67 Fuel Pump Bolts (two large ones)

[Lawrence S.]

Can someone post the correct bolts and head markings that hold the fuel pump to the block?

Thanks,

Lawrence

[Scott S.]

Re: 67 Fuel Pump Bolts (two large ones)

Can someone post the correct bolts and head markings that hold the fuel pump to the block?

Thanks,

Lawrence

Lawrence,

Mine have the "RBW" headmark, there may be others. They are located on UPC 6-C1, Item 7, GM 3778526. It is a grade 5 indented hex flange-head screw assembly with attached split-lock washer. Size is 3/8-16 x 1-1/4" and 7/16" across-the-flats.

If you search eBay for "corvette fuel pump bolts" you will find a used set claimed to be for Corvette, Camaro and Chevelle, and a reproduction set from CC.

The used set is similar to mine except for the headmark, and mine do not have what look like pinch-marks where each hex-point meets the flange. The other difference is the length. My originals have a 1/4" unthreaded upper, with 16 threads on the lower section (resulting in 1-1/4" overall length from tip to underside of hex-head).

The used set on eBay has the unthreaded upper, but the lower section has 20 threads so it is approximately 1-1/2" long. I thought there might be a concern with bottoming out at that length, but the repro set from CC (which also has the unthreaded upper) appears to have 19-20 threads too, so that length must work.

[William L.]

Re: 67 Fuel Pump Bolts (two large ones)

Lawrence these are the bolts in my 67 big block and I'm pretty sure the are original to the car. I also believe that small blocks used the same bolts.
Bill
67-435 028.jpg67-435 029.jpg

[Scott S.]

Re: 67 Fuel Pump Bolts (two large ones)

Lawrence these are the bolts in my 67 big block and I'm pretty sure the are original to the car. I also believe that small blocks used the same bolts.
Bill
[ATTACH=CONFIG]39921[/ATTACH][ATTACH=CONFIG]39922[/ATTACH]

Bill,

The big block fuel pump bolts are called out on L36-A8, item 10, GM 3874876, different p/n than small block. The P&A says 3874876 is 3/8-16 x 1-1/8" with attached lock washer, but Joe Lucia has noted in other discussions that the big block fuel pump bolts are actually longer than GM spec.

[Scott S.]

Re: 67 Fuel Pump Bolts (two large ones)

These are the fuel pump bolts from my '67 with L79. Length is right at 1-1/4", with 16 threads and 1/4" unthreaded upper. There is a small dot below the "B" of the "RBW" headmark, which I had not noticed before. Also note the absence of the raised ridges where the vertical edges of the hex-head meet the top of the flange. The type with the raised ridges seems to be characteristic of the big block fuel pump bolts.

[Gerard F.]

Re: 67 Fuel Pump Bolts (two large ones)

Lawrence,

The pictures below are the original fuel pump and bolts from my 67 327/300, late June 67 convertible (22049)



My long bolts were different from the ones others have shown you. They did not have the flanged head, just a captive lockwasher, and were 1 1/2" long, tip to bottom of the head. They were black phosphate.




The head marking was an anchor as pictured above. The small bolts were an EL within circles.
Sorry for the fuzzy pic.

[Joe R.]

Re: 67 Fuel Pump Bolts (two large ones)

The black ones on the left are BB and are Grade 5 with an "E" headstamp. The ones on the right are zinc plated, Grade 5 and have an unknown headmark. These are for a SB.

JRDSCN3705.jpgDSCN3706.jpg

[Gerard F.]

Re: 67 Fuel Pump Bolts (two large ones)

Nice replacements JR.

But the originals from my S/B 67, are in my post above

[Scott S.]

Re: 67 Fuel Pump Bolts (two large ones)

Lawrence,

The pictures below are the original fuel pump and bolts from my 67 327/300, late June 67 convertible (22049)

My long bolts were different from the ones others have shown you. They did not have the flanged head, just a captive lockwasher, and were 1 1/2" long, tip to bottom of the head. They were black phosphate.

