rebuilding a 304 for 80 series

[dynomite]

hi guys
i''m currently running a stock 304 out of a vp ss its been in for some time now and has had a flogging. the engine still has the stock cam ,it has a sidewinder single plane manifould with a 600 holley and a sprintgas mixer on it and averages 25 ltrs of lpg per 100km I reringed it and added the bolt ons just mentioned before i put her in but wished i,d done more. I want to make sure i get it right this time.I,d like it to be a bit of a performer as i do like to give her a bit of a rev & leave it there but i also need to toe a heavy vessel now & then so if anybody has some genuine suggestions on the ideal compression ratio,cam selection etc it would be appreciated.
thanks. Dynomite

[Struth]

Stroke it 355, 304 is too small for an 80 series IMO.

Cheers

[dynomite]

yeh i already been looking at stroker kit prices etc but i still not sure wich way to go im just waiting for a bit more feedback from out there before i start spending the dollars ay
Cheers Dynomite

[georgey]

Stage 3 cam,gilmour drive,yella terra rockers maybe lighten your flywheel so it revs a bit freeer and quicker
Definitly upgrade the exhaust and get some extractors
Yake the carby in to get tuned and jetted either for low down torque or whatever you need.

There are alot of options depending on what you need it to do and your better off going and seeing an engine builder and telling them what you want it to do.

[Cammo30]

keep it simple, the easier to work on, the easier to fix if something goes wrong, stocker kit yes, 355. the blocks are already recessed from holden. ive been told to stay away from the evilbay and scat kits as they dont balance to well. pocket port the heads, dont polish, extractors and and free flowing exhaust.
Custom grind camshaft, depending on your fuel, I use clive cams, can PM you his number, just tell him what your doing and he can grind a cam to suit.
are you running petrol aswell?? if not go a 425 gas mixer mounted to a quadrajet throttle plate. then set the tune for lpgas only, what dizzy are you running? get that regraphed to suit. what year is your 80, there are two different adaptor kits. the earlier one had a smaller flywheel to spin and worked pretty good, but the 1fz gearbox adaptors had one bloody big flywheel and lost a shitload of low down grunt, great when there up and spinning tho..

gilmour drive,

What the hell for????? something else to go wrong

Cammo

[84sloth]

gilmour drive,

What the hell for????? something else to go wrong

Cammo[/quote]

because gilmour drives sound awesome

[Shifta]

the blocks are already recessed from holden.

The VP block wont be recessed, they were cast with the recess from VR Series II on ie VR stroker in GTS

[DIRTY ROCK STAR]

my 2c is keep it simple.
but hey make it go hard and enjoy

[wagone]

Start off by doing all the correct machine work. Bore + hone, 0 deck the block, Balance the assembly. Dont go to big in the cam shaft a crane 276 hydraulic would be a good cam. Some decent LT1 valve springs or if you have the money put some bigger double valve springs and rolller rockers on it. Id also convert back to the original banana manifold as there great for torque. A nice single 3inch exhaust and extractors would free it up.

For 4wding with that cam id keep it inbetween 9-9.5:1. If your out the scrub and only have shitty 91octane fuel to get you home you dont want to detonate it to death.

[Modified Toy]

If you stroke it get a VT Engine as the block has more clearance and most 355 kits no cleanence required and only a little with 383 and you will get roller cam also better than flat tappet and you can get more lift with roller.

Fit stainless valve seats to head for gas as the standard heads are only harded on the cast. Dump the banana manifold the are shit look at the port entry , go custom manifold in the 80 as you have more room to do this it will be the best thing you do.

If you go injection you can run say a haltech ecu with dual fuel maps and run gas injection also all from the one computer.

look wisely at you cam your will get one of the biggest from it.

prob need about 10 to 14 grand to do it right.

[Struth]

Any more than 2 1/2" single exhaust will cost you in torque, tri Y headers into a single 2.5" will work very well.

304s are already zero decked so maybe some flat tops and moly rings.

How much Hp or how many killerwasps are you chasing, remember that it's better to have less power and more torque, unless your car is a mall queen.

Cheers

[dynomite]

yeh she's already breathes through a 2 1/2 exhaust and sounds pretty sweet for an old cruiser. Yeh it does go to the mall a bit these days but probably not as much as some thats for sure it gets a run up the beach now and then and often gets sideways around the forestry trails at full noise but no real ruff offroad stuff anymore due to a work related back injury but i do have to toe my 2 1/2 t boat to the coast now and then.It certainly goes better than it used to when it had the original 1990 4 litre petrol donk in her, but you know how it is i just want more power,more fun.Some of us never really do grow up we still need our toys ha ha.I just sent a heap of emails around the place to get prices on 10:1 comp 304 and 355 short and long engines so i know where i going to put the goal posts but i trying to keep it under five grand if i can ?. I'd like to get around 300-350 hp without causing it drink more than i do. I also been looking at 350 chev crate engines to but i dont know if they will bolt straight in? bellhousing? spiggot shaft? engine mounts? radiator plumbing side? sump position ? I havn't really asked anybody yet !

