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304 rebuild

whiskeytango

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304 rebuild

After months of debate with myself/bank account I’ve decided I want to do a freshen up with higher compression pistons to allow for a decent mild cam while keeping it standard stroke.

I’m looking for a minimum of 9.5:1 compression to possibly pair it with a Camtech 49907. @50 223 227 and 585 lift.

Engine’s a VT roller cam 304 with MAF, banana manifold (will keep) and 5 speed manual. It’s going in a VS Ute with Pacemakers into dual 2.5” exhaust. Diff will also be 3.45 or 3.7 by then.

Honestly I’ve never rebuilt a bottom end before. I have no worries that I can do all the mechanical work, I am a little lost as to how to properly calculate compression when choosing what pistons to use. I mean will any flat top on a stock rod get me over 9.5:1 or do I have to fully measure the bores and do the math?

Throughout the rest of the year I’m going to start collecting parts so I can hopefully get it moving around the Christmas holidays.

Here’s a list I’ve started with what I believe I’ll need. Bolt ons, oils and all that good stuff. I’ve got some quotes on some items but most are just rough prices.

It’ll be a great help if you can let me know if I’m forgetting anything. Any input apart from “buy an LS” will be great even though looking at that total it’d make more sense.

Full gasket set $250
Bolts $150
Camtech 49907 $770
Link bar lifters $595
Valve Springs/retainers $462
Yalla Terra Roller Rockers $660
Rollmaster Timing chain $150
Powerbond Race Balancer $300
Pistons $300
Rings $200
Head skim/cleanup $400
Bore and hone $400
Tune $1,200
Coolant $30
Oil/filters $100
Waterpump $100
Oil pump $200
Belts $70
Engine Mounts $40
Paint/sealant/deg/random $200

Total $6,577
 

immortality

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There are plenty of compression calculators online to help you figure it out.
 

gtrboyy

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Here to be bad influence...scat or come stroker crank.....arp rod bolts & cometic headgaskets


*typed up more then deleted it
 
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immortality

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To calculate compression you need to know the following,

Stroke (304): 3.02 I think for 304...
Bore: 4" plus over bore Assume .020" so 4.020"
Compression height: 0 (get the block zero decked)
Head gasket thickness: .040" is fairly typical
Head gasket bore size : 4.040 to 4.060" is typical
piston volume: 0 (true flat top)
Head volume: ~61cc I think is fairly typical for VT heads.

Plug all that into an online calculator gives you about 10.1:1 CR
 
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whiskeytango

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Here to be bad influence...scat or come stroker crank.....arp rod bolts & cometic headgaskets
*typed up more then deleted it
Trust me I don't need the influence my head has been fighting me for months.
I had all the listed but I'm starting to build a house and other life **** so decided to cut a few grand.

To calculate compression you need to know the following,

Stroke (304): 3.02 I think for 304...
Bore: 4" plus over bore Assume .020" so 4.020"
Compression height: 0 (get the block zero decked)
Head gasket thickness: .040" is fairly typical
Head gasket bore size : 4.040 to 4.060" is typical piston volume: 0 (true flat top)
Head volume: ~61cc I think is fairly typical for VT heads.

Plug all that into an online calculator gives you about 10.1:1 CR
That is pretty much exactly what I needed thanks heaps for that!

I just had a quick search and think VT heads might be 58cc but using 58-62cc they're calculating either side of 10 which is perfect.

So essentially if I get the block zero decked, standard head gasket and any old flat top I should comfortably make it.

Any advice on a brand of pistons?
 

Not_An_Abba_Fan

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Look up the 304/308 oil mod, I did it to a stroker I built and it worked well.
 

immortality

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Back in the day I would have said ACL but I don't think those are available any more.

I was looking at the MACE pistons a while back but I can't comment on quality.
 

whiskeytango

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Look up the 304/308 oil mod, I did it to a stroker I built and it worked well.
From what I've seen I can easily remove the casting crap for the drain back channels and radius the pump in and out holes myself.

The only other one I've seen was the cam bearing hole and channel that Come does. Is this what you're talking about?
Is it worth it in a mild engine that I don't intend on flogging over 6k for extended periods?


Back in the day I would have said ACL but I don't think those are available any more.

I was looking at the MACE pistons a while back but I can't comment on quality.
Yeah there isn't too many options that come up. Probably save the pistons till last so I have more time to do some research anyway. I'll start collecting the rest first.

I wrapped my head around the compression thing now so I'm feeling more confident thanks for that.
 

Not_An_Abba_Fan

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From what I've seen I can easily remove the casting crap for the drain back channels and radius the pump in and out holes myself.

The only other one I've seen was the cam bearing hole and channel that Come does. Is this what you're talking about?
Is it worth it in a mild engine that I don't intend on flogging over 6k for extended periods?
The priority oil mod that is on the COME site is pretty good, I followed another tutorial, can't remember where from though. Oil pump mod, drilled an extra hole and ground the relief in number 1 cam journal, blocked another hole in number 4 (I think) crank journal. I can't remember the details as it was about 7 years ago. Even if you don't do sustained revs it's still a good mod to keep everything lubricated evenly, extends the life of your bearings.
 

VS 5.0

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There is quite a bit of content on aussieV8.com.au re the oiling mod.

IIRC TK383 on there has plenty of good info.
 

Not_An_Abba_Fan

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There is quite a bit of content on aussieV8.com.au re the oiling mod.

IIRC TK383 on there has plenty of good info.
Ahh yep, that's where I got my info from.
 

immortality

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There is quite a bit of content on aussieV8.com.au re the oiling mod.

IIRC TK383 on there has plenty of good info.
Best place for Holden V8 info.
 

losh1971

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Back in the day I would have said ACL but I don't think those are available any more.

I was looking at the MACE pistons a while back but I can't comment on quality.
ACL reopened a couple of years ago. They are making bearings again but not sure if they make pistons anymore. They no longer make gaskets but I wouldn't recommend ACL head gaskets anyway. They weren't a very good product compared to some other brands.
 

whiskeytango

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Best place for Holden V8 info.
Yeah sweet I'll look through his stuff over the weekend.

The priority oil mod that is on the COME site is pretty good, I followed another tutorial, can't remember where from though. Oil pump mod, drilled an extra hole and ground the relief in number 1 cam journal, blocked another hole in number 4 (I think) crank journal. I can't remember the details as it was about 7 years ago. Even if you don't do sustained revs it's still a good mod to keep everything lubricated evenly, extends the life of your bearings.
Yeah ok I found some youtube vids about it. Don't know if I wanna try do it myself though.
I'll certainly ask some engine shops when I get the block done though.
Suppose I have plenty of time to figure it out.
 
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