Intake bolts for 1970-1972

[D S.]

I have twelve original intake bolts, 'A' headmarks. Below the flange on the shank there is 1/4" area that is unthreaded. I have some other original bolts that are exactly like the 'A' bolts but have 'M' headmarks and are threaded all the way to the flange. Are these also intake manifold bolts or exhaust manifold bolts? Or both?

Thanks,
Scott Sims
Texas Chapter

[Monte M.]

Re: Intake bolts for 1970-1972

Scott,

Do the "M" bolts look like this?

Monte
1970 LS-5 Chris Hewittt.jpg

[D S.]

Re: Intake bolts for 1970-1972

Exactly. I also received original 'A' headmark bolts and NFP headmark bolts, all from 1970-1974 intake manifolds. And after all I have read from the TDB I'm going to mix them up when I remove the kit set and install the originals.

[Monte M.]

Re: Intake bolts for 1970-1972

Scott,

I can only tell what I have experienced. I am not saying it is all true, but it is what I keep hearing.

It appears that there is still a lot to be figured out in regards to these bolts.

I am not 100% sure what you are working on right now. A 70 if I am not mistaken.

Anyway, the "M" bolts seem to be the most desirable for 70 and 71. The "A" I have heard go on 70 to 72, but I have never actually seen them on a 72.

The only place I have personally seen the "NFP" is on 72.

If I were you I would put the "RSC" regular bolt head on the lifting bracket and the "M" and the "A" on the rest and sell me the "NFP'

Sorry, a little self promotion there at the end. lol

But, I did mean what I said about the bolt set-up for your car.

Maybe there is someone else out therewith better advice. I am open to what anybody has to say. You and I have both been trying to figure this out. I gathered my information by sending a PM to all the BB owners I could find and asked what was on their original cars. Just remember: free advice is worth exactly what you paid for it.

Monte

PS In doing my research I put the car and persons name on each picture. If you hold your cursor over the picture in my previous post, it will tell you what kind of car and the owner it was from.

[D S.]

Re: Intake bolts for 1970-1972

Yes, '70 LS-5. The 'M' bolts are threaded all the way to the bottom of the flange. Several knowledgable members describe intake manifold bolts as having 1/4" unthreaded area beneath the flange. I don't know the purpose of that but I assume it's to help seal the intake. I suppose both styles can be used in intakes. Both the 'M' and 'NFP' bolts retain their phosphate finishes. I already have the longer TR bolts on the engine hoist bracket.

You have my email address and we can discuss the 'NFP' bolts. I believe there are eight of them. I cleaned them up.

What is the headmark on your alternator adjusting bolt?

[Dick W.]

Re: Intake bolts for 1970-1972

I have twelve original intake bolts, 'A' headmarks. Below the flange on the shank there is 1/4" area that is unthreaded. I have some other original bolts that are exactly like the 'A' bolts but have 'M' headmarks and are threaded all the way to the flange. Are these also intake manifold bolts or exhaust manifold bolts? Or both?

Thanks,
Scott Sims
Texas Chapter

Both intake bolts

[D S.]

Re: Intake bolts for 1970-1972

Thanks, Dick! Now I can remove those kit bolts and install mixed originals.

Looking forward to seeing you at Frisco. If you go. You're usually busy at those events.

[Monte M.]

Re: Intake bolts for 1970-1972

Scott,

If you go on Flea Bay you can see OEM, new in the box, exhaust manifold bolts that the top 1/4" is not threaded.

I thinks this confirms what Dick said, not that we needed to, but that both fully threaded and the one with the top 1/4" not threaded are used for intake bolts and I guess exhaust bolts too.

Monte

[D S.]

Re: Intake bolts for 1970-1972

Now I have discovered two styles of M "intake" type bolts. After posting the photo of the larger M bolt I discovered six of the smaller M bolts in a small Baggie that someone sent me a while back. Which to use?

http://

[D S.]

Re: Intake bolts for 1970-1972

M bolts.jpgNow I have discovered two styles of M "intake" type bolts. After posting the photo of the larger M bolt I discovered six of the smaller M bolts in a small Baggie that someone sent me a while back. Which to use?

http://