[north]

69's definitely did not have the flapper from the factory.

[NotaT/A]

I have a late Nov 67 build 68 RA1 Coupe. Original engine/manifolds. It has a 9779494 RH LB exh manifold with a flapper.

[400HO F-BIRD]

Here's some info I've found on the net (don't know if it's correct though):

67 RA
9779493 RH
9779495 LH

68 RA I
9791607 RH
9779495 LH

68 HO
9791607 RH
9779495 LH

69 HO/RA III
9797073 RH
9779495 LH

I've also read about a couple of people saying they had 9779494 RH manifold from 68 with heat riser valve.

But I also remember reading that the heat riser valve disapeared during the 68 model run. I think a service buletin from april 68 was mentioned.

The question is what part number the late 68 HO RH manifold without heat riser valve had in that case.
Same as 69?

My car is pretty late (May 68) and has other late 68 options such as variable ratio power steering (same as 69), so maybe the RH manifold also was same as 69?

[Hikin Mike]

Very nice!

[north]

I just looked at a set I have from a 68 Firebird

LH is 9779495 no date
RH is 9779494 K227
Both have a -1 following the pn

My 69's also factory are on a car with AC so I can't read the PN but there are some visible differences on the size of the bosses where they bolt to the head

[north]

Forgot to mention that my 68 manifolds had a flapper

[north]

Just looked at my 69 long branch, from a 69 GP, oct -nov cast dates,

Left is same as all of them
Right is 9797073

Which is correct for 69, and I imagine is correct for later 68's as well

[400HO F-BIRD]

Ok, so the GP used the exact same manifolds as the Firebird.

Would be very interesting to know what the earliest cast date for this 9797073 version is.

The service bulletin from April 68 that I seem to remember someone referring to would also be nice to find.

[judgeman6970]

Great job. Beautiful Bird!!

[johnta1]

The service bulletin from April 68 that I seem to remember someone referring to would also be nice to find.

From Craftsman Service News:

[400HO F-BIRD]

Wow, that was fast

Really interesting reading.
That's approx. 10 000 engine unit numbers before mine so it feels like it could have been issues around April 1968.

So, if the heat riser valve was kept in the long branch manifolds in April 68 but was not present in 69 long branch manifolds when was the switch-over?
Was it a model-year change?

[north]

Sounds like the changeover was at the start of 69 production, unless a second service bulletin was issued.

Does anyone have a longbranch manifold without a heat riser valve dated before say august 68?

[johnta1]

The pic was in the July 1968 issue.

I'd say it was a running change and after that number, all the manifolds were without the valve.

[north]

Originally Posted by johnta1

The pic was in the July 1968 issue.

I'd say it was a running change and after that number, all the manifolds were without the valve.

But the long branch are specifically exempted from that running change. I don't remember the start of this thread anymore but why are we questioning that all long branch had the valve until the start of 69 production?

[400HO F-BIRD]

It was me asking when the change appeared since I thought I remembered reading about a service bulletin from April 1968 saying that the heat riser valve was removed.

After seeing what johnta1 posted this is probably the one referred to and it clearly says that the HO/RA manifolds were excluded from the change.

It appears that all manifolds were without this valve in 1969 though, so the changeover was probably in the model-year change which also prompted a new part number on the manifold (9797093).

I'm posting a picture I found today of a 9779494 manifold with casting date of 4:th of April 1968. It's not shown in the picture, but the poster said it had the valve. So they did for sure still have the valve on that date.