2.0 911S motor build for my '68, advice?

[Fritter]

Question: Could I take the stock '68 longblock and install S heads and cams and then get the normal Birals reconditioned and put 81mm JE's in there? Machining to head hopefully not required if I did this?

A stock spec '67/68 S motor with SSI's and a slight displacement bump would be sick.

[gtgroupe3]

Answer: Yes you can.

Option #2: Skip the 81mm P, Bore out the Birals to 84mm and use a set of ‘71 T heads (relatively cheap and common). With the money you save on the heads, have the ports enlarged to 36mm.

Better performance, reliability and would cost about the same.

[Fritter]

80mm birals can be bored to 84mm?

All these options are making my brain hurt....

[t6dpilot]

Fritter, good luck with your project. I will be following your progress. BTW, did you source a spare 2.0L block, keeping your car driveable?

Not to take this too far off topic, but I want to ask the gurus a question here. Would running 67S heads with a 2.2L displacement affect rev performance? In other words, would the motor not rev to its redline of 7300? I am almost positive that it would not affect it, but thought I would ask for confirmation.

[Fritter]

80mm birals can be bored to 84mm?

All these options are making my brain hurt....

Bump, can the 80mm biral cylinders be bored to 84mm?

[kenikh]

Bump, can the 80mm biral cylinders be bored to 84mm?

Pretty sure they cannot. Cheaper to buy 84s, as-is.

[gtgroupe3]

Since I am not a proper tech and cannot confirm or support the statement based on my own skill sets. I will say that mine are bored out to 85 mm.

Not that someone will allude to or question the skills of my engine builder; I can also post some pictures of the 910, 907 & 935 (Kremer) engines (e.g., engine porn) in his shop.

I would think the owners of these somewhat more valuable pieces of history trust in his abilities may speak to his skill and knowledge a bit more succinctly than I may.

Sumner

[kenikh]

Since I am not a proper tech and cannot confirm or support the statement based on my own skill sets. I will say that mine are bored out to 85 mm.

Not that someone will allude to or question the skills of my engine builder; I can also post some pictures of the 910, 907 & 935 (Kremer) engines (e.g., engine porn) in his shop.

I would think the owners of these somewhat more valuable pieces of history trust in his abilities may speak to his skill and knowledge a bit more succinctly than I may.

Sumner

I knew 84mm could be bored to 85mm, but not 80mm. Very interesting!

[304065]

80 can be safely bored to 81, 84 to 86 or so.

80s cannot be bored to 84 or more, the design is different.

[kenikh]

80 can be safely bored to 81, 84 to 86 or so.

80s cannot be bored to 84 or more, the design is different.

Is this a typo? They either can or cannot..