[Rugratman]

Yea, there is suction. I was just reading Geoff's post and He got me thinking about the vacuum strength. Just making sure....

[JSchmitz]

I just swapped my aluminum Flowcooler pump out for the NOS pump I bought. Here's a picture of the .160" gap between the Flowcooler impeller and the divider plate.

[JSchmitz]

Here it is.

[JSchmitz]

Here's one of the pump itself. It has a cast impeller with a metal plate welded to it. They chose to turn down the outside diameter to 3.775 from 4.400". The vanes are 5/8" deep like the factory one.

[JSchmitz]

Here's a picture of the two pumps for comparison.

[JSchmitz]

The picture of the new pump to divider plate didn't turn out very well. With a new gasket and the divider bolted to the pump there was about .055" clearance. So, I left it alone. I will test drive it later and post the results. I predict it will do better on the highway,and similar at idle. I'm fabricating a shroud. It should be done soon. I think it should help the idle cooling big time.

[JSchmitz]

Well, I just returned from driving the car about ten miles. It was a combination of 40-45 mph driving and stop lights. Outside temp is 90 degrees. The car seemed identical. Steady cruising at 45 would keep it about 175-180. As soon as I stop temp starts rising slowly. It got to around 190-195 at stop lights. It would quickly drop after I got moving. Again, I need a shroud. We will see how it behaves on the highway. It certainly doesn't seem like a magic bullet so far. The battle continues.

[Gordy Doyle]

Hey JB what are you going to use to fabricate the shroud?
I'm in Maryland Hts and have similar problems on my 455. I'd be workin on it now but as you know the index is 105 in St. Louis today.
Gordy

[JSchmitz]

I had a friend make an aluminum shell on a roll brake. I just made some templates for the mounting brackets. Now I need to make them in aluminum plate, and weld it up. If this doesn't work, I guess I'll hack up my factory shroud.

[Gordy Doyle]

Thanks for the info. Jim. In one of your other posts i saw you're also running 96 heads on a 455.
Gordy

[WCWhitey]

I have been following this post for a while. I have a 66 Lemans with a 400 .030, CC XE256, stock intake, 650 holley, Accel ignition (tunable and adjustable), 7J2 heads (Screw in studs, 1.77 exhaust valves) milled for about 8.5:1, stock manifolds, Pypes 2.5" "X" system. I am running a sumit aluminum radiator, with a 18" 5 blade solid aftermarket fan, B&M transcooler, modified 66 a/c shroud. Running 12 degrees initial, 24 mechanical all in around 3400 (got some adjusting to do there), 18 degrees of vacuum advance (manifold) with 20 inches of vacuum. When I put together the motor this thread had already started, I have a 8 bolt cast impeller pump (from Ames, didn't have to ask for cast, not sure if the 11 bolts come that way, might be a hot tip). Clearance was tight from the get go with the single plate, right at .090. I run no higher than 170/175 (180 tstat) on a 90 degree day as long as I stay on the open road, get stuck in traffic and it will rise as high as I let it. Checked for flow at idle and the fluid moves, not great but it is moving thru the system, give it gas and if moves very rapidly. The only thing I have been able to accomplish is to slow the rate of climb by richening the idle mixture up. I also have one other observation, I run the idle right at 650 in gear, 850 out of gear, if the car is left in park, it will not go over 200. This leaves 2 possibilites, more air flow, more coolant flow or the combination of the two. Also, going with the cool air in, cooler engine theory, I opened up an extra hood insert and installed a pro-flow air cleaner for my version of Ram Air, run much better but not cooler. I just ordered the dust covers for the inner wheel wells hoping that this 10 job might make some difference, we will see! Thought my trial and tribulations might be some help to someone, keep up the excellent thread.

[WCWhitey]

As A side note and this may be a stretch. Could the design of the pontiac grill be a hinderance to good flow at idle. The large center section that makes it look like a Pontiac is really not present on other equivalent models of similar years. A 66 Chevelle has a large aluminum grille instead of the pontiac split plastic grills. Same goes for the TA - Camaro comparison. Motor design asside all other things such as radiators, shrouds, etc. are similar. Can this be a big enuff obstruction to cause this problem, just an idea, LOL Bill

[JSchmitz]

I don't know about the grill design. But, the early cars are at a disadvantage. The core support opening is smaller. My car can only fit a 26" x 19" radiator. It's the 1-14" tube variety. More frontal area is much better than more thickness. As a radiator gets thicker it gets less efficient.

[buwalda]

WC,
My advice is to fit a smaller water pump pulley. This will increase water flow AND fan speed [ hence, air flow ]. Every V8 I have owned has run cooler after fitting a smaller pump pulley.
The companies like www.stewartcomponents.com that specialise in cooling always recommend overdriving the water pump on a street engine. If you have a 8" crank pulley, I would use a 6 - 6.5" pump pulley, or a 30% overdrive.

[kate`s67gto]

Here is just a thought i have been having. When i took the coolant temp with a thermometer i held the thermometer just high enough not to touch the core of the rad. The temp was 20* cooler than the guage reading (Auto Guage) if i touch the thermometer to the core the temp rose quickly. Which brings up are the sending units length, the same, after market to factory? I think if i had a factory sending unit and a after market one i would like to know if the lengths are the same or one is longer than the other ? I should mention i took the readings at the rad after a good run of hiway and town driving, i left car idling when i came in to get thermometer. My car has not got over 180* Temps here are now in high 80 with high humidty. July 13th had car out yesterday and last night . ROdney Red rad cast pump 160 stat edelbrock rpm intake edelbrock 1411 carb 94 octane gas stock cam stock 670 heads flowmaster exhaust 18" fan cadillac with shroud on rad (not sealed stock shroud).

[WCWhitey]

Geoff, thanks for the reply, what pully would be considered a donor. Swapped all the pulleys from the 326 (8bolt waterpump) to avoid mis-alignments. The waterpump does have the 8". Any ideas of where to look, model, year, etc. Are all the pulleys the same depth? Thanks Bill

[pontiac6269]

Im going to try this on my 400 thats in my 62 GP. Its a 67 400, is the timing cover on this year suppose to have the rubber seal that goes against the seperator plate? Its only on one side for this year cover, 1967.

[buwalda]

WC,
I went to a wrecking yard & bought two pulleys from the same model car. I turned them in the lathe until I got the pieces I needed to get the correct offset and extra pulley, because my pump pulley is a dual pulley. I then welded it. This would be difficult to do without a lathe. In my GTO Restoration book by Paul Zazarine, there are a couple of pages devoted to pulley combinations [ sizes are given ] for 64 onwards. a/c, non a/c, p/s, etc had various size pulleys for pump, crank etc. You may be able to get from this list, a size combination with the correct offset, that works for you.

[WCWhitey]

Thanks Geoff, MSM provided me with the correct part number its the 66' 7" PS/AC pully, #97826769. If anyone out there has one drop me a line. Thanks Again for your help, Bill

[guentherjohn]

Is there anything to the intake gaskets? I read where Fel-Pro #1233 must be used for different head to block years or there will be an exhaust leak at the heat crossover passage.
What about compression ratio? What is the highest compression you can run on 89 Octane without heating problems?