1700 compression ratio

[hercdriver]

I'm rebuilding a 1700 cc (1679) type IV coded as CB. I'm getting down to the final assembly and would just like a reality check before I finish.

New 1700 dished cylinders/pistons.
Heads rebuilt by RIMCO (flycut, new valves, seats 3 angle ground, new springs (tension set for the cam))
New cam and solid lifters from WebCam (model 73)
Initially I'll reinstall the weber carb to break in the engine, but plan to install fuel injection (it's going into a 1975 westy).

From what I've been reading, A compression ratio of 7.4 is ideal for longevity (my goal is reliability/longevity).

Here's my math......

90 mm Bore
66 mm Stroke
Deck Height .060 (.020 + a .040 barrel shim) Wilson says .055 to .065 is optimum.
Combustion chamber average is .51cc + .05 piston dish = .56 cc
With a compression ratio of 7.4

Calculator used.....
http://www.msgulfcoastvwclub.org/TechPages/Tech10.html

I think I'm right on the money. But since this is my first rebuild, I'd like some affirmation.

[Amskeptic]

90 mm Bore
66 mm Stroke
Deck Height .060 (.020 + a .040 barrel shim) Wilson says .055 to .065 is optimum.
Combustion chamber average is .51cc + .05 piston dish = .56 cc
With a compression ratio of 7.4

I'd like some affirmation.

Piston dishes come in 7cc shallow or 15cc deep. Shallow dishes have gentle slope on their sides, the deep dish pistons have steep walls.

If you have the shallow dish up there, you'll be fine.
Colin

[hercdriver]

They must be the shallow dish (7 ml). Thanks. It was my first attempt at using the cc measure kit from Aircooled.net

[dtrumbo]

It was my first attempt at using the cc measure kit from Aircooled.net

Having just rebuilt my 2.0L engine and suffered the learning pains associated with measuring combustion volume I highly recommend doing it over and over and over again until you get predictable results. Do not allow "typical" numbers to sway your judgement when reading your measurements. Measure, measure again and measure again until you get the same number each time. Then, use that number whether it be piston dish, head combustion chamber volume or deck height for your calculations. You can't guess or use "typical" numbers just because yours don't quite match.

The compression ratio calculator on aircooled.net's site is very handy.