304 VN AERO REBUILD (304 stroked to 350ci flat top pistons std 4" bore)

[bjf66]

seems numbers look correct and found this article by COME dated 23/12/2014
Our stock engine has an actual compression ratio of barely over 8.0:1 Yes, we know GMH literature boasts 8.4:1 for these engines but the truth is that was factored without the thickness of the production .050" thick head gasket. Add the gasket and you will have no more than 8.0:1 Not exactly a compression level ideal for performance applications or for the addition of large increases in camshaft duration. Add large duration without a consistent proportional increase in static compression
Holden V8 Project Engine back on the dyno | COME Racing

 

[Immortality]

Yup.

Stock stroke 3.025"
Rod length 5.625"
Piston Compression height 1.71"

Deck height - (1/2 x stroke + rod + piston) gives deck clearance.

8.875" - ((.5 x 3.025") + 5.625" + 1.71") = -0.0275" deck clearance (piston down the bore on a nominal 8.875" deck height)

Been told stock 304 deck heights vary from 8.875 to 8.880 which only makes things worse.

 

[bjf66]

so if you deck block 0.040", piston top now sitting proud of the block by 0.007"
gets compression to 10.29:1 with 0.027" gasket and 63cc heads
the top of piston ring is 0.224" down from top of piston, so durable

Bore: (diameter)	4 in.
Stroke:	3.025 in.
Cylinder Head Volume:	63 cc.
Effective Dome Volume: Use (-) for Dome and (+) for Dish.	0 cc
Deck Clearance:	- 0.007 in.
Compressed Gasket Thickness:	0.027 in.
Number of Cylinders:	8
CALCULATE​
Compression Ratio :	10.29 : 1
Total Displacement (in.3) :	304.11
Total Displacement cc's :	4985.41

 

[Immortality]

You need about .040" clearance between the piston and head.

I'm going to move this thread to the V8 development area and change the title as it's become a technical discussion rather than a simple wanted thread.

 

[Deuce]

My other question is why your calculations keep coming back with 4985.41cc instead of as literature says 4987cc
Is your stroke calc out by a smidgen? Would that reduce calculated piston to deck clearance and change everything?

Also, do not aim for 0.020 clearance between piston and head. Pistons rock and will touch.

 

[bjf66]

not sure why the calculators off slightly used another one and shows similar results for comp ration however doesn't give the litres
so if need 0.040" then we are back to zeroing the block and skimming 3cc off heads to get to 10:1
seems I was a little generous with gasket at 0.043" thinking of Chevy BB
that should work

not sure how many thou 3 cc represents, and whether the intake side of head needs to be trued up

Bore: (diameter)	4 in.
Stroke:	3.025 in.
Cylinder Head Volume:	60 cc
Effective Dome Volume: Use (-) for Dome and (+) for Dish.	0 cc
Deck Clearance:	0 in.
Compressed Gasket Thickness:	0.041 in.
Number of Cylinders:	8
CALCULATE​
Compression Ratio :	10.1 : 1
Total Displacement (in.3) :	304.11
Total Displacement cc's :	4985.41

 

[Immortality]

Most gaskets are .040 or .041 crushed thickness.

 

[bjf66]

deburring block today cleaned up valley, a little polishing in corners where the head oil drains flow onto valley, starting to look a little cleaner

 

[gtrboyy]

If going that far what oil mods planned?

 

[bjf66]

What do you suggest ???
I don’t know anything about holden v8 other than what I’ve read over last few months and pulling this one apart