C2 Water Pump Plate... Bolts or Slotted Screws?

[James W.]

Is the access plate on a 1965 396/425 water pump held in place with recessed hex head bolts or pan head slotted screws?

The reason I ask is because the rebuild kit from CC came with pan head slotted screws with star washers? Currently the water pump GM casting number 3856284 date F235 was rebuilt with the recessed hex head bolts.

Also, does the original access plate have the letter "B" stamped into it?

Thanks again,

James West
Omaha, NE.

[Michael H.]

Re: Calling Bob Jorjorian

James,

I THINK the pan head screws are correct for 65-66 but I'm not 100% sure. Maybe we can get Jorjorian in on this one because he would know. Also, I think the back plate is different on 65-66 than it is on 67 and later. I believe the 67 plate was a much thinner stamping than the thicker 65 plate.

Michael

[James W.]

Re: Calling Bob Jorjorian

Michael,

Again, thanks for your input. I do hope that the other person you mentioned will give his input also. FYI, the back plate measures just shy of 1/8" in thickness.

Best Regards,

James West

[Wayne M.]

Here's what's on "284" pump E-5-5

Large pan-head screws (you have to look closely to see the star washers underneath) Back plate is COMPLETELY flat -- no (inward) debossed ring or outer lips bent towards engine. Thickness is as you describe. No letter stamping on the plate of this particular pump.

Another point -- the bypass nozzle has no raised rib (added later to prevent bypass hose from blowing off under pressure).

[James W.]

Re: Here's what's on "284" pump E-5-5

Wayne,

Thanks for your response. You stated that the bypass nozzle should not have the raised rib. I just finished installing the current reproduction bypass nozzle from CC that has the raised rib. Will this be a deduction in judging? I would guess that it wouldbe visible under the bypass hose. I guess I could carefully remove it with a dremel tool or hack saw, but I'd rather leave it on since it serves a purpose, i.e. keeping the hose staying put under pressure.

Thanks,

James West
Omaha, NE.

[Robert Jorjorian]

Wayne is 100% correct in his descriptions. *NM*

[Joe L.]

Re: Here's what's on "284" pump E-5-5

Robert-----

I, too, agree that the description which Wayne M provided is as it was for the 1965 water pump. I would leave the barb on the hose fitting. Even if it can be discerned with the hose installed, it would be worth any minor point deduction that might ensue.

[Joe L.]

Addendum

I should also have mentioned that while the "flat plate" style water pump backing plates may be "correct", they can be problematic as far as sealing goes. GM changed the design of these plates for a reason, and I'm quite sure that the reason was sealing. Not only are these plates susceptible to leakage under even normal cooling system conditions, they are especially susceptible to leaking when cooling system pressure exceeds design specs (like with a failed radiator cap relief valve or if a higher pressure cap is installed).

The later design plates had an embossed "ridge" around the periphery of the plate and "curled" plate edges to add rigidity to the plate (yes, I realize that this was partially necessary due to the fact that the plate thickness was also reduced). The later design plates seal FAR better than the original style. I would NEVER, EVER use a waterpump with one of the these "flat plate" style backing plates, big block or small block.