Big Block Valve Covers and Bolts

[Joe R.]

I'm in the process of "judging" my engine because I'm starting to assemble the parts I need to eventually put it together. In the judging guide (JG), it says "the surrounding outer lips on original covers have a minimal flat area."

How wide is minimal? On the inboard side, the flat area is about 3/8 " wide on mine (that doesn't include the seam, 7/16 " if you do). The outboard side flat area is about 5/8 " wide.

Here's another quote from the JG, "Each cover typically is secured with seven recessed 7/16 " hex head bolts... Late production cars may have flat 7/16 " hex-head bolts." My car was born on May 24, 1966.

What do the recessed head bolts look like? How about the flat hex heads?

I have enclosed some pictures of my parts. Do I have the good stuff or what?

Thanks in advance,
Joe

[Joe R.]

Re: Big Block Valve Covers and Bolts

Here's the bolt pictures.

[Joe L.]

Re: Big Block Valve Covers and Bolts

Here's the bolt pictures.

Joe------


These bolts are the "flat head" style. Actually, these are called "trimmed" head bolts. Considering the headmarking and the build date of your car, I'd say these are likely original bolts.

By the way, if the judging guide calls these bolts 7/16" bolts, then the judging guide is incorrect in terminology. These bolts are 1/4-20 bolts which use a 7/16" across-the-flats wrench size. Bolts are described by the thread size, not the head size.

[Joe R.]

Re: Big Block Valve Covers and Bolts

Joe------


These bolts are the "flat head" style. Actually, these are called "trimmed" head bolts. Considering the headmarking and the build date of your car, I'd say these are likely original bolts.

By the way, if the judging guide calls these bolts 7/16" bolts, then the judging guide is incorrect in terminology. These bolts are 1/4-20 bolts which use a 7/16" across-the-flats wrench size. Bolts are described by the thread size, not the head size.

Joe,

Thanks for the info! That was what I was hoping to hear. I was quoting from the JG. I didn't think about it until you mentioned it, but you are certainly correct. They should have said 7/16 " head maybe, but even that isn't the usual practice, like you said.

Joe

[John C.]

Re: Big Block Valve Covers and Bolts

Joe

The lip the judging guide is referring to is very very small. Most reproduction valve covers don't have it. It looks like your valve covers have it but it is hard to tell from your pictures.

The two pictures below show it. First picture is a valve cover with the lip The second is without.

John

[Ronald L.]

Re: Big Block Valve Covers and Bolts

Joe if your car was a little earlier it would need a dent in one of these covers and that was the way for many years to avoid the repro junk, they didn't make one with the dent. Fortunately I have the originals even though its' late to the JG on when that dent went away, I'm not changing a know original part.

[Michael H.]

Re: Big Block Valve Covers and Bolts

Joe,

They should have said 7/16 " head maybe, but even that isn't the usual practice, like you said.

Joe

Just curious... does the 66 JG mention that the indented head bolt on early cars is 3/8" wrench size instead of 7/16" ?

[Joseph T.]

Re: Big Block Valve Covers and Bolts

Hi Joe,
I have an early June 1966 and it utilizes the same 7/16" Flat Bolt head w/ "RBW" Headmark attaching the Valve cavers.

[Joe R.]

Re: Big Block Valve Covers and Bolts

Just curious... does the 66 JG mention that the indented head bolt on early cars is 3/8" wrench size instead of 7/16" ?

Michael,

No, what I put in quotes is exactly what the JG says, 7/16 " for both styles of bolts.

Joe

[Michael H.]

Re: Big Block Valve Covers and Bolts

Michael,

No, what I put in quotes is exactly what the JG says, 7/16 " for both styles of bolts.

Joe

Joe,

Pretty sure the early (first few months of production) valve cover bolts had a 3/8" hex head. In fact I'm sure of it. Same bolt used for the 65 396 covers.

I think the reproduction bolts with 7/16" dished head may be incorrect.
I don't remember a 7/16" hex head with the same dished style.

Does anyone have an early car with original bolts?

I remember this same discussion here a few years ago and Dick Whittington agreed that early 66 cars had the 3/8" hex bolts with dished head.

[Harvey S.]

Re: Big Block Valve Covers and Bolts

Guys:

Just checked my value covers and bolts on a Sept 65 BB. Value covers have small lip and bolts are 3/8" hex.

Hope this info helps.

[Michael H.]

Re: Big Block Valve Covers and Bolts

Guys:

Just checked my value covers and bolts on a Sept 65 BB. Value covers have small lip and bolts are 3/8" hex.

Hope this info helps.

Thanks Harvey. I think some of the guys were starting to think I've lost my memory.

I'm not sure if a 7/16" hex with the lip was ever used on any 66.

[Ronald L.]

Re: Big Block Valve Covers and Bolts

Michael,
I digging through buckets of orange bolts, small 3/8 indented head and flat head 7/16 predominate - no to the one you haven't seen. I see several variations of head marks, RBW, TR, and then some D, A and others that to me are a 70's thing such as the blue bolts are a sure give away to the later vintage.