[Len66]

well, my 66 has been in the hands of two very reputable mechanics who have been in the business for over 30 yrs, and they are stumped as to why my car is still running hot. They have tried everything, diffrent water pump, pulleys,thermostats/restrictors, adj tiiming out, carb adjustments. They did notice a temp difference of 20 * between the right and left heads. As a last ditch effort we are going to pop the freeze plugs and see if there is anything restricting flow in the block. We dont know if the previous owners used block hardener or anything that might be blocking adequate flow. If anyone has any thoughts or ideas on this opinions are appreciated... Thanks

len

 

[tnblkc230wz]

Let an amature ask a few questions. How are measuring the temperature? What are you considering hot? You have verify the radiator cores are not blocked? the inside of the lower hose isn't colapsing is it? You would have to remove it and inspect it to know for sure. Is your fan pulling enough air?

 

[Carl 66]

Might try pulling drain pluge on block and jam a coat hanger in there. I had an old Corvette that would run hot did this and all kinds of crap came out, and then flushed out the system worked great after.

Carl 66

 

[blownnova]

You didnt say anything about running lean.

 

[Len66]

Thanks guys.. I forgot to mention the radiator is a new summit alum radiator, new water pump, and i'm running a derale electric fan with a rich 66 fan shround setup. Radiator is flowing nicely and the fan is pulling plenty of air. As far as popping the freeze plug i think thats our next step. It hits 230* and continues to creep, and its only been in the 70's here in Fla. We also have played with the carb adj to check if it was running to lean. When you get on the motor it runs strong, it just runs hot, and I want to put a/c on this car. So 230* + is not going to cut it.

Len

 

[tbills66]

Any specifics on the engine?

 

[Len66]

355 sb, trick flow alum heads, rpm airgap intake,aed 750 carb, hooker headers, flat top pistons, msd pro billet dist. I have only had the car about a year and half and the block is the only thing I have'nt torn into, so I dont know what the make up is of the block. Except the pistons everything mentioned above is new.

len

 

[Brooklyn]

I had that problem after I replaced the radiator hoses and thermostat. I put the old thermostat back in and it was fine. It was a new $11 thermostat and it was defective...have you tried running it with no thermostat just to double check?

 

[Len66]

we've gone through 3 thermostats, and they pulled the thermostat and have tried different size restrictors as well.

len

 

[wht73]

You said 1 head runs hotter then the other. Maybe somethings up with the head gaskets?

 

[rodent]

Blown head gasket, plug gap to tight?

If it's any consolation, my engine done the same thing and still haven't worked it out

 

[MPLS66]

I had same problem after my build up . Everything was new in the build radiator /pump/ thro/etc but would run hot . I took thermo out hoses off and flushed system runs great now with ice cold air on at 90+degrees . The parts may be new to us but they could of sat on store shelves a long time before we get them . good luck

 

[Len66]

the head gaskets were just replaced. everything double checked and torqued. a leak down test was done on the block and checked out good.
a pressure check on the cooling system was also good.

Len

 

[69NovaSS]

have you tried a mechanical fan?

 

[Mr Nova]

The fact that the engine gets warm and then creeps up from there leads me in the direction of a coolant flow issue.

I agree that the block may have some corrosion build up in it...

If the car ran hot in town, but cooled down on steady state cruising (such as interstste) I would tend to think the problem is airflow related (fan, shroud,etc...)

Artie

 

[Nova SS]

re check timing issues, retarded timing will build heat fast.

 

[TechGuy]

when you say they adjusted the timing...

are you runing 36-40 deg. total in by 3000 rpm ?

has the TDC & balancer & pointer all been verified ?.. many folks start changing these parts & don't confirm that TDC is at 0 deg on the balancer....

 

[tony]

Heater still in it ??? A restriction in the heater core will cause this...
Try flushing out the heater core and running the heater afterward...
Just a thought/suggestion before you get into the block...

 

[tbills66]

Looks like you are going in the right direction. Are you running stock size pulleys? How does the flow look in the radiator while it is running?

 

[uk1966ss]

have you tried a mechanical fan?

X2
got a similar spec motor in my 66,
26"x19" ali northern rad, same thing, 230+deg and rising with the shrouded 2000cfm 16" permacool fan running,

fitted a 19" factory GM 5 blade clutch fan,NO shroud,
had to fit 180deg stat to get it to warm up!!!, running too cool with the 160stat,
maybe try a factory mechanical fan, it may work?