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69 Z28 engine compartment bolt head markings

6K views 14 replies 8 participants last post by  rszmjt 
#1 ·
Hey Guys, I was wondering if any TC member who knows their car has ORIGINAL bolts, can help me out? I am helping a friend on his 69 Z28 in the engine compartment, and i can not remember the design and bolt head markings on a few parts. My own car is in winter storage and i can not get at it to verify for a while.
Anyway my questions are
#1. On the 4 bolts that hold the fenders to the rad support, do they have captive washers or built in non rotating washers, and what are the head markings?
#2. Same question on the fender to rad support bars-do the bolts have captive washers or built in non rotating washers, and what are the head markings?
#3. Same question on the hood latch the horns bolt to- do the bolts have captive washers or built in non rotating washers, and what are the head markings?
#4 . Same question on the horn mounting bolts-do the bolts have captive washers or built in non rotating washers, and what are the head markings?
Do ALL of the above bolts also have pointed thread ends or non pointed.
Dont bother to pull any bolts just feel underneath on the bolts that are accessible.
Thanks in advance, and Happy New year to all TC members!
Mike.
 
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#2 ·
For all that you are asking about, I believe they all have captive washers with pointed ends. As far as the head markings, I cant say for sure off the top of my head, but I have a car that I'm finishing up that has the original hardware there.

One way to tell if it has a captive, spinning washer is that in the assembly manual, it will be labeled as a "screw assembly", meaning it is not one solid piece.
 
#3 ·
Dave, Thanks for that. I checked in the assembly manual and it shows 3 different part numbers for the screws that i am asking about. The 4 fender to rad support and the front of the rad support bars use #3846201, the back of the supports as well as the horns use #3960314, and the latch uses #3946202. Are you sure the latch screws are the pointed type? The reason i ask is the wiring is close proximity and the pointed ends might dig in?

Any one else have any info regarding bolt head markings? John? Kurt? Sure would like to hear from someone with a known original car. My car is original, but i can not get near it for a couple of weeks.

Thanks Again.
Mike.
 
#4 · (Edited)
Mike, you sure the latch screw isn't 3846202? That's what's used for the hood latch on my '67. My hood latch bolts are original, they have pointed ends, and a capture, spinning, non-toothed washer. The head has an 'E' in the center with a dash at the 12, 3 and 9 o'clock positions. According to the 67 AIM, this is the same screw that fastens the TOP of the fan shroud to the shroud bracket on a small block motor. I'll look at the other screws you mentioned tomorrow. I seem to recall the screws for my horns have a toothed washer, presumably to help with grounding the electrical connection. Might be different fo a '69, however.
 
#5 ·
Hi Mark, Yes you are correct, it was a typo error. It is 3846202. Makes sense regarding the horn mounting screws, with the serrated washer. 69 use a different small head screw for the shroud, i do remember that, the assembly manual also lists a differnent # for it. Seems to me that he has some bolts with like a big half a plus sign and above it a smaller half circle with a smaller complete +, and also some bolts with a semi circle with 3 smaller slashes off the circle.
I seem to remember that my own car has the bolts with the small "E" in the centre.
Will wait for your reply.
Thanks for the help.
Mike.
 
#10 ·
Loved the info that John posted! But in case inquiring minds want to know still - and remember - I have a 67 - the screws that fasten the rad support bars to the rad support and to the fender are pointed end, flanged head (no washer), and the heads are marked with the semi circle with 3 smaller slashes off the circle as you described above. The screws that fasten the horns to the rad support are pointed end, serrated washer with the head marked SEM or SEMS (should have written it down) inside concentric circles.
 
#6 ·
I wouldn't get real hung up over headmarks - Chevrolet had a minimum of three suppliers for every part number of fastener, each supplier had its own headmark (which wasn't on the drawing), and the bins on the line were re-stocked by part number, not by supplier; the configuration of the fastener is unique to the part number, not the headmark.

My original '69 has lots of different headmarks, some are mixed for the same application on different sides, but the configurations are uniform. Anyone who thinks that any one application only had one headmark is living in a dream world - it didn't work that way.

As the Senior Production Engineer - Passenger Cars at Chevrolet, I spent a LOT of time working with fastener engineers to improve sheet metal assembly, and I know a little about that end of the business. While I was in that position, I invented the roll-point machine-thread bolt and developed it with Anchor Fastener for production use starting in 1968, and hold the patent jointly with GM and Anchor; made it almost impossible to cross-thread front sheet metal attachments. :thumbsup:



:beers:
 
#9 ·
I wouldn't get real hung up over headmarks - Chevrolet had a minimum of three suppliers for every part number of fastener, each supplier had its own headmark (which wasn't on the drawing), and the bins on the line were re-stocked by part number, not by supplier; the configuration of the fastener is unique to the part number, not the headmark.

My original '69 has lots of different headmarks, some are mixed for the same application on different sides, but the configurations are uniform. Anyone who thinks that any one application only had one headmark is living in a dream world - it didn't work that way.

As the Senior Production Engineer - Passenger Cars at Chevrolet, I spent a LOT of time working with fastener engineers to improve sheet metal assembly, and I know a little about that end of the business. While I was in that position, I invented the roll-point machine-thread bolt and developed it with Anchor Fastener for production use starting in 1968, and hold the patent jointly with GM and Anchor; made it almost impossible to cross-thread front sheet metal attachments. :thumbsup:
:beers:
Great info as usual. Very cool on the patent. Who ever said Frrd had a better idea?
 
#7 ·
Thanks John, I kinda figured you would know. I dont get to concerned personally, regarding head markings, i have seen different bolts side to side on upper and lower a arm bolts on Corvettes for years. In fact a friend of mine has a 6,000 mile 67 435 from the Corvette Museum, and i was telling him about the different A arm bolts and guess what his car has them. I was just trying to get my buddys car as close as possible with what he has. I am still unsure what bolts go where regarding the captive washer type bolt and the built in washer type bolt.
Thanks for your reply and neat that you helped develop the bolt shown. You always amaze!!
 
#12 ·
I'll add just a comment:
I've never seen a 69 with a bolt like John developed (at least the main sheetmetal bolts being discussed). Not sure what the implementation date was for the different fastener designs, but the threads didn't extend down to the very end like the one pictured.
I think I've seen Pontiacs with this and 70's cars. The grille attachment bolt may be like that, but it's not a sheetmetal bolt.
 
#15 ·
Just for interest sake- I finally got over to where my own car is stored, and the rad support bars have the E bolts with rotating washers, and the are not pointed, also the hood latch reciever has bolts with B&H on the heads as well as the horns, and they also have rotating washers. The front bolts on the latch that go into the header panel have "e" on the heads and they have built in non rotating washers. This car is original, i have owned it since 73. It also has the original phospahating on the hood reciever latch, and if you look at the marks made by the bolts, the bolt arrangement jives as the non rotating washer bolts have a smaller washer head size.
Just thought some TC members might like to know.
 
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