ajrothm

So this weekend I have spent testing different different things on my car to see what helps with water temps....all of this in preparation to buying a new radiator/fan combo... Here is where I am at right now...

DAY 1 Testing....88*
Change made:
As an experiment, bumped the timing to 37.5* locked out....(mixed 2 gals of C16 fuel into 12 gals of 93 for safety) from 31*

Test:
Warmed car for 10 mins in driveway, turned on the AC, and headed to the highway....By the time I got to the entrance ramp, I was at 180*. Got on the freeway, running 70 mph (2950 rpms), by about 15-20 mins in, I was at 195* and SLOWLY creeping about 1* per mile. I ran about 15 miles or so of steady highway, and it was pretty much holding at 200*..... I U-turned around and headed back, I ran it up to 3200 rpms for a brief minute and the temp climbed to 205*, I backed off to 2600rpms and it stayed at 205*.....I ran it the same 15 miles back and it was still at 205* and holding....I exited off the highway, got into town running about 40 mph and it cooled to 200*.....right about that time, my AC evaporator froze up requiring I turn the AC off. With the AC off and running about 50 mph it cooled to 195* and stayed there...Eventually I got back up to 70 mph(2950rpms) without the AC and it climbed right back to 200*......

Deductions:
*The car wants to run 200* on avg but on the highway it will continue to heat up I believe on longer runs...may stabilize at 210-215*....not sure, I don't let it get that hot to find out....

*The AC doesn't seem to make THAT much difference in running temps suprisingly.

*Going from 31* locked to 37* locked seemed to slow the warming process, seem like it was stable at 200-205* and made the throttle response and low speed pep considerably better...


Tomorrow's testing will be in the mid day, 95*

....I am going to bring the total timing back down to 31*, but hook the vacuum advance back up and measure the total timing at cruise rpms....It will likely be 40-45* and test it (still on race gas ofcourse) and see if it continues to reduce temps at freeway cruise. Log the data....

....I will remove the thermostat, do the same freeway route/mileage/drive style. Log the data


....Add a bottle of Water Wetter....(I don't think this will do a damn thing but for $8 its worth a try), repeat the same freeway route. Log the data....

Then we'll see where I end up. Ultimately I will install a Dewitts Aluminum radiator but I want to see how much I can reduce temps with the stock stuff first.....I may also try I trick I stumbled onto with the oem fan clutch...

TESTING DAY 2......TEST#1....85*
Changes made:
Cut fan shroud back 1.5" to expose 1/2 of the fan blades. Adjusted thermostatic spring on fan clutch to allow max friction to come in at an earlier temp. Timing still at 37.5*

Test:
Warmed the car up for 10 mins, switched on the AC and headed out to the highway, I arrived at the highway at 160*. I ran the same test route I have been running. After about 15 mins on the highway at 70mph (2950rpms), the car was running a steady 195* and seemed to be holding. I ran the entire route and back home, a total of about 30 miles of highway, ran 195* the entire time, even in town.

Deductions:
Seems to be making progress, temps at least seem stabilized. On average it ran 5* cooler but it was only 85* out compared to yesterday's test temp of 86-88*...


TEST #2.....88*
Changes made:
I decided to play with the timing some more since it seemed to help, this time I moved the timing back down to 31* locked, but hooked the timing advance back up yielding 48* at max vacuum, 3000 rpms. (Yes C16 fuel is still in the tank)

Test:
AC on, leave the house and within one mile I can hear noticeable light pinging at low load, low RPM..., I got on a feeder road and eased up to speed, temp was running right at 200*, I only went 1 mile and decided to go home to disconnect the vac advance....By the time I got home, temp was 205*.

Deductions:
Vac advance added way too much timing, even for low load/low rpms, it started to lightly ping, even with a mix of C16 fuel. Also seemed to run a tad HOTTER with the additional timing....due to the detonation I'm sure.


TEST #3.....90-92*
Changes made:
Disconnected the vac advance, checked the timing was at 31* locked, decided to try that and see what it would do.

