I have a SB 416 stroker, ,Mezeire electric water pump,195 degree stat; aluminum radiator. New build less than 500 miles on motor. Distributor has been professionally curved . Water temperature at radiator cap is around 195 degrees as measured by Mr. gasket radiator cap with built in thermometer, also using an infrared thermometer with adjustable emissivity and a KD radiator thermometer. I noticed however that when I point the IR thermometer at the thermostat housing that it reads around 277 degrees. Shut motor off after warming and driving and it barely wants to crank. Starter is brand new Powermaster Ultra. just wondering if high temperature reading is normal "surface" temp for aluminum housing or indicative of something else going on. Car does appear to be overheating as radiator cap can be removed by hand 20 min after shutting down and as I said earlier temperature at cap is around 195. Am I missing something or is the hard to start evident if tight motor rebuild?

Did you mean to say that the car DOES NOT appear to be overheating cuz the cap can be safely removed? 195 is excellent. I would take off the cap & check it with a candy thermometer from your grocery store (they're cheap) just to get that out of the way. then we can move on to the cranking: check the cranking voltage at the battery then pull the secondary coil wire out of the dist & ground it & crank again. that'd be a start

My bad. Car is NOT overheating. Battery is brand new
Optima red top. Just wondering if the surface temp
of housing is normal. Also if I might have to experiment
with timing to solve cranking issues.

I would go by the coolant temp & 195 is perfect. on the temp gun someone posted about using a piece of duct tape on shiney surfaces to get a good reading (iirc). If you ground the coil wire that will take timing/DCR out of the picture and then do cranking voltage for the battery/cables. starters are weird electrical devices in that the slower they turn the more amps they draw & this compounds in a matter of seconds till you are down to slow cranking or machine clicking of the pull in/hold in circuits in the solenoid. EDIT the battery is always the starting point, do you have another known good battery that you could borrow for a quick test. I've heard bad regarding Optimas' (but we are the fixit dept so we get nothing but bad) with a few exceptions. MORE EDIT you might put a torque wrench or just a breaker bar & a 1&1/4" socket on the crank bolt & check it when hot, then when cold. the more info the better

What does the actual temperature gauge read?

Autometer temp gauge in the dash reads around 210 which is why I purchased
IR gun with adjustable emissivity so I could accurately read temp. I figured along with the radiator cap with built in thermometer and using the KD insert thermometer that between the 3 devices I should be getting a fairly accurate reading wouldn't you think?

Thanks to all for your input

the temp is good, now we can check other potentials for the hard cranking. Keep us updated

If you want a dead nuts on reading the only way to get it is with a digital temperature meter and a thermocouple probe placed in the coolant as close to the thermostat as possible. I have seen new after market gauges etc be off by as much as 40+ degrees for a number of reasons and they normally go further out of calibration the warmer the coolant. infrared meters are only good for an indication unless they are calibrated to read the specific surface they are being pointed at.

Latest development: Started car up to warm it up and check timing and do some troubleshooting based on suggestions in this post.Barely after warm up period radiator started spewing antifreeze out the filler neck with or without cap. Not overheating though as filler neck was around 170 degrees. Thermostat housing surface temperature reading around 246 degrees. Trying to figure out the big delta between housing and radiator. Infrared meter has adjustable emissivity feature so I can calibrate to type of surface I am reading. Sounds like bad thermostat which I will need to replace before I cam follow up on other suggestions.

Stuck stat (hopefully) or cracked block/head(s) or head gasket(s). impeller might of slipped (rare tho)

I agree with RR..

Problem solved. As I began to trouble shoot I noticed that the motor on the electric water pump wasn't running. Checked the fuse holder and noticed that the blade type 20 amp fuse had worked its way up and out of its well. I secured the fuse snapped the cap on the holderand fired her up and no issues with water spewing out of the radiator. Duh! I guess a blind squirrel finds an acorn once and a while. Never thought to check the water pump. It is usually the simple things that trip us up and instead I was looking for something more complicated.