[67blackcherry]

I just completed my 455 build, and yesterday driving home on the freeway she ran between 190-230. She cooled down when I wasn't in stop and go, but while waiting at the light to my neighborhood the temp guage was at 230. What's up???

Alumitech 4 core radiator, Water Wetter & distilled water, 180 stat, stock shroud/fan/clutch assembly, timing at 32. The carb is pulling vacuum at idle (I've got to take it back to the guys I got it from) but that shouldn't be an issue, right?

Is the new engine going to run hot until it's broken in? Suggestions???

[David Jones]

The gauge is right?

[67blackcherry]

Originally Posted by David Jones

The gauge is right?

My set of AutoMeter guages...they were right before the engine swap. The LeMans used to sit at 190, no matter...stop and go traffic, lots of lights, doing 80 on the freeway...solid like a rock, temp-wise...

[David Jones]

On your car what is the stock fan? How does it sit in the shroud? Is the shroud sealed to the radiator?

[DBONES152]

I would check to make sure your carb isn't running too lean. You also might need to go to a higher octane fuel or use a booster.

[67blackcherry]

Other than the vacuum issue, the carb's fine. And I filled it with 91octane yesterday, that's premium out here!

The fan is sitting 1/2 way inside the shroud. Would having the radiator an open system make any difference? I've just got a piece of hose running off the overflow port...it's not a sealed system, and I'm running a 13lb cap.

[David Jones]

In sealing I was talking about the gap between the shroud and the radiator. You want to pull air through the radiator, not around it. I run a 16lb cap and have an overflow pipe only. No reservoir.

What is a "stock" fan? One that used to work for a 350? What you are describing sounds like poor air flow through the radiator at low speed or while stopped.

[Region Warrior]

Agree with Mr Jones.
Low air flow at idle/low speeds.

50/50 in/out is good.
19" 7 blade fan?
Check impellar to divider plate distance?
Might try a 15lb cap. Thats what the factory used.

[67blackcherry]

Originally Posted by David Jones

In sealing I was talking about the gap between the shroud and the radiator. You want to pull air through the radiator, not around it. I run a 16lb cap and have an overflow pipe only. No reservoir.

What is a "stock" fan? One that used to work for a 350? What you are describing sounds like poor air flow through the radiator at low speed or while stopped.

Ames Part# P151A / 64-67 Molded Fan Shroud 15 1/2" core
P154FA / 7 Blade Clutch Flex Fan 17"
P154G / Fan Clutch

I have the stock fan that came with the 455, it's the bigger 19" fan that wouldn't fit in the stock fan shroud, and we figured (and the general consensus of these fellow board members) was to go back with stock. The shroud seals up nice and tight with the radiator. Would a 16lb cap help?

Region Warrior - I checked the gap in the water pump impeller - it was within specs. Bought it so long ago, don't remember the exact #'s but it was within what's posted in that long running impeller thead.

[GTOGreg]

I know we talked about gauges, but what about senders? Did you change the sender on the manifold? Those AC Delco units are junk if you bought a new one - they can read up to 20d (!) off. Lectric Limited makes one that reads spot on. There was a thread a couple of years ago on it. You can test the one you have if you have a candy thermometer and pot full of water. I'm pretty sure you're looking for a resistance value, but you'll have to search for what it is.

Is the engine exhibiting any signs of actually overheating? Do you hear boiling, is it running over, is it pinging, are you losing power, does it diesel when you shut it off?

It will run a bit hotter when new, but not 20-30d.


Hoping you get 'er squared away!

[GTOGreg]

Read this thread...

http://forums.maxperformanceinc.com/...testing+sender

[SupergasDil]

Remember also that more horsepower creates more heat.

Are the fan blades the big square type or tapered ? You need the biggest blade you can get.

Automatic or stick ? If you have an automatic make sure you are running a separate tranny cooler.

I would up the cap to at least 16 lbs.

If you still run hot when you're sitting then I would mount an electric fan in front of the rad that you can switch on when you're in stop and go. But make sure it's one that moves a lot of air when mounted in front or pushing.

[67blackcherry]

Originally Posted by SupergasDil

#1)Remember also that more horsepower creates more heat.

#2)Are the fan blades the big square type or tapered ? You need the biggest blade you can get.

#3)Automatic or stick ? If you have an automatic make sure you are running a separate tranny cooler.

#4)I would up the cap to at least 16 lbs.

