One of the previous owners wrote in their notebook that they had the manifolds resurfaced and had a new gasket installed. Eventually, the records state that the manifold was too thin to resurface and just had a gasket installed.

As I have been considering adding the Howell Fuel Injection to the engine (455) I figured I would replace the manifold at the same time. I contacted a mechanic/racing friend of mine for advice as he has replaced many manifolds and installed FI systems. He suggested looking at the Edelbrock Torker ( http://www.summitracing.com/parts/edl-2730/overview/make/oldsmobile ) with the MSD Atomic Fuel Injector system.

Does anyone know if this would, in fact, work on our motors? If so, is there anything special that needs to be done to the manifold?

Bob

Hi Bob. It seems maybe that your PO is talking about resurfacing exhaust manifolds instead of intake manifold. The 455 MH uses a lower than stock intake manifold for floor clearance. To keep the floor level the only choices are stock MH, Toronado, or Rockwell Alum. You do need to remove the intake to block the exhaust crossovers. Mr Patterson has gaskets with the plates needed.



thorndike wrote on Thu, 31 July 2014 23:24

One of the previous owners wrote in their notebook that they had the manifolds resurfaced and had a new gasket installed. Eventually, the records state that the manifold was too thin to resurface and just had a gasket installed.

As I have been considering adding the Howell Fuel Injection to the engine (455) I figured I would replace the manifold at the same time. I contacted a mechanic/racing friend of mine for advice as he has replaced many manifolds and installed FI systems. He suggested looking at the Edelbrock Torker ( http://www.summitracing.com/parts/edl-2730/overview/make/oldsmobile ) with the MSD Atomic Fuel Injector system.

Does anyone know if this would, in fact, work on our motors? If so, is there anything special that needs to be done to the manifold?

Bob

The page on the AppliedGMC site for the Rockwell manifold states: Built-in exhaust bypass. Does this mean that Rockwell already blocked/removed the exhaust crossovers and thus comes with the correct gaskets?

Bob

Thread drift warning. I read somewhere that the exhaust crossover is not a totally bad idea, but the implementation on the Olds 455 was overdone. It was suggested that a 5/16" to 3/8" opening on both sides vs the huge rectangular one would be about right for generic temperatures in North America.

What would happen if the stainless steel plates in the kit each had a 5/16" to 3/8" hole in the center?

It seems there were several things used over the years to stop the heat under the carb, and the Rockwell manifold seems to be the most current (though not cheapest) option. Is there a general consensus on how well the Rockwell is working (sealing issues?, other issues?) now that it's been out for a while? Also, there was some talk about filling the crossover on the stock manifold with a product called HardBlock, but I don't know if that was ever tried with results posted. That did sound like a reasonable solution that may also allow a cracked manifold to be salvaged, but I've never heard any results.

Carl
Those same people would likely have the same problems installing a factory stock manifold. It is not an issue with the Rockwell manifold but rather totally an installation problem. The do-it-yourselfers are generally not experienced manifold installers and often don't have the gaskets properly aligned or the front and back of the manifold sealed properly.

When I filled my manifold with the Mondello zinc material years back I had a leak on the front of the engine. I was able to fix it well by squeezing more RTV into the small pinhole. I thought I had done everything right but shit happens.

Emery Stora
77 Kingsley
Frederick, CO

On Aug 2, 2014, at 1:17 PM, Carl Stouffer wrote:

> GeorgeRud wrote on Fri, 01 August 2014 07:03
>> It seems there were several things used over the years to stop the heat under the carb, and the Rockwell manifold seems to be the most current
>> (though not cheapest) option. Is there a general consensus on how well the Rockwell is working (sealing issues?, other issues?) now that it's been
>> out for a while? Also, there was some talk about filling the crossover on the stock manifold with a product called HardBlock, but I don't know if
>> that was ever tried with results posted. That did sound like a reasonable solution that may also allow a cracked manifold to be salvaged, but I've
>> never heard any results.
>
>
>
> George,
>
> I think there are a large number of the Gary Rockwell intake manifolds installed on 455s. I have heard of several people having problems getting them
> sealed and sucking oil from the lifter gallery, causing high oil consumption. I installed one on my coach a few years ago with little drama. It has
> no exhaust crossover and I'm sure, runs cooler than the stock manifold. I'm not sure it has helped with the heat on the carburetor as much as one
> would think. I'm pretty sure it gets plenty hot anyway. From my point of view and experience, the Rockwell works as designed.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
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Emery, I had the same problem only with the back 'China wall' seal. I used enough Right Stuff, but evidently nicked it when I lowered the manifold into place. I had to remove the distributor to clean the area up, but after I worked some more Right Stuff into the (small) hole, it has never leaked since. I have rebuilt several engines and had the top end off of several more, so this was not a big deal for me. However, I DID approach the job with quite a bit of GMC Net inspired anxiety. Like most things things I have done to the coach, it turned out to be no big deal.