[65 tri-pwr]

Trips, you said you retarded the timing. Won't that cause higher temperatures? I would think that you would want it advanced so the engine isn't working so hard.

[Trips4me]

65... My thinking is that if you're running too far advanced then you are subjecting the engine to possible detonation (heat). I was taking that out of the equation by bumping it back a bit.

[george kujanski]

Hey trips: Rugratman had success changing to a larger 7 blade fan with wide blades. That won't answer the question why you are heating now, but if it works...

George

[Trips4me]

George, that's a thought... Do you know where he got this fan?

[george kujanski]

Dunno..ask him yourself on the '160 degree hot enuf" thread.

geo

[Trips4me]

George.. thanks.. I found it and contacted him.. I already have a 17" 7 blade fan so I'm unsure if a 18" will make that much difference but we'll see.

[buwalda]

George,
The reduction in size of the bypass made no difference that I could see on the gauge. It seemed to run a little cooler on cool days, but once the engine was running for awhile on a hot day, it would be at the same temp, with standard bypass or the smaller one. I would encourage others, though, to try it out, because there seems to be many variables with different cars behaving differently. It might work for you.

[70GS455]

Cooling at speed (lots of airflow) and overheating at idle (low airflow) indicates one thing - not enough airflow at idle. You need more fan.

[Trips4me]

Well guys I'm really leaning towards the lack of coolant flow at idle vs. the airflow. However, it could be a combination of both so I am going to try 2 things:
1) Find a '65 389 A/C water pump pulley which is 7 3/8" vs. the 8" I have now. It seems to me that since Pontiac designed a smaller pulley for A/C cars they felt that the coolant needed more flow at idle with the extra load.
2) If that does not work (or I can't find one) then I am going to add the same fan that Rugratman installed. The only issue with that is that I need to space it about 4-4.5" to get it into the shroud properly. My stock spacer is only 1.5".
Any thoughts on this?

[Trips4me]

Update...

I found a pulley, have ordered the 18" flex fan and should have all in a week or so. Will post the results as soon as I get it running again. My remaining issue is the spacer to get the fan inside the shroud. I ordered a 2" spacer with the fan and my also have to add the 1.5" stock spacer to that. There was some concern about adding the extra spacer but it seems to me that it should not be a problem considering the weight of the stock fan and clutch will be removed.

[quicksilver97ta]

Jim, just found your thread. I don't feel like the clutch has been looked into well, not by reading the thread anyway, maybe I missed it. I've been surprised how much a new high quality clutch improved idle and low rpm cooling, even when the old one still seemed within operational limits. Been a while since I bought one but a good one cost over $50 easy, don't get a less expensive (cheap) one. I read a thread not too long ago that had part numbers for Imperial and another brand and info about one company making clutches for another company, good info especially for the part no's. Maybe you already have a brand new one but I just wouldn't over look the clutch if you don't. Best of luck.

[Trips4me]

Danny.. How ya doin' man... I put a new fan clutch on it about 9 months ago. It seems to me that if I am able to move it when the engine is warm then I am not getting the full benefit of the fan. According to the manual they never "lock" up so it seemed to me that I am losing idle air flow. Also, Rugratman had very good results going from the clutch to the flex fan. I am installing the same fan he used which he said moved a ton of air at idle and is pretty quiet for a flex fan. We'll see....

[george kujanski]

Ok, per the pix on the other thread "paging George..." and Malky's observation that the diveder plate splits the flow from the vanes, here's my assessment of how the early 8 bolt pumps work.

Looks like the front part of the vane (engine front) channels flow to the driver's side block, flow being deflected towards the block by the bent end of the divider plate.

The rear portion of the flow is channeled to the round tube of the timing cover towards the passenger side of the block.

In another dwg from the manual posted recently, the dwg shows a "reciculation passage" on the driver's side. It looks to me like the flow to the driver's side of the block is inferior due to this "recirc" passage since flow can "fold around" the bent deflector back to the other bank.

Since the design was later changed somewhat as evidenced by OLDGOAT's pix on the '67, and the later 11 bolt style pump with dedicated tubes for each bank, I'd say the Pontiac engineers saw this alleged defect in the early pump design and subsequently changed it.

Any thoughts? I'd like to hear others' opinions.

Geo

[WCWhitey]

George, I have always read where the 8 bolt pump design did not cool as well as the 11 bolt pump. I often asked why but got no answers. When the 326 came out for the 400 I wanted to keep the bracketry from the 66 so the 8 bolt set up and the 326 timing cover were in. A new cast iron water pump (large vane), the factory divider plates (they were immaculate, and checked the spacing as the "cast impeller debate had already began). I updated to an aluminum radiator and added shroud as a matter of course. With a 180 degree Tstat I can run for hours at 65 mph or better and have lower than Tstat temps. I do have some symtpoms of temp creep at idle, but this is only on 90+ humid days and tuning has elimated it for normal weather. From reading all the horror stories I feel that I am much better off than some and at least as good as most. Would the 11 bolt pump be any better for me, not sure.

[Trips4me]

OK... RESULTS. I finally got the smaller pulley (7 3/8 from a A/C car) and installed it with the new fan. I let the car idle for about 20 minutes and it did not get past 180. That's the good news... the down side is that it is only about 77 degrees here (in my garage) and it was about 97 degrees when I was having the idle cooling problem. So I don't feel that I have a definitive answer to the problem yet. I guess I'll have to wait to see next summer. There is a chance I may get to check it this weekend since it's supposed to get to about 81-82 outside. It could get hotter in the garage so I'll give it a test.

[george kujanski]

Take a drive to Arizona...

geo

[Trips4me]

That's funny George....I'll let you know when I get back.....

[george kujanski]

Seriously, tho, I was there last weekend & it was 95 during the day.

Geo

[raws6]

Has anyone run with an eletric fan, I have a 64 389, is also running hot, have been considering trying an eletric fan? Looking for advice on makes, sizes,etc. Thanks

[Trips4me]

That's a pretty good drive from here, George. About 12 hours each way if I remember correctly. I think I'll just wait until summer.