#5)If you still run hot when you're sitting then I would mount an electric fan in front of the rad that you can switch on when you're in stop and go. But make sure it's one that moves a lot of air when mounted in front or pushing.

1) Absolutely
2) Tapered...it's the stock 17" for the 66 A-body. I have the bigger 19" fan, it won't fit the stock shroud
3) Auto - yes, I have a separate tranny cooler and I'm running a manual radiator - no internal tranny cooler
4) Will do
5) Really don't want to do that

Had a long talk w/ Don from Alumitech Radiators, he have me a bunch of pointers as well as an education on cooling systems! He recommended switching to a high-flow stat and getting at least a 15lb radiator cap - so I'll start from there. I know it's just a little kink I have to work out! Thanks for the suggestions, please keep them coming!

[ctgross]

Is the fan clutch new? If it's an older one let the engine get up to temp....say 190-200 and kill the engine and watch the fan. If you can count to 5 or 6 before it stops spinning when you kill the engine...it's worn-out...made a big difference on my 66 last month. Good luck.

[Alumitech]

Paul
Often its a lack of airflow and good coolant flow at idle/slow speed that can cause a motor to heat up in traffic .

But since it’s a new motor and tight .. it may take some break in miles ..and may have multi issues like poor fan airflow and coolant flow at idle thru the radiator along with an improperly tuned motor which can cause the engine temps to rise faster then normal .


But we need a lot more info like:

Does the motor/radiator actually over heat and what is outside temp when this is happening? 210 is nothing to panic about ...but as you say 190 at cruise with good air flow and coolant circulation

Have you tried a new high flow stat to go along with high flow water pump need them as a combo !! one of the big keys to cooling is good flow ...the higher the flow the better ...hence hi flow water pumps and hi flow t/stats .


Have to verified the temp gauge is reading properly? This in it self are important .. verify with a infared gun .. don’t trust gauges alone
If motor doesn't ever really over heat then that may be a clue that the temp gauge is not working properly, you need to verify it.


Does it have stock fan and if so what type, clutch fan ... standard units are only a 50% lock up Has anyone verified the fan clutch is working properly?


If you have a clutch fan,is the clutch new or old, std duty or h/d/ac type, thermostatic?

I always fine the ac/hd fan clutches do a better job of cooling a bbc in traffic which is why I run a h/d one ..Hayden sells
heavy duty 80% lock up

A few lb higher psi cap wont help his engine temps come down ,been there done that,it will just increase the boiling temp
coolant at open atmosphere boils at 211 degrees and turns to steam .. for every lbs of cap pressure you increase boiling point 3 degrees .. 15 lbs cap .. you boil at 256 degrees .. does nothing to bring temps down !!!


Are you running any kind of perf cam, if yes what base and total timing are you running?
you need approx 18 deg base + 18 deg mech in dist in by 2800rpm for 36total by 2800rpm.
(Retartded timing/esp base timing can contribute to heating up in traffic) burning gasses in the head .. not in the cylinder

Are you running a vac adv which you need for a street motor.
(No vac adv or vac adv hooked to ported vacuum with also contribute to heating up in traffic.

Is the vac adv hooked to full intake vacuum all the time when it should be for most setups.

The vac adv could simply be defective/diaphram riped/torn and notadv the timing at idle .

Running low grade fuel in a higher comp motor can also contribute to higher temps.

Lean fuel calibration or a vacuum leak leaning our cam mix can also contribute to higher temp in traffic.

So check this stuff out and get back to us with what your setup is and what you have found thus far.

[DPlum]

We all know that a straight fan is the cure for hot idle mine was 215 plus with new hd clucth went to a flex fan 190-200 traffic 160-180 driving

[GOAT8U2]

Run less coolant with the 16lb cap so the distilled water and Water Wetter can do a better job yet give you the boiling the 16lb cap and some antifreeze can offer.

Your timing is about 16 degrees off, run 46 to 48 total which will also bring up your idle timing and cool things down. Manifold vacuum with vacuum advance should be on every street car.

If this does only a little then it's time to get twin electric fans if the temps bother you.

[SupergasDil]

Goat, I have to disagree on the total timing. 32* is about perfect for a 455. You may be able to run more with higher octane but California 91 is pushing it. JMO

[GOAT8U2]

My post probably came across like I was talking about WOT timing, I was referring to cruise timing and it should have a total of 46 to 48 with the vacuum advance on top of the WOT timing.

[455Grandville]

Drill a couple 1/64" ths holes in the thermostat.