Test:
Now the car is good and hot, been running for near 2 hrs on and off....I attempt to take my usual test route again but the traffic was stopped, so I headed across town to a buddies house. I ran a mix of light highway speeds(55-60mph) and some in town, 40 mph and less, lots of stop lights. The car pretty much ran 200* the whole time...Never really cooled below 200, after about 25 mins I got to my buddies and shut the car off....About 40 mins later we head out for a ride, now it is 92*, 55% humidity.... "Feels Like" is 105*.+...We run on a 40 mph road for a few miles, catch a few lights etc and temp is at 205* but seems stable...after a 20 min run, I dropped him off and I headed home on the 25 min drive back, seemed to run right around 200* the entire time back.

Deductions:
The car seems to like the 37.5* setting for the timing, it seemed to run about 5* cooler in all conditions BUT the ambient temp had a 5* difference also. Looks like I am gonna have to shop around for a vac advance that will add about 8* at the crank..... Then I can run 31* locked and with the added 8* of vac advance that should get me 38-39*.....hopefully that will keep it in the sweet spot and not ping at low load, low rpm.

At this point I am kind of at a loss as to what to do.....I am guessing the next purchase needs to be the Dewitt aluminum radiator, I am puzzled as to whether I should get the electric fan package or not....I was pretty happy with the stock clutch fan's performance in town but now that its getting hot(ambient temp), it is able to stabilize the water temp but not cool it any....but I am not sure electric fans will also. I am tempted to try the aluminum radiator WITH my stock fan/shroud but if it doesn't help, I will kick myself for not buying the electric fan package that comes fully assembled, with switches, relays, wiring etc....BUT if I spend the money on the electric fans, I will also have to upgrade the alternator/wiring etc and if THAT doesn't help the temps, I will be QUITE pissed off that I threw a ton of money away....


Thoughts on my tests or advice? I would like this thing to run 180* all the time.....It is noticeably down on power when the water temp is over 185* so.....I want to cool it down..Not to mention is isn't that hot yet....here in Aug will be 100*+....


TEST #4....temp 85* (ran out of time to test again at peak heat)
Changes made:
I figured I would try my luck with a little snake oil.....so I drained 1 gal of 50/50 coolant out of the radiator, dumped in a bottle of Redline Water Wetter and topped off the system with a gallon of plain water.....Timing still only at 31*.

Test:
AC on, Same drive, same route, difference was the ambient air was only 84-86*, so roughly 6* cooler...interestingly enough the car ran exactly 6* cooler....Pretty much ran 190-192* the entire test, highway, in town etc...

Deductions:
Test inconclusive due to the ambient temps being cooler. I will test this combo again tomorrow as well as bumping the timing back to 37* and dumping in some race fuel.....I am hoping I will get the same 5* reduction in temps from bumping the timing that I got the first time I had the timing at 37.

1970-Bronze

I missed some of your earlier posts.

Can you refresh my memory:

What thermostat are you running?
What radiator is in the car?
You still running the TH400 w/2500 stall - correct?
Is the trans connected to it?
Are you running a supplemental trans cooler?
Have you tried running the car without the front plate (I know it is required in Texas- mine runs much cooler without)?

It lookes like if you had a vac can with ~6º of advance, you would be about where you want to be timing wise.

It is also curious that you are noticablely down on power above 180º. I wouldn't expect that until 220º or more. Sounds like you may be intaking hot air from under the hood also which will add to your issues.

Tim

ajrothm

Thanks for the reply....

7T1vette

You can install a 160 deg. stat...but that won't cause the cooling system to stabilize at 160. The thermostat only sets the LOW temp value of the system. It is there to allow the engine to warm up quickly to the rated thermostat temp. BUT, how much farther the temp raises is dependent on the capability of the cooling system.

From your "experimental" data, your car never got over about 205F. So what's the problem? That is not "HOT". In fact, that is about where most cars run these days [as most have 195F stats in them]. If your engine was running at 230F or higher, you would be having a problem.

If I were you, I'd quit experimenting on a non-problem and just enjoy the heck out of your car.

