To all (especially Lou),

I got the Purple People Eater (71 Swinger w/ 68 225) running last weekend after completing Lou's "The Perfect Slant Six Rebuild" (from the .com site), and it is a kick in the you know what. Anyway, on with my questions. The engine is not really overheating, but the temps seem to be higher than they should be. If I fire the car up and let it idle (no load), it holds the temp at 195 (thermostat temp) as I would expect. But with a load, and at any speed, the temp rises to between 205 and 215. So questions #1, is this hot or not for a freshly rebuilt engine?

Initial advance is @ 12 deg and total including vac is near 45 deg. I installed the cam at 2 deg advanced per Doc's advise (don't know if that effects anything). I've got the big radiator, and the 6 or 7 blade fixed fan (don't want to get up and walk to the garage to count), and no shroud (dang it). So question #2, how much improvement in cooling does the shroud supply, should I visit a scrap yard and try to find one?

Please feel free to throw any and all advise my way. And feel free to ask me any questions that may help get an answer.

Thanks,

Erik

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There's someone in my head but it's not me!!

Well you're just going to have to get used to it. The sl6 is a natural fire breather. It runs on the hot side no matter if it is brand new, or 30 years never rebuilt. It is just the way they built it; positioning of everything, size of motor compared to the size of the coolant flow. There is really nothing to worry about unless you start to here lots of pinging and panging. Do you have a fan shroud? What fan are you turning? I've got a 7 blade without a fan shroud. I'm in the process of trying to find a shroud, or making one fit. I guess it's a good thing they made these motors iron, head and all. I actually ran the car for a month without any coolant in the radiator, in Tucson. No signs of overheating

I guess I need to read the whole post before I reply The fan shroud actually makes more concentrated air get pulled through the rad. which provides in faster cool off. I've heard of people getting them out the yard of even '90 cadillacs. so I guess you could make a lot of ^%$t fit

I don't remember it running this hot before I did the rebuild. Will it cool off a little after break in is complete, or do I truly need to "get used to it"?

Thanks,

Erik

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There's someone in my head but it's not me!!

I am by no means an expert but the potential exists that when you did your rebuild you may have dislodged some crapola in the cooling system which could be restricting the flow. Maybe you should consider a flush of the cooling system unless your rebuild included a new Rad.

Just a thought.

Good Luck!

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It is easier to REACT,
than it is to THINK!

Middy.

Engines will often run a little hotter after a rebuild, but it should get back to normal within a couple thousand miles. Your timing is different now, and that will also affect operating temps.

A shroud helps, but it still shouldn't overheat without it. If you changed radiators with the rebuild, I would look at it as the possible culprit. Was it a used unit?

I bought the car from my father-in-law about 6 years ago, and he installed the radiator a couple months before I bought the car from him. I'm pretty sure he had the radiator checked for leaks and flushed when he bought it.

During the initial firing of the engine, I ran it with straight H2O. After the break in run, I drained the system and put in a 50/50 mix. The drained water came out pretty clean, just a little bit of brownish-green which I'm guessing was rust and left over fluid from the radiator and heater core because the water jackets in the head and block looked amazing when I got them back from the builder.

Thanks for all the input,

Erik

_________________
There's someone in my head but it's not me!!

The shroud will help most when the car is sitting still up to about 15 or maybe 20 mph. When either sitting still or going slow there is no ram affect forcing air through the radiator. As the speed of the vehicle increases so does the amount of air through the radiator.

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Former bent 6 owner
Mark

205-215 isn't really all that hot anyway. You're not going to hurt anything till you're over 240 (IMHO).

A fan shroud will certainly help, especially at slow speeds, as mentioned.

I use an electrical fan from a Jeep Cherokee in my '74, and it works great.

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It's a Slant thing. Even I don't understand.

1974 Duster, EFI /6 soon to be turbo...

Get that Monkay! Get that nasty thing!!

When I had trouble with my engine, Doug suggested that I limit the total advance to about 30 degrees. Sounds like you might need to play with that.

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Chuck Rivers, Webmaster

Thanks for all the advise, opinions, etc. Sounds like I just need to get used to it, and maybe do a little playing with timing, air flow, water flow, etc. to see if I can get things cooled down a little... As usual. These things wouldn't be as much fun if it all went perfect the first time.

Thanks again,

Erik

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There's someone in my head but it's not me!!

When it comes to high speed overheating, I never trust the thermostat, try a different one, these are cheap and easy to change.

Also, never under estimate how much rust scale and "crud" there is in a "rebuilt" engine block. Often the cleaning / rebuilding process just loosens-up this crap, which can quickly find it's way into the radiator tubes.
You may want to drain the radiator down to the top of the tubes and take a look with a flashlight, if your see lot's of rust scale, backflush the system.
DD

Thanks for the advise Doc. I am pretty sure it isn't the thermostat, I'm on my third since the rebuild (apparently you and I think somewhat alike). I don't trust these things either.

Is the "backflushing" something I can do myself, or do I need to haul the Swinger to a shop?

Thanks,

Erik

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There's someone in my head but it's not me!!

Erik,

Glad you got the car together, and I hope my advice works out. It is perfectly normal to see higher temps when the motor is breaking in, but I also do not consider 205-215 too hot. I have never used shrouds, so I can't comment on that. I did just put a "universal-Chevy" style Griffin radiator ($190 from Summit) into my '64 and it cools wonderfully. I had to make my own mounts for it and get custom hoses.

I have seen plots of engine temp vs. wear, and basically anything below 180 makes wear go up, there is not much difference between 180 and 220, and it gets worse above about 220.

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou.

As far as the engine performance goes, I could not be happier. Other than this temperature thing, which seems to be more a problem with the driver than the car, everything is working great. Dual 2-1/4 inch pipes into Flowmaster Delta 40's sure does sound awesome. I think I even converted my dad. He always wanted a 65 cuda with a 360 or larger, but after hearing my slant, he changed his tune.

Thanks,

Erik

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There's someone in my head but it's not me!!