chevy 362 engine temps

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chevy 362 engine temps

shaneschiller5 shaneschiller5
New User | Posts: 1 | Joined: 09/15
Posted: 09/28/15
09:30 AM

Looking for alittle insight on water temp. just got the car out racing last weekend. had a driver in it as i am new to the sport. When he came in from the second 25 lap feature water temp was up to 260. I am concerned about engine damage as this is a fresh motor just built. any input would be great it is a hobby stock car. motor wass built professionally. 365 with 64cc heads bored .040 new stock waterpump, aluminum radiator, race fuel running 4412, timing set at 36.

Builder said it should have been around 210 or lower  

Just Try It1 Just Try It1
New User | Posts: 5 | Joined: 04/15
Posted: 10/18/15
09:40 AM

are you running a restrictor instead of a thermostat..?? or no restriction at all..

you did not mention what types of fans....

i am taking you are running straight water.. not coolant..

if i had access to a lathe and mill..   currently i don't..  i would modify a thermostat housing.. so i could have something like a jack screw set up to move a tapered cone in and out of the restrictor... i would also have a cooling system pressure gauge .. with it monitoring the pressure in the intake manifold coolant crossover  you will need probably a 100 PSI gauge.. and please use decent hose or copper tubing with brass SAE FLARE FiTTINGS to the gauge not rubber hose.. at least not in the drivers compartment..

let me describe a few things..

hope you get this..

the water pump pushes water into the block.. up thru the back of the heads.. forward thru the heads to the intake crossover where in a street driven car it will be blocked by the closed thermostat..  this builds pressure in the block and heads increasing the boiling point of the coolant.  in all street motors there is some kind of bypass circuit that allows coolant to flow past the closed thermostat and back into the water pump inlet.. this allows the coolant to circulate in the block and heads picking up heat and keeping the engine temps equal for the most part..

when the coolant trapped by the closed thermostat reaches the temp that opens the thermostat..  some of the hot coolant will exchange with the cooler coolant in the radiator.. that will get into the block and heads causing the thermostat to close.. stopping the hot coolant in the radiator to allow it to be cooled..  while the coolant in the engine circulates picking up heat again..

if you don't run in racing some kind of restrictor .. you will circulate the coolant so fast thru the radiator that the ram air and what ever fan you have won't cool the speeding water..

the various sizes of restrictors.. allow the coolant pushed thru the block and heads to be increased in pressure because of the restriction in flow.. but it slows the flow thru the radiator down that there is some chance of it being cooled..

you may want to install something like a 5/8 ID bypass circuit..  feeding back into the water pump..  work this with the restrictor..  

a lot of racers will run a 30 pound radiator cap..  each pound of pressure increases the boiling point of the water 3F... so 15 pounds would increase it 45F..  a 30 pound cap Could increase the boiling point of the coolant close to 90F..

the issue.. not seen... is the hottest spots around the exhaust ports,  valve seats and the exhaust guides can reach slightly over 300F during high power conditions..

with the restriction installed .. you can increase the mechanical pressure in the block and heads... to increase the boiling point in the hottest spots..

you will also want to keep an eye on the radiator tubes..  there have been issues with 30 pound caps and high rpm operation with and without restrictors that the pressure in the radiator expands the coolant tubes from a flattened oval.. into a circular shape.. this crushes the fins between the tubes and no airflow can go thru..  no air passing thru the radiator.. no cooling..

i hope this explains some of the hidden thermodynamics of cooling systems.

i personally won't put on a head gasket without thinly spreading some permatex 85420 on both sides and letting the solvents evaporate for 20 to 30 minutes before i set the gasket in place and bolt the head on.

you can check for compression/combustion leaks in several easy ways..

a piece of sandwich wrap across the radiator filler neck..  a depression pushed into it.. a rubber band to secure it..  start the engine for 15 seconds.. the depression should not inflate..

you can use a compression tester hose with the valve core removed .. do basicly a cylinder leak down test..  using shop air.. leak down testers have a tiny restriction that allows them to be calibrated..  a compression tester hose with the check valve removed will flow a LOT of air..  if you have the sandwich wrap installed over the filler neck. if it inflates when you apply compressed air.. or you start getting bubbles in the cooling system. it will show that you have either a leaking head gasket or a combustion chamber leak.. it will not show cracks in the exhaust port past the valve seat..

and really off the wall.. was the carb jetted for your set up on a dyno.. so its not running too lean..  causing an overheat and damaging condition to the pistons ..

oh... is your water pump turning in the proper direction.. there are normal direction water pumps and reversed direction water pumps.  water pumsp don't work well in reverse.. but the pressure gauge on the coolant crossover may show you if this is an issue.