72 base 350 4 spd. car. Its got a cam, don't know the specs but its lumpy. It provides enough vac to run the brake booster. I think there is some head work done but still runs like a low compression engine. No pinging even when hot, engine spins easy even when hot. Not sure of the HP output. Maybe an extra what? 40 HP max with cam, intake and ignition updates? Trying to quantify the heat output.
It has a new OE brass/copper pin mounted small block rad. No AC. 2" thick core. Steel barrel type shroud, new fan clutch. All seems proper for my model. It cannot keep itself from overheating. The temp hits 210 and then continues upward till it pukes or stops idling/starts hard starting. I've added the missing shroud seals, adjusted the shroud and then added a 13" electric pusher fan offset to the drivers side (the side the shroud does not cover). And....it continues to overheat. The electric fan now delays how long before overheating, that's all. Ran her around with the ambient temp around 88. On the freeway no problem although when I make a few full throttle passes, even on the freeway, the temp will rise above the 180 thermostat temp, then drop back to 180. After around town driving, the temp rose to 210 plus and I nursed her to the freeway. Even then, with the electric fan running she only dropped to like 200 after 3 miles at 55 MPH. It probably would have come down to the 180 if I stayed on the freeway. It should have dropped quicker.
So, tell me if the sounds right, with the above info, I do not believe its an airflow issue but rather a radiator issue. Not enough BTU loss through the core. The freeway trumps the fans. They are overcome I've read above 35-40 MPH. Unless the water pump aint flowing or the rad is clogged....not sure what else could be the issue other than the rad. I'll check the plugs again but she's not pinging, even when hot. I doubt is a lean out issue. Thoughts? Sorry for the long winded rant. Dave


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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

210 degrees is not overheating for a C3.  If it doesn't go any higher than that I would think you're ok.  Normal for a C3 small block should be in the 180-210 degrees depending on the individual car and equipment.

Yea, have you replaced the thermostat?  They are pretty cheap.  Also the fan clutch may not be working right, is it old or have you replaced that too?  Do you have the plastic chin spoiler extension (the black part)?

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As far as the engine work, the pistons are standard and system does not show any signs of increased compression...which would be the main cause of increased heat (from milled heads). Its a Edelbrock performer intake paired with the Edelbrock repro q-jet made for this model year. Its all reasonably matched. Mis matched bolt on's may make the car run crappy but really won't give you a heat issue unless its leaning out or creating a lot of cylinder pressure...which neither exist.
Cap is new, thermo is new and tested, the fan clutch is new (its even Delco correct). Radiator is new (PO installed). There is no air in the system (I recently drained it to swap replace the thermostat) I added the chin spoiler. At 210 throttle response drops and a tick or two above that it may die at idle and become hard to start. So for this particular car anything above 210 is unsafe. The carb may be overly sensitive to the heat...it does have a nice thick insulator under it.


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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

Let me start by saying I'm an idiot. I'm just throwing things out there. Are you sure it's overheating and not the fuel lines getting too hot? That would/could explain the lousy idling and restart after temp reaches a high. One other thing, how about running the car with the rad cap off to see what kind of flow you're getting? Do you have fire insurance? It would be a shame to have to collect the insurance money and have to look for another birthday present! Remember, I did say I'm an idiot.

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Dave C..........My mantra: I can not be bought!!      Long and short term leases available.

Hey no prob Dave. Ya it has flow. I have the external overflow so when I changed the thermostat I burped it with the cap off and watched the flow. I just measured my rads core....I think the rad is possibly wrong for the car. The actual core is 18" wide by 15" tall. that is very accurate. Overall width is 23". It appears about 4" too narrow for the core support and a tad short...maybe .75" as its not coming close enough to the top baffle. I'll post pics tomorrow. 

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

 No pinging and easy to start hot......sounds like it needs more ignition advance. Retarded timing will make it run hot and  not ping.....just a thought....

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Joel, how much hotter? I was wondering if I need to advance mine a couple of degrees.

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Dave C..........My mantra: I can not be bought!!      Long and short term leases available.

Depnds on how much the iggy is retarded. 5-6 degrees will make a big difference. And folks, DON'T trust yer timing lights....the harmonic balancers(nor the timing lights) are not always 100% accurate, even when new. Best way to set timing is with a vacuum gauge connected to full manifold vacuum. You want the highest vac reading you can get. Ben(cthulhu) can elaborate more on it, but ever since he originally posted his method of setting timing using vacuum years ago, that's the only way I've done it. Once I get the thing set right like that, THEN I connect a timing light just to see where it is on the marks, and then I can use that as a starting point from then on.
Retard the timing on yours, and then run the engine at high/fast idle for a few minutes....see if the exhaust pipes at the manifold don't turn cherry red....

HERE'S one of Ben's threads on timing lights, and they're uselessness.....and info on how he uses vacuum to set the timing.


|UPDATED|5/19/2014 9:03:54 AM (AZT)|/UPDATED|


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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Just a thought I think you posted the electric fan was  pusher. The fan should pull the air through the radiator.

My timing is set at 17* using an adjustable timing light.  I use full manifold vacuum, not ported or the TCS solenoid.  Factory says 4*.  Definitely try advancing your timing.  Drive it, if it pings on hard acceleration, back it off a bit and test again.

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13" Electric fan is mounted on the front as a supplemental to the OE mechanical in the rear. With anything thicker than a 1.5" core pushers are more effective at passing air through all that resistance.
Timing with a light is at 14 degrees. But I'll read up on the vac system of timing. If I build an engine I'll typically put a degree wheel on it and timing tape the balancer. 
I'm starting a new thread with pics of the rad. I think its the wrong model.

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My Christmas present to ME! Bought Sat 11-30-2013. 72, 350 4 spd, Silver with blue interior...Can't you just hear Pablo Cruz playing in the background?

Joel be the man!!!!   I have set timing solely by Vacuum and use the timing light only to get a "ball park" reading. If you set timing with a vacuum gauge you would be more accurate along with being sure your valves are opening and closing correct.If you get a "bouncy" needle you have a incorrect valve or adjustment,just be sure to have your vac advanced is closed off and you are connected to straight vacuum source,i.e. intake manifold vac or at least straight off the carb(UN METERED PORT).You will advance timing while increasing vacuum from what you have now ( abase number i.e.10 inch hg.)to a larger number.If you have a big cam you may not get more than 12 -15 hg. and if you can get to 16-17 in.hg. you are looking good,however you should have to decrease your throttle linkage (idle screw) to your desired idle RPM.Once you have your curb idle down where you want it then reconnect vacuum advance line.       

On the heating problem;  I had the same scenario with my '80 and subsequently had to take it out and have it severely cleaned and have not had a problem since.It seems as it sits around it precipitates the inorganic solids i.e. Ca,Mg,etc and reduces the available resident time for the water to allow it to cool properly. Also when I refilled my radiator/engine I filled with distilled water,ran the engine for 10-15 minutes to be sure all the "hose" water was gone,drained and added desired coolant to radiator until full,installed 16 lb. cap to radiator started it up and idled for 15-20 minutes allowed it to cool until next morning with the cap just sitting on opening of radiator to allow any air bubble to escape overnight then top off radiator and the check next two days to see if will take more coolant,assuming you don't have a leak.As you can tell by this manuscript I have done this a few times in my life..Take car and good to great luck.