[fast72lemans]

I'll see how it does in the Ocean City Md. traffic in a couple of weeks....80 blocks of bumper to bumper muscle cars!

[pmdclassics]

Wow this is one massive thread! Can someone that has followed this thread through its life please recommend a impeller for my 69 Firebird 350? The short story is its a fresh rebuild that gets way to hot on idle. I already replaced the radiator with a desert cooler and that did not help. Of course I will tap down the divider plate as well.

[limejudge69]

Get the pump from NAPA. Part #DPW-1301280. It has the cast impeller. Nuff said!

[esmoore]

I read the first few pages of this thread, and got all excited that the vane to plate clearance thing could be my problem. Symptoms are as described after all: car slowly creeps up in temp no matter if idling or on the highway. Temp seems to know no limits, but I've always turned it off when it tops 210-215 (I have aluminum heads).

But then I remembered that I've got a Flowkooler water pump, and the pump has a plate welded to the vanes. If I'm not mistaken, this feature of the pump should do everything that a tight clearance would do, correct? Is it worth pulling the pump off to check this clearance with a Flowkooler pump?

The rest of the system is fairly well equipped- large griffin radiator, electric fan pusher on the front, well fitted flex fan with shroud on the back.

Engine is a Jm Butler 468, solid roller. No vacuum advance, but the timing is locked down at 45 or so, mixture seems right according to power and plugs. Since it doesn't seem to matter whether idling, cruising, or highway, I am reluctant to diagnose it as a tuning issue- seems like it has to be a water flow issue, but I'm not sure how to check or what to look for. I ordered a Raytek infrared thermometer that should be here next week, and intend to check temps in upper and lower hoses, but even then, I'm not sure what to do with the data.

[Geoff]

The plate on the FK pump does the same thing as tightening up the divider plate clearance, so you can leave as is.
A poor flex fan, coupled with a shroud that is too large for the fan, & a pusher fan further impeding flow will do little for cooling.
If your fan was originally 19+ inches, a replacement fan needs to be the same size for the shroud to work. An 18" fan in a 19 1/2" fan shroud will be no better than no shroud at all. The only flex fans that are 19+ inches that I know of are the genuine Pontiac RA 7 & 5 blade fans, & the Flex'a'Lite s/steel blade fan. Both pull lots of air & are good fans.
I would ensure you have one of these fans & remove the pusher fan, it might be hindering air flow.

45 degrees timing. At idle, centrifugal, what? Much too high for both using alum heads. At idle engine should want about 28-34 idle for best idle quality & cooling. I am assuming the cam is larg[ish] being a roller. Centrifugal adv would depend on which heads & other factors. If the dist is locked, try bringing it back to 32 degrees.

[esmoore]

Geoff-
Thanks for responding. I don't remember what size fan is in there. It looks _fairly_ well fitted, but could easily be an 18" or 17" in the original 19.5" shroud. Is this the Flexalite fan you're talking about? DIameter is 19.312", but that seems _Damn_ tight for a 19.5" shroud. Radiator is a custom Griffin that's close to the original dimensions, but I'm worried that any discrepancy in fit from original would make for a difficult fit with a fan that big. If you're talking about another fan, could you be more specific?

http://store.summitracing.com/partde...5&autoview=sku

As for the pusher, it has no shroud, and is switched by a 170 degree temp switch, and so is almost always running. The car gets hot even at idle, you think that it could be harming airflow then?

As for the timing, I'd have to check specifically, because it's been a while, but I know that it's over 40, I don't have detonation problems that I can tell. It's a solid roller motor (263/274 @.050, .626 lift), so I don't think I'd be able to hear it, but I've never seen any evidence of detonation on spark plugs. I arrived at that total timing through much testing, and am fairly confident that backing off would cost a lot of horsepower.

There is no mechanical advance and no vacuum advance. Seems to me that if I had initial of 34 or so, and a vacuum advance, my total at idle would be close to back where it is now? Would too much timing at idle cause cooling problems? The car seems to idle really well.

Thanks again.

[george kujanski]

My opinion is that the clearance should be minimized regardless of the welded plate. Too much clearance will cause the suction of the pump (the center hole) to draw coolant from around the vanes rather than thru the center hole.

George

[esmoore]

Thanks George-
I am going to pull the water pump later this week and check it out. Have you heard of anyone with a flowkooler pump seeing results from this?

Also, I attempted to measure my flex fan today, and as best I can tell, it's 18", and the shroud measured closer to 20". There is about an inch of clearance all around between the fan and the shroud, so I think I am going to try a larger fan per Geoff's suggestion. Now, I need to decide between another flex fan, or a clutch fan. As far as Flex-a-lite goes looks like it's between these two

19.3" flex fan:
http://store.summitracing.com/partde...5&autoview=sku

19" clutch fan
http://store.summitracing.com/partde...5&autoview=sku

and thinking about this for a fan clutch:
http://store.summitracing.com/partde...5&autoview=sku

Anyone have any input as to which setup would be better, or are there different parts I should be lookingat? At this point, cooling is highest priority, but power is always a close second.


Thanks

Erik

[fast72lemans]

Originally Posted by fast72lemans

I'll see how it does in the Ocean City Md. traffic in a couple of weeks....80 blocks of bumper to bumper muscle cars!

