Will my GT500 overheat when I get done building it?

[tonys_shelby]

I hear a lot of talk about how the GT500's especially with inboards can overheat.  Is this a real problem and is there something I should do to head this off? Not use stock radiator, fan etc? Will have everything newly rebuilt, engine, water pump, clutch fan on and on.  Or will this really not be a problem?

[Greg]

Use a 180 or 190 deg thermostat as it keeps the coolant in the radiator longer where it is cooled, then circulated.  Your water pump should be for a big block.  Some people put the wrong impeller in when it is rebuilt as they don't think it matters.... it does.  As long as your block and radiator are clean there should not be an issue.

[67 GT350]

A 180 or 190? What about a 160?

[Rickmustang]

Use at least a 180, for sure. In my GT 500, with a 600 hp 427 with 12.5 compression, I ran mostly distilled water, with two small bottles of water wetter, and a little coolant. Never overheated in Texas summer with stock radiator and 180 thermo.

[shelbydoug]

It all depends on what you consider over heating?

Do you mean "boil over point"?

The GT500 has a 12 psi pressure cap and system. With a 50/50 mixture of anti-freeze, it won't boil over until around 240F. Anything under that is not over heating if you are talking about boilover.

Do BB Mustangs run hot? You bet ya'! Try one with an automatic transmission with A/C in Phoenix? 

Probably the biggest problem is going to be a restart when the engine is at "full operating temps".
Secondarily, with a '67 GT500 in particular, the carbs will boil over immediately after shut down as built and delivered new.

The best solutions to that is to isolate the carbs and to put in a high torque starter. Personally I wouldn't run anything but a 160 thermostat and a full three core radiator.

[tonys_shelby]

I absolutely plan on isolating the carbs and fuel logs and gear reduction starter.  Don't want it running at 210+ at a stop sign hurting anything puking out water.

[rhjanes]

A 180 or 190? What about a 160?

Not a good idea. Lot of opinions about why not.  The engines have to reach the designed-to-operate temperature and 160 doesn't allow that to happen.  On a big block, get the distributor set up correctly then time the engine correctly.  A timing issue is sometimes seen in running hot/boil over. 

[shelbydoug]

Fellas. You are both missing the point. The normal operating temperature of this engine is in the 220 range. That is NORMAL. It's not overheating there.

It's actually good to at least 230-235.

Look at the 50/50 anti-freeze chart at 12 psi. That will show you what is normal.

There is no place that you are going to get a 428 to run at 212 or over unless you are talking Antartica.

This is the same issue people have with Panteras. As soon as they see 230 on the gauge they become "Chicken Little" and right away, "the sky is falling".

The pressurized system is used for a reason. If you are boiling over at 212F then you radiator cap isn't permitting the system to properly pressurize.

[tonys_shelby]

Are you saying that from the factory the temp gauge would be reading dead center of "normal" and the engine temp would be at 230? I don't know big blocks much witch is why I ask these questions but it seems like when you parked it you would be walking out to a puddle of antifreeze when you came back to the car?  That's my goal drive it around and not freak that the temp gauge is climbing and leaving a streak of water/antifreeze.  Can I do that with stock components?

[acman63]

nobody has mentioned the engine build.

did you take the block and heads  to a rust stripper to make sure all the insides are stripped of rust?
did you have the block baked out to clean all the passages after stripping?
what is the overbore more than 30
did you use torque plates to machine the bores - they simulate a head being installed,  we measured a block in 3 places  prior to installing the torque plate and it was .004  difference after sitting overnight -  rings have to move that far each time up an down
did you machine the block at operating temp - real high end shops can do this
did you have the block blueprinted?  square the decks

Ive found that if you do these the engine runs very smooth and cooler  -  its not something the normal engine builder does

[tonys_shelby]

It is a 100% No expense spared rebuild .030 bore by Barry Rabotnick of Survival  in MI

[2112]

nobody has mentioned the engine build.

did you take the block and heads  to a rust stripper to make sure all the insides are stripped of rust?
did you have the block baked out to clean all the passages after stripping?
what is the overbore more than 30
did you use torque plates to machine the bores - they simulate a head being installed,  we measured a block in 3 places  prior to installing the torque plate and it was .004  difference after sitting overnight -  rings have to move that far each time up an down
did you machine the block at operating temp - real high end shops can do this
did you have the block blueprinted?  square the decks

Ive found that if you do these the engine runs very smooth and cooler  -  its not something the normal engine builder does

I hadn't heard of machining the block at operating temperature before. I like it, but guess it would be hard to find a shop to do it.

Are you  saying up to .030" should be ok for the bore increase?

[shelbydoug]

I absolutely plan on isolating the carbs and fuel logs and gear reduction starter.  Don't want it running at 210+ at a stop sign hurting anything puking out water.

230 would be considered normal. 220 would be better. 210 isn't hot enough. As discussed all clearances spec'd by manufacturers are stated for "normal operating temps". The temperature is part of the clearances specified.

All engines NEED to operate above the boiling point of water (212F) in order to boil out the moisture in the engine oil. Otherwise all you are doing is creating oil sludge which WILL create excessive engine wear and accelerate it.

You need to be careful with this also with oil coolers. They really should be run with an oil thermostat that doesn't open until it's over 212. Otherwise you are actually over cooled.

Engineering wise, this was all taken care of with a 12 psi cooling system. It raises the boiling point of the coolant to about 242 F. That's the boil over point.

What exactly the silly stock temperature gauge indicates is almost irrelevant to this discussion. It has no temperature markings. You need an accurate way to measure the temperature and give you an accurate reading.

[tonys_shelby]

That all makes perfect sense!

[mustmore]

I have found that it is beneficial to add a GANO or TEFBA filter into the upper hose
to catch rust particles and debris left over from the rebuild process.  This saves
the radiator.  We have caught debris in all the engines that have been rebuilt.


Sue