drjr56

When running aluminum heads what engine temp is too hot,on a street driven 468 roller motor....using a restrictor right now but want to use a stat.Knowing that my 1969 30 over long stroke 400 with c heads and a little more cam 491/518 226/234 @050 with a 160 stat ran at a temp of 180 with a new and correct 4 core radiator, shroud,flex fan and would heat up to 210-220 in traffic. Restrictor in this motor takes 25 minutes to get to 160,and then 170-175 in traffic.This is a fresh rebuilt 455- 60 over motor, still in break-in stage and has about 300 miles on it

ah64pilot

If mine hits 230 I would shut it down. However mine runs at 175 all the time now with a 160 thermostat, new clutch and good 4 core aluminum radiator.

History: I had a blown head gasket (motor was 6 months old) that was causing my car to run hot for a while. It finally manifested itself in a cylinder full of water. After fixing that, it still ran a little warmer than I would like so I started looking elsewhere and noticed the clutch on the fan was broken. I replaced it and now it's peachy keen in 105 degree Houston weather.

bccan

I would suspect the flex fan, might want to try a stock fan & clutch. Since it sounds like an air flow issue to me, I would give thought to an electric fan set up.

drjr56

I hope mine runs as cool as yours pilot... 175 where you live is peachy keen,I'm going to try a Mr Gasket high flow 160 and see what happens. Temps where I'm at are in the 70's right now......

drjr56

bccan....my 455 specs are very close to yours.....if I run anywhere near 12.2 I'll be a very happy camper....my car's 3700 lbs + 175 with me in it....I'm hoping for 12.7's...I'll find out after break-in.....

drjr56

For as long as I've had this car (28 yrs) it has had a flex fan....I thought that was the correct fan for this car...

64Rocket

"flex fan" is not stock. That should be the first thing to get rid of. I would run an electric fan. You can get one with a controller, or run it with a relay and a key on set up .
Just like what has been said, in traffic not enough air flow.

Intragration

Being that it's still a new motor, it might tend to run a little hotter. The thermostat doesn't lower the temperature you're ultimately going to run at, unless your cooling system is able to cool things down lower than the rating of the thermostat. A higher thermostat just speeds up the process of getting to the temperature rating of the thermostat. With a 195 thermostat, my 455 jumps up to 195 very quickly, and then goes up to 205 ALL the time, except when I'm on the expressway, where it runs 210. If I put in a 160 thermostat, it would jump up to 160 very quickly, and then work it's way up to 205/210 anyway.

507OLDS

I don't let anything get near 200* at all.Even on the hottest,most-humid day,I can sit in city traffic,and still be at 180*-185*.I think everything I have has a 160* or 180* stat.As far as the flex fans vs electric,that will always be debatable.I ran a cheap $15.00 Flex-a-Lite nylon fan for many years,without fail,along with the factory fan shroud.One day I was reading an article about which fans rob the most power,and mine was the winner,so I decided to try the switch to electrics.I removed the flex fan & factory shroud,and installed twin puller fans.I run them off of a toggle.once I get the car started & running,I turn on the fans.The car still runs the same 180*-185* max temps.The only difference I have found is that if I am sitting in traffic for a long period of time,or sitting in a parade,it will creap up to 185*,whereas it would not go quite as high before.My thought is that the puller fans are depending on the car to be moving,so that air can be forced through the radiator.I think the flex-fan just had more force or pull to it,and it didn't depend as much on the car moving or not.

drjr56

Always appreciate the imput fellows.I just don't want to hurt the heads or blow a gasket on this motor.Lot of determing factors that cause an engine to run a little warmer,in this case a .060 455 with more cam,more stall speed,and advanced timing.(34 total) The builder has a restrictor in it and it takes too long to get to 160.I want to use a thermostat,and plan on putting a Mr Gasket high flow 160 in.Hopefully that will keep the motor at 170 to 190 and no hotter. Not sure why a restrictor was even used on this build,but I want it to run warmer than 160,and would like to see it get to operating temp(170-180) sooner than 30 minutes.

Rickman48

In my experience, the cooler the car ran, the better it ran.
Only thing heat was good for was catalitic converters.
Even at 160, we still got enough heat for Chicago winters.
Leave it alone - where it's at is fine!

drjr56

Thanks Rickman....the builder said the same thing,and it does run great with the restrictor,my concern is sludge,and premature wear.I need to see what restrictor is in it and maybe use one smaller,this is a streeter that I use when I want to go out and play,and it does get cold here on the East coast as you know..that's why I wanted to switch to a thermostat.

