Lower Bolt Holding Power Steering Pump Bracket to Engine

[Allen N.]

I have looked high and low and cannot find a description of bolt 9417756, which holds the lower corner of the power steering pump bracket to the engine in a 1970 big block w/o air. I would greatly appreciate knowing the size, grade and finish of this bolt.

Some Corvette parts suppliers sell a 3786494 for this location and for the bolt holding the upper corner of the power steering pump bracket. There surely must be a difference or they would use the same part number for both.

Thanks,
Allen

[Leif A.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Allen,
Someone with more knowledge than I will reply regarding the 9417756 bolt, but here is what I found regarding the 3786494 bolt.

3/8-16 X 1.0 GR5.1 HX SPLIT SEMS PHOS. 2 pk

Phosphate & Oil

[David B.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

GM 9417756 is 7/16 - 14 x 13/16 Plain

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

GM 9417756 is 7/16 - 14 x 13/16 Plain

David,

I have a problem in that the threads in the block are 3/8 - 16 for the lower bolt. The threads are 1" deep the same as the threads in the block for the upper 3786494 bolt.

Thanks,
Allen

[David B.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

As requested gave description of GM bolt 9417756. Obviously not correct for your block.

[Leif A.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Sounds like wherever you got your information for the upper bolt is incorrect. Also, sounds like 3786494 bolt is what you're looking for...see post #2.

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Thank you David and Leif with your responses.

It appears the judging guide is looking for a black phosphate bolt at this location, so I am going to use a 3/8 - 16 x 1" black phosphate bolt and see how the judges like it.

Thanks,
Allen

[Gary B.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Allen
Is this the 2-holes you are looking at? This is a 69 427 block, but I thought 70 454 were the same? Both of these holes are 7/16"-14nc.
Curious...
Gb

20210415_102944.jpg

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Hi Gary,

Yes, the two holes are horizontal to each other in the center of the first picture.

I ran a 3/8"-16 tap in both of these holes to a depth of about 1".

The AIM calls for a 3786494 bolt in the top hole. AMK says this is a 3/8-16 x 1" bolt.

Maybe 69 and 70 are different?

Should the bolts in the top and bottom holes both be black phosphate?

Thanks,
Allen

[Gary B.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

I'll try and sneak into the "library" next week and look at a 70. Only have solid lifter small blocks around the house right now.
Gary B

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Thanks Gary!

[Gary B.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Allen... Was into the Library today. Looked at a 71 454 on the 4-post hoist, no PS. a 3/8" bolt slipped into the hole about 3/8 of an inch with turning the bolt. They are definitely 7/16" threaded holes. Try running a 7/16 in them and see if it works..
Gary B

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

Gary,
I tried a 7/16", and it won't fit. A 3/8" fits perfectly. Once the bolt is installed no one is going to know what size is installed. All you are going to be able to judge is the head of the bolts. Are the original bolts regular hex head black phosphate or something different?
Thanks,
Allen

[Mike E.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

And the head of a 3/8 bolt is a different size than a 7/16. We judges don't miss anything!

Gary,
I tried a 7/16", and it won't fit. A 3/8" fits perfectly. Once the bolt is installed no one is going to know what size is installed. All you are going to be able to judge is the head of the bolts. Are the original bolts regular hex head black phosphate or something different?
Thanks,
Allen

[Allen N.]

Re: Lower Bolt Holding Power Steering Pump Bracket to Engine

And the head of a 3/8 bolt is a different size than a 7/16. We judges don't miss anything!

That is fine. If a judge thinks the bolt is the wrong size and wants to take off for configuration, that is fine. I am not going to drill and tap my block to put in a larger bolt.

Now, can someone answer the original question of what finish the bolt should have so I don't have to lose 20% of the parts points for finish.