How much to mill?

[JackFish]

The spare head is at the shop and they say it has a bit of a warp which they can plane. I don't want to pull the stock engine yet for rebuild (unless I have to), just clean up the pistons and put the new head on.

What would be a good amount to tell the machinist to take off the head at this point, given that I may do the block maybe in about a year. I think I have seen here .060 suggested as the total maximum amount, is that right? And you can split this 50/50 between the head and the block for .030 off each?

 

[wsa111]

Jackfish, if your engine is stock I would take .030-.040 off the head & zero deck clearance. If you have any camshaft above 204 degrees @.050 then you can go .080, .090 is the very maximium on the later big combustion chamber heads. If you do take this much you will probably have to use 91-93 octane fuel.William

 

[JackFish]

Stock cam for the moment but I ordered the 264/274@112* which has a lift @.050 of 214/224 so maybe .040 at this point? Not sure when the new cam will be going in.

Can you describe what you mean when you say "& zero deck clearance".
You have a newbie here so any info you or anyone else here cares to provide is most welcome.

 

[MustangSix]

Zero deck is when the top of the piston is fluch with the deck on the block. That allows good "quench", which provides a cooling effect to the compressed charge.

 

[JackFish]

Thanks! Do you know what would be the amount "above" zero that the stock block would be? In other words, how much would normally end up being milled to get to zero?

 

[Anlushac11]

8)

IIRC piston to deck clearance is normally about .022" to .025"

Your machinist will have to measure it because it will vary from engine to engine.

 

[mugsy]

I have been into two 200 engines so far. One had the pistons down the hole 0.030 and the other was right around 0.020. With the production tolerances, or lack thereof, the best bet is to meaure. I would not give a machinist a number until I measured it and was sure.