So I have a question. I have heard many many times that if you do not put a bolt in the upper smog pump bracket hole that you will have an oil leak. I installed a new 350 and now have an oil leak on the pass side somewhere.

My question is, when I pulled the bolt out to look through, I can't see anything but milled threads. I put a nail in there to see if it goes into the crankcase and the hole is only about 3/4 of an inch deep. I went to look at the old 305 I pulled out and it is the same.

I do not see how oil could leak there if at the end of the threads there is solid metal. The only thing I can see is the lower bolt hole goes through where the fuel pump would be, and there is a tiny hole in that passage. You have to be under the engine to see it. Right next to the fuel pump block off plate.

 

The top bolt which is the one circled in this pic (which I ganked from another member just in the last couple of days!!!) is the one in question. Note that it sits on a kind of lump; that lump is the passage that the fuel pump rod goes through. If you take out the bolt that's in the pic, and look in there, you can see the rod.

The lower bolt hole (the one with no bolt) isn't a problem; it goes into one of the block's master locating dowel holes, that the entire block is measured off of during the machining process.

 

Some newer replacement 350's will not have the passage bored out completely for a fuel pump push rod. If you remove the fuel pump block off plate and the cavity is completely dry, this is likely the case with your block. Would probably still be easier to put the bolt in and be safe...

 

Doesn't apply very well to a TPI engine, though. . .

 

Well the two engines I compared are from factory fuel injected setups, one is an '89 305 and a newer 350 block. I tried to see where a fuel pump rod would go but both holes a very shallow and blocked.

I still have the hole bolted because I'm still using a factory accessory bracket for the air conditioning. So I have a smog delete pulley on the bracket, and Both holes are bolted up on the block.

So what else could be making oil drip off the starter, besides valve cover and smog pump hacking.