Shaving i head

[danzo]

I have an i head laying around (w/related electrics) and want to do the ol' put it on my eta block mod. I've searched but can't find out how much material I should remove from the head to retain a 9:1 CR. I also plan to use a stock head gasket.

Thanks in advance for any and all help.

[SpecM]

-I'm sure you can shave it some, but not enough to keep 9:1 CR. You have to use an adjustible cam gear, tho.

[digger]

to retain the same CR you need to remove ~5cc (difference in head chamber volume) which if you decked the block would be 0.9mm so it would be a tad more than 0.9mm off the head since its tapered. I would look at the machining allowance recommendations in the Bentley before doing it.

[danzo]

The Bentley lists the "new head thickness" at 125.1mm and the "after machining thickness" to be 124.7mm. Difference is only .4mm so I guess it's a no go.

Thanks for the info guys.

[kenika65]

Just buy some Super Eta pistons (1988 ) seta. I wouldn't shave anything unless it is worped or pitted. And before you put the seta pistons in have valve reliefs cut in to them, for good insurance.

Then again I would buy some custom pistons that already have valve reliefs in them and are made to run with the i rods. That is a true stroker.

[Flash]

You wont make a noticable difference by shaving the heads on the 885 casting as there isnt much to work with in the first place. We decked serveral heads up to .020 and thats a LOT, after that you are compromising the bowl of the combustion chamber and can lead to compression loss.
Super eta rods and pistons will get you to 8.5:1 compression ratio and are meant for the 885 casting from the factory, and have valve reliefs in them from the factory. Thats more than enough for a naturally aspirated engine but tends to be a dog with a higher lift camshaft where that calls for a higher static compression ratio.

[SpecM]

Then again I would buy some custom pistons that already have valve reliefs in them and are made to run with the i rods. That is a true stroker.

-Metric Mechanic is your friend here. Your expensive but reliable friend.