Whose 1970 LS-5 exhaust manifolds have AIR holes??

[Joe L.]

Re: Whose 1970 LS-5 exhaust manifolds have AIR holes??

My driver side exhaust manifold has part number 3880827 cast into it on the front side along with LH and GMT. I wasn't able to locate a cast date on the back of the manifold, but I was able to find on the back side the numbers 827 with an LH next to it, which I assume is the last 3 numbers of the part number. This is a manifold that was used through 1969 production on all 427 engines. The exhaust manifold on the passenger side has part number 3880828 cast into the front of it, which is correct for all 1970 454's. I haven't located a date on this manifold either. My car had a aftermarket side exhaust system added to it by the 2nd owner at some point. I know that side exhaust was not offered in 1970 as a factory option so it is possible that the 2nd owner put a 1969 exhaust manifold on the driver side so that he could purchase a 1969 side exhaust system for the car. This would make sense, since the car had under car exhaust on it originally and since the drivers side exhaust manifold was new for 1970 the under car exhaust system would have been different for 69 and I'm sure that Chevy wouldn't have put a 69 exhaust system on a 70 car! Since he bought a aftermarket side exhaust system, I don't know why he just didn't by one for a 70, unless it was available at the time. Guess I have another part to by when I start my restoration on this car! Still curious why I have the brass plugs on the driver side manifold?

Bob------

That's what happened; the guy that converted it to side exhaust had to change the driver side manifold to the 66-69 manifold. Most likely, any then-available side exhaust system was only configured to work with the 66-69 driver side manifold.

Why does the driver side manifold have the brass plugs? Very simple. He obtained a manifold from a 1968-69 Corvette application, all of which were drilled and tapped for AIR. The use of brass plugs to seal the AIR fittings was quite common back in the day when AIR was removed.

[Thad L.]

Re: Whose 1970 LS-5 exhaust manifolds have AIR holes??

I once owned 7907 and it had the holes pluged. I currently own 8114 and it does not have holes.

[Gerard R.]

Re: Whose 1970 LS-5 exhaust manifolds have AIR holes??

I own 70 LS5 vin 14398,late car,bought from original owner,67k miles and no air holes.

[Kenneth B.]

Re: Whose 1970 LS-5 exhaust manifolds have AIR holes??

My plugs were NOT brass. I will look for the picts. I also recall that only one side had plugs but I cant recall which. The plugs look like the ones in the post with the pict in the thread #4 with female square plugs.

I stand corrected. Both sides of my SN 7601 have plugs. My son-in -law in MI. took picts for me. Still looking for the picts I took when I rebuilt the engine.