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

[gtrboyy]

You have that chart as 0 deck height & no dish in pistons.

Pistons will sit way down the bore unless block gets decked a decent amount & good forgies will have slight dish for flame progation where as cheap casties is usually a chev piston with valve reliefs.

Other side of it after all that mucking around with 308 crank instead of 304 will mean buying crank & pistons then getting balanced plus other machine work to get comp you want...scat crank won't be much more in the end except more torque & nicer manners with same cam.

 

[bjf66]

Yes the spreadsheet format didn't come out that well
Managed to buy some ACL (std) flat top pistons #RA9104 in weekend, this at least removes 10cc dished piston and moves compression up a point
although cant find much detail on the ACL part # as was originally looking for ACL #9490 not sure whether this was the Race series piston
looks like the block needs to be decked to get compression + 9.5:1
0.027" gasket: 10:1
0.043" gasket: 9.68
still in two minds whether to go stroker kit,

Bore: (diameter)	4 in.
Stroke:	3.025 in.
Cylinder Head Volume:	63cc
Effective Dome Volume: Use (-) for Dome and (+) for Dish.	0 cc
Deck Clearance:	0 in.
Compressed Gasket Thickness:	0.043 in.
Number of Cylinders:	8
CALCULATE​
Compression Ratio :	9.68 : 1
Total Displacement (in.3) :	304.11

Now to locate machine shop Southern Melb area (Mornington)
what would be going rate for:

decking block:
clearance for stroker:

 

[Immortality]

What is the compression height on those ACL pistons?

 

[bjf66]

not sure when they turn up in a few days I'll measure them up along side the 10cc dished piston taken out, cant find much about the #RA9104

 

[gtrboyy]

I wouldn't zero deck block if staying 304 just check with straight edge & maybe hit it with stone...baby 276 or similar modern grind & treat it as a speed rebuild.Bolt on yella terras rockers & spring upgrade will work fine with stock stally.

All that machine work,time & money will go out window if turn around & decide to go stroker later on.

Must say used to think 5 litres was enough untill got my first stroker....then wanted them all either 355 cubes or near standard with bolt on mods...night & day difference lol

 

[bjf66]

pistons turned up
set #2 piston up
with piston at TDC, have 0.033" gap which brings compression to 9.27:1 with standard 63cc chambers, and 0.027" head gasket
which is an improvement over the 10cc dished with 0.043" giving 8.03:1
However need to get the compression up so looks like will be decking block to 0.
that will give:
0.043 gasket: 9.68:1
0.027" gasket: 10:1
reducing CC from 63cc to 60cc (not sure how much that is in inches) will give 10.51:1, but that's getting up there

10:1 should be enough

 

[gtrboyy]

Personally I'd leave it there just go 276'ish baby cam & bolt on yella terra...will have more go than stock & should work fine with stock stally & diff gears.

Fairly sure compression factory vn-vs 8.5:1cr & vt 8.8:1 so not sure how you got 8.03cr

 

[Immortality]

What is the compression height on those ACL pistons?

I was under the impression stock compression was 8.4:1 but if the machinist was having an off day and didn't mill enough of the block decks than it's easy to loose a bit of compression.

 

[bjf66]

yes the pistons taken out 10cc dished 1.71
the pistons going in 1.72" flat top
if you take away the gasket thickness then numbers in comp ration look okay, however when you add gasket thickness compression drops considerably

Bore: (diameter)	4 in.
Stroke:	3.025 in
Cylinder Head Volume:	63cc
Effective Dome Volume: Use (-) for Dome and (+) for Dish.	10 cc
Deck Clearance:	0.033 in.
Compressed Gasket Thickness:	0.043 in.
Number of Cylinders:	8
CALCULATE​
Compression Ratio :	8.03 : 1
Total Displacement (in.3) :	304.11
Total Displacement cc's :	4985.41

this using flat tops, and 0 deck height with 0.027" gasket

Bore: (diameter)	4 in.
Stroke:	3.025in.
Cylinder Head Volume:	63cc
Effective Dome Volume: Use (-) for Dome and (+) for Dish.	0 cc
Deck Clearance:	0 in
Compressed Gasket Thickness:	0.027 in.
Number of Cylinders:	8
CALCULATE​
Compression Ratio :	10.1 : 1
Total Displacement (in.3) :	304.11
Total Displacement cc's :	4985.41

 

[losh1971]

Some engines don't use head gaskets.