Would it make any difference where I mount gauge sensor for water temp gauge on a big block? Still having trouble running warm at road speed with the new electric fan/shroud kit. I drilled 8 more 1" holes in the shroud(12 holes) for more air flow, but still runs 210+ in 75* weather. I slow down it cools down. Stop and go runs under 200. My Autometer gauge is 20+ yrs old, thinking about replacing with new. No issues with 17" mechanical fan other than a power eater.
This fan kit uses 2 12" spal fans.

Verify the gauge readings with a infra red handheld gun first
Don't be surprised if the gauge is bad, I've had several different Auto Meter gauges read bad

I suspect your A/F ratio is lean.
Give it a little more fuel and try it.

Fans cannot move air comparable to 30+ mph.

It could also be a timing issue.

I would take off the fans/shrouding & from a dead cold start get out on the highway fast & see if it is OK now which would point to airflow. Electric water pump? I hear some of em dont flow enough at speed. A partly clogged radiator would do it or a stat not opening all the way(rare tho on the stat).

Pretty sure its an air flow problem. Cooled just fine with a shroud and 17" mechanical fan. I couldn't get the temp over 165* with a 19" fan. I may just use these til after I run it at the track, then put the mechanical fan back on.

I use one cab and what I see is every different area of the engine reads a different temp. The back of the block and one area of the dr side head under the ex porst reads 5* below what my gauge reads. I think just for sh!ts and griggles i'll put a new guage in it as well. Gonna try removing the restrictor today and see which way it goes. When I check the temp at the sensor it reads 20* below what the gauge reads.

Do you have an aftermarket trans cooler mounted in front of the radiator??

The water temp (street driving) would be in the 210-215 deg. range before I replaced that trans cooler setup with a remote (w. fan) cooler. Afterwards, the temp would max at 185-190.

some have success, but i really don't like ANY aftermarket fan kits, shroud or not. they just don't stack up to their claims.
most of the time, the included shrouds block airflow at speed.
i always use OEM electric fans. way more airflow and durability. however, you MUST be sure your electrical system can handle their load, as they take a TON of amps at start up.
just my opinion, your mileage may vary.

So, the theory behind replacing the gauge is....... it reads fine with the mechanical fan, but somehow is no longer functioning correctly when the electric fans are used?

That's a good one!!!

No, its old and would have more piece of mind knowing if its reading correctly. Ever at 165* could of still been reading high. Who knows, but I will find out.

Yes, I have an oil cooler and a trans cooler in front of the radiator.

Well,,,,,the best place to mount the temp sensor is in that hole in the water pump

C’mon Dave....... let’s be honest here.
You had zero concerns the motor was running hot when it had the mechanical fan on it........ and if the gauge still showed 165* with the new fans, you still wouldn’t think anything about it.
You def wouldn’t be installing a new gauge just to verify that the 165* reading you were seeing was correct.

But instead, it’s reading over 200*..... and now you’re grasping at straws hoping the gauge went bad and that the electric fans are working just as good as the mech fan did.

Possible?
Sure....... never say never........ but that would be some coincidence that the gauge went bad just as the new fans were installed.

Yup........You’d expect the factory would know where to install the sender.

Yep, but funny thing is fanman suggested mounting it in the radiator tank. They sell a bung for it. Thought maybe someone might have been creative mounting it somewhere I haven't thought of. Didn't think it would really matter.

Not exactly. The 19" flex fan seemed to make some power disappear, so thought I would try electric . At 165* temp I don't care if the gauge is off by 5 or 10*, But at 210 to 220* I would like to know. I don't think its off by much, but I want to know how much, that's all. Being that the gauge is 20+ yrs old, whats the harm in switching it out with a brand new one. Just went for a 15 miles ride down the freeway at a constant 3000rpm. About half way thru, the gauge topped out at 218*. So 218* it is at 77* air temp. Don't think its hurting anything, and no worry of boil over as I use the Evans coolant that has a boiling point of 375* . If i'm not mistaken nascars run at 280* for a long time. I think the conclusion is I don't get enough airflow thru the radiator with this fan set up just as some others here have said. Right now the fix is to reinstall the 17" flex fan.

If you are going to do any testing then I'd suggest pulling the electric fan out completely and taking it for a drive on the freeway. If it stays cool then you know that the fan is blocking the air. If it gets hot then you have a water flow problem. The engine might get a little warm at idle or slow speed without a fan but if it is cool outside and if you live close to the main road then there shouldn't be any harm in driving it that way.

A clutch fan is probably the best setup if you can fit one in there.

don't know if this is relevant or not, but I put one of those 440 source edelbrock clone water pumps on my r/t and my engine temps went up 15+ degrees. took me a little time to figure it out; trail & error. put the old six blade pump back on with the larger diameter blades and i'm back to normal.

Don't have room for the clutch Andy and i'm not sure how you fit yours in there. I don't believe the gauge failed at the same moment I installed the electric fans and if I were to reinstall the old mechanical 17" flex fan and shroud, problem would be solved as far as cooling. Im sure it will cost a couple hp thou and im heading to the track as soon as I can get there. Just trying to make the electric fans work and it looks like its not happening unless I can get used to 219* temps. Boilover it not a problem. Do you see any other problems with that temp? Using Amsoil 15/50 and oil pressure is 60# cruising at 190* oil temp. I will mention something else, the engine seems to have better street manners with the high temps. I'm thinking the Indy 400-3 is running hotter and vaporizing the fuel better?