Looks like I may be into an intake gasket change on my fresh RHS Vortec Pro Torker headed 355. Numbers 6 and 8 plugs are oil fouled and I've been using a lot of oil, about 1 quart for every 500-1000 miles.
The current gasket is a FelPro MS90131.
RHS recommends their own RHS 1707 Intake manifold gasket, 2.09" X 1.28" port, .060" thick.
For what it's worth, the FelPros worked without any problems at all, even re-used , on the OEM Vortecs.
I'm guessing these RHS castings are different enough in that perhaps a thicker intake gasket is needed. I have no dimensions for the FelPro part.
Does anyone have any other recommendations?

 

I've found this Fel Pro 1255 gasket.
Small Block Chevy Vortec Engines
Gasket Material: Composite W/Coating
Port Size: 1.08" x 2.16"
Thickness: .120"

Thicker than the .060" that the Fel Pro 90131 advertises theirs at.
I'm thinking that the .015" that's been cut off the block deck may be the difference between the gaskets sealing on the old engine and not on the new one.
Anyone use the 1255?

 

Interesting in that Fel-Pro advertises their gasket at .060" but it measures .120". That's the thickness of the plastic carrier that supports the silicone bead that's molded into it.
The Fel-Pro 1255 has a thickness spec of .120". It's what GM uses (or one similar) on their Fast Burn 383.

 

Another thing I've discovered is that Edelbrock recommends their own special intake bolt and washer for their Vortec Air Gap intake. I'm using the GM dedicated bolts that were used on the OEM Vortecs. It's designed to bottom out in the head. Not sure what the Edelbrock bolts would do differently.
Perhaps a change there is needed too.
Anybody?

 

Here are a few of the choices. Some of the plastic carrier type with silicone beading (which is the 90131 as well as the GM 12529094 and the 1255 which I believe is a Printoseal type of gasket on a composite paper.


Fel-Pro 1255 composite gasket. Printoseal on composite paper


Fel-Pro MS90131. Original edition of this gasket similar to GM 1259094. Plastic/nylon carrier with silicone bead.


Fel-Pro MS908000T. The latest version of the MS90131.

 

I would not recommend using the GM bolts, because of the fact that they bottom out. If your intake gasket is slightly thinner than the OEM gasket and/or the pad height of your aftermarket intake is shorter than the OEM intake, it won't seal properly. I'd stick with standard bolts, standard paper-style gasket (Like the 1255s) and tighten to the 11 or so ft/lbs that aftermarket Vortec intake instructions tell you to torque to. I did a lot of research to figure out what intake gaskets to use on my Vortec TPI build, and over and over I kept finding complaints of the stock style gaskets leaking with aluminum intake manifolds. I don't know if the pad height on aftermarket intakes is the same as on the stock plastic Vortec intake, so the stock style bolts may not be tightening the gaskets enough.

 

That's the direction I'm going.
The Fel-Pro MS90131 worked with no problems on the original Vortec heads even with the Edelbrock intake. Edelbrock recommends their own bolt but I used the OEM parts and never looked back. Thousands of trouble free/leak free miles logged. The problems started with the fresh short block and new RHS heads which went in last fall. There must be just enough difference between the OEM and the aftermarket heads to keep the intake from sealing.
I'll know soon enough I guess.