68 Small Block water Pump Gasket Question

[Kurt B.]

Greetings All,
I need help once again and the Judging Manual nor the Assembly Manual have the answer.
1. On a 68 small block L79 motor (327 cid/350HP) one of the gaskets that mounts between the water pump (#3782608) and the motor, has an extra hole in the gasket which sticks out. Should this be so or do I have the wrong gasket?
2. Which gasket material is best to use, cork, paper, neoprene, or whatever?
3. The rear of the center of the pump is touching the timing case cover; can I use double gaskets or a thicker than regular gasket to get a few thousand's of clearance?
Thank you as always for any help you can provide.
Kurt Bunting # 26406

[Joe L.]

Re: 68 Small Block water Pump Gasket Question

Kurt------

The gaskets are the same for both sides. Since one of the water pump legs has a bypass hole and the other doesn't, you always end up with an extra, lower hole on the non-bypass side. You can trim the gasket, if you wish, but it's not necessary. As I recall, the factory left the extra hole on PRODUCTION engines.

I prefer the gaskets that are manufactured from heavy fiber gasket material. These are usually dark gray or black in color. Apply a VERY THIN film of silicone RTV to either side of the gasket before installation.

On 55-70 Corvettes with small block engines, the water pump rear plate often contacts the timing cover. Sometimes, this is caused by a waterpump rear plate gasket which is too thick, but you don't have much control over that. If the water pump legs seat on the block with the gaskets installed, you'll be fine. If they are just a "scoche" shy of seating, usually you can install the bolts and torque down without causing any problems. If you wish, though, you can use double mounting gaskets, IF you use the type gaskets that I mentioned.

[Mike M.]

Re: 68 Small Block water Pump Gasket Question

Joe: you mean 63 up vets, don't you. The C1`s had the front motor mount interspaced between the water pump and the timing chain cover.regards, mike

[Joe L.]

Re: 68 Small Block water Pump Gasket Question

Mike-----

Yes, I think you're correct. I'm not greatly familiar with the C1 configuration. On C1s, I think that the motor mount ("oxbow") bracket may have actually gone between the water pump and the block, spacing the water pump out even further from the timing cover. I thought that there was a semi-circular "cutout" in the bracket, though, that insured no interference between the timing cover and the bracket. I'm not real sure of any of this, though, as C1s are not an area of expertise for me.

One thing that I do know, though, is that most, if not all, C1 waterpumps used a flat water pump backing plate which would even more reduce the chances of interference with the timing cover. The flat plate was inefficient and leak-prone, but it was a lot lower profile than most C2 and C3 covers.