I built a 400 over the winter for my 68. And of course it wants to run 225 in 80deg weather..

My question is- will plugging the passenger side head and water pump housing that leads to the heater core affect coolant flow or higher temps?

I have done all the usual.
stamped impeller water pump
divider plate mod
180 stat
Running a aluminum rad with 2000cfm elect/fan with shroud. complete build so I know the block is clean.
Timing is set at 14deg intial with adjustable vac advance it come all in at 28deg total at 2000 rpm

Anyone know how to get a 5" diameter water pump pulley, Vbelt 2groove?

I don't know the direct answers to you questions, but have a few comments to consider...

I do not consider 225 to be an overheat situation. It's fairly normal in my opinion, but admit it's getting to the upper limits of comfort if it stays there often. But if it never exceeds that number you might be fine. Factory recommended 190 t-stat in these cars.

As for you doing "the usual"...

1. Cast impeller pumps are generally considered to be better at moving coolant than stamped.

2. Electric fan/shroud have been shown time and again to not cool nearly as well as a factory belt driven fan/shroud setup on these Firebirds.

3. According to Flex-A-Lite, 2000 CFM is not enough for a V8...they recommend 2500 for minimum:
http://flex-a-lite-blog.com/2010/04/24/how-to-choose-an-electric-fan/

You don't mention shrouding in front of the radiator. Do you have proper x-panels in place at front of radiator support? Lower baffles? Side baffles? Need everything in place to direct air thru the radiator and not around it, and the electric fan & shroud with small diameter openings they have in comparison to factory shroud makes this more challenging and more critical.

My bad about the impeller, thought it was the other way around.

I checked my paperwork on my electric fan it states 2560cfm.
I have heard over and many times over about stock clutch fan and shroud set up. I know it works well, but bottom line is it robs horsepower.

Prior I had a stock 350 in the car, good flowing block, had a new 4core, shroud, stock fan and it would still creep up to 220.
All stock filler panels are in place.

At an idle my electric fan is drawing alot more air through the rad, than a stock clutch fan at an idle. And after 25 mph either fan should not even be a factor. Does Flex-O-Lite explain that?

Either way, I know there are guys out there with similar configuration to mine that claim their temp never goes above 200deg. I just wanna know how they are doing it. One last summer at a car show, 68 mild 400 with an aluminum rad from 90's camaro, electric fan, no electric fan shroud. and he said it never goes over 195?? He didnt show me, but i don't know why he would lie about it either.

As far as "the usaul" That water pump divider plate mod did not make a difference for me, 350 or 400. Logical, but it did not make a noticable change.

Maybe I should ask the guys over at PY forum, being how this is no longer a stock setup.
All I really wanted to know is if capping the normal flow from the rear passenger side head and the water pump housing could affect coolant temps.
Also curious if anyone has overdriven their water pump by decreasing the crank pulley diameter?

First problem, you live in a warm weather climate and it's very humid there.
If it was recommended 2500 CFM fan should always go larger, never on the border, because in FL it will work hard and with a Pontiac engine even harder.
Look into the stock filler pans for the top of the radiator and the bottom.
Sorry to burst your bubble but the robbing of horsepower of a stock fan over an electric, if you notice it with a 400ci then the engine is junk. I would never trust an electric over a belt driven fan. That electric motor quits it's Goodbye engine, at least with a belt driven I have to lose both belts. Call me old fashioned. I'm an electrician by trade and I know electric motors overheat and seize without warning.

By decreasing the crank pully diameter you will be lowering the rpm's of the water pump. I don't think that is what you are trying to achieve.

let it run for a few miles, they always tend to run a but hooter when freshly built...run it in, then see how 'hot' it runs...

the idiot lights they put in these things without gauges came on around 243F. so 225F is not bad for a fresh motor. but, i would run a hose from the water pump housing to the nipple on the pass. cylinder head. coolant is pulled out of the heater core by the pump and thus out of the back of the engine as well. with them plugged off it's going to take longer to circulate all that hot coolant through the radiator...my .02 cents.

Hank is correct. Another member pointed that out to me today. My division was wrong, and made me think smaller drivin pulley makes accsessary pulley faster, but its the other way.

Finding a 5.250 waterpump pulley does look good either. Thanks for all the input.

Try frankspontiacparts.com, he has just about everything

Ragu,

Your not bursting my bubble, because your statement is opinion not fact.

Its called science, when you pull,turn something through air it creates resistance. When a clutch fan engages it creates a drag. 2hp or 20hp dont know! Does not mean an engine is junk, maybe its just not a noticable loss to you.

Your more than welcome to come down to Crestview and run your Bird against my 68 well, junk as you put it at the local dragway. I am curious as to who would win, my hot junk or your cool shrouded fan 400. Even run for a little cash. Put some money where your mouth is, get it?

If that's an open invitation I'd love to go to Florida and check on running temps, maybe have a few beers and catch a redfish after. Don't know if I want to bet any money as I've never raced and at 62 my reaction time may be down a bit, maybe not.

