Intake manifold fit after decking block

[paint4metal]

Hi all , Anyone had problems aligning their intake manifold, to the heads, after having Their block deck ground? I am preparing to have work
Done on my 389 Pontiac block, decked, align honed,
Just want to get some insight, before I proceed.
Thanks, Dave

[big gear head]

If they only remove about .010 from the deck you shouldn't have any problems.

[DAVE H]

It's when the heads get over milled that you run into problems. Found that out the hard way with a set of 074's. Ended up having to mill the intake gasket surfaces to get it to sit down between the heads and gaskets. Those heads were milled down to where the edge of the intake valve seats were also being cut.
Dave.

[tjs44]

Verify the deck of the block now unless you have owned it from day one and know it has not been decked before.A great machine shop in IL would be Ric Johnson at Custom auto in Crete IL.Old time pontiac racer and machine shop.Tom

[paint4metal]

Ok, Thanks you guys. My heads have been re surfaced,- .008 . If my block is decked,
-.010, that's -.018 all day. If this is the outcome, would this be enough to be concerned about? If so, I guess will be having my intake ground to fit. Dave

[hogdaddy]

When I previously had a block zero decked, the engine shop made the appropriate cut on my intake manifold to match IIRC. I don't remember how much was cut.

[big gear head]

You can use thicker head gaskets to make up the difference if it turns out to be a problem. You will need to check the deck height of the pistons when you do your trial assembly. If the pistons end up being above the deck then you will need thicker gaskets anyway.

[tjs44]

Just do it right!Get the deck,order correct pistons to get your CR you want with ordinary 39-45 head gaskets.I give this advice from a engine we just built for a good friend.He supplied the 4 bolt 455 block and crank and a set of 48 heads.Did not recheck the deck and found out after the fact it had been cut .125 which lead to issue of the valley cover fit and the intake manifold fit.All doable,just numbers in a check book.Tom

[paint4metal]

Yeh, I'm with ya Rick, thats what I'm thinking. Dave

[paint4metal]

sorry, " Tom"

[BCreekDave]

Some numbers here:
https://www.crankshaftcoalition.com/wiki/Milling_cylinder_heads#Correcting_the_intake_flang e

If you do it right, you can ditch the crappy rubber end seals on the china walls and use RTV. A good target there is 0.005-0.010.

[paint4metal]

Thanks, Great information