Ocean city was easy, 2hrs in bumper to bumper traffic with 65 degree temps, never moved above 180 on the gauge(168 real temp). Just got back from a 2 hour roadtrip in 90 degree weather, never went above 200 on the gauge.(188 real temp) It only started to creep when driving at 70mph.....need a larger fan, I only have a 17" flex fan. Thanks for the info George, really helped me out.

Mark

[esmoore]

Update. I am embarrassed to admit that I did not have a Flow Kooler pump after all- I had earlier replaced my 7 bolt Flow Kooler with an all aluminum 11 bolt (cast impeller) a few years back and had forgotten.

Last Thursday, I pulled the fan and water pump, and I had about .220" clearance from the plate. I hammered it down to 0 without the gasket, and then put the gasket back in. I also replaced my 18" flex fan with a 19.3" one for a tighter fit with the shroud, and replaced the parts store 180 degree thermostat with a Robert Shaw 180 degree thermostat.

In short, my cooling problem seems to be solved, and I believe the pump clearancing gets the credit. I drove around for about an hour on highways and in stop and go traffic on a 95 degree day, and the temp never got above 185.

[gtoman6]

After installing an oversized $600 Griffen Alum Raditor, 2 Spal electric fans, a Moroso High volume Water pump, a 160 high flow thermostat, Purple Ice (2 bottles) and two changes of coolant (Dextron 1st, then back to Ethylene with Distilled water) - All with a whooping changes of NOTHING, NADA, ZERO - Still runs at 200 +. Then Reversed the electric fans to push AND Put my Clutch fan back on and it dropped maybe 5 - 10 degrees with all 3 fans - Temp goes up with speed and RPM's (Hotter on Hwy than in traffic), so all this makes perfect sense.
I will try adjusting the plate and if this works - what an idiot for spending a grand to not cure the problem for something this simple.

Thanks George

[george kujanski]

Let's see if it solves (or helps to solve) the problem. Take measurements before adjusting; if larger than .050" or so (especially if MUCH larger), your coolant flow is undoubtedly suffering.

george

[R68GTO]

I've been battling a hot running 68 400 for a couple of years. Checked my impeller clearance last year per this post and found that I had a stamped impeller with losts of clearance. Bought a reman pump with cast 8 fin impeller (11-bolt) and adjusted the clearance to .060 with only a slight improvement in temps. Found out my radiator (4 row Harrison) was in poor shape so I am in the process of changing it out with an Alumitech. I pulled the pump again just to re-verify my impeller spacing and noticed that I have quite a bit of crud accumulated on the divider plate isolated to the area from just below the outlets where the o-ring bushings connect to the bottom of the plate. Is this accumulation of crud a symptom of a problem I should be concerned about or normal. I also noticed the pump had a rust line starting from about 1/2" above the impeller shaft to the top of the pump. Again is this normal or another sympton of a larger problem. Sorry for the long post but I'm working on it this weekend and this problem is wearing me down.

Thanks
Jim

[T70GTO]

George, I told you I would post and do my part in keeping the thread going. To all I have a 66 GTO, 19" hd 7 blade stock fan , no shroud , 4 row radiator and have been running up to 220 after just 30 minutes in Arizona's dry heat !!! This while temps were in the low 90's. Pulled the water pump and found a steel impellar and a rusted with holes divider plate. Picked up a shroud from PY, an 18" 6 blade steel fan and a cast impellar pump from napa. already got the clearance in place. Just have to paint and get all back together. I will update back hopefully next week with good news.

Thanks Tom/ Fremd High Grad!!

[Old Goat 67]

You go guys!

More important than keeping the thread going, is to get them Pontiacs cool!
Just remember to do as George suggested on page 1, "THINK"!
And please post results for others to key off of.


Charles


Page 1, Posts 4, 15, 16 & 17

[webfoot]

My neighbor has a 67 GTO that is having overheating problems, I'm going to have to talk to him about this.

[General Z]

I just wanted to share my success story with a 67 Firebird, with a 455 punched out to 469.

Through trial and error, I ended up putting an aluminum Jegs radiator in, a 160 degree high flow thermostat, a cast impeller water pump and an electric fan. After doing that, the car would run 180 all day, stop and go, and normal driving below 60 mph.

On the Freeway, it would start to climb to 200, then 210, then 215, and it even hit 220 one day. The car has a 700R4 trans, so the RPM's weren't too bad. When I got off the Freeway, it would come back down. So, I figured that it was an airflow problem, with air going above and below the radiator. I then built baffles to mimick the missing stock baffles above the radiator and below it too, to force the air to go through instead of around.

Now, it stays down around 170 around town, and 180 on the freeway. I'm loving it.

[Z Code 400]

Originally Posted by limejudge69

Get the pump from NAPA. Part #DPW-1301280. It has the cast impeller. Nuff said!

Picked up one from NAPA last week for a customer......Stamped steel impeller....Robert

[T70GTO]

Update on my 66 cooling. Went for a cool first am drive today, 92 degrees desert heat and never got over 190. Took almost 35 degrees out with new cast impellar pump , setting divider plate clearance to a minimum, added a shroud and a heavy duty fan clutch . Thanks to George and all on this thread for the tips.

Tom

[george kujanski]

Score! Another success story!

George