[OZZIEVILLE 67 2 door]

I use a 7 blade flex fan with no problems..
check out scambay au ,usaspecials for local fast service on fans..

John L.

[geeteeohguy]

I,m running an 18" GM 7 blade flex fan on my '67 GTO that I pulled off of a junked '69 Caddy 20 years ago. Dead quiet and cools GREAT. Has a really deep pitch, and pulls air like crazy at idle speeds.

[getmygoat]

I'm not an expert on '67, but did they come with clutch fans stock? Have you tried a non-clutch stock pontiac fan from that era?

Sorry if I missed it - but only A/C cars came stock with clutch fans. - That fan shround doesn't look particularly stock either.

If you haven't already - I'd revert to a stock '67 setup and see what happens.

[fiesta62]

thanks for all the info on this issue, i have just ordered the 19.3 inch 6 blade flexalite fan and spacer , i'm confident this will be the answer, although moving fan position and adjusting clutch spring did help a lot i feel this flex fan will be better than the 17.5 clutch fan i have now......

[geeteeohguy]

Getmygoat, all '67 GTO's came with a clutch type fan, AC and non AC. The size of the fan and radiator differed between the two, but all were clutch type.

[android 211]

I would say that is a poor fit and the fan is pulling air through the open space and not through the radiator. I had a TA that cooled noticeably better once I replaced the damaged fan shroud with a good one. It would sit in traffic in gear on a hot day with the a/c on no problem.

[Alvin]

Subscribing

[gilg]

Try Hayden fan clutch #2731 its long shaft like the original and check this: http://forums.maxperformanceinc.com/...highlight=2731

[Brett_ty]

I chased the "heating" problem for awhile as well. All of it helped a little- water pump/plate, custom alum radiator......finally what fixed it for me-

1) close off the gaps that surrounded the radiator in order to force air through the radiator rather than around it

2) THE BIGGEST HELP: put in a remote oil filter on the firewall. Due to header spacing, the oil filter was small and sitting all wrapped up by the headers. I moved the filter because a) it was a bitch to change b) I knew it was cooking off the headers.

Moving the oil filter to a larger capacity and away from the headers dropped the temp significantly. Will not climb during idle like it once did (I have a 455- 600 hp engine with some "Mad Dog Headers" that really cooked the oil filter where it was located).

In my particular case- all the tips and tricks helped keep the engine cooler, but the two that I highlighted really put that problem over to th "solved" catagory.

[Chris65LeMans]

I've just got two thoughts:

1. wheelspin on here told me "never trust your gauges." I got a laser thermometer and found that my SW gauges run 10 degrees high. I think you said earlier that your stock gauge and your aftermarket one read the same. I'd read this as "the gauges are definitely wrong." (I don't have a lot of faith in 45 year old gauges.)

2. Are you sure that your "I want to run at 190 all the time" goal is a reasonable one? If 225 is as hot as your engine gets, I'd personally just leave it alone.

[Pontirag]

none of these problems existed when the car was new so there is still a fundemental problem with his cooling system. I have owned several pontiacs and drove them regularly in SE arizona summer heat and never encountered a temperture that regularly reached and stayed at 210 to 215 degrees. its not normal! it never was and is not normal.

Pull your distributor and send it off to have it checked and calibrated,

flush your cooling system, run some distilled water mixed with some CLR , take it out on the hiway and run it good for an hour or so then drain and flush it untill no more rust comes out,

If ever there is an opportunity to replace your freeze plugs, spend additional time to remove all the junk and rust that builds up in the bottom of each cylinder bank, you would be shocked at what you will find down there so take the time to clean it out if you can.

add coil springs inside your upper and lower hoses, yes both hoses. Its absolutely scandalous that vendors now remove the coil springs and then charge extra for a part that needs to be there,and worse still that the part is carbon steel which is prone to rust, break up and jam thermostats and end up going through your pump impeller, and better yet, if you dont have them, then make your own from stainless steel safety wire and a pair of safety wire pliers.

beating the devider plate to death is not a good idea especially if its stainless, I have seen countless pictures of the do all end all beat to death divider plate, if you know anything about pumps and thier efficiency, yea we all do, then you know that the surface of the devider plate that runs parallel to the impeller blade must be very close to it all along the space between the devider plate and the impeller. Every illustration I have seen shows some poor fool beating the divider plate down towards the impeller at the divider plates opening, this does not work at all well and if you have a stainless repro, you know that it will work harden long befor it ever comes any closer to the impeller. any way, whats a poor girl to do?

remember that the devider plate clearance must be tighter But it must run as close to parallel to the blades/vanes in the pump, beating the divider to death around the opening only tightens up the clearance at the opening and leaves the clearance much greater further back, so essentially by beating the divider to death you have only created a slight taper at the opening of the divider and have not tightened up the clearance around a majority of the rest of the impeller thus the inefficiency is still there,
How ever many people insist that this modification is the do all end all solution to the coling problem, and maybe it is so lets take the theory of reducing the clearance to a natural progression or evolution or....to the next level.

