SBC Inlet Gaskets

Spongo · Post by **Spongo** » Tue Mar 03, 2015 10:07 am

OK so I have the gaskets on order, I have ordered 2 lots of Felpro gaskets as they seem to be some of the best on the market (I Hope). I need 2 sets as there are adapter plates in between the manifold and the heads (not one of Overfinch's finest ideas)

Anyway some advice please do I assemble dry or with gasket goo and if so what would you all recommend, I have always used Hylomar Blue in the past and had normally pretty good results but do I need it?

As its a NA engine then I am guessing it doesnt really need any sealant but would appreciate any advice you guys may have.

Eliot · Post by **Eliot** » Tue Mar 03, 2015 11:33 am

Felpro's are indeed good gaskets. They can be dry assembled, i sometimes use hylomar - but only out of habbit, i dont think its actually necessary.

Spongo · Post by **Spongo** » Tue Mar 03, 2015 12:49 pm

Phew thats good to know, they arrived today and I must say they do seem to be very well constructed.

I think my Hylomar habit may be intact as well, just a small amount though

DaveEFI · Post by **DaveEFI** » Tue Mar 03, 2015 12:52 pm

My BL manual for the SD1 recommends Hylomar - but only round the water ports. And with a standard gasket, obviously. But that standard gasket is already coated with a sealer in the form of a clear lacquer.

Spongo · Post by **Spongo** » Wed Mar 04, 2015 9:03 am

I remember the 3.5 V8 has a laquered gaskets, the ones on the SBC are not laquered but do have a sealant ring incorporated into them so I think a small amount of Hylomar on the ports cant do ant harm.

My previous attempt at doing these gaskets appeared to initially work well, I bought gasket material and made my own, the seal between adapter and head was perfect but over time the seal between the adapter and inlet degraded and after making my own inlet pressurisation tool found it was leaking on nearly every port with only about 5lbs of pressure. Not to scientific but as I had an LPG smell on tickover I assume that it was also leaking while running.

I tested all of the LPG and other stuff whilst I was at it and all is well there so maybe this time it will be ok.

Last question to any guru's out there, the gaskets between the adapters and the heads will need the bolt holes moving due to the way that the heads were machined to allow the fitment of the inlet manifold, what is the best way to cut the Felpro gaskets as they are really tough and appear to have a metal core, was thinking of tin snips but would appreciate any other ideas.

Eliot · Post by **Eliot** » Wed Mar 04, 2015 11:46 am

got any photo's of these adapters? I'm assuming its to adapt between classic SBC and the later SBC Vortec style?

Spongo · Post by **Spongo** » Wed Mar 04, 2015 1:49 pm

Thats the ones yes, I will get some pictures and upload later

Spongo · Post by **Spongo** » Wed Mar 04, 2015 3:22 pm

They still need cleaning I know

but these are the adapters, the heads have been re drilled and tapped to allow the bolt holes to be used on the actual manifold casting, there is also a little aluminium adapter for the front and back of the valley.

Eliot · Post by **Eliot** » Wed Mar 04, 2015 5:46 pm

Is it a Vortec manifold you are trying to attach to a SBC head? I thought you could re-drill the manifold to make it match the SBC bolts? (

Spongo · Post by **Spongo** » Thu Mar 05, 2015 8:02 am

No its a standard Chevy Injection Manifold circa Corvette 1985 I believe, the heads have been re-drilled already.

Unless of course there used to be a Vortec manifold on it and that has been replaced sometime ago

Eliot · Post by **Eliot** » Thu Mar 05, 2015 9:22 am

I'll have to admit to being out of my depth on this now. If its been re-drilled, surely the manifold should go straight on without any adapter?
I wasn't aware of any need for an adapter, I thought it was always simply that the inlet manifold bolts were vertical on vortec and slanted on the sbc (well, 90' to the face of the actual inlet port)

Spongo · Post by **Spongo** » Thu Mar 05, 2015 9:54 am

No idea either, but the current inlet manifold will not fit on the engine without the adapters as the tappings in the heads are in the wrong place.

The heads have a bolt hole that is filled with what appears to be a stud and a new drilling and tapping is just above it.

I will take a picture and post it so you can see what I mean

Spongo · Post by **Spongo** » Fri Mar 06, 2015 12:00 pm

Ok took a photo of the head, for orientation this is drivers side front, you can see the studs in the original bolt holes towards the valley area and the new bolts holes for the current inlet manifold as well.

Now I am curious do the older bolt holes go in at an angle to the inlet face? If so is there another injection manifold that I could use on there whilst keeping the TPI plenum etc?