My block and heads have been decked so the intake manifold probably needs to be milled, (more milling is required the thicker the intake gaskets are).

Is there any reason I can't use RTV instead of a intake manifold gasket on my (turbo'd) LT4 heads/intake? No reason to have the intake machined and buy intake gasters if RTV will work.

 

You could try measuring what clearances you have there between the intake and heads. Use some clay if you want to and if it's a little less than .060 you might be fine with intake gaskets (I measured them at .060 last time I did this) and if its a lot more than that I might be afraid to use silicone because it might push out. If it's way less then you may just want to get it milled. If it was me, I would measure it and get the intake corrected if needed then use the right gaskets and some coppercoat. And do a dry fitment to see if your bolt holes still line up, otherwise you need to slot those a little.

 

Because the block/deck have been milled, the bolt holes (and ports) will line up much better without intake gaskets. I'll find out for sure later today when I put the heads on.

 

You cannot eliminate the intake gaskets and just use silicone.

 

It will leak w/o a gasket.

Rich