I could write a bunch of formulas and fill the letters with numbers- ohms, energy to accelerate the mass of my twin electric fan blades, voltage drop/foot of wire, rotaional resistance at different air densities, efficiency ratings of the fans and A/C generator, Lenz's law, Newtons second and third laws but that would take about a week so I'll just tell you when my car is idling in the driveway, on the rare occasion the engine is actually in the car, the rpm slows when the fans come on. It takes horse-power to drive the electric fans as well. I suppose if you're at the strip you could switch the fan/fans off just at the lights and turn them on agin at the end of the run.

I have an aluminium rad with twin spal fans and shroud on my car and have not had overheating issues. I don't live in a hot state.
The fans, rad and shroud came with the car when I bought it, I would not take off good factory cooling components and exchange for what I have but I'm happy with it. I also have a smaller dia. water pump pulley so the pump is turning a bit faster. But as Ragu says these things can over-heat and burn out, one reason why I wired mine separately with a relay for each fan.

I agree-if your not running a heater then run a hose from the back of the head to the pump to keep the water flowing through the head.

I trust I didn't offend anyone.

I am old school thats all. and have seen the electric motors melt
or catch fire.
Yes it's only my opinion and only mine, don't have to believe me, it's ok.
I didn't call your car junk only if you can notice the difference then somethings wrong with the engine, thats my opinion, the forum is about opinions and which one will work for you, hey I'm pointing out what happened to me when I lived in FL to baby sit a house for 2 years, I ran electric fans while living there and it didn't help cool it, I couldn't drive during the day at all.
The over temp was caused by the engine and issues with cooling and vacuum leaks that was worked out here with the help of the forum.

Not only the fan motors but the sender switch. I have a friend in Houston Texas who has the type that slides between the radiator fins. It failed and the fan quit. We pulled the fan power wire off the connection and wrapped it around the battery post to get home. Good thing it happened on the highway and not in bumper to bumper freeway traffic, that big Olds 442 creates a lot of heat. The second time it happened he put in a switch under the dash to power the fans bypassing the sender switch. Maybe the third time it happens he'll put a real switch in the water crossover.

Oh I maybe moving back this summer if the job situation doesn't improve in CT., I loved to go to the track but your making 20 more HP than My engine and my Mech. fan is slowing me down that would not be a fair race. LMAO

I found an article by a fellow named Steve Jack. He put a chev 350 on a dyno and tested various fans for HP loss. I was shocked at the amount of loss. He also did an alternator HP loss- not much. When I get my 428 back together and on the dyno I'll take the rad, shroud and fans with me and do a test with and without the fans hooked up to get a real [for me] number of HP loss with the dual fans. I think it's higher than the 1.28. I have a 600 FP engine and over 400 at 2000rpm and when the fans come on at idle they drop the rpm about 200. We'll see when I get it on the dyno.
I don't know who Steve is or how reliable the test result are but it's interesting reading.
I don't know how to post a website here so I scanned the pages and will attach.
Al

NSGRN
I should have started a new post for this. This has nothing do do with your original question. Sorry, anything else I find on the subject I'll post elsewhere.
Al

Not sure where the HP level on stock vs electric w/p and fans come into play.
Made no diff on mine.
Average runs where 12.0 @ 114 mph for both set ups.

I have never seen any electric fans, aluminum radiators keep any engine constantly cool as a proper clutch fan and shroud set up over the past 30 years of working on these cars.

To answer the question about the heater hose, yes it will help IMHO. the stock system simply pulls coolant off the back of the head which is not a bad thing but it then returns it to the inlet of the water pump. I'm sure some heat is pulled from that coolant but not near as much cooling as the radiator will do.
I use a stock shroud, a Hayden severe duty clutch fan, and all the factory filler panels. I also fabbed up some filler panels at the radiator support because I do not have the masticated panels in place. Also, I used foam insulation around the radiator where the shroud does not contact the radiator which is on all four sides really.
Results are I rarely see anything close to 200 and usually hangs around 185 or less and that's with the a/c on.
That fan clutch is tight though, but its a clutch so I don't know how much it drags at WOT especially at higher rpms. No doubt temp dependent as well. But if I was concerned I have a cheap clutch that is very loose by comparison if I wanted to swap it out for that extra 10th.

The original question is why he's running hotter than normal.

newly built engine, that is just breaking in.
I brought it up about the electric fan, the gains aren't proven theory.
I have even heard the electric fan will cause some loss HP too.
I'll stick with my Trusty -20 HP Flex Fan and run cooler not worry.
It's OK to believe the hype of someone who's paid by the company who makes the fans.
Answer this, if the electric fan is so much better than the Flex and clutch fans, Why doesn't GM, Ford, Chrysler, and the truck makers use them on all their vehicles.

I dont like electric fans because of the noise.

