Thanks to @Lumens, I was able to scan the 1973 TSB Nissan Publication.

An interesting TSB on the E88 head change for Feb 1973 shows a larger combustion chamber where the piston extends into.

The compression height of the piston is longer so that the piston's deck height is greater by 0.7mm.  If you need more "squish" on a 240z with E31 or early E88, seek out these pistons!

 

I just entered the 73 pistons in the engine calculator and they will push the compression close to 9.5:1 if used with earlier E88 head however the squish will only be 0.36mm.  Very close head/piston proximity.

 

~ 0.7mm is the ideal squish.

 

There is also variance in who measures gasket thickness.  Below I used 1.14mm as measured by engine builder with handle Phred.

 

 

With E31 head the compression goes to 9.9:1

 

Edited December 29, 20177 yr by 240260280

10 hours ago, madkaw said:

What I meant as far as measure is to install a piston in the block on the crankshaft and measure the ‘pop out’ of the block. I would be surprised if any additional thickness of HG would be necessary . 

I agree with madkaw......one exception......if the block was machined. It would be nice to know what the safe clearance is between piston and head (drag racers install with almost no clearance), and you can get numerous answers depending on who you ask. . Valve clearance should not be a problem because 73 pistons are  flycut. The stock L28 pistons come out about .018 inches with no problem. If the block isn’t decked , I would think the stock gasket would be fine. If you are concerned (if it keeps you up at night) you can always shave the top of the piston down to the sleeping point. 

Edited December 29, 20177 yr by Diseazd

BMC in Arizona state 0.7mm to be the target squish. They did a lot of work with Maxima N47 and P90 heads.

Note that Rebello recommended 0.9mm to be the target squish.

Valves colliding are more dependent on the cam however they must always be considered and checked during assembly.

Edited December 30, 20177 yr by 240260280

15 hours ago, 240260280 said:

I just entered the 73 pistons in the engine calculator and they will push the compression close to 9.5:1 if used with earlier E88 head however the squish will only be 0.36mm.  Very close head/piston proximity.

 

~ 0.7mm is the ideal squish.

 

There is also variance in who measures gasket thickness.  Below I used 1.14mm as measured by engine builder with handle Phred.

 

 

With E31 head the compression goes to 9.9:1

 

which engine calculator is that?

12 hours ago, Diseazd said:

Valve clearance should not be a problem because 73 pistons are  flycut.

I've got a '73 complete engine with the E88 head,  it's the deeper head,  but the pistons are flat with no cut-outs..  no flycut...   I'm pretty sure that it is a euro version 240z engine L24.

Interesting.....anyone on Hybrid Z know the compression thickness of the stock Nissan head gasket?

8 hours ago, Jason240z said:

which engine calculator is that?

You can use it here:

http://www.240260280.com/Tech/Engine/Planner/S30 Engine Modeller V3.html

 

You can manually enter bore, HG, thickness etc. if your configuration is not there.

 

I'll also add parts or correct parts as needed. Just PM me.

 

 

 

2 hours ago, Diseazd said:

Interesting.....anyone on Hybrid Z know the compression thickness of the stock Nissan head gasket?

Hi Guy,

 

I pulled a few measured values from some reputable builders on line and included in the engine planner:

 

 

Nissan HG was measured at 1.14mm and 1.20mm by "Phred" and 1.25mm by "Zya"  both are great Z builders.

 

Felpro was measured at 1.15mm by "Braap" and 1.20mm by" @madkaw"  likewise experienced builders.

 

Ishino was measured at 1.00mm by @Lazeum. Weber and engine expert from "The Continent"!

 

I have an L26 HG that I am about to measure to add to the mix.  Any data from your engine building is welcome!

 

Here is what you should be able to assume with closest proximity:

 

• 1.00mm Ishino
• 1.15mm Felpro
• 1.15mm Nissan

 

 

 

 

 

 

 

Interesting.....anyone on Hybrid Z know the compression thickness of the stock Nissan head gasket?

I thought it was 1.25mm


Sent from my iPad using Classic Zcar Club mobile

BMC in Arizona state 0.7mm to be the target squish. They did a lot of work with Maxima N47 and P90 heads.
Note that Rebello recommended 0.9mm to be the target squish.
Valves colliding are more dependent on the cam however they must always be considered and checked during assembly.

I’ve read where Blake has said less than .7- but doesn’t recommend it for the average builder . I think he ran less than .6


Sent from my iPad using Classic Zcar Club mobile

44 minutes ago, madkaw said:

 

I’ve read where Blake has said less than .7- but doesn’t recommend it for the average builder . I think he ran less than .6


Sent from my iPad using Classic Zcar Club mobile

 

Shhhhhh!

Edited December 30, 20177 yr by 240260280

Oops