Mounted the new waterpump yesterday and i stripped the threads on the two lower screws that
hold the pump to the front plate. So i took all apart again and i,m thinking to weld nuts on the back
of the plate instead.

Was very careful , oil on the screws and tried less tourq than recommended 13 ft.lbs .

Have all the 455 engines this thin frontplate also ??

 

Yep!

 

Ok thanks , welded 1/4"- 20 nuts on the backside of the frontplate.

 

Yes, all 65-90 Oldsmobile engines SBO/BBO use a similar timing chain cover. There are a number of water pump bolts that thread into the timing chain cover. If you welded nuts onto the back of the timing chain cover you'd have to change the water pump hardware so it would fit the nuts.

 

I went to 1/4-20-1.25" allen bolts and washers because the end threads on the stock bolts are iffy. Make sure what goes into the timing chain area doesn't hit the gear, etc.

 

Ok thanks for input i used small pieces of flatbar 5mm thick and made 1/4'-UNC threaded holes so original fasterers can be used.

Yes , have mounted the fuelpump and front plate and turned the engine around and checked for clearence thru bottom of engine.

 

Just had to do the same on my 455 and I used the original hardware. The bolts were still long enough to have a few threads past the nut.
link to post

 

Hi should check your thread