First how do you tighten up the clearance between divider and impeller across the entire face of the inpeller, Its actualy so simple and easy,

first place your divider plate up against the pump, dont include the gasket, place the divider against the impeller and measure by feeler guage the gape or clearance between the divider and the impeller, measure three times , note that distance, gap or tollerance.

place the pump in a press, carfully support the impeller, not the housing and not the fan flange and not the bearing shaft BUT the impeller. It will take some thought how to do this and we all respect diversity so figure it out for your self with the resources at hand but support the back side of the impeller and with your press gently push the bearing shaft that is inside the impeller, push it off just about the same distance equal to the gape, or tollerance you noted befor maybe a little less because some gape is needed and the additionof the paper gasket will create some additional tollerance. make sure that you only support the impeller and the whole rest of the pump is allowed to move freely when the shaft is pressed out, if not you will instantly damage the pump housing, the fan flange or the bearing shaft, especially the bearing shaft, make sure there is plenty of clearance all around the pump to allow it to move with the bearing shaft. any accidental load on the pupm bearing will damage it and it will fail in quick order.

so essentially what I am suggesting is, rather than beat your divider plate opening to create less gap or tollerance, try pressing the impeller back off the shaft the distance you need. It does not result in the divider plate beaing beat to death, and the gap/tollerance is tight, its uniform and its controllable in a way no hammmer can do it.

press the bearing shaft out of the impeller the same distance represented by the gap between the plate and the impeller.

a warning though, dont go pushing the impeller back and forth on its shaft too much or it may loosen up and will be no good, (Practice on an old core before you bust out on that $200 Evans pump!) And again be absolutely sure that there is no other area of contact that will keep the whole pump from moving with the bearing shaft when you press it out of the impeller.

I dont know how many people beat that poor divider to death to creat that little bit of clearance but the whole therory behind these types of pumps support the need for the clearnce to be tight all across the face of the impeller and not just at the opening

another consideration is that the divider plate angle may be different from the angle od the face of the impeller, you must look to see if that is the case and make allowances for the differet angles of these two parts where the interface.

I cannot take credit for this, I think I read about it on this forum back about 6 years ago, but I have done it on every pump I install in cluding the sheet metal impeller pumps and have never had an overheatin problem, even when running a v8 with a single core six cylinder radiator across the deasert, Only a slight increase in temps when I come off the freeway after hours of sustained 70 +mph driving in miday august heat.

You have nothing to lose by experimenting with old pumps and trying this. tighten up that gap by moving the impeller on its shaft rather than beating the divider plate to death.

try it and see.

[68blackbird]

Have you checked your pulley diameters?

[fiesta62]

thanks for all the thoughts but i have temp under control now, i did various things, but one of the most noticeable improvements was when my friend modified the copper spring on the clutch fan, i bought the hayden extream duty clutch and my friend then set the spring so clutch kicked in sooner, car now sits on 190 temp all good, but i just finished installing air conditioning and thought this will probably make temp go over 190 so i have now installed a larger fan and shroud, but this time its a flex fan, no clutch, i am hoping as its larger and larger shroud it will pull more air and on those hot days with ac on i hope all is ok, its winter here now so wont know for a few months, yes i could have waited and seen how the clutch fan handled it but i had the larger flex fan and shroud so decided while car is apart for ac the time was right to install the flex fan, i did lots of other mods to help temps including pulleys , and never needed to go to aluminium rad, my harrison is 4 core and doing a great job...

[fourfivefivegto]

Originally Posted by fiesta62

thanks for all the thoughts but i have temp under control now, i did various things, but one of the most noticeable improvements was when my friend modified the copper spring on the clutch fan, i bought the hayden extream duty clutch and my friend then set the spring so clutch kicked in sooner, car now sits on 190 temp all good, but i just finished installing air conditioning and thought this will probably make temp go over 190 so i have now installed a larger fan and shroud, but this time its a flex fan, no clutch, i am hoping as its larger and larger shroud it will pull more air and on those hot days with ac on i hope all is ok, its winter here now so wont know for a few months, yes i could have waited and seen how the clutch fan handled it but i had the larger flex fan and shroud so decided while car is apart for ac the time was right to install the flex fan, i did lots of other mods to help temps including pulleys , and never needed to go to aluminium rad, my harrison is 4 core and doing a great job...

Hi there,

Sorry to dig up an old thread but I'm curious how your 19" flex fan and bigger shroud are performing compared to your clutch fan set up?

I'm considering the same combination, i.e 19" flex-a-lite fan (model #1309) & big shroud (model RPE67P from PY) on my '66.

Currently my temps go up to 212 in traffic with a 17" flex and the smaller shroud.Temps go down to 190-195 when moving so I'm suspecting not enough air-flow at idle...

Cheers

[fiesta62]

hi...I tried flex but I think it was a bit noisy so I bought a 19 and quarter inch 6 blade fan and put the clutch back on......but I am still having heat issues.....it did not cure the problem, i also think the issue is i am not getting enough air over rad when car is still, when driving I'm around 185 to 190 but soon as I get held up in traffic or stop lights temp rises real fast.....my mechanic has done lots of mods, water pump welded plate inside, smaller pump pulley, overflow tank, adjusted spring on clutch to cut in sooner, alum manifold, heat cross over blocked off, 4 core rad....it goes on....I actually talked to him just today and he wants me to remove thermostat just to see if its a pressure problem, he suspects the pump is not pushing enough water thru, so its a test to see how it goes with no thermostat....he is not suggesting i have no stat for the long term , its just to see if it makes a difference at idle , less pressure with no thermostat so water might pump thru better....will remove stat tomorrow, he has other ideas but this is another test in the ongoing heat issue.... test drive next day so stay tuned !

