63 Intake manifold bolt length

[Steve D.]

After I had R&R'd the intake manifold to fix an oil leak, I had an intake bolt interfere with (and bend) the push rod for the #5 exhaust rocker. I removed all of the intake bolts and found them to be 1.25". I inspected the rocker stud and it appears ok. The same bolts were used when I reinstalled the manifold, and since they are all the same length, I don't know what triggered the problem. What is the prescribed length for these bolts?

Steve

[Michael G.]

Re: 63 Intake manifold bolt length

Steve, The ones I've got measure 1.12" from under the head to the tip. They have an "AP" marking on the head. As I recall, we checked the clearance to the push rod using a spacer instead of the FI manifold. There was not much clearance, so I wouldn't doubt the 1.25 long parts could hit the push rod.

[Steve D.]

Re: 63 Intake manifold bolt length

Steve,

The A/P bolts on my 340 hp measure 1.07, they were installed without washers...

Steve

[Steve D.]

Re: 63 Intake manifold bolt length

Mike and Steve

Thanks for the feedback. I think I will replace the 8 interior bolts with 1".

Steve

[Rich P.]

Re: 63 Intake manifold bolt length

Steve,

the factory used 1-1/8" Bolts I would not suggest using 1" bolts.

Rich

[Steve D.]

Re: 63 Intake manifold bolt length

Rich

Was a washer used with the 1-1/8" ?

I can't find any specs in my reference materials (AIM, Service manual, Specifications booklet). What is your source?

Steve

[Rich P.]

Re: 63 Intake manifold bolt length

Steve,

no washer on 1-1/8" bolts.

Rich

EDIT: source, Workin on them since '82. Also I think this is specified in the judgeing manual (or it should be) Anyhow no washers were used on any intake bolt Big or Small Block in the 60's. This is true for steel and aluminum intakes.

[Steve D.]

Re: 63 Intake manifold bolt length

Rich

Thanks. I had lock washers with the 1.25" bolts. I haven't measured the thickness, but I would guess between 1/16 and 1/8. That would mean that my setup would be off by 1/16 at most and possibly on spec . Since these differences are so small, I have a nagging suspicion that there is another issue besides bolt length. In another thread, Jack mentioned rocker stud integrity. I've checked that, but I'll look a little closer. Although I don't know exactly what I'm looking for, since it is already unbolted I am going to pull the intake manifold and have a look around.

Steve

[Rich P.]

Re: 63 Intake manifold bolt length

Steve,

There is another issiue that can come into play here: if the block and heads have been decked and cut excessivly then the intake would also need to be cut to fit. I have seen this on one or 2 cars and that could account for some lost space. Not saying thats what it is but just trying to help you rule that out.

Rich.

[Steve D.]

Re: 63 Intake manifold bolt length

Rich

I don't know the history of the block and heads, but I have not had any cutting done on either. The intake manifold is easy to align when installing, so it doesn't appear that there have been any significant dimension changes. I'll let you know what my weekend explorations turn up.

Steve

[Edward J.]

Re: 63 Intake manifold bolt length

Steve, the 4 bolts in the middle of each side are the only bolts that interfere with the engine push rods, on those bolts the length is important, if you don't have the correct bolts maybe home depot?

And a quick look down the the intake bolt holes will let you know if there is a problem with alignment of the intake bolts, They should be centered in hole, most machinist who mill cylinder heads know the maximum amount they can take off the heads without intake mounting problems today.

if you have a problem with bolt lengths add a lock and flat washer, ,not NCRS but will work ,until you order the correct ones from paragon or one of the corvette venders.