507OLDS

You can get the same effect as a restrictor by taking a stat & gutting it.I am wondering if the builder was having problems with it running even hotter with a stat in it,so he switched to the restrictor.

drjr56

I'm wondering as well Brian,Guess I'll find out when I put the thermostat in.That is one bad*** 72 Cutlass.71 and 72's are the best looking years...jmo

380 Racer

I tried a gutted thermostat once, but didn't work so well. Went with a 5/8" hole restricter. Still use it now.

drjr56

I may end up doing the same Racer ...better to run a little cooler and protect it,than chance getting too hot, and I know it's gonna get to 200+ in traffic, even with a 160....

ah64pilot

Your engine is not a racing engine and is not so wild that it should have this problem. I would troubleshoot it before I ran with a restrictor rather than a thermostat...I have a hard time waiting 10 min. for mine to warm up let alone 30!

There is a problem somewhere in your system. My 500 hp BBO runs cool with a 160 thermostat and stock clutch fan (new clutch). I had an engine almost identical to what you have when I was in high school and I had a $30 steel flex-fan on it. It ran just as cool as mine does now. I wouldn't continue to mask a problem by pulling the stat or running the restrictor. Figure out what's wrong and save yourself money in the long run. It could be a blown head gasket, or it could be a really tight engine. Until you know you are just driving blind. Hell, you could have a really bad air / fuel ratio or something odd like that...or even have the fan on backwards (as was discussed in another thread a couple months ago).

Also, the Mr. Gasket thermostats are not high flow thermostats anymore. They are overpriced run of the mill thermostats. You will find that the Stant Superstat is a really high quality design and it is made in the USA. I switched over to it (from a Mr. Gasket "high flow") and am having much better temps.

drjr56

If there is a problem it's not obvious yet...or is there!Won't know till I put in a thermostat..I do know the builder wants to protect the heads and gaskets,and also feels these motors run best when kept cool....I understand all that,but would still like to see 170....and get there in 10 minutes..I will look into these Stant Stats,and maybe a clutch fan, but on the highway the flex fan works pretty good,stays at 170 degrees,until we hit traffic,then it starts to creep up,and I don't want it near 200+

therobski

This is very good advice from these guys, Brian ( 507Olds) has helped me many times with the 67 build. My 455 runs maybe 170-180- in Dallas summer heat. On the freeway 105 degree heat sustained 70 MPH @ 3100RPM the temp will gradually climb to 195-200, as soon as back off to 65 mph shes back to 180 or less. I don't run the motor at 3100 RPM for long periods of time, just my preference. Also installed is a Mr. Gasket HP adjustable thermostat, whether that makes a difference. I have experienced that running these BB Olds cooler you can get a few more degrees of timing out of them-if need be. Currently running 20 initial-36 full on 93 pump gas and it will pull your shirt off from a stop light. Aluminum heads, radiator-perfect for aiding in heat dissipation.
IMG_1189.jpg

drjr56

Thanks therobski....very nice 64,motor looks awesome!Sounds like you have a clutch fan on yours.My 69 has a flex fan for some reason,which causes the temp to creep up when stuck in traffic,but on the highway the temp drops a little.

oldcutlass

How far is your flex fan from the radiator? Which flex fan are you using?

drjr56

Wow....Real nice 67,my fan is about 7''from the radiator I believe,with shroud,everything is like new,as far as the type..it's a pull,and I'd have to count the blades,hell I should know that,the car is covered up right now.My issue is the builder uses restrictors instead of thermostats,and the motor takes 30 minutes to get to 140 degrees.He (the builder )tells me not to touch a thing,just leave it that way,but I live in Philly and it's getting cold.Even with aluminum heads I like to see at 160.....Damn nice 67 oldculass!!

oldcutlass

Thanks for the compliment. I run a flex fan and no shroud. I've got mine about 1 inch from the radiator. Mind you I also have a bored out 454 BBC in mine. I ran a 160 degree thermostat for a year and it would not really heat the car in the winter.

I had an issue at first at idle and moved the fan closer to the radiator and that solved it. During the summer it would run about 175 at cruise but get no hotter than 195 with 100+ ambient temp. I changed it to a 180 last month and it goes no higher than 200 - 210 at idle in traffic. The radiator is a cheapie 1 inch thick aluminum with plastic tanks.

This is what it looked like before I moved the fan closer.

drjr56

Sometimes it's something that simple,your lucky.I'm reading where another guy had his fan close to the radiator and it caused problems,but he uses a shroud,and it's in a bbo.Right now I'm using a restrictor as per the builders advice,and he's adamant about it,and I'm just trying to get a little more heat in the motor,so would like to use a 160 Stant superstat and see what I get.The restrictor in there now is 5/8 and when the outside temps are 65-70 I barely get to 140...unless sitting in traffic then gets to 140-150,but the heater does blow warm air. I put an IR thermometer on the block and it's reading and the inside gauge read the same.The area where the headers meet the block was at 350 up to 415 degrees.That's my concern,having enough heat in the cylinders,so there's not a lot of wear there and on the rings.

