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Discussion Starter · #1 ·
Hi to all vette owners ,Its been a while since I visited smokin vette, Had a great visit to the US in september and got to the Corvette funfest in Effingham, ILL and the Corvette National Museum in Bowling Green. Anyhow finally got vette on the road but as normal I have some issues 1. Excessive heat coming through center air vents even though the hot water to heat core is shut off with a manual valve and air diverter flap is in the cold position. 2 My owners manual says that the normal operating temperature is around 230f . This seems to high ? Any help welcome. Regards Torn
 

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if your heater hose is closed with a shut-off then the heat is probably engine heat thru holes in firewall or the blower/evaporator housing ..... 230*F is not normal.. it should stay between 190*F and 210*F ... if its running that high, check your cooling fan clutch ..
 

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Hi Ian from south australia i had same problem and found on mine it was the seals around the vent flaps .i pulled out whole dash and did all vent seals and put new heat sheild on fire wall . if u contact me [email protected] can go through what i did.
but these blokes on this site probally no more than me
 

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There is supposed to be a seal along the rear of your hood. If that seal is missing a good portion of the engine's heat will escape thru the rear and get sucked into the plenum intake; raising interior temperatures considerably.
 

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Discussion Starter · #5 ·
Thanks for the help guys, Fishslayer , I run twin thermo fans as the factory fan and shroud was missing when I bought the car. I have had the dash and heater box out Ian when I replaced heater core and resealed but will look into it again . Toobroke , you could be on the money as that seal was replaced but yesterday I had a look and it appears to not be touching the firewall edge when hood is shut. I still only have the right side locking pin in place due to alignment issues with the left side.(looks like more hood adjustment is needed) My vet has a/c does it get no outside air intake when set on a/c max as my owners manual says? What do you think about the owners manual stating 230f as normal operating temp Toobroke? Regards torn
 

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Thanks for the help guys, Fishslayer , I run twin thermo fans as the factory fan and shroud was missing when I bought the car. I have had the dash and heater box out Ian when I replaced heater core and resealed but will look into it again . Toobroke , you could be on the money as that seal was replaced but yesterday I had a look and it appears to not be touching the firewall edge when hood is shut. I still only have the right side locking pin in place due to alignment issues with the left side.(looks like more hood adjustment is needed) My vet has a/c does it get no outside air intake when set on a/c max as my owners manual says? What do you think about the owners manual stating 230f as normal operating temp Toobroke? Regards torn

As far as I know it wasn't until 1984 when they started running higher temperatures and that was because of their pitiful 2-tube radiators and electric fan. For the price of a new shroud, fan clutch, and 7-blade fan I would go back to the stock fan setup. The twin electric fans puts a substantial load on your alternator. To deal with the increased amperage demands the '84's came with the larger 15-SI 70 amp alternators then went to an even larger alternator the following year.
 

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I have a 'big-block '71 with an aftermarket L-88 hood. Seeing the possibility of easily removing heat I cut the rear of the hood open; giving it 40 square inches of breathing area. During this last summer I checked my underhood temperature one day when it was 105 degrees with my A/C on and was astonished to find it was only 200 degrees after returning from a 200 mile trip.
 

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Thanks for the help guys, Fishslayer , I run twin thermo fans as the factory fan and shroud was missing when I bought the car. I have had the dash and heater box out Ian when I replaced heater core and resealed but will look into it again . Toobroke , you could be on the money as that seal was replaced but yesterday I had a look and it appears to not be touching the firewall edge when hood is shut. I still only have the right side locking pin in place due to alignment issues with the left side.(looks like more hood adjustment is needed) My vet has a/c does it get no outside air intake when set on a/c max as my owners manual says? What do you think about the owners manual stating 230f as normal operating temp Toobroke? Regards torn
it doesn t get outside air on max.. the electric fans may be your high temp problem if you are in a very hot climate.. we have several members in south Florida that have given up on the electrics and gone back to mechanical fans ...the front of a C3 is too restrictive at hiway speeds.. do you have the lower frt spoiler on the car? http://www.ecklerscorvette.com/corvette-lower-spoiler-front-1973-1979.html it is needed to direct air up into radiator ..also the seals on top of radiator are necessary too.
 

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Discussion Starter · #9 ·
I have a lower front spoiler on the way from the US , Hope that will help on the highway , Interesting that the Florida people went back to the mechanical set up . That may happen yet, Radiator and condensor have seals all round.
 

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Aluminum is not more efficient at heat transfer than copper,in fact its almost 1/2 as good... but the alum radiator can have 1 inch tubes that give more surface area to offset this and increase heat transfer ,where copper cannot....the most important things are airflow across the tubes and volume of coolant
 

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either will work fine, if large enough ..a 4 row copper /brass radiator will cool as good as any alum radiator.. if you live in a really hot climate, I would stick with Mechanical cooling fan, tho. ..where I live it gets 100-110 * in summer .. I have a copper/brass radiator with a hi-perf stainless steel flex fan... even on hot days with A/C on, in traffic, my 525HP stroker motor w/ auto trans , never gets over 180-190*F
 

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Hi Fish Ian from Australia i need to change my radiator so do u recommened aluminium or original was thinking of going alumin with electric fans should i keep original fan maybe thanx for any advise.

Ian, to avoid a LOT of complications go with a stock 4-tube brass radiator and keep your 7-blade clutch fan. Once you start changing parts to "fix" things it snowballs out of control and you will likely end up with less cooling than you had.

And copper or brass far out-cools aluminum and that's why Revere Ware has copper or stainless steel bottoms.
 

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Discussion Starter · #18 ·
Here is where we are up to : Factory copper/brass radiator in ok condition (was flow tested and passed) 170f hiflow thermostat, 15lb radiator cap, twin 12 inch thermofans (biggest I could fit in and clear upper control arm bushes) mounted to radiator with seals around edges to stop air being drawn in from the side instead of through , no lower air dam as yet , driving around town in 31c or 88f car was running 230f when pulled into driveway, Didn't boil over when turned off. Would run stock fan shroud set up but cost of purchase and freight to australia not in budget as yet. Put car on hoist yesterday and found that when a/c heater box was reinstalled I omitted putting sealer around the lower part of a/c heater box directly under where to blower fan is. I am going to squirt sealer into there today after I run the fan to see if it is drawning air in from that point as well as check firewall for air leaks and adjust hood down so rear hood seal is contacting propertly. Q: What diameter fan and how many blades on factory 454 with a/c? Wish me luck. Regards Torn
 

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Thats exactly where I expected engine heat was entering ..that needs to be sealed up.. ... 230F is just too hot... I think those 12 inch fans are just not moving enough air.. whats the CFM rating on them? .....the OEM Clutch fan/ shroud will do the job..7 blades , I believe.. you can also go to a severe duty fan clutch ,for additional cooling , available from Hayden .. { Summit, Jegs, etc. }.. the lower frt spoiler will help... also, are you using a 50/50 mix anti-freeze /water ?...whats your ignition timing set at? too little advance also produces more heat.
 

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Discussion Starter · #20 ·
Fishslayer .Timing set at 8 degrees BTDC with vacuum advance plugged. Fans flow 910 cfm max each according to manufacturer, coolant is on the weak side at 26 % last time I checked it with a refractormeter. Torn
 
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