[75TA]

I do not have a severe overheating problem, but would like some advise on upgrading my system. The engine is a 505 CI IAII with a mild solid roller cam street engine approx 600 to 650 hp. Currently I have a hd 4 row rad with a stock clutch fan. On hot days in SC the temp climbs just under 220 (stock gauge) may be 200 or 210 when running highway speeds - 4.11 rear gears with a built 400 automatic (stock gears). I have an additional trans cooler.

I was told that I should run a flex fan - if so what make or brand should I use. Also looking to possibly go to an aluminum rad. Was looking at PY or Be cool. Talked with JEG's and they indicated that BE COOL would not recommend just changing the rad as it would overheat and damage the aluminum rad (core would expand and burst). They indicated that I must buy the full system for $1600 or I would have a problem - is this true or can I do things in stages?

Again just looking for advise

Thanks

[johnsma22]

I was never able to achieve proper operating temps with my E-headed 400 with a factory clutch fan. And yes, it was a brand new HD clutch, 19" 7 blade factory fan, proper location of fan in the shroud.

I've got a four core Desert Cooler radiator, FlowKooler water pump with properly clearanced divider plate, 180˚F balanced sleeve T-stat (high flow). With the factory clutch fan I would consistently see temps in the range of 205˚-215˚F. No other changes other than switching to a 19" Flex-A-Lite flex fan with a spacer to get it properly located in the shroud and she runs at 180˚F all day long under any conditions.

The downside? The flex fan sounds like an F-16 going down the road when I wind the snot of of it, but I'll take that over the alternative of running hot with a quiet clutch fan.

[GTOLou]

I put an alumitech radiator in my 76 - I would get rid of the stock four core one and put in the alumitech. I had a mild 455 in it and swapped out a decent butler built 474 w/ 10.5:1 compression and KRE dports this winter. I forgot to put in a thermostat (used an aluminum crossover w/o one) and the combo of that radiator and my KRE's = a motor that just won't warm up and stay warm. (I've been messing w/ my gto lately and just haven't gotten to putting in that thermostat)


I think the guy who sells these still is on these forums...


On another note, I took the 474 out of my 69 gto and put in an IAII. That thing makes some heat....my non-alumitech 2 core aluminum radiator barely can keep up with it. Still,....it doesn't ever get over 200 (I was used to 180-185 w/ the 474).


I HAVE used a four core desert cooler before - it could not compare to an aluminum 2core.

[GOAT8U2]

Don't bother spending $1600 on this issue.

4 rows can't compete against aluminum 2 rows, especially with a weak fan trying to suck air through a thicker core. Does Jegs or Summit make their $300 aluminum rad for you guys?

Stock fan with that sized motor and rad is inadequate unless you don't mind 200+ temps.
I'd personally see if you can run a dual electric fan setup with a new rad and end this issue forever.

Timing can aid in the cooling, manifold with vacuum advance will help reduce EGT's. I run 22 degrees at idle and 48 cruising around town.

Many are finding that their water and crank pulleys are close in diameter, finding an underdrive water pump pulley helps too. I noticed the March crank and water pulleys are almost identical = horrible idle cooling for sure.

Fill it with Distilled Water, some Anti Freeze and RMI 25 to aid in the cooling if you want to get greedy in the temps.

[75TA]

johnsma22 - What spacer did you end up with to get proper fan spacing for the flex fan. I also have a high flow aluminum water pump, do not remember the brand.

GTOLou - I am going to call several aluminum rad companies to see what they say. Money is tight so I was looking at changing to aluminum rad only first. Do you recommend alumitech and can you PM the non - alumitech company.

GOAT8U2 - As indicated above, money is tight so I was hoping to go in stages starting with an aluminum rad and then electric fans at a later date. Do not think I can swing both at the same time. My concern was what JEG's tech indicated BE COOL company said that I have to do it at one time or I could damage the aluminum rad. Based on being some what hot - I though the aluminum rad should pull the temp down fairly good. I do not seem to have a problem with over heating going under highway speeds. My timing was set during an initial dyno tune - I do not have vacuum advance (mechanical). Changing pulleys is not an option at this point as I have a March serpentine belt system - I do not think they make different pulleys. Jegs, Summit and PY make aluminum rads for the TA - I want to know if there are certain things I should look for when buying an aluminum rad - why do some cost so high compared to others - is it just brand or is there some difference. I notice that some use 1 inch tubes versus 1 1/4 inch tubes

[johnsma22]

It's a Flex-A-Lite spacer, but I'm not sure of the length. I think it's a 2.5" spacer, but I'll check it tomorrow and get back to you.

[GOAT8U2]

Price range is usually due to fluid coolers and fit. I've seen dual cooler aluminum rads with a custom fit go as high as $800, way crazy if you asked me. I personally would ditch the rad coolers and run large externals anyways. No need for more than twin 1" core aluminum rads when you have a great dual fan sucking air through it.

Not sure how you have your initial timing set but you probably have a WOT timing around 36 degrees coming in around 2500 so you're leaving 12 degrees on the table while cruising to help drop temps. Idle timing is usually where older cars get hurt in the EGT.

[HWYSTR455]

I don't understand what jeg's tech was meaning when saying you'll damage the rad, think it may have been a sales pitch. Changing to an aluminum would give you a cooling advantage over a stock 4-core copper, and makes sense that would be a good starting point.

You say anything under highway speeds is your problem, which indicates lack of air flow through the rad. Check the obvious too, obstuctions, seals, shroud, etc.