I have been watching this thread since the start and always wonder about this info:

"Timing is set at 14deg intial with adjustable vac advance it come all in at 28deg total at 2000 rpm"

Yes, I have E-brock heads, but my engine was broken in and tuned on a dyno. We verified via the dyno sessions the same values that Edelbrock put out for those heads - 36 degrees total timing at 3200 or so RPM?. Working backwards, my inital timing is at 8 degrees BTC. I believe stock was 6 degrees?

This may be oversimplified but here goes; amps x volts = watts. 1 hp = 746 wats. electric fan =1.28 hp according to the earlieir test. 65 amps @13.65 volts = 887.25 divided by 746 = 1.189 hp so their tests ar accurate or they couldn't get an accurate test at that low a hp measurement so they just did the math like I did. If another fan takes 20 times the energy to run even at 50% efficincy it still has to be moving ten times the air as an electric fan. Also a good system uses the extra volume of the radiator to maintain a buffer of cooler liquid to allow for periods of more heat/less cooling like long hills and stop lights. If your system isn't keeping your average temp. comfortable then you have no reserve for those hot moments.

Listen I drive big rigs we have clutch fans on them and they are 30+ inches in size most are 33" and we lose 30HP with these fans, so come on Pontiacs little dinky toy flex fan doesn't even come in that ball park.
I believe what was written by Pontiacman8 on HPP about this, his facts state as such 2 to 5 HP can be lost and he went on to write that it's more in tune of 2 HP.
He's a professional GM engineer and strictly Pontiac and can build with his eyes closed.
You want to talk or hear what he has to say go to HPP forums.
I can't believe we measure moving air mass, it just reminds me of when I was 16 and believed if I waxed my car it would win the race at the strip.

A friend put it best, nothing beats a good running engine and a flex fan or clutch fan set up. The only issue is when they idle the electric fan will keep it cooler than the Mechanical fan.
Now he was saying when an engine is over bored it can have cooling issues and the electric fans will have a tough time cooling it.
This is a proper setup: mattsonscustomradiator.com
it has a shroud which is always left out.
Again I just read a clip about timing which can be a factor here.

I use stock fan, stock shroud flowcool(changed from stock when it went out) waterpump.....after all the fillers were corrected , installed and I took off the 'extra electric pusher" fan prev owner had installed (obviously he had heat problems) I gained 15F...to get down from 225-230 normal running in Texas August...it ran 200-205...no problems , but before we cruised to Estes Park (in an August)I changed out radiator to a bigger one , aluminum ,and now car runs almost too cold in winter...166-170, but 190 -195 in summer

Another problem is when water flows to fast thru the system.
Usually happens when guys don't use a thermostat and A/C pulleys.
Doesn't stay radiator long enough to exchange heat.

I have a built 400 and had cooling issues.
Tried the 7 blade clutch fan, then the 4 blade fixed, then 5 blade flex, then an electric fan (Lincoln MK5).
Also installed lower baffle/air dam, AC fillers, did the water pump mods (divider plates) and put in an aluminum radiator w/stock fan shroud.
After all said and done, I get the best cooling with the 5 blade stock flex fan. Temps stay around 185-190 unless I'm ideling for a while in 90+ degree weather then it will creep up to 200.
Just saying this setup work best for keeping my 400 cool and that I had tried many other options.

Interesting Electric Fan story for all of you. My wife (gf at the time) drove a 1987 VW Cabrio for many years in Michigan. The car was in an accident where the front end was smashed in and repaired. Years later in Michigan still the car ran and drove fine.

Fast forward a few years to her living in Chicago. She's in traffic and the car is running hot, but not over heating while crawling on the Kenneday expressway. Fan kicks in and cycles as normal but still runs hot. Trying to figure out what the issue is, we decide to replace the old decrepid radiator.

after another traffic stint, the car still is running hot and with similar pattern as before.

While the car is idling and I am bent over the front end looking at the fan, it kicks on and I notice hot air blowing on my legs and realize the numb nuts who repaired the car years earlier, plugged the fan in backwards.

All the years of cool Michigan summers was masking the real issue of the fan running backwards. At highway speeds it didn't matter, but in traffic it did. Switched the fan wires and never had another problem.

What T stat are you running?

Working on a 68 and this is what i found. The temp went up to 200 on a 95 degree day here just driving 5 miles. Hard to tell in the picture but there is 3/8" or more spacing from the blades to the divider plate. NAPA did have a nice cast iron impeller pump that is going back in.

I have never had any luck with running a 160 stat, seems to run too hot or overheat. I currently am running a 180 stat and I still seem to run over 200 degrees, but am not positive exactly what it is. I checked with one of those laser things at the T-stat neck the other day when it was about 80 outside and it showed 207. Not sure how accurate it is, but everytime I went to try and start the car, it was acting like I was having some heat soak issues with the starter, which I never had before, but I just recently removed the starter to swap the tranny out and I put the starter back in after tranny was swapped. Should I be running a 190 stat instead of the 180?