How hot is to hot?

[Oldsproject]

I've been reading a lot about overheating in present and past forums. As usual, there is a wealth of knowledge and information. Unfortunately I can't completely diagnose my problem or if I even have one yet as my car isn't road worthy (but close). However, I do have the above concern and would like some early advice:

As background, I've got a 1965 F-85 that I put a fresh 1967 425 into. Completely rebuilt by myself and my son so I feel pretty confident in the build and the gasketing (but we are humans and mistakes can be made).

The motor was built with reproduction 10.5 comp pistons (.30 over), beefy cam (mondello 22-25), performer intake, valley tray (in lieu of turkey), duel timing chain, roller rockers, etc. The carb is a 750CFM (might actually be 650, need to double back) edelbrock, new 3 core radiator (rock auto), MSD plug and play ignition and so on. All in all a pretty good and stout build.

I'm pretty confident I have it slightly retarded which causes some of the problem and will advance the timing abit more, the carb is probably leaned out a little right now too and 65's, don't have a shroud (some rubber pieces around rad only) and I believe the 400 was the biggest option in 65 and was in 442's. I'm also running a 160 Tstat.

With that long winded wind up, sitting idle in my Oregon garage it takes about 15 minutes or so to get her up into the 200 - 210 range. I don't know if it will continue up (as I usually shut it down) and I don't know how she'll react on the highway but curious if you guys think we have a problem and at what point should I be concerned? This is my first Olds, just don't know how hot is to hot for this engine and what normal is? Thanks

[joe_padavano]

Originally Posted by Oldsproject

With that long winded wind up, sitting idle in my Oregon garage it takes about 15 minutes or so to get her up into the 200 - 210 range. I don't know if it will continue up (as I usually shut it down) and I don't know how she'll react on the highway but curious if you guys think we have a problem and at what point should I be concerned? This is my first Olds, just don't know how hot is to hot for this engine and what normal is? Thanks

200-210 stopped at idle is not unreasonable, so long as the temp doesn't continue to climb. Keep in mind that with a 15 psi radiator cap, the boiling point of water is actually about 250 deg F.

[Oldsproject]

Originally Posted by joe_padavano

200-210 stopped at idle is not unreasonable, so long as the temp doesn't continue to climb. Keep in mind that with a 15 psi radiator cap, the boiling point of water is actually about 250 deg F.

Thansk Joe, at what point should I get concerned? Above 210 - 215 - etc??

[joe_padavano]

Originally Posted by Oldsproject

Thansk Joe, at what point should I get concerned? Above 210 - 215 - etc??

I'm more concerned about trending than absolute numbers. If the temp just keeps creeping upward, you have a problem. If it goes to 210, 215, even 220 (though that might be pushing it), but is rock steady at that level, not a problem.

I've also noticed that some parts store thermostats behave differently than others. For example, when I first start the car, the t-stat in my 86 307 will stay firmly shut until the gauge reads 220. It then opens and the temp drops like a rock. In normal driving it never goes above 210 on the hottest days except for that initial opening. I have to admit that it freaked me out the first time, but it's extremely repeatable, so I don't worry about it.

Of course, I'm also waiting for this low mileage 307 to die so I have an excuse to put in the 403...

To quote Monte Python - 'e says 'e's not dead yet.

[Texascarnut]

Originally Posted by Oldsproject

I'm also running a 160 Tstat.

You may want to consider bumping that thermostat up to a 180. A 160 may not give the radiator time to properly bring the coolant temperature down on a warm day.

[Oldsproject]

Originally Posted by Texascarnut

You may want to consider bumping that thermostat up to a 180. A 160 may not give the radiator time to properly bring the coolant temperature down on a warm day.

Thanks guys, I'm not in a good position to really troubleshoot it yet but I do think I may have a Tstat issue. I watched the temp today from cold, took quite a while to creep from 160 - 190 (15 minutes or so), a little less to go to 210 but once she hit 210 within minutes she was moving steady to 220. Tstat didn't ever seem to really open unless it went right away as I never saw the usual drop when it opens. In any event I believe I have a number of things working against me right now (timing, carb, Tstat, etc). So until I can get it out of the garage, I'm not going to get concerned. Thanks, I'll keep you posted as I'm hoping to get the final touches on the headliner done, dash back together and maybe a seat in so I can take her for a quick spin. Assuming I've got the spongy breaks bled too...... lots on the list for Saturday!

[Lady72nRob71]

Oldsproject,

If you replace the thermostat, go with the Mr. Gasket (or Robertshaw) Hi-flow model like is shown here. It is a little more expensive, but worth it.
I have used the 180* one in 3 of my cars and they keep the temps almost rock solid. So far they have never done the "pops open at 210*" like the more standard t-stats. Yes, I had that problem in at least one car before with a standard t-stat.

And if you do decide to drain and refill the system, pull the 2 engine block plugs (9/16" hex head) on the sides of the block (if your engine has them) so you can flush the block out real good with the hose. On my 72, a lot of crap came out that settled to the bottom of the block cavities over 35 years.

Where are in Oregon? I will be all along the coast this October, 6 days in Brookings and 4 days in Astoria. I love it there...

[Oldsproject]

Originally Posted by Lady72nRob71

Oldsproject,

If you replace the thermostat, go with the Mr. Gasket (or Robertshaw) Hi-flow model like is shown here. It is a little more expensive, but worth it.
I have used the 180* one in 3 of my cars and they keep the temps almost rock solid. So far they have never done the "pops open at 210*" like the more standard t-stats. Yes, I had that problem in at least one car before with a standard t-stat.

And if you do decide to drain and refill the system, pull the 2 engine block plugs (9/16" hex head) on the sides of the block (if your engine has them) so you can flush the block out real good with the hose. On my 72, a lot of crap came out that settled to the bottom of the block cavities over 35 years.

Where are in Oregon? I will be all along the coast this October, 6 days in Brookings and 4 days in Astoria. I love it there...

Just outside of Oregon City (SE Portland), agree it's a beautiful place!