P.S. If the A/C is freezing up on you, check to see if their are leaves, debris...maybe a mouse nest...plugging up the air intake pathway in the A/C plenum and/or right kickpanel ductwork area. If you don't get a lot of airflow through your vent system, it is probably plugged up and will cause the A/C evaporator to freeze up.

noonie

Try one of your test runs with the rear of the hood propped open 3 or 4 ".
Don't worry, it's safe.

ajrothm

Yeah technically, 205* is not hot, especially for todays cars.... but on a 10-1 comp, steel head, 657hp engine with air conditioning, 205* is pretty hot. This thing is very prone to detonation so everything has to be right. The engine builder wants it no hotter then 185*.....and said not to hammer on it if its over 180* so.....that pretty much makes this big engine useless if you can't play with it....thats why I gotta cool it down....Not to mention out on a long road trip, I don't know how hot it will creep to on the highway...it may never stabilize...We are only in the low 90s here right now....this time next month it will be 100*+ so.....I need to get the ball rolling on this...

chevymans 77

once the under hood and engine is heat soaked take a short drive and then check the temp DP across the radiator. It should have 20* to 30* drop across it if the combination is working and sized correctly. If the radiator is the same temp inlet and outlet than you have reached the capacity of this combination (this is if the radiator and fan combo is working correctly and in good shape).

Mine would reach the same temps across the radiator with just a few miles of driving at 40 mph once the under hood and engine would get heat soaked. There was no cooling it down until I let it idle for a while and than it would not cool back to 180* it would stay in the 200*+ range.

Neal

0Tom@Dewitt

It sounds like you have hit the wall with the radiator that you have. If you run straight distilled water and a bottle of WW you might drop 5-10 degrees. Electric fans won't do much for highway speeds. At the end of the day, I think the aluminum radiator is the way to go. The average change in temps is about 30 degrees when changing from copper to aluminum. This is the single biggest change you can make and it would give you a little extra cooling capacity when you hit that 100* day or heavy traffic. You shouldn't need to go with electric fans, as the radiator alone is a pretty big upgrade.

Chris Johnson

I may be able to save you alot of money and pain. My motor is a 714hp 565, and I'm on my 3rd fan combo and 2nd radiator now. I think it is dialed in now, but I'm waiting for the real Florida summer heat to come before I can declare it resolved. Following are the iterations I have been through.

1) Dewitts radiator and dual spal 11" fans = 2712cfm
Worked well on the highway, but couldn't handle stop and go traffic. Overheated badly, which was made worse because the Autometer mech water temp gauge capillary tubing failed. So the gauge was reading about 60 below what an IR gun indicated. It overheated so badly that it 'popped' the radiator - the tubes expanded into a football shape. This happened with a 14psi cap.

2) New Dewitts radiator and Spal's most powerful dual fan setup - 12" = 3168cfm
Helped, but these fans kept blowing the 30amp fuses (30 amp fuse PER fan). According to Spal tech support, they spike to a higher amperage on startup. Overheated again of course, but my new Autometer mech gauge, and it's backup Autometer elec gauge, worked this time, so I shut it down before permanent damage occurred. I went thru some wiring experiments, but finally gave up and went with...

3) Same Dewitt's rad and custom fabricated shroud setup with Spal's extreme performance 12" individual fans = 3616 cfm
These fans require a High Output relay, and 60amp (yes, that is correct, 60amp) fuse PER fan. The relay is much heavier duty than the regular relays, and the fuses are the huge MINI type. It pulls around 30amps when running per fan. I haven't had an oppurtunity to run this in really hot Florida summer weather yet as it hasn't gotten much over 95 degrees. The other day, after blasting around a little, and then getting in stop and go traffic, it made it up to 205. Which is not a problem with my 9.6 to 1 compression and aluminum heads. I do have to mix 100octane race gas with 93 as it tends to run on when I shut it off. If it levels off at 215, I'm more than happy with that.

Here are links to the fans. If I were you, I'd skip the smaller fans and go straight to the biggest you can. These fans are a VERY tight fit, especially at the sway bar of all places. Those big holes were a real pain to cut. I used .060 aluminum to fabricate the shroud, and one advantage was I built it to cover 100% of the radiator surface area.
http://www.spalusa.com/store/main.as...&item=30103202

http://www.spalusa.com/store/main.as...tem=FRH-HO-KIT

I'm running 36 degrees timing. If I had to retard timing at all, I'd probably have heat issues again. I tried the 100% distilled water, and the water wetter, to no avail. The problem is a simple matter of airflow. With a 160 thermostat, it runs 180 all day long on the highway. I'm afraid you'll really have problems when you get in traffic... Tom's opinion when I spoke with him was that I'd probably continue to have problems as long as I had this monster motor that produces a ton of heat. If I continue to have issues, my final last ditch plan is to divert some of the coolant off into a -16an line to a rear-mounted small Scirocco style radiator with one of my left-over 12" fans. I already have the -16an fitting on the water neck. If this were to fail, I guess I'd be switching to alcohol injection, which would require a new liner for my ATL fuel cell, and new fuel pump I believe.

