systems are a very important part of good running motor. Most people can get away with using a factory setup. Some (including myself) run into problems, for whatever reason, with the same stock setup. I kept chasing down the overheating part not even thinking it could have been fuel related. We get these vehicles and right off start upgrading this & that, bigger carb, better heads, larger radiator, etc... But aside from upgrading the stock mechanical fuel pump we never really pay much attention to the fuel system. I always focused on the compression and spark side of things and never gave a second thought to the fuel delivery as long as it worked. There is a whole lot more to it than I thought...and now I know

I am happy (now) that I was able to find the issue and resolve it. Could not have figured it out without the help of you guys here on the best Chevy truck board! Never had these problems before so going forward I will have a better idea if I run into this issue in the future.

Funny thing is that my son's 72 Nova, which sits at my house and drive now & again, has a 350/350, same carb, same intake, same distributor, same fuel pump, similar radiator with a clutch fan and has never got hot?!?!?
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