Technical Ram Air III exhaust manifold information needed

Hi guys & gals,

I recently acquired a set of what are advertised to be '68 RAIII exhaust manifolds and I have a couple of questions that I'm hoping someone on the HAMB has some insight/experience with.

First off there is only one bolt used on the center ports as the second bolt hole is covered by the manifold. On one of the manifolds the front port has a bolt hole but is looks like it has not been used. My question is does this cause exhaust leakage problems? From what I see on the manifolds it looks like they hold but I am hoping to hear from someone that has run this type of manifold.

Secondly the center port in the exhaust manifolds are divided. I intend to put these manifolds on a '63 421 and the center port on the head is not divided. Is there any advantage (or disadvantage)to fabricating and installing an insert to divide the center ports in the heads?

I am wanting to use these manifolds to increase exhaust flow. Looking at them it is clear that they will provide no "tuned scavging" effect. At some time in the future I expect to but a blower on the engine and so hopefully the cast iron manifolds will hold up better to the resultant heat.

The reason that I don't want to use tubeular headers is that I don't like them (short answer). I have had problems with fit, leaks, heat and noise with tubular headers. I am hoping that these manifolds will be an improvement in those areas.

The manifolds have the following casting numbers:

left side GM3 9791637

right side 9797072-RH28

I am unable to find any date code casting. I did find a place on each manifold where one could be but nothing is there. Is this a normal thing for this type of manifold?

Thanks in advance for your positive answers,

Norm

 

probably have to try a Pontiac forum. I had a Ram Air III in my GTO and never even knew they had different manifolds.

 

I believe 69 was the first year for the RAIII. There was a RAII available in 68.

 

Quality headers such as Sanderson or Doug's fit well and don't leak. You will need them if you expect a blower setup to be anything more than eye candy.

 

The RAII had round exhaust ports. The RAIII had D port exhaust heads.

 

I was thinking Ram Air IV had the round exhaust ports, but it has been 30 years since I paid attention to Pontiac muscle

 

I would bet that with a blower those dividers inside the manifold will be toast before long.

 

The part numbers correspond to a 1969 GTO Ram Air III 400. The left one (9791637) was also used the previous year on the 1968 GTO Ram Air.

 

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