Les

Tom may sound like he's trying to just sell you his radiator but based on my experience with my 69 I think he's simply trying to help. Granted I'm only running around 500 HP and far less cubes than you but I went through all the steps to max my cooling and nothing got it done until I got an aluminum radiator from Tom. I had drilled holes in my T-stat to help water flow and after I installed the aluminum radiator I had to swap a new T-stat in because the car wouldn't even warm up unless ambient temps were downright hot. Money very well spent IMO. Good luck.

HamadUP

Alan, if Tom's stuff is working for me, then it SHOULD work anywhere else in the world, I say invest on Tom's aluminum radiator and I'm sure you'll get rid of any excessive engnie heat issues.

when my car was totally stock with the mech. fan and B/C radiator with no A/C I had really tough time driving it in a 95*+ day, it tends to overheat in heavy traffic, and now after I upgraded my engine to 9:1 CR and added the A/C along with Dewitt's radiator/fans combo, I can drive her all day long in a 100*+ days with no more than 190*, even I tried the ultimate test where I let it idle in mid day's desert heat (it was like 110*F) with the A/C on and it stabilized right on 210*F for about half an hour, try that with the stock cooling system and I'm sure it would steam out the coolant in few minutes.

Actually yesterday I drove it for 1.5 hours with A/C on in a 95*F day and the temp never went past 185*F, actually in few times it cooled to under 175* where the electric fans were turned off and then on again at 195*.

HamadUP

BTW, my timing is 12* initial and 36* total, and when I hooked the vacuum advance I felt the engine ran a little cooler.

ZL1powr

Here are is another data point in support of DeWitt’s aluminum radiator. I converted my small block 71 to a BB over nineteen years ago by installing a 454 HO. I originally utilized a stock BB radiator and it worked marginally until I started making performance mods. Too much water over the dam for me to remember specific data, but I do remember that it tended to run very hot in stop and go traffic (210-220) and at speed down the highway (>200). I installed a Dewitt’s Aluminum radiator with dual 11” spalls and it rarely exceeded 185. I have continued to use that same set up with a 694 HP aluminum 489 BB and a 800 HP aluminum 565 with no cooling issues at all. In the 454 and the 489, I ran 20* initial and 36* total mechanical advance with 8* of vacuum advance. In the 565 I run 18* initial and 34* total with 8* of vacuum advance. I am sure the aluminum blocks contribute to the cooling but the difference between the stock radiator and the DeWitt’s radiator was dramatic.

I assume you are locking in your advance to help keep the temperature in check but it might be worth an experiment with less timing at lower RPM’s to see how much it affects your temps and its effect on detonation at lower RPM’s under load

blue427

This has to be one of the best and most interesting posts I have read in a long time.You took a problem and systematically listed results which limited replies to things you havn't tried.I wish magazines handled things in that manner.I can not really be of much help as you have way more Knowledge about thisthen I.I can only suggest two minor things that were not mentioned.1-Roger Huntington said B.B. can run 42 degrees advance with no problem and since your not running real high compression it might be worth it to bump your timing a bit till it pings ,then back off,(if you don't know who Roger Huntington is ask an old Knowledgable gearhead).2-if power drops off over a185 degrees it seems your under hood temps are affecting the density of the gas,so a cool can might be a solution to your power drop off.195 degrees does not seem bad for your B.B.

ajrothm

THANKS FOR ALL OF THE REPLIES GUYS!!


I did a little more testing this weekend, made some progress....BUT I still think a Dewitts radiator will be a necessity.....

TEST DAY #3.....85*
Changes made:
Removed thermostat all together per 427Hotrod's advice.