The black ones on the left are BB and are Grade 5 with an "E" headstamp. The ones on the right are zinc plated, Grade 5 and have an unknown headmark. These are for a SB.

JR[ATTACH=CONFIG]39932[/ATTACH][ATTACH=CONFIG]39933[/ATTACH]

Jerry and Joe Ray,

The 1963-1966 AIMs all show GM 3751842 "Screw Asm." for the small block fuel pump. The 1967 AIM shows GM 3778526 but the Revision Record shows that it WAS GM 3751842 until 7-26-66, or whenever they ran out of the old bolts. GM 3751842 is shown in the 1967 P&A as "SCREW, w/lockwasher (3/8-16 x 1-1/8) (washer head)". The later GM 3778526 Screw Asm. is not listed anywhere that I can find so far.

At this point, I suspect that my Jan. 11 1967 car has the older 1963-E1967 style GM 3751842, while Jerry's late June '67 car has the updated/revised GM 3778526 small block bolts which are black phos, 1-1/2" indented hex Gr5 with attached split lock washer but without the flange-head.

Seem right?

[Lawrence S.]

Re: 67 Fuel Pump Bolts (two large ones)

Guys thanks so much for the information.

My 11/66 build L79 bolts are per Scott's post above.

Thanks,

Lawrence

[Gerard F.]

Re: 67 Fuel Pump Bolts (two large ones)

Scott,

That would seem to make sense, a July 66 AIM change that shows up in a June 67 car. I too, can't find any reference to the GM 3778526 bolts other than the change in the AIM. I wonder why they went to the extra length on the bolt.

I also have another anomoly to the JG on my 06-26-67 HE engine. I have no french locks on the exhaust manifolds. Instead, I have these special self locking bolts in the positions where one would expect the french locks. There are some posts and pictures on this in the archives.

[Joe L.]

Re: 67 Fuel Pump Bolts (two large ones)

All-------



There were three different fuel pump mounting bolts used on Corvette small blocks over the 1958-81 period. These are as follows:

1958-E67-----GM #3751842

L1967-E72----GM #3778526

L1972-81-----GM #3895411

All 1965-74 big block------GM #3874876

I have NOS examples of all of the above except (yet) the 3895411.

Actually, functionally, any of the above are interchangeable including big block and small block. So, why were different screws used? I have no idea. Probably some reason that's "lost in antiquity".

[William L.]

Re: 67 Fuel Pump Bolts (two large ones)

All-------



There were three different fuel pump mounting bolts used on Corvette small blocks over the 1958-81 period. These are as follows:

1958-E67-----GM #3751842

L1967-E72----GM #3778526

L1972-81-----GM #3895411

All 1965-74 big block------GM #3874876

I have NOS examples of all of the above except (yet) the 3895411.

Actually, functionally, any of the above are interchangeable including big block and small block. So, why were different screws used? I have no idea. Probably some reason that's "lost in antiquity".

Joe
Are the bolts that I have pictured from my 67 B/B Correct? If not can you post pictures of the correct bolt?
Thanks
Bill

[Joe L.]

Re: 67 Fuel Pump Bolts (two large ones)

Joe
Are the bolts that I have pictured from my 67 B/B Correct? If not can you post pictures of the correct bolt?
Thanks
Bill

Bill-----


Yes, they are correct with respect to configuration. As far as manufacturer's ID goes, yours is a very common one but not necessarily the only one used.

Also, note that these bolts are GM 275M material grade (3 lines at 90 degree spacing). This is a generally uncommon material grade and virtually never found in hardware store fasteners or fasteners used outside the "GM world". So, why did GM use it for certain applications rather than the far more common GM 280M material grade (3 lines at 120 degree spacing)? I have no idea.

[William L.]

Re: 67 Fuel Pump Bolts (two large ones)

Thanks Joe
I think these bolts are original to the car but after all it's 45 years old and had 5 other owners. I'll have to go through my fuel pump bolt can and see what other head markings I can find.
Thanks again
Bill