Can't find mine.
Those three that fasten intake to exhaust.
What size and, especially, what length?

Thanks,
Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

i was wondering that myself. But first what do i do with a bolt the just turns i think it's broke. what can i do to fix?

They are all 5/16" course thread.
The inner one (closest to the engine) is a bolt. Not sure of the length, you'll just have to get a couple and try it. Its probably around a 3" bolt.

The Outer two are made from 5/16" threaded rod, they have to screw down through the exhaust manifold and stick up a couple inches so they can go through the intake manifold, then use nuts on the top. You will also be putting nuts on the bottom to hold your throttle/kickdown linkage. Should be easy to figure out what length they need to be, just set the intake manifold on the exhaust manifold and measure. Leave a little xtra bolt sticking out the bottom to bolt up the throttle linkage mount.

And when you put it together, its a good idea to put some anti-sieze compound on the threads, in case you ever have to take it apart again.

OK, on the slant sixes that I've worked, I've seen both stud and nut and bolts on the inside hole which looked original, and the outside two were all definitely bolts, not threaded rod. The problem is finding grade 5 5/16 NC bolts with enough thread for the given length (in other words, the unthreaded shank portion is too long). Most of the fully threaded bolts you find are grade 2 or less. My solution has been to cut more threads on the requisite length grade 5 bolt. I don't remember the length right off, but I can measure and report back later.

The inside stud or bolt always breaks off in the exhaust manifold (I think maybe one time this failed to happen with me, but that was probably a stud that looked OK and I left in place), and you've got about a 50/50 chance on the outer ones soaked with penetrating oil, heated, etc. If you have not already done this, plan on lots of burrowing with a drill, tapping, rethreading, breaking taps or screw extractors off in the holes (I would advise not even bothering with screw extractors - you're pi$$in' in the wind with those) inserts, you name it, there will be lots of swearing involved, if you don't swear, have a heathen neighbor or buddy come by to do the swearing for you, because it will be a requirement!

D/W

_________________

If it ain't broke, fix it!

Early manifolds used three 5/16" bolts. Later manifolds used two (outboard) 5/16" bolts and one (inboard) stud. Both kinds work.

When replacing this hardware, it's best to use stainless steel bolts and brass nuts. Second choice is stainless bolts and stainless nuts. Third choice is grade-8 bolts and brass or stainless nuts. Fourth choice is grade-5 hardware. You don't need the breakage-resistance of the stainless or grade-8 hardware, but it helps ensure you can disassemble the manifolds again when the time comes. (I also use brass nuts on all the manifold-to-head studs except the front and rear which require special castellated acorn nuts only available in steel).

Great suggestion!

D/W

_________________

If it ain't broke, fix it!

We're past the breaking extractors and swearing part. Did that two weeks ago. Wound up taking the manifolds to a machine shop to have the center bolt hole drilled out and tapped. I also had the two manifolds bolted together and resurfaced to get a good flat face.

I like the idea of stainless and brass to prevent this from happening again. We have three fastener supply stores here, I'm sure they can come up with something.

Thanks, once again, for the input,
Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

I stand corrected. When I went to take my manifolds apart the outers were made from threaded rod.
Maybe I should replace mine with stainless bolts !

Length is 3.25" for the inboard (bolt), and 4" for the outboard 2. Like I mentioned, you will probably have to cut more threads on those outer 2. It might be a good idea to replace the inner one with a stud no matter what it had originally, to simplify any future disassembly issues, but I guess a stainless bolt would address that, too.

D/W

_________________

If it ain't broke, fix it!

Thanks for checking lengths, Dennis. I've got my shopping list ready for a trip to the bolt supply shop.

Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.