SB oil pan screws

[Patrick B.]

Among my supply of 1/4 - 20 oil pan screws, there are two types. Most have captured star washers with about 0.40" of thread beyond the washer and L head markings. Some others have a captured split washer with about 0.42" of thread beyond the washer and Anchor or RBS head markings. Are they used interchangeably or are the screws with split washer used for a different purpose?

Since I am using a one piece oil pan gasket they all may be too short, but I am curious about the differences.

[Ed D.]

Re: SB oil pan screws

I used the one piece pan gasket on my sb 72 with the original bolts. If you use the bolts that comes with the gasket and torque it down, you can replace the screws one at a time. There is enough tread on the original bolts to make a good purchase. You can then prep the gasket for paint and use an artist brush with Chev orange to make it look original. I knew I as going to get the car judged, but I did not want any leaks.
Ed

[Harry S.]

Re: SB oil pan screws

I used the one piece pan gasket on my sb 72 with the original bolts. If you use the bolts that comes with the gasket and torque it down, you can replace the screws one at a time. There is enough tread on the original bolts to make a good purchase. You can then prep the gasket for paint and use an artist brush with Chev orange to make it look original. I knew I as going to get the car judged, but I did not want any leaks.
Ed

[Mike E.]

Re: SB oil pan screws

Patrick,
My experience is that oil pan bolts, C1 through C3, were 1/4x20 with star washers. I also have ones with split washers in my parts inventory and they were used in numerous other locations.

[Terry M.]

Re: SB oil pan screws

I seem to remember reinforcing plates at the corners of the oil pan (or am I mixing up SB & BB??). I used to only know small blocks, but my life has changed in the last several years.

If there are reinforcing plates at the corners I would expect slightly longer bolts at those four positions and potentially different locking systems.

Oh well, just a WAG I'm throwing out there.

[Mike E.]

Re: SB oil pan screws

I seem to remember reinforcing plates at the corners of the oil pan (or am I mixing up SB & BB??). I used to only know small blocks, but my life has changed in the last several years.

If there are reinforcing plates at the corners I would expect slightly longer bolts at those four positions and potentially different locking systems.

Oh well, just a WAG I'm throwing out there.

Terry,
I know that I have taken off the bolts you refer to that have had split washers. But those are 5/16, not 1/4x20.

[Mike M.]

Re: SB oil pan screws

Splits in all 4 corners and captive star washers with L head marks everywhere else. However, a variety of other head marks have been seen . Mike mccagh

[Terry M.]

Re: SB oil pan screws

Terry,
I know that I have taken off the bolts you refer to that have had split washers. But those are 5/16, not 1/4x20.

Drat.. It's been too long since I had a SB oil pan off. I just thought it was worth a shot.

[Patrick B.]

[Joe L.]

Re: SB oil pan screws

Mike — The corner bolts with the split washers are 5/16 as Mike Ernst said not 1/4. Do the 1/4-20 with split washers go on the timing chain cover?

Patrick------


No, the timing chain cover uses the same 1/4-20 bolts as the oil pan.

[Patrick B.]

Re: SB oil pan screws

Thanks for the info fellows. I have plenty of screws with the star washers for the oil pan and timing chain cover, and maybe they will work with the one piece gasket like they did for Ed. I'm still curious where the screws with split washers go.

[Timothy B.]

Re: SB oil pan screws

Patrick,

I have found the 1/4" w/split lock washers attach the spark plug wire heat shields on the side plus spark plug wire guides in the rear of the block. They are used in other areas but I believe the length was longer.

[Patrick B.]

Re: SB oil pan screws

Thanks Tim. That explains why these screws were in the jar of bolts I saved when I took this engine apart almost 40 years ago. Mystery solved.