C-2 66 SB Oil Pan Bolts

[Daniel C.]

After cleaning my oil pan and timing cover bolt, I noticed that I have two types of GM bolts. 7 bolts were of one type and the remaining are another type. Car is original 1966 SB. Any help?

[Joe L.]

Re: C-2 66 SB Oil Pan Bolts

Daniel-----

Your photo did not come through. However, I can tell you this much: generally speaking, the bolts used for the timing cover and most of the oil pan bolts were of the same head configuration and 1/4"-20 thread size (7/16" across the flats), if not exactly the same length ( I think that the timing cover bolts were of minutely shorter length). This configuration is an indented hex head with a captured external tooth lockwasher. "E", "EL", and "L" were common manufacturer's ID headmarkings.

The 4 CORNER oil pan bolts were larger and of 5/16"-18 thread size (1/2" across the flats). These were also indented hex head and used a captured split lockwasher.

[Robert E.]

Re: C-2 66 SB Oil Pan Bolts

Daniel,

I hope you don't mind, but I posted the picture for you.

Robert
41801

[Joe L.]

Re: C-2 66 SB Oil Pan Bolts

Robert and Daniel-----

These are both the typical head configuration of the bolts used for the front cover of 66+ small blocks. They are also used for most of the pan bolts for small blocks (except the end bolts on either side).

The "flag" headmarking is an alternative marking for "Elco Industries" (now a divison of Sundstrand Corporation) which also used the very common "E" and "EL" headmarkings found on these bolts.

I can't make out the headmarking on the lower bolt in the picture.

[Daniel C.]

Re: C-2 66 SB Oil Pan Bolts

The lower bolt in photo has “EL” What puzzles me is out of all the bolt from the oil pan and timing cover (excluding the 4 corner pan bolt) 7 of them were of the “flag” type. The only thing I can think of is when they restock the assembly line bolt get mixed together?

[Joe L.]

Re: C-2 66 SB Oil Pan Bolts

Daniel-----

Very definitely they get mixed together and there may be a combination of headmarks in the bin at the same time. As I mentioned, the "flag" and the "EL" are both headmarks for Elco Industries.