Blocking off a rad?

cdnpont · Canadian Poncho Superstar!

Blocking off a rad?

jmont64 · Canadian Poncho Superstar!

Mark, what temp is your thermostat? That should keep it at 180 or whatever or am I missing something.

rabbit64cs · Canadian Poncho Superstar!

Agree with Jerel! What thermostat is installed ?

4SPEED427 · A Poncho Legend!

I'm likely a minority here but I like 195 thermostats.

My thinking is, if your engine cools easily, 195 is great to run at to keep things clean.

If your engine struggles to stay cool, a 160 thermostat won't be anything except wide open anyway.

As far as blocking the rad, I've been taught to always block off the rad symmetrically if that's a word! Don't block off just the top or just the bottom (assuming you have a mechanical fan, I forget) because the thinking is constant pressure on the same side of the fan all the time puts sideways pressure on the water pump bearing. Block off both sides equally, or the centre, you get the idea.

cdnpont · Canadian Poncho Superstar!

I'm using a Mr Gasket 180* 4364 high flow. It's obviously not stuck open, as the engine temp comes right up fairly quickly at idle. The next temp up high flow TStat for the BBC seems to be a 195, which is probably the way to go as suggested Carl.

I've gone and blocked off a section of about 4x14 symmetrically on either side of the rad, went out for a cruise and still only see about 175 at best. A little better but not much,

Is there a possibility that the small bypass hose carries enough to cause this? Funny though, how often is a too cold high compression BBC ever an issue.

cdnpont · Canadian Poncho Superstar!

I should mention I also run a EMP Stewart high flow WP and a March high flow WP pulley.

CdnGMfan · Canadian Poncho Superstar!

The Chevy engines used 180° thermostats through 1966, then switched to 195° for 1967. I'm with Carl, the hotter 'stat helps boil off condensation in the oil & crankcase.

4SPEED427 · A Poncho Legend!

I've never really seen the point in a colder thermostat. I wonder if the reason they had them in the 60's cars was they thought 200 was too close to water boiling point (not under pressure like it is in an automotive cooling system) so they ran engines cooler. Sure they make more power if they're cooler but I would guess the benefits of a hotter running engine outweigh those of a cooler engine.

If anyone remembers when the 82 and up F bodies came out, those things used to run close to 220 on the gauge during normal driving (I'm assuming it was accurate). That always felt a bit unnerving seeing that on a hot day though.

North · Guru

cooler engine increases power and decreases octane requirement but I agree that it is most often a moot point since most engines will run hotter than the thermostat anyhow in most weather conditions.

427carl · A Poncho Legend!

cdnpont wrote:
So, I have a evening drive to complete in the 67 coming up, and it looks like it will drop a few degrees below freezing that night.

Thanks,
Mark

68beaumont · Guru

I agree with Carl, I think the engines are more efficient with a 195 stat.

OURWAGON · Guru

Carl Stevenson wrote:
I'm likely a minority here but I like 195 thermostats.

My thinking is, if your engine cools easily, 195 is great to run at to keep things clean.

If your engine struggles to stay cool, a 160 thermostat won't be anything except wide open anyway.

As far as blocking the rad, I've been taught to always block off the rad symmetrically if that's a word! Don't block off just the top or just the bottom (assuming you have a mechanical fan, I forget) because the thinking is constant pressure on the same side of the fan all the time puts sideways pressure on the water pump bearing. Block off both sides equally, or the centre, you get the idea.

RIGHT ON !! smile

cdnpont · Canadian Poncho Superstar!

It's not happening this year. But next spring I'll try a 195 for sure. Makes sense.

Nothing to loose since it never goes over 190 in summer anyway. No winterfront Carl!

I came back tonight at 175 or so all the way in the cold. And here's a funny thing, after about a 10 kilometer final drive down into town at 80, when I stopped and pulled up to the lights, both tailpipes were showing exhaust steam while stopped at a light. No other cars had any. I was actually kind of proud of it and it actually looked cool compression puffing away. Too cold? Or too old school?

66 Beau · Poncho Master!

I suspect all the other cars you saw have catalytic converters, which tend to raise exhaust temperatures (I believe the converters operate at 800+ Fahrenheit). Your exhaust was cooling enough that the water vapor was condensing as it exited the exhaust system.

4SPEED427 · A Poncho Legend!

Yes, and also very few of the vehicles have true dual exhaust (where the pipes run cooler than single) so that might make a difference as well.

oshawacliff · Poncho Master!

cooling temps

oshawacliff · Poncho Master!

Mark do not have one of those digital gauges that you point to any surface for a quick temp check. Better than guess work Cliff I use mine to check the temp of my coffee ð

hawkeye5766 · Canadian Poncho Superstar!

Might need educated. Thought blocking off rad was to prevent extreme temp changes in the engine? If 40 below and driving down the highway the engine takes longer to reach thermostat temp. This leaves the the radiator dormant for a longer period of time which may cause it to get too cold. Say you were running straight water in the system(more dramatic), the water may become almost frozen by the time the thermostat opens. So with cold air(around and over the engine) it will take longer for the thermostat to open compared to sunny day driving(warmer under the hood). So if you put in a higher temp thermostat it would prolong the closed cycle causing the rad too get even cooler. Think this would give the engine more of a "shock" cycle on the expansion/contraction of the cast iron? I know the trucks(old days) I used to drive had flaps/louvers in front of the rad and were controlled by the engine/rad temp (not thermostat).

4SPEED427 · A Poncho Legend!

From what I know, that is all correct Jim. The only thing is, I don't think the thermostat allows enough cold water in to shock the engine. I've asked guys the same question over time and always had the same answer, "nothing to worry about".

And you are right about the rad getting too cold on the highway with just water. I've seen a too-weak antifreeze/water mixture in a vehicle that was fine in town but on the highway the rad froze up. Obviously, the ambient air temperature is no different town vs hwy no matter how fast you go, but just the increased air flow on the highway through the rad made the difference. Also, I would assume on the highway the air-cooled effect on the engine block would be better. Less of the heat in the engine compartment because it gets pulled out the bottom.

All speculation on my part, I'm no engineer!