Return to ForumsReply to Thread
1972 String Ray Corvette - Hot climate running problem

Hi All I'm new to this forum - an Irish guy living in Dubai - I've recently purchased a 1972 Stingray Convertible here - beautiful car ! I've dreamed of owning a Corvette since I was 20 yrs old when visiting the USA back in the late 80's - now I have one and need to learn a bit, infact - a lot ! . The other other night I was driving on a highway (60mph) for about an hour in roughly 90deg ambient temperature (it's getting very warm now in Dubai) and the car started to bunny hop - I slowed down to 50mph, it ran ok for another 5 / 10 minutes but then got worse and eventually cut out - I had to get rescued with a recovery truck. When the recovery truck arrived 90 minutes later, I was able to start her and drive up onto the truck no problem. A mate of mine advised me last night that V8's and high ambient temperates are not paired well. That the issue might be vapourization of the fuel mixture in the manifold - a known problem when the engine block gets very hot which occurs at higher revs in a hot climate over prolonged driving. I had however been watching the water guage and the needle never climbed. Any advice / feedback would be highly appreciated. Thanks - Mike.

Submitted by: Mike O'Brien


ReplyPosted By
Hello Mike, I have a 76 Vette Stingray L82. It overheated too! I live in Florida and its hot most of the time, 75 t0 100*F in summer. Several tips for cool running: keep cooling system clean inside and out. Flush Radiator, AC condenser too! Add 50% glycol anti- freeze coolant, or more... use AC system sparingly: make sure clutch fan is working, and Most important, Pull out thermostat, gut spring and plunger from it, cut off out side faces of thermostat plate so it looks like an "H" and reinstall. check waterpump for flow ability, pop off cap and watch coolant cross flow ***Don't forget C-3 Vettes are "bottom feeders", they get their air for cooling right off the road! They will heat up from road temp, say, 180*! Keep fuel lines away from block also, insulate to reduce heat buildup. My Vette runs cool in winter months, *130+/-; summer heat , tops so far 180* F. !!!! runs great all the time no overheating. My best tip is trim the thermostat to an H! near free flow but restricts just enough to allow some heat to coolant! I never overheat or vapor lock.... No heat riser in my exhaust! removed! also & dual exhaust. A trick! you can dump/ push more air under hood by releasing hood latch and raising headlight assemblies!!! doubles air flow!!! Hope this helps! Tom Barth Thomas Barth on 7/1/2014 11:00:29 AM
Hi, Mike, Without being physically present, it is hard to say exactly what the problem is. That said, as temperature rises, the cooling system of the engine will do little to reduce the temperature of the ignition wires, alternator, carburetor, coil or anything else under the hood ("heat soak"). Notice the vents on the sides of the front fenders that are put there to try to reduce some of the heat under the hood. The fact it is a V-8 is not the issue, the issue is "heat soak". Common issues as a result of "heat soak" are poor idle quality, misfiring, bucking and diminished performance as you described. When the best plug wires get hot, their ability to insulate is diminished. Old and dried out plug wires or poorly made brands will give up as soon as they get "heat soaked". What happens is that the electricity leaks through the insulation and arcs to ground. Electricity is "lazy" and follows the path of least resistence. Later when the wires are much cooler, the engine runs smoother. A carburetor "percolation" problems (vapor lock) may also occur. Todays fuels may be more prone to percolation during heat soak since it is chemically designed to work best in a fuel injection system that is under high pressure and very difficult, if not impossible, to boil the fuel. So what can you do to try to diagnose the problem? A simple solution is to turn off the engine, open the hood and allow the heat to escape. If it starts, then you probably have a carburator percolation problem. Check the float level, bowl vent and the heat riser to try to limit the temperature the carberator endures during heat soak. If the fuel line is not like the one from the factory, make sure the fuel line is not too close to the engine. Again, does this sound familar? So what is the solution? Changing to a fuel injection system would be one solution. New plug, higher resistance, wires would be helpful. Finding a way to cool down the engine such as an electric fan which is temperature regulated may also be useful. To be on the safe side, you may also want to check out the fuel pump and filter to make sure they are working correctly. Enjoy for Corvette for many more years. Gerald Lotzer on 6/16/2014 9:55:07 AM
Make sure the heat riser is opening. Dennis Hrinda on 6/12/2014 9:00:55 PM
I had a 1969 Corvette Convertible from 1971-1973 and had this happen while giving a demo to a friend on the 350 cu. in. 300 HP performance and it just shut down. A friend who had worked on my cars for years knew it was vapor lock and simply rerouted the gas line away from the hot exhaust manifold....end of problem. I have just recently bought a 2007 LeMans Blue Corvette Coupe and no longer have that sadness of having sold my beloved 1969. Dan McCrea on 6/12/2014 8:41:37 PM
There is no reason a V8 should have any more problems in the heat than any other engine layout. Agree that the problem is probably a vapor lock which involves the fuel temp and not the engine temp. Any good mechanic should be able to help you address the problem with your vehicle and should involve insulating the carb and/or fuel lines/pump/filter from heat sources. Philip Souza on 6/12/2014 1:54:57 PM
I think you are getting a vapor lock. Replace the fuel pump and fuel filter. These should be cheap even in Dubai. Good Luck. Lou Patch Louis Patch on 6/12/2014 11:03:55 AM

Return to ForumsReply to Thread