[bignate]

I’m going to get these cleaned up and cc some chambers and ports this week. I would like to get them on a flow bench at some point too, just for curiosity’s sake.

After I get them cleaned up I’ll post up some better pictures.

Nate

[Dragncar]

There were 2 sets of SD 455 heads with 90cc chambers made up. 96 cast on them and they even had the pushrod tubes.

[grandam1979]

I don’t know if it’s just me but those chambers don’t look that small to me. I’m thinking around 100cc + or - a couple. Please post when you check them.

[25stevem]

Do those 191s have only one set of paired rocker stud bosses?

As I recall from a set of 191s I had on my shelf for years, the shallow side of the chamber was darn close to .500” deep in stock form.

[Skip Fix]

If you put a straight edge across the chamber at the closest spot of the intake valve my RAIV heads chamber was 0.073 deep. Some of those look like it will be deeper.
http://forums.maxperformanceinc.com/...=chamber+depth

[bignate]

Ok just doing a quick cc job using a plate and a graduated cylinder I’ve come up with:

Chamber: ≈75cc
Intake port: ≈200cc

I say approximately but I’m sure it’s within 1cc either way.

I measured the valve sizes which are as expected 2.11” and 1.77”.

I also took a scuff pad to one chamber to clean it up and took some more pictures.

Nate

[bignate]

Originally Posted by 25stevem

Do those 191s have only one set of paired rocker stud bosses?

No paired rocker stud bosses on these.

Nate

[bignate]

Numbers stamped on center exhaust ports.

Nate

[grandam1979]

Sorry I was looking at the picture you post of your head with no valves. Those are definitely some odd heads.

[Skip Fix]

Second picture in post #6 shows a definite "ledge" at the back (intake side) of the chamber these do not have

[Skip Fix]

#6 also has the "ridges" in the chambers sharp and the other shots are smooth.. Different HO head?

[bignate]

Originally Posted by Skip Fix

#6 also has the "ridges" in the chambers sharp and the other shots are smooth.. Different HO head?

Yes the picture in #6 was one I grabbed from Rocky’s for sale add on here of an unmolested (except for the obvious repair) head.

Nate

[Skip Fix]

Got you!

[25stevem]

Your heads for sure started life with RA4 size chambers and you can see that if they where milled they where flat milled only enough to make up for the enlargement that took place from the valve job and chamber polish.

['ol Pinion head]

Originally Posted by 25stevem

Do those 191s have only one set of paired rocker stud bosses?

As I recall from a set of 191s I had on my shelf for years, the shallow side of the chamber was darn close to .500” deep in stock form.

70 SR RAiV heads were cast with the paired rocker bosses on one end, as the first roundport heads cast at the Pontiac Central Foundary right after the Fall UAW strike. This revised style also carried over to the first of the second style 197 castings in early Dec of 70. Both of these styles of round port heads will also have external date codes.

[bignate]

Dug into these a little farther tonight.

Exhaust crossover is cast blocked off, not filled or welded.

There are several bolts screwed through the deck against other passages and surfaced flush, not sure if this was to strengthen the deck in those areas?

Looks to me like the valve job was botched at some point, intakes were converted to 45°. They have titanium intake valves but they are knifedged and no longer usable.

Valve weights are: Intake-88.2 grams, exhaust-117.5 grams

Port work looks pretty nice from what I can see.

Nate

[bignate]

Other pictures.

[PAUL K]

Is this a crack?

[turbo69bird]

Originally Posted by bignate

They for sure have had a bunch of work done… I was told by the previous owner it was done by Diamond-Elkins in the late ‘70s.

Just going by a measurement off the lower accessory hole (I know it’s not super accurate) compared to a untouched head, they may have been milled .050”.

What has me puzzled is the spark plug location in relation to the chamber floor. There is a large space between the spark plug and the intake valve seat on a normal HO head, and these are just as close as a RAIV head.

I’ll attach another angle of the shallow side of mine and a picture of a normal HO chamber.

Nate

Diamond Elkins did the RAV heads for Stephens Pontiac so it’s certainly possible they did later Pontiac heads.

[PAUL K]

It looks like those heads may have originally been ported by Elkins. Then at some point the guides were replaced and the valve job redone. Or atleast in the one cylinder you posted a picture of.

Would you mind posting a picture of the end of the heads? The side that would show the freeze plug and accessory mounting bolt holes.