[fourfivefivegto]

Originally Posted by fiesta62

hi...I tried flex but I think it was a bit noisy so I bought a 19 and quarter inch 6 blade fan and put the clutch back on......but I am still having heat issues.....it did not cure the problem, i also think the issue is i am not getting enough air over rad when car is still, when driving I'm around 185 to 190 but soon as I get held up in traffic or stop lights temp rises real fast.....my mechanic has done lots of mods, water pump welded plate inside, smaller pump pulley, overflow tank, adjusted spring on clutch to cut in sooner, alum manifold, heat cross over blocked off, 4 core rad....it goes on....I actually talked to him just today and he wants me to remove thermostat just to see if its a pressure problem, he suspects the pump is not pushing enough water thru, so its a test to see how it goes with no thermostat....he is not suggesting i have no stat for the long term , its just to see if it makes a difference at idle , less pressure with no thermostat so water might pump thru better....will remove stat tomorrow, he has other ideas but this is another test in the ongoing heat issue.... test drive next day so stay tuned !

Sorry to hear you're still battling this issue, will be interesting to see how it performs without the stat, good luck!

Besides the noise, did the 19" flex seem to move a lot of air?

[fiesta62]

hi....with the flex fan i put a towel in front of grill and it pulled better than my original fan and shroud.....but i changed it to the 19 and quarter inch 6 blade and this pulled just as good.....i like the clutch setup better as i think and i must say "i think" its quieter but cant be sure, i got a new heavy duty extreme clutch too, i'm getting what i think is noise from fan but it might be because i fitted the larger 21 inch shroud too, i had to cut a bit of shroud to fit around bottom hose but that was no issue , its not too noisy but just a little annoying...even doing all this i really didnt notice much difference if any in temp drop....i will see what happens with the car with no stat......i dont think there is a better mechanic on the planet when it comes to the gto, if the heat issue can be fixed he will be the man to do it....

[fiesta62]

well i took out thermostat, took for test run, on highway it would run at 165 to 170....so big drop from usual 190...at lights on a short stop crept up to 175/180.....but quickly dropped to 170 when moving, got home let car idle in driveway for about 7 or 8 minutes it got up to 200 and i'm sure would keep going.....so no thermo is not the answer it still rises in temp when not moving.....i see that now i have installed the larger shroud i have large gaps around it where it meets rad, this would be effecting the fan pulling air over rad, i put towel in front of grill with car at idle, it pulled towel in but i think could be better, so today i plan to block off all gaps so shroud so it fits snug against rad....and while i'm at it i plan to re-install the flex fan, i am not sure if it was more noisy than the clutch fan , but will try it again, i would think the flex will be better as there will be no slippage like the clutch fan, though my clutch is a new hayden extreme duty, but worth a try...i think closing gaps around shroud will make a difference..stay tuned

[fourfivefivegto]

Originally Posted by fiesta62

well i took out thermostat, took for test run, on highway it would run at 165 to 170....so big drop from usual 190...at lights on a short stop crept up to 175/180.....but quickly dropped to 170 when moving, got home let car idle in driveway for about 7 or 8 minutes it got up to 200 and i'm sure would keep going.....so no thermo is not the answer it still rises in temp when not moving.....i see that now i have installed the larger shroud i have large gaps around it where it meets rad, this would be effecting the fan pulling air over rad, i put towel in front of grill with car at idle, it pulled towel in but i think could be better, so today i plan to block off all gaps so shroud so it fits snug against rad....and while i'm at it i plan to re-install the flex fan, i am not sure if it was more noisy than the clutch fan , but will try it again, i would think the flex will be better as there will be no slippage like the clutch fan, though my clutch is a new hayden extreme duty, but worth a try...i think closing gaps around shroud will make a difference..stay tuned

I'm not sure if you've seen this article, but it provides a good methodology for nutting out cooling issues:
http://www.hotrod.com/techarticles/1...#ixzz2pNwkC7Yu
Although the car in the article runs hot all the time (not just at idle), it has some good suggestions...
Good luck with the flex!

[fiesta62]

well this hot idle issue is a bugger we have done everything.... aluminium inlet manifold and blocked off crossovers....modified water pump internally.....installed smaller 6 inch water pump pulley down from 8 inch.....installed recirculation overflow tank...installed external tranny oil cooler no more hot oil in radiator....got hi flow 4 core copper rad....bigger shroud....sealed shroud gaps....went from 17.5 inch clutch fan to 19 1/4 inch derale flex fan....car runs at 170 to 180.....but 10 minutes at idle hits 210 and would go higher, problem is car pings at 190 or higher so need to keep 190 or less....any ideas anyone ?