69OldZman

Hi everyone,
While replacing the water pump, even though I was being cautious, I've stripped one of the self-threading screw locations.

I have a new GM timing cover, but on close examination, the screws that I have that are supposed to be self tapping-- aren't. I want to be sure to use the correct fastener for those locations, and I would prefer to use a GM replacement.

Best I can find for a part number is 9428097 screw, pump to cover. I'm sure this is an obsolete part number.

Can anyone cross it to a current number?

If not, I'm thinking about buying some of these
http://www.fastenal.com/web/products...ex?sku=0142585

Would these match the OEM?

Would it be a good idea to change the timing set while I'm in there? The engine is a 77-79 403 with unknown number of miles.

Any tips on replacing timing set and cover?

Thanks!
Charlie

My442

Inline Tube sells a reproduction set.

Motor City Musclecar on e-Bay.

Oldsmaniac

I do not think the screws are self tapping. I do think there may be enough metal there to tap new threads for a larger bolt. Maybe even go metric to get the proper size. I usually tighten the larger bolts first and use a nut driver on the smaller bolts and just snug em up.

66ninetyeightls

Can't you heli-coil it??

69OldZman

First I wanted to say thanks for the responses.

MY442,
I finally found it. It looks like he changed or added an ID, its listed under MotorCitySupercars.

Oldsmanic and 66ninetyeightls,

The ideal fix would be one that I can do with the timing cover on. I'm worried that if I drill it to heli-coil or go oversize that I would be putting metal shavings into the engine.
If I'm going to pull the cover, then I already have the new one, and I figure I would start with fresh screws.

Any thoughts on replacing the timing chain?
Will it be hard to get the cover back on without leaks?

joe_padavano

Congrats and welcome to the club. We've all done this at least once.

There isn't enough meat to install any kind of thread insert. The threads are just formed in the upset sheet metal of the cover. I'm pretty sure the 1/4-20 screws are self-tapping. Since you already have a new cover, just replace it. If you didn't, I would simply use a fine adjustment hammer to tighten up the upset area of the threads on the cover. If you're not comfortable with that, then grind the backside flat and weld a nut onto the back of the cover.

Yes, you MIGHTASWELL replace the timing chain.

The trick to reinstalling the cover is to trim the ends of the front oil pan seal (the parts that normally get trapped between the pan and the block). If you can loosen the pan bolts, it helps. RTV the corners of the seal and have fun forcing the cover back on the dowel pins. It helps to file a taper on the ends of the pins. I usually get the cover close on the pins then pull it down with the bottom bolts.

You'll want to put a sleeve on the balancer if there is any groove at all on the seal surface.

69OldZman

Thanks for the advice so far. Of course with two children under 2, projects never happen as quickly as I would like. I'm hoping to work on it this weekend.

I have a split timing cover on the way, and I have some cam advance bushings for my timing set.

What keeps the bushing in? Do you use loctite on it? I know I should try to degree the cam to see that the timing set is set up right. As far as I know, this is the stock cam. Do I just try to figure out the factory cam specs to degree it?

joe_padavano

The bushing is captured between the front of the cam and the fuel pump eccentric, so it's not going anywhere.

Warhead

I like going to a ever so slightly larger size, don't go crazy here. You will have to enlarge the water pump hole the same amount if you do so. I have done this fix, and it works very well.
If you have to do this, take off your fuel pump, and with a pencil tip adapter, put a VACUUM cleaner to the backside of the hole while you enlarge it. This is the best fix here, without putting on a new cover.
2 pc covers can be leakers, if you don't seal them right.
JMO
Jim