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Get a burbon tube stewart warner temp guage. electric gauges can be erratic. your 327 might have a higher temp thermostat? Ive found that a temperature sending unit located on the side of a cyl head will have a hotter reading than one located at the top & front of the intake manifold.

Mine's on the intake.

 

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Hook up a vacuum gage to any port on the intake or carb that has full manifold vacuum and adjust the mixture screws to obtain the highest reading,could be that they're set a bit too lean. You can also check your eng. temp. readings with an infrared temp. gun,i have one from Harbor Freight and it reads pretty accurate. Check several areas,like the upper and lower rad. hoses,stat housing, and rad. tanks and fin areas. Compare the readings to your temp. gage. Good luck Tri, hope this helps señor. Buena suerte. Big Bob:anim_25: :bowtier:

Thanks BB. I have used a multimeter with a heat sensing thermocouple I bought at Lowe's. Not the greatest, and I know how defective cheap T/C's can be. We make Type K's at work. Maybe I can "borrow" one.

 

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I've been building small blocks since the '60s and the first thing I do is install a calibrated temperature gauge. Saying that the gauge is at one half or one quarter is meaningless. Install a reliable gauge and go from there. I've always used a stock V8 radiator whether it's a 283 or a 327. As has been stated there are so many variables, compression ratio, what cylinder heads, amount of camshaft overlap and induction. Good luck!

I agree 100% with you in regards to stock gauges. For me they are a matter of reference. I had already talked to the mechanic about replacing the tach, and getting a good set of ammeter, temp, and oil pressure gauges. I don't want to change my cluster panel for one that incorporates all these gauges as I suspect they're not the best quality.
Can you recommend a good brand. Can I get one for fuel as well?
Compression ration is about 10:1, cylinder heads are later power pack heads with hardened seats open to 1.9. I use premium gas. Cam is a very efficient Lunati Voodoo performance cam 10120701. Nothing radical, but I'm hoping it will work great with the Edelbrock 600cfm dual plane intake set up.

 

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The 265 and 327 should not have very much difference in running temp. There are a few variables that can cause a big difference. A couple are cylinder wall thickness and how much crusted sediment there is in the water jacket. Sometimes just boiling or baking the block will not get it out. I have had to go in through every freeze plug hole and just about chisel the crusted sediment out even after the block had been "cleaned" at the machine shop.

I'm sure you remember the timing can and will make a big difference from when you had heating issues with your 265.

I Remember Bruce, and I remember going with your suggestions for the large cap radiator and the 17 inch 6 blade fan. It worked much better but the shroud I got from Danchuck finally solved my heating problem for good.
That is why I went with the same set up with the 327. I plan to use the same setup with the 265 in the other Chevy.
Timing was off. He reset it and adjusted carburetor. Runs smoother.
Bruce one thing that bothers me now is that when I was letting the engine idle, as it got hotter, the rpm's started to jump from the 900 it was set at down to 600 then back up. I noticed the hole in the passenger side manifold was left open. Isn't there a pipe that goes from this hole to the choke? Shouldn't it be plugged if I'm using an automatic choke?

 

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Are you using the same temp sender and thermostat? The center dot is normal operating temp. with stock 170 thermostat and original 56 sender. Any other temp sender will make the gauge read inaccurately.
You need to determine how hot the engine is. There is too many variables to compare 1 engine to another.

Neither the 265 or the 327 ever ran close to the half way mark on the temp gauge unless it was on the way to overheating. Normally between 1/8 and 1/4 mark.
As I may have said, after 25 minutes it wasn't quite touching the center bullet. Engine is still breaking in (150 Miles). Fan blade is about 1 inch from radiator. Will try to space within 1/2 inch, but shroud may be too deep. I wanted 1/2 of blade exposed,
I live in California. Some areas in SoCal remove their thermostats.