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When an engine block has been decked, do the head or intake surfaces need to be modified/angled to account for the slight change in their position or does it depend on how much is taken off the block?
Yes if too much is removed from the heads/block the intake manifold will not fit properly.
I have always been told you cut the heads to fit the stock intake- then ANY intake will fit. If you cut the intake to fit then that intake now only fits that engine/head combo
Obviously with angles involved if you cut a lot things have to be machined to fit. As long as you don't cut more than about .040" total off of either it should all fit together. But do you know how much has been cut off the last 50 years.
If you put gaskets on it, the bolt holes line up, and the intake doesn't bottom out on the end pads of the block that's all you really need to be concerned with.
We used to cut .150" off of race heads routinely but we angle milled them cutting the intake side of the head back to the correct angle. This is done to increase compression to the max and not cut away the gasket surface at the bottom of the intake port. I've seen this area cut thin many many times. I know this is drifting away from your question this is just an example of what is done.
If you cut the heads instead of the intake then the head ports will be at risk of being lower than the intake runners - which can get into port matching. If the intake is cut the relationship between the head and intake runners is maintained. But, I understand what you are saying about ending up with an engine-specific intake that can not be easily swapped to another engine or another un-cut intake to this engine and a little port matching is not unusual. The bolt holes in the intake may need to be clearances a little too. I’m not sure which is the more common approach now. Hopefully your block only needs a light cleanup which doesn’t require either head or intake to be cut.
It's normal to cut the heads and not the intake as Tiger Joe said, that way you aren't making an intake that only fits one engine. Removing material from the head surface or the intake manifold ends up the same as far as port matching.
It's unlikely that enough was removed from the deck of the block to give you intake issues. You can mill heads a lot and create intake fitment issues but if you remove too much from the deck the you wind up with pistons coming above the deck and that's a whole other can of worms.
Whoa! I came to this discussion topic to find out if a block can be decked without destroying the original identification numbers stamped on it at the factory.
Two people that know more about rebuilding engines than I do have different opinions on the subject. Care to comment?
Whoa! I came to this discussion topic to find out if a block can be decked without destroying the original identification numbers stamped on it at the factory.
Two people that know more about rebuilding engines than I do have different opinions on the subject. Care to comment?
I would never do that on a Corvette for that reason. Watch the value go down the drain.
It is possible to deck a block without shaving the stamp pad, but not all machinists can do it, or care to try. Find somebody who gives you an iron-clad guarantee that they can before you let them have at it. Referrals from somebody who's had it done are strongly encouraged.
Here's the stamp pad on the engine that's in my '63. The block has been decked, but the machinist knew what he was doing, and had the proper equipment that allowed him to leave the numbers alone. Examine the photo closely, and you will see where the circular cutter stopped short of the numbers.
The old style mill was a StormVulcan 85B I had one and operated it for years. You could do it but you had to be careful. Many shops now have a CNC machine for block work. It bores the cylinders in precise location and can easily deck the block and not touch the numbers.
Engine Block Decking
