Re: lower intake gasket question
I recently used the Felpro 1202 and they seem to be ok - at least so far. (stock LB4 heads)
After I fitted them, I actually came across a pair of NOS GM 14097298 gaskets this side of the pond on fleabay.
As has been already mentioned, the gm gaskets are a 'sandwich' type with a thin aluminum centre and also have silicone screen print on ports. They also have an aluminum heat ring for/around the egr port.
They differ from the Felpro 1202, which are just a composite type that are pretty flexible and probably contain quite a bit of 'rubber' in their composition they too are screen printed around ports.
The 1202's have the L35 central divider on the two siamesed ports, but no raised eyebrow cut out that I recall, but they also have NO egr provision either.
To use the 1202 on stock LB4 heads, you need to cut out the central divide on both siamesed ports, or else risk it becoming foreign material in one of the ports, because it isn't clamped on the LB4's as it is on the L35's.
Also, unless you want to risk a burn through and/or want to retain egr functionality, you will need to cut out for the egr port flow on the R/H head. Not an issue I believe if you are using the L35 heads.
Regarding the egr, I was in two minds here, as whether to try and dig out a stainless steel shield that used to (and maybe still does) come in older style 'universal' sbc gasket sets and cut the gasket to suit. This would probably be a much better solution than the various 3/8" npt plugs that some people use to block off their egr. I have left mine intact, by cutting out for the port, but removed the egr valve and fitted a blanking plate. Thats just my choice at this time.
I did find that the 1202's needed very careful positioning due to the clearance holes in the gasket for the manifold bolts and the fact that the gaskets had less material at the top of the intake ports. It would be easy to get it wrong and have very little gasket material there, which would possibly blow out under higher boost levels. If I remember, I had to trim the ends a touch to get them right. The old GM ones fitted and located just right, with more cross section there, but you would expect that I suppose.
Proper preparation and clean flat surfaces are essential here. I also found that the manifold has large clearances on the bolt holes and its worth a trial fit to determine best fit for port alignment before laying the silicone on the valley (China) walls. Mine originally wasn't, but to be fair 'best fit' on mine seemed to pretty much line up with the centre of the tapped holes. I also use hylomar around water jacket ports. Again, a personal choice. Helps to keep them in place too.
Hope the above helps.
