divider plate clearance
 

have we come up with a standard tolerance for divider plate clearance? is .100" acceptable before compressing the gasket or should we shoot for less?
i just bought a flowkooler water pump and i am in the process of "adjusting" my divider plate. so far i'm at .080" down from .200", should i stop here or try to get closer,or am i too close?

I went for zero clearance with no gasket. Then put it together. Once I had it tighened down I gave the pump a spin and had no interferance at all. It runs super cool now :D

Suppose this is nice-to-know for the factory Iron-pump folks...

This issue is no matter when you use the REVISED modern aluminum pump:
The GMB pump has been improved by Flow-Kooler model # BRA-1649 sold by Summit:

The divider plate's function has been welded to the Impeller.
So, the impeller has a sheetmetal hat welded to it now.
So, I took out the OLD GMB aluminum pump, and installed this UPDATED pump into the Timing Cover with factory divider plate. No clerance issues.
My car hardly warms-up.:ranger: HIS

so if i'm understanding what you're telling me, with the 1649 water pump, there is no need to adjust the divider plate due to the "hat" they welded on the impeller?

Here's the way i see the pump design:

Any comments?

That is correct George. Plate or no plate, you have to close that gap between the divider plate. Technically, if you have the plate welded to the impellar, you only need to clearance the divider plate around the center hole. If you have the open impellar design, that gap technically needs to be tighened up allong the whole surface of the impellar. That forces the water to stay in the veins and be pumped instead of just being mixed between the plate and the impellar.

so then i'll remove the gasket, go for zero clearance, and reinstall the gasket, divider plate and bolt it up to the timing cover, torque it and check for interference. do i have to worry about heat expansion changing any clearances? or... will i be alright with the .080" with the gasket in place as is?

Mine is fine. I listened for scraping after the engine was warm and it seemed perfecto.

I am getting ready to pull my engine and am planning on replacing the water pump to a high-flow one...
Was initially thinking of the Milodan brand...but now I am thinking about this one..
Is that part # for a 455?

1649 is for aluminum and 1649CI is for cast iron. both will work for your 455.

I see that, went to the site and noticed that water pumps for pontiac come with a 4" or 4 1/2" shaft...getting the wrong one can mess up pully alignment (FK only comes with 4 1/2" shaft) Anyone know what was stock and how to know what you got..Went out to see if it was possible to measure the shaft...but I dont know what/where to start the measure point.

first of all, i believe the only pump with the 4" hub is on the '69 engine, the rest are 4.5"....i believe.

as for measuring, if the water pump is off of the car, start the measurement at the machined surface on the impeller side of the housing where the gasket would go and measure to flange surface where the fan would mount. for ease of measurement, use a straight edge and line it up on the flange and measure back to the housing.

hope this helps.

I didn't know they made a water pump like that. will pick one up. good info !

I just tried to decrease the gap btwn the divider plates and the impeller this weekend. I was using a rubber mallet and got the clearence down to about .100. The car ran warmer than it was before I made the adjustment. My questions are: what kind of tool is everyone using to decrease the gap, and what should that gap ideally be. My next question, should the entire divider plate be manipulated down to meet the impeller, or just the inside edge. If anyone has pictures showing the ideal gap, I would appreciate it. I have been chasing this overheating problem for about 3 years, I have a stroker 400 pushing over 600 horses and connot afford to let it get hot. Please HELP!

So Goat4three...How did it end up? Any Tips/observations to make?
I bought a Flowkooler WP and a new stainless steel divider plate this weekend..when I pull my engine at the end of the month...I'll be adding the new WP and Plate in.

BRA-1649..still working after 1 week, no drips, no noises. Engine seems cooler in bumper-to-bumper traffic but that could be my swap to dual carbs and Idle ADJs.

I also assembled plate onto pump with no gasket, then got to whacking. I only whacked about a half inch around the center hole. I have no clearance problems due to heating or otherwise.

Besides, if there were any slow creeping clearance issues, the impeller would take care of that when contact was made.

dumb question, but do they make a after-market highflow or revised pump that will work in a 67 8 bolt timing cover? I have seen in the catalogs that they make them for the 11 bolt but not the 8 ?

Have a look at the post 'Timing cover with Chev water pump'. Allows you to use a Chev pump, many possibilities.