Big Block Temp - When to Panic?

[Glenn B.]

Just took my 67-427-390 on it's longest ever road trip (500 miles). Got stuck in some horrific traffic - and of course the temp guage began to climb as I sat on the baking ashpalt. I have a totally stock setup - with re-cored rad and rebuilt water pump (don't know when block was last flushed).

Whenever the guage climbed up past 210 (maybe 15 or so minutes of hot idling) I'd start to get nervous and turn on the heat full blast (which did not add to the pleasure of the drive). The temp guage never went more than about 1/16 of an inch past the 210 line (with heat full on).

What was considered "normal" for these cars under such conditions? Am I just too conservative? (it's not exactly clear what the actual temp is on the guage after 210 and before the red zone). When should one get worried and take action to lower the temp?

Thanks

[lyndon sharpton]

Re: Big Block Temp - When to Panic?

yes! that is par for the course. you might also what to pop you head lights up get you some more flow. but that is not to bad at 210 for the conditions you were under. I just seen where it was a 67 forget that about the head lights that is just for C-3s!

[Michael H.]

Re: Big Block Temp - When to Panic?

Glenn,

I understand your concern. It's the feeling of being stranded, stopped in traffic, with visions of coolant spewing out of the front of your car. However, 210, or even 220, is not an issue. My 66 big block often sees 210 or 220 in traffic after a long run. I've seen the needle somewhere between the 210 and 250 marks a few times in parades and still had no real problems.

My car usually runs at 180 on a short cruise but on the highway on long trips in 90* air temp, it will stay near 200*.

[Jack H.]

Agree with others....

Even my 454 Suburban heats to +210F when it's really hot and I'm taxing it, so underhood temp's approaching 220F aren't a cause to worry. The next time you're stuck in grid lock on a hot day, try boosting idle RPM a tad instead of turning on the heater! The TCS and CEC systems used in Shark cars did just that by having a 3-way heat switch in the RH cylinder head (cold, normal, hot) that would feed the distributor vac to advance the spark under cold and hot conditions.

This raised engine speed about 150 RPM ONLY and I've watched my '71 Corvette climb to nearly 230F, the hot switch kick in, engine RPM climb just a tad, more air flow through the radiator and the temp gauge gradually fall down to the 190-200F range. What I'm saying is you don't have STAND ON IT to suck more air through the radiator in order to compensate for hot idle conditions...a little bit'll do ya!

[Dick W.]

Re: Big Block Temp - When to Panic?

Rule of thumb, unscientific of course, if you do not push water out of the overflow the temperature is acceptable. Providing, of course, that you have water in the radiator.

[Harmon C.]

Re: Big Block Temp - When to Panic?

I had a small block that showed it was running 230 but whem I put the gun on radiator neck it was 195. New senders usally make the temperature read high.

Lyle

[Glenn B.]

Re: Big Block Temp - When to Panic?

Thanks guys.

The concensus is clearly that I was overly concerned, and that next time I should use just a touch of throttle rather than sit there sweating buckets with the heater on.

Will make a mental note for next major road trip (maybe NW NCRS 2007?)

[mike cobine]

Re: Big Block Temp - When to Panic?

My '68 427-390 hp used to never go over 200, even in a parade. However, that was when we still had the good gas. Before I stored it several years back, it would unfortunately hit 210-220 far too frequently in traffic in Fort Lauderdale where you are stuck in the sit 5 minutes, move one car length, sit 5 minutes stuff.

One of the big blocks in my '66 used to hit 240-250 at the end of some races. Oil temp stayed around 250-260, so basically the engine was still ok, it was just nerve-wracking. Of course, you don't have an oil temp gauge to watch.

[William C.]

Re: Big Block Temp - When to Panic?

What shape is the fan clutch in? Higher temp in traffic is one of the symptoms of a bad fan clutch.

[Jack H.]

Add on...

It was HOT when we were in England/France for the UK Chapter's Flight 2006 meet. We'd finished our Flight Judging duties on Thursday and set out Friday to make the 40 mile treck north to LeMans to pickup our track race credentials. In LeMans itself traffic was a nightmare of grid lock getting to the track and you easily spent over an hour in bumper to bumper traffic.

On Saturday, the race officially kicked off at 5:00 PM and we gathered up to make the trip (should be worse traffic today) at 10:00 AM. As I walked over to climb into the 'Yank-mobile' a Mitsubishi SUV hire car from England, Rob Mustquetier approached. He flipped me the keys to his '69 427/390 convertible and said, "Hey, Jack, how about taking my car up to the track for me. I'd rather ride in your A/C SUV today."

Wow! A chance to drive a Shark BB on the French D-roads, what a hoot!

Of course, Rob was kidding about preferring to ride in a A/C equipped Jap SUV, but I took him up on his kind offer. Rob's real reason for tossing me the keys was to get a second opinion on his car (how it drove, what to do next in his restoration/preservation program).

Other than the suspension components showing wear and the the speedo/tach needing work (speedo didn't work at all and tach would run intermittently like the cable was fractured), the car drove like a dream! At LeMans the traffic came to a stand still, as expected, and I sat idling/crawling in traffic for more than an hour.

No surprise here. But, what WAS pleasant was to see the temp guage sit ROCK HARD in the 180-185F range through all that stress. Since I'd done Mech judging two days before, I knew the engine was wearing a factory original 5-blade fan AND a real McCoy original Schwitzer bar clutch.

So, as Clup mentioned, you might want to consider the integrity of your existing fan clutch in your efforts to obtain a better cooling profile.