[308] carby 308 and carby 304

[DANNY8]

Thx heaps for the replies guys.

I'll hunt down a red/blue block and make a start with that. Is red/blue any better then the other. I just don't wanna be too picky coz I normally only buy them when they pop up cheap lol. And yeah I'll be getting the bottom end balanced on this one.

How would I go about getting 10.5 compression? I'll be using flat tops, and gonna get it zero decked. Is that enough or is there a certain amount that will have to come off the heads as well? Wanna run a crane 304 cam, also gonna be using arp main studs and rod bolts.

 

[soop]

Depends on what heads you use, carbie style heads will have higher static compression then the VN style.
I'm not sure if the 10:1 pistons for the VN is the same as the VK for that reason.

 

[ari666]

Engine Compression Ratio (CR) Calculator

your welcome

 

[383 hatch]

Ah, there is a notch taken out of one of the counter balances on the 304 cranks!

I'll find a picture for you!

EDIT: I found the photo but my PC keeps having a hissy fit when i try to put it on.

Basically the 304 cranks are missing a casting on the front of the crank, when you see the two side by side its very very obivious.

Yes, I'm aware of the crankshaft differences, thanks

 

[soop]

lol, no doubt. Your post just jolted something in my brain. Might be helpful to the OP anyway.

Worst photo ever but you can still kinda see it.

The little dongle bit on the front of the crank.
The one without it is the 304 crank.

 

[383 hatch]

Technically, that's not quiet correct....There's a bit more to it than that. 308's had the whole bump on the 1st counterweight (as per your photo) VK 304's had the whole bump still there but they were de-stroked (which resulted in an un-balanced engine) VL 304's had the bump machined off at the factory to re gain balance with the de-stroked crankshaft. VN-VR 304 cranks were then cast out of a mould made off a machined VL 304 crank so you can see the machined down bump on them. VS onwards cranks had a new mould which had the bump completely gone (as per your photo).

All 3 of my 304's have the machined down bump out of the mould as they're all VN cranks.

 

[soop]

Yep that's exactly what the information in that book says. What's really strange is I have a crank from a VQ 5ltr and there's no machining present where the bump is.

 

[DANNY8]

Engine Compression Ratio (CR) Calculator

your welcome

Thanks mate.

So to work out combustion chamber volume I'd have to measure the chambers in the heads? Like fill them with liquid and measure that? Piston dome volume would be zero with flat tops I'd presume. And zero for piston deck clearance if it's been zero decked?

Wat's the standard chamber size for VN heads? And wat roughly would the compressed gasket thickness be?

 

[ari666]

vn i dont know. 308 are 56cc, vn were more than that 88 or something. i thick the squish or a normal gasket is about .02 thou

 

[383 hatch]

VN heads are 64cc stock, compressed head gasket will be about 40thou. Flat top pistons will be 0 unless they have a valve relief, then it will need to be measured. 0 deck height will be 0 piston clearance on the calculator.