You mention you have no vacuum advance? And your timing was set during a dyno session? I'm guessing you know the curve then? You can add initial, and limit it at the top for the same results, which would help your low-speed cooling some.

Another option would be to either swap the distributor with one that has vacuum, or use a ignition box that has provision for map signals/advance.

There's a big-car 5 blade fan that you can use that would provide more airflow. Combine that with a 'truck/towing' clutch and it will pull air at low RPMs. Problem with some of those is you walk a line of belt-slip, but it can be done. Some say the 7 blade fan actually will block air and not pull as mush as the 5.

I personally used the 7 blade with a truck/tow clutch and it cooled fine for me, and that was with a 4-core copper. It would get belt slip at high RPM though, and switched to aluminum and electric fans when I had the chance.


.

[bnorris_74]

My .02.
I'm running a little over 9:1 CR and no where near your HP but...

I bought the two core Afco crossflow aluminum from Summit. It's about 2-1/4-in thick. Fit perfect.

I was running a stock two core and was running at 210 to 220 cruising in town and creeping higher at Highway speeds with a thermal clutch, big water pump pulley and big blade fan.

Switching to the aluminum netted 170 to 180 degree temps all the time with a 160 Deg stat. The radiator was the only thing I changed.
FWIW 12 Initial 30 Total and 10 deg vacuum adv.

[Z Code 400]

75TA,

I have tried all kinds of fans/shrouds and the very best, under street and competition has been the 7 blade flex fan. Just as an experiment, why not grab a 7 blade flex fan from your local Pik-N-Pull, along with a spacer and try it???? The ones from Ford Trucks are plentiful and you can easily redrill the larger, GM bolt pattern using the spacer as a marking template.

I have included a link to a post you might find helpful...Robert

http://forums.maxperformanceinc.com/...light=flex+fan

[Region Warrior]

I had good luck using pulleys from A/C cars with 19-5/16" Flexalite(1300 series) fans.
All 71-79 Pontiac V8's use 8" crk with 6-5/8" w/p.
You will need a spacer(probly 2.5"), but best to get the blade and measure distance 1st.
Have the blades about 1/3'rd into the shroud opening cause even at idle it will flex further INTO the shroud.

[75TA]

GOAT8U2 - I run both coolers (internal external) as I have a 4000 stall converter. It was suggested by the trans guy. As far as the timing is concern, I believe the timing is all in at 2500 and I have not checked my total timing as I was having problems with the timing light bounching which from another thread is due to my electronic MSD box - need to have an isolated battery. I feel my total timing is near 40 (I have aluminum heads - edelbrock) running approx 10 to 10.5 to 1 compression. Note that on highway speeds in the 2500 to 3500 RPM range.

HWYSTR455 - I did not understand it either that is why I am looking for advise. My problem is at Highway speeds. Going around town I do not have a problem. Since I assembled the car, there is no obstructions and I have all new parts such as rad shroud, no air conditioner and just an additional trans cooler. The 4 core rad was refurbushised. I ignition is all new MSD pro billet with a digital 6 box with mechanical advance - I believe it is all in at 2500. I really need to check the timing but have to find a spare battery to get a good read with the timing light. The car runs great.

bnorris_74 - thanks for the information, I am hping that I have similar results. Do you have a TA or another car?

[bnorris_74]

bnorris_74 - thanks for the information, I am hping that I have similar results. Do you have a TA or another car?

1974 Formula 400

[GOAT8U2]

A large external cooler with a fan is the best. I have a restalled stock 11" converter in my AWD 4 speed Talon and it's temps were insane until I added a second external cooler. My buddy took my advice and ran a huge external with the rad fans sucking on them and his 9.5" PI converter launching at 4000 hits 210 at the end of the run.

Sounds like they are trying to get more $$ from you, I'd start with Bnorris's rad and see what happens.

[Squidward]

75TA,

1. Remove the shaker scoop from the formula hood.

2. Patch hole, repaint, and pray for forgiveness.

Any cooling issues would probably result from a giant shift in karma.

...Sorry, couldn't resist!

[71 T/A]

Originally Posted by Squidward

75TA,

1. Remove the shaker scoop from the formula hood.

2. Patch hole, repaint, and pray for forgiveness.

Any cooling issues would probably result from a giant shift in karma.

...Sorry, couldn't resist!

I agree. Cutting a hole in a Formula hood should be illegal.

[75TA]

OK guys - how do you know it is not a SD Formula hood with shaker top. I need the extra space for the Victor intake.

Car is in shop right now getting dash fixed so I can not work on this issue at the moment. The shop that put in my roll bar cracked the dash - we are going to try one of those dash caps as you can not buy a new dash at this point in time.

Hope to get back on this soon. I have been shopping for the new rad.

[turbogta]

Originally Posted by 75TA

OK guys - how do you know it is not a SD Formula hood with shaker top. I need the extra space for the Victor intake.

Car is in shop right now getting dash fixed so I can not work on this issue at the moment. The shop that put in my roll bar cracked the dash - we are going to try one of those dash caps as you can not buy a new dash at this point in time.

Hope to get back on this soon. I have been shopping for the new rad.

The SD 455 Formula used the same hood as a TA, not a Formula.

[75TA]

When you put electric fans on what do you do to support the upper part of the radiator? Currently the stock fan shroud supports the radiator. Does some one make a support or do you have to get something fabricated?

[bnorris_74]

Take a look at this:

http://www.summitracing.com/parts/MOR-78700

might work for you.