[dynomite]

i''v got it sorted the holden 304 vp engine is coming out of the 80 series i just picked up a fully rebuilt 375HP 10:1 comp 350 chev carby intake engine that i'll run duel fuel for now complete with all new bolt ons ready to bolt in for under 4 grand. It was going to cost around 7 grand to stroke the 304 out to 355. Less painfull and quicker job this way. CHEERS

[mick80]

keep us posted
cheers mick

[wagone]

Any more than 2 1/2" single exhaust will cost you in torque, tri Y headers into a single 2.5" will work very well.

304s are already zero decked so maybe some flat tops and moly rings.

Cheers

How will a 2 1/2 inch exhaust cost you torque?? thats an age old wives tale. Maybe on a 3l diesel. Not on a healthy 5.0l.

And 304's are not factory 0 deck. There all over the place. Usually around 20thou down. Soon as you change pistons, resize conrods, grind cranks, etc it all changes again to. That why you dummy assemble the engine with the fully preped engine assemble. Measure deck heights at all four corners and mill the block accordingly. Flat tops will net you about 10-10.5:1 in a 304 if you do the sums.

630cc swept volume.
59cc's cylinder heads.
8.5cc's head gaskit.

697.5 / 67.5 = 10.33:1 compression.

[wagone]

I Dump the banana manifold the are shit look at the port entry .

So you can tell port flow by looking at the manifold??

While they are not good on a big cam, high comp screamer they work great on torquey engines like something for 4wding. The length of the runner helps this. We used to do some machine work on engines for peter starr and his 355's with his big throttle body manifolds worked killer with a fairly conservative cam shaft.

I built a 304 for a mate with good heads, double valve springs, crane 286, 9.5:1 comp (flat top piston with a small custom dish we machined in), standards manifold and throttle body it made 375hp and just over 400ft lb on the engine dyno.

Look at neil coopers hilux he runs a 383 holden with a banana manifold and its a real stump puller. He places up the front in nearly every event he goes in.

[Struth]

Any more than 2 1/2" single exhaust will cost you in torque, tri Y headers into a single 2.5" will work very well.

304s are already zero decked so maybe some flat tops and moly rings.

Cheers

How will a 2 1/2 inch exhaust cost you torque?? thats an age old wives tale. Maybe on a 3l diesel. Not on a healthy 5.0l.

And 304's are not factory 0 deck. There all over the place. Usually around 20thou down. Soon as you change pistons, resize conrods, grind cranks, etc it all changes again to. That why you dummy assemble the engine with the fully preped engine assemble. Measure deck heights at all four corners and mill the block accordingly. Flat tops will net you about 10-10.5:1 in a 304 if you do the sums.

630cc swept volume.
59cc's cylinder heads.
8.5cc's head gaskit.

697.5 / 67.5 = 10.33:1 compression.

I keep thinking solely of my VT 304 which is/are zero to plus .005 deck height. If you want to get pedantic then yes the cylinders may not necessarily be perfectly zeroed from the factory.

If you remove too much exhaust back pressure by over compensating on pipe size you will lose some of the bottom end torque these motors are good for.

[Modified Toy]

I Dump the banana manifold the are shit look at the port entry .

So you can tell port flow by looking at the manifold??

While they are not good on a big cam, high comp screamer they work great on torquey engines like something for 4wding. The length of the runner helps this. We used to do some machine work on engines for peter starr and his 355's with his big throttle body manifolds worked killer with a fairly conservative cam shaft.

I built a 304 for a mate with good heads, double valve springs, crane 286, 9.5:1 comp (flat top piston with a small custom dish we machined in), standards manifold and throttle body it made 375hp and just over 400ft lb on the engine dyno.

Look at neil coopers hilux he runs a 383 holden with a banana manifold and its a real stump puller. He places up the front in nearly every event he goes in.

Nope but a flow bench can! You have just have to feel the port entry to the heads and it's a 45 deg angle and it could be better.Thats why the ls1 manifold is heaps better,But it's just not the manifold it is the engine combination that makes it work just every little thing helps.


375 hp and 400ft lb torque just at 6,000 rpm not 2500

[dynomite]

I have give up on the chevy conversion and sticking to the 304 rebuild. I just hit the buy now button on a 355 Scat assembly with scat / chevy rods and 10.5:1 forged probe pistons for $2000 .No turning back now Just a bit more shopping and a bit of machineing and assembly to do and the old cruiser wont know what hit it.
Dynomite

[Struth]

You won't regret upping the cubes, the Cruiser will move along so much nicer now

[pricey]

Absolutely agree with NOT putting a Gilmer drive on. Just something else to go wrong I had one on the first motor in the comp 40, and all it did was do my head in. On a daily driver. . . . . . Not a chance. If it was a supercharger making the whine i could handle it, knowing its there for a good reason, not just a loud whine that does fark all else. I'd piss the petrol off as trying to tune both is going to be a comprimise in power. And as a few have mentioned keep it simple. A HEI dizzy is a good option as gas performs better with the better ignition. I've heard Iridium plugs work well with LPG but im only using standards.