TripDeuces

The problem is the restrictor is too big allowing coolant to flow through the engine and radiator too fast. It doesn't allow the coolant time to get hot in the engine and then the radiator is further cooling down an already cool mixture. Either use the smaller restrictor size or put the thermostat in. In my opinion the restrictors should be left to race only motors. Use the thermostat on the street always. You have to allow the coolant in the block to get hot and then let the radiator do it's work.
I tell you this from experience not some oddball theory. Restrictors have no use on the street.

drjr56

Thanks Tripdeuces...with the 400 I also used a thermostat always,but that is an all cast iron motor,and would get to 215 putting around town.The motor in my car now is a .060 455 with aluminum heads,and I want to keep it under 190,just to be safe,Olds builds are expensive as we all know.

oldcutlass

Why not try installing a 160 degree thermostat and try it out.

drjr56

Yeah going to try the smallest restrictor and see,if still too cool going with a 160 Stant.Boy I'm happy the only problem I have is getting more heat in the motor......so far anyway!!Also good to know there are some very knowledgeable people here.

drjr56

Temps are in the mid 50's now,and my car's temp gauge gets to 135-140 in about 15 minutes....so I replaced the 5/8 restrictor with a Stant superstat 45356.Now driving in stop and go traffic,and sitting at traffic lights the gauge gets to 179 and stays there until I get moving,then drops to 170. I think this fresh build needed a little more heat for break in.

therobski

DRJR56, I"m sticking with the same note: cooler is better. When it gets to be in the 50's here in Dallas, my 455 stays at 150-160 and just purrs! Enjoy

oldcutlass

I think it's fine if it gets to 170-180, it will go higher with higher outside air temp.

drjr56

There are a couple Olds builders that feel the same way....cooler is better,but that means 160,and when building street/strip cars use high flow water pumps and 5/8 restrictors.I myself like 160-180 for performance,and if the engine temp does go up,and I expect it will come the summer the 5/8 restrictor goes back in, 85-90 degree weather the motor stayed between 150-160 with restrictor.

drjr56

Raising the temperature in aluminum heads from 140 to 180 might effect chamber heat so to not lose as much hp........just wondering.

oldcutlass

I personally like to get the temp up to at least 170 to keep the oil at a good operating temp to keep moisture to a minmum. I run a 180 deg thermo and keep my temp at around 185 - 190. My heads are not aluminum.

scumdog

What he said - if your cooling system is up to scratch a hi-flo thermostat beats a restrictor hands-down for convenience and engine life.

(BTW:I'm talking about a street car here)

drjr56

Yeah I like stats better too,and to see a normal operating temp,for all the reasons mentioned, superstat is doing the job nicely right now...

matt69olds

The oil temp is a good point to consider. My opinion is 170-180* is about ideal for performance. Its also my opinion that its really hard to beat factory engineering. The Olds engineers had far more resources at their disposal, there is no reason a engine in good internal condition with all the proper shrouding in place and functional should overheat. Put the proper shroud on it, with the correct fan and thermal fan clutch and I bet it stays at a reasonable temperature. The factory temp warning light doesn't come on until 240ish, I wouldn't be too concerned with a engine running temp of 200* or so. On my 69, I used lots of extra pieces of the heavy tar paper to build extra shrouding in the bumper and grill area. Any air the enters the front of the car has to go thru the radiator. The wife and I drove it on several stops of Power Tour this year, even in the heat idling for hours on end the temps never went over 200.

drjr56

The fan and shroud is an area that I could change in my 69 442....someone at sometime put a flex fan on, and the shroud looks like it could be sealed up a little better than it is now.But for the time I'm happy it's running at 170-180 consistently,I have aluminum heads on this car.

442rocketdave

I have had good luck on the street with 7 blade fans with clutches and a 160 stat, and like oldcutlass said the distance between the fan and the radiator is a factor and using flexible tar paper to seal up the shroud and help with the air coming thru. During summer it gets hot in Florida and I use water wetter and it helps the temps stay down. Lots of good advice on this forum. Especially the one about keeping it under 200, your engine will last alot longer. Stay cool!

drjr56

Thanks 442rocketdave.....my 69 442 now has a fresh street/strip 455 in it. I've put 400 miles on it. My builder uses restrictors instead of thermostats and my concern was the motor running below 160 and now in November not reaching 140. Since changing to a Stant superstat the car is getting to between 170-180. Come summer I hope it stays that way but if not will look into making the necessary changes to keep it cool. Not sure why someone put a flex fan on this car,but it works pretty good,and there is a shroud,that could be sealed up a little better. This is an awesome site with many very smart people that are more than willing to help in all areas of this passion we car people have.....I always appreciate all the input and read everything.