1969 BB Exhaust Manifold bolts

[ko-lek-tor]

Did a lot of research on this site and TC with no definitive answer, so here goes: 1969 396 exhaust manifold bolts-cast iron heads. I know the resto parts book show a shouldered bolt used throughout, but a guy I met at a show with a 69 396 Chevelle tells me that 2 different bolts were used. Where the larger hole is in the manifold, the bolt with washer is used and the shouldered are used on the other holes. This would be 1/2 and 1/2,8 shouldered and 8 w/washers, if correct. Can someone shed some light? Along this topic, as I understand, No french locks used? No heat shields on plugs? correct? Wanting to put an end to the BS and get the facts. Thanks, as always.

[Don_Lightfoot]

I did the same research several years ago for my 69 Velle.  Turned out to be four bolts with shoulders and four bolts without shoulders.  No washers on any.  I ordered a set from AMK.  I'll go through my invoices to try and find the appropriate part numbers and post back in here.  At that time they did not have a "kit" per say, but you had to order two sets of four individually.  Maybe that has changed by now.

[Don_Lightfoot]

Here are the part numbers I used from AMK.

Inner eight bolts (four inside runners)  - B-10147.  
Outer eight bolts (four outside runners) - B-10429.

At least that is what my research indicated.  Hope this helps.  Good luck.

[ko-lek-tor]

Thank you Don. I was pretty sure on there being two bolts, just needed confirmation. Too many resto catalogs tell you wrong info. I 'll throw the washers back in with the SB bolts bin.

[Steve Shauger]

The outer manifold ports 1 & 7 drivers side and 2 & 8 on passenger side received flanged bolts. I have seen this on all the unrestored BB cars i've inspected.

(modified washered to flanged, per request.   Kurt)

[Don_Lightfoot]

The outer manifold ports 1 & 7 drivers side and 2 & 8 on passenger side received washers (. I have seen this on all the unrestored BB cars i've inspected.

That is very interesting Steve and I certainly do not question you due to your stature in the hobby.  There are so many threads over on Team Chevelle about this subject which reveals no washers being used and some of the respondees would be considered to have similar credentials as yourself.  Certainly intriguing considering all the engines essentially were built at the same plant.  Makes for some interesting discussion and debate if nothing else.

As mentioned in my previous post, I did mine based on my research. However, I am never "closed minded" about any of this stuff and am always interested in hearing about various alternatives that might have taken place.

[ko-lek-tor]

Thanks SZteve and Don. Guess you can see why I am having so much trouble with this ?

[Steve Shauger]

The outer manifold ports 1 & 7 drivers side and 2 & 8 on passenger side received washers (. I have seen this on all the unrestored BB cars i've inspected.

That is very interesting Steve and I certainly do not question you due to your stature in the hobby.  There are so many threads over on Team Chevelle about this subject which reveals no washers being used and some of the respondees would be considered to have similar credentials as yourself.  Certainly intriguing considering all the engines essentially were built at the same plant.  Makes for some interesting discussion and debate if nothing else.

As mentioned in my previous post, I did mine based on my research. However, I am never "closed minded" about any of this stuff and am always interested in hearing about various alternatives that might have taken place.

Hi Don,

We may be talking about the same thing. You referred to the outer bolts as shouldered. A shouldered bolt to me refers to a portion of the stem that is not threaded. Did you me flanged? Attached is a picture of an original 69 BB, notice the difference in the two outer bolts versus exhaust port 4, bolt.

[Steve Shauger]

Notice the outer bolt heads are indented and flanged. The inner bolts are not flanged and do not use washers. The correct bolts are readily available.

[Don_Lightfoot]

Yes Steve, we are definitely referring to the same thing.  Glad to get that clarified.  Might be one of those Canadian/American term discrepancies 

[ko-lek-tor]

Hey Don and gang,
No need to take the blame on the terminology, it's not a Cannuck thing this time, it was me. I referred to bolts as shouldered in my initial post and ,yes, I guess I meant flanged. You see what getting old does to you!,LOL. Thanks Steve for straightening me and Don out. Thanks Steve also for the pic. I have several topics that I want to clarify and get frustrated when a catalog says one thing, a forum on another site says something else, guy tells me something else. I always come to the CRG to get the truth. Bentley.

[JohnZ]

To confuse things further, 1969-up Corvette big-blocks used self-locking exhaust manifold bolts - flanged head, with a tri-lobular thread form; turned in freely two or three turns, then needed torque to overcome the friction of the rest of the locking thread form. Photo below shows the standard bolt on the left, and the tri-lobular bolt on the right.

[Steve Shauger]

The flanged outer bolt threads were interference fit for all BB engines. This was done to prevent them from loosening, causing manifold warpage. The exhaust manifolds did not have gaskets so leakage was an issue and loosening bolts were a contributor. Again this is why the bolt threads were designed as interference.

[L78racer]

Does anyone know what they used on aluminum heads? Those interference thread bolts would tear things up.

[JohnZ]

Does anyone know what they used on aluminum heads? Those interference thread bolts would tear things up.

Aluminum heads had Helicoil inserts in the exhaust manifold bolt holes.