Test:
This road test was early in the day so the outside temp was not up there yet, but I figured I would try the same highway route that I have been doing to keep it all the same. Car never got over 190* in the 30 mile road trip. Definetly stabilized the temp AND I even ran the car as high as 3200rpms which would normally shoot the temps up but it stayed at 190*...


Deductions:
No stat definetly seemed to help stabilize the temps....maybe lowered them 2-3* but that was inconclusive due to the low ambient temp of 85*.


TEST #4....91-92*, 50% humidity

Changes made:

Replaced new Delco fan clutch with Hayden 2799 severe duty fan clutch. No thermostat, timing still at 31* total.


Test:
Car was already at 180* before I even left the house, AC on, headed to the highway for the usual route, temps crept up to 195* before the turn around point (about 12-15 miles out) and stayed there.... u-turned, came back and still at 195-196* the entire time....I continued on past my usual exit and ran it atleast another 15 miles, varying RPMS up and down....Suprisingly slowing down to 65 mph increased temps to 196-197*, speeding back up to 70mph brought it back to 195-196*.....got to the next town over and went into town, sitting at several stop lights and low speeds....temps got to 200* and stayed there. Stopped at a buddy's house for a Memorial day party..



Deductions:

Severe duty fan clutch definetly helped at freeway speeds, considering it is running 195* on average with the timing down at 31*....no doubt with some more timing it would be 190*....I am glad to see improvements but honestly, it still needs to be cooler.....our ambient temps will go up another 10* at least during the mid-end of summer AND I haven't been on a long trip yet.... Also noticed the better locking fan clutch definetly zapped some power out of it....its pretty noticeable in its response on the hit....



Odds are the engine would be fine running at these temps but the fact that I can't hammer down on it when the temps are up past 185* or so irritates me.....I am still thinking the aluminum radiator will help.

After reading all of these electric fan stories, I am thinking I may continue on with my stock clutch fan with the new SEVERE duty clutch....Granted this new clutch seems to zap some power away for sure but it actually made an improvement on highway temps as well as hold a decent temp in town......

I am thinking the Dewitts radiator and my stock fan might be the combo...I can always add fans later on I suppose..... I do think I can play with vac advances to try to get an additional 8* of advance at cruise will help knock another 4-5* off.....Any more then 38-39* total at cruise (initial + vac) will send this thing pinging....even with some race gas mixed in so....We'll see though....

73, Dark Blue 454

Some notes:

1) Removing the stat "and stabilizing the coolant temp" is a band-aid for other problems. You need a T-Stat, preferably a hi-flow unit. The ambient temps won't always be in the 80's no matter where you live.

2) On the street, you need the vacuum advance and around 50+ degrees advance at cruise. If you have some pinging, back the mechanical down a bit until she's happy. 37 degrees isn't enough at cruise and will aggravate the over-heating condition.

3) Your radiator is maxed-out. Sounds like you've added some HP to your mill which means more heat that has to be removed. Your stock radiator was designed for a stock engine. Time for an upgrade.

4) A Stewart-Warner Hi-Flow water pump would be a good idea. More here:

http://www.stewartcomponents.net/Mer...FlowWaterPumps

Lastly, somebody above said that an engine won't run at the thermostat's rating. That's incorrect. Assuming your cooling system is up to the task, yes, it should run at the stat's rating.

Lastly (I mean it this time). A 160-F stat is a bad idea. Go with a 180 once you have the cooling system upgraded to meet the needs.

True Blue Vette

It's as simple as that....

Chris Johnson

I think this sounds like a good plan. I should have switched to a mech fan and good shroud a long time ago. If 427Hotrod is running a mechanical fan with his 555, in Texas, then it should easily work for you.

bobbarry

I've also seen (in other vehicles) a good severe-duty clutch drop engine-temps at highway speeds; theory is that airflow through the radiator due to vehicle speed should be sufficient on its own, but I've seen where the temps drop by 10º once I hear the roar of the fan kicking in. Not impossible, but hard to duplicate that kind of airflow with an electric fan setup.

ajrothm

yep Jim runs some kind of old Flex fan....it obviously works for him....

I just ordered my new radiator from Dewitts and all new shroud/core support seals (again) so hopefully next weekend I can slap it all in and continue the testing. Also gonna look at different vac advances that will give me about 8* max.....hopefully between the two upgrades I can keep this thing at 180* with the AC on....