Hot Rods Need Chevy 6 wisdom

I’ve got an old ELLIS in-line 6 Chevy intake manifold with no casting numbers, part numbers or numbers at all for that matter.
I’m searching for the wisdom of the in-line 6 guys & gals to help me identify it. I’m guessing the distance between ports will be the only way to identify it. I don’t currently have any I6 engines to match to so.
The guy I got it from said it was Chevy but I forgot what engine size (long ago). Measuring with a tape measure ports are 1 1/2” and appear to be 8 1/2” apart center to center

 

Not so much the span, it’s the diameter of the runner to head having to match up.

 

https://www.jalopyjournal.com/forum/threads/216-235-intake-manifold-differences.402067/

 

The port size measures 1 1/2” and they are 8 1/2” apart

 

I have a series 2 GMC one with a part number (so I know it’s GMC) and it’s WAY bigger than this one

 

Just sold the 235 we had here so I have nothing to measure spread. But at 1 1/2” put’s it to be later 235 because early 235 shared the smaller ports as a 216.

 

Thanks for the info, it’s a start at least. I’m hoping someone has an intake or head they can measure so I know for sure what I have.

 

You ROCK!

 

I think you may have nailed it sir. I found comments on another site that said the 216 and early 235’s had 1 1/4” ports and the later version 235 had 1 1/2” ports.
I’ll know for sure when Moriarity measures his 216 intake

 

Late 216, 235, and 261s port "spread" are the same I am running an Edelbrock 216 intake (I had the intake manifold ports machined) on my 261.

 

IIRC some manifold suppliers had stepped bushings that adapted the later manifolds to the early 216" manifolds.

 

In all my years of running GM 6 cylinders starting in 1961 only my first one used the rings. As I ported and tapered intake and heads I found I couldn’t use them so I didn't. A large port intake on a smaller port heat that I tapered to the manifold size gave me the best street drivability torque by making the intake runner a venturi.
Food for thought!

 

^^^^^ The ring for me are to ensure proper alignment. I’ve assembled a few with out ring with no issue. Just took my time.

 

I need to add though, they do offer a fair amount of support so as not to be able to slide down ward especially when running in stock form with exhaust manifold attached.

 

Plus, these are clamped to the head and not through bolted...