Holden 304 rebuild

[AC]

Hi,
just about to freshen up my 304 in my GQ auto. I am wanting to build it for torque and maxing rpm out at around 5700.

just after options on what the engine should contain i.e should i go 355 stroker or keep with standard internals and install a better cam etc, GRP A injectors etc

Any thought would be appreciated, the engine will have heads designed for lpg


Thanks Alan

[bogged]

speak with joel at PGS in Mornington.. seems to know his shiz.

PGS 4WD is his name on here

[ZAPPA]

The injected heads flow alot better than the old red heads, Im pretty sure they will flow 460hp as they are. As you are building it for tourqe the standard valves and ports are perfect. Small ports and valves equals air speed, which also helps atomize the fuel better. Stroker cranks are getting cheaper now. You have heaps to choose from, come racing, pro stroke harrop and there is a mob called pro-comp making really cheap gear. As far as a cam goes if you can affford it you cant beat a hydraulic roller for drivability and response. I dont know what sort of block you have, but the later blocks have the longer lifter guides for the roller lifters and also are already releived for stroker cranks as they were offered by holden. The standard intake should be alright up to about 6000rpm , they get restrictive after this.
Cheers
Zappa

[AC]

The injected heads flow alot better than the old red heads, Im pretty sure they will flow 460hp as they are. As you are building it for tourqe the standard valves and ports are perfect. Small ports and valves equals air speed, which also helps atomize the fuel better. Stroker cranks are getting cheaper now. You have heaps to choose from, come racing, pro stroke harrop and there is a mob called pro-comp making really cheap gear. As far as a cam goes if you can affford it you cant beat a hydraulic roller for drivability and response. I dont know what sort of block you have, but the later blocks have the longer lifter guides for the roller lifters and also are already releived for stroker cranks as they were offered by holden. The standard intake should be alright up to about 6000rpm , they get restrictive after this.
Cheers
Zappa

Thanks for the info, the engine is a vp block which I will keep with, I have been told that if i place a vr/vs block into the vehicle that i may have to get it re engineered. Do the 355 engines run much hotter than the 304?
Currently the 304 runs consistent and never gets hot, i do run a 30mm body lift which probably helps. long term I am thinking about LPG so I would need to factor the additional heat from 355 and LPG. Is there a particular preference to camshaft, ie 218 crow can that is best suit to the 304 once it has been stuck in a GQ. Standard 304 engines probably have the right came for a commodore but not for a GQ. Any ideas on the preferred cam would be appreciated. The current 304 is matched to a stage t700 not the original nissan auto.

thanks Alan

[ZAPPA]

JUst because you stroke it wont mean that u will get overheating problems. I guess its proportional to power output. If it were a 400hp mill yeah maybe. You will pick up some horsepower with the stroker but its the tourque that will increase alot. After i stroked the 308 in my tonner i only picked up 15hp,(the hi stall and auto zap abit) But the you notice the extra tourque. Obviously when you increase the tourque u wont have to work it as hard so it may even run cooler!. As far as the cam goes, the standard cam is probably not too bad, dont forget holden had to get the best emmissions so they are efficient. Go onto COME racing and have a look at their cams, they are a little bit dearer than catolouge cams but you get a cam that is specifily suited to your combo. Give them a ring and just make sure you have all the info. Tyre size , diff ratio, gearbox ratio(they will know that im sure) Vehicle weight and obviously tell them exactly what u intend to do with the vehicle and they will grind you up a cam!! If they are to pricey you can try and match there specs to a catolog cam. Dont forget to tell them if its gunna be lpg dedicated or dual fuel.
There is lots of info if you need it let me know how you go. What sort of economy do you get with the 308 as is?

[AC]

JUst because you stroke it wont mean that u will get overheating problems. I guess its proportional to power output. If it were a 400hp mill yeah maybe. You will pick up some horsepower with the stroker but its the tourque that will increase alot. After i stroked the 308 in my tonner i only picked up 15hp,(the hi stall and auto zap abit) But the you notice the extra tourque. Obviously when you increase the tourque u wont have to work it as hard so it may even run cooler!. As far as the cam goes, the standard cam is probably not too bad, dont forget holden had to get the best emmissions so they are efficient. Go onto COME racing and have a look at their cams, they are a little bit dearer than catolouge cams but you get a cam that is specifily suited to your combo. Give them a ring and just make sure you have all the info. Tyre size , diff ratio, gearbox ratio(they will know that im sure) Vehicle weight and obviously tell them exactly what u intend to do with the vehicle and they will grind you up a cam!! If they are to pricey you can try and match there specs to a catolog cam. Dont forget to tell them if its gunna be lpg dedicated or dual fuel.
There is lots of info if you need it let me know how you go. What sort of economy do you get with the 308 as is?

Currently get 400ks of 90 litres, just run 33's, other than memcal upgrade and extractors it is stock. i was considering looking at puttng a slightly bigger throtle body on as well..

[PGS 4WD]

Good advice, the only thing is the manifold, unfortunatly the 65mm throttle body and manifold are hugely restrctive, you will be hard pressed to make power over 4500 rpm with a 355 and the standard EFI manifold. Just recently I rebuilt and tuned a 304 Walkinshaw(twin throttle group A manifold), mild cam stock heads, it made 187 rwkW with a very flat torque curve, a few months earier I tuned a 355 stroker. It had a larger cam, crane 386 which is a popular choice for the Holden V8, with a standard manifold the most it could muster was 165 rwkW at 4500 rpm, the power stays at that untill 5800 rpm and you can clearly see the manifold vacuum building up and the dyno datalog.
There are manifolds available, JHP make a big throttle body manifold, previously STARR Performance manifolds, and C.O.M.E. and Harrop. A budget option is a 4 BBL manifold, and a twin throttle adapter, or a 4BBL throttle body such as the Holley one.
I have used the C.O.M.E. crankshafts in numerous vehicles without a problem and can reccomend them for cost effectivness, the Harrop and crankshaft rebuilders products are possibly better but unless you are reving the engine over 6500 rpm or adding forced induction I wouldn't bother.
The most important things for you are camshaft selection and compression ratio, these must be selected so as to work most efficiently with the weight of the vehicle, gearing and use.
The engine will require retuning and larger injectors if you've done it right.

Cheers

Joel

[ZAPPA]

Im pretty sure you can still get the starr manifolds, they were basically the front chopped off the old one and a bigger throttle body and neck welde4d on. Before you buy a manifold check out comes new twin throttle body! Its a ripper. Not really that pricey as they give you absolutely everything you need to bolt it on. I run 10.5 c.r in my tonner and its right on the borderline, have to run ultimate to control pinging although mine is not injected. PGS would know what you can get away with on the injection. I think he meant a 286 cam which is what I have, probably no good for 4wheelin, talk to COME about the cam.
Zappa

[PGS 4WD]

Yes thats what I was saying, they are available through JHP, they bought the patterns and rights from Peter STARR when he went under.
It is a changeover manifold where they cut the front off and replace it with a larger casting and a 90mm throttle body, it works well and accepts all the standard IAC and TPS, all you need is a larger air box and ducting.
I ran twin gas carbies and retuned Delco EFI on my VK 304 with Higgins ported VN heads soild cam etc (12.7 sec at 108 mph) 220 rwkW. The Redline Sidewinder carby style manifold was a chearper option but requires a bit of fabrication as you have to drill the injector bosses out and mount fuel rails and stuff.

Joel

[AC]

Good advice, the only thing is the manifold, unfortunatly the 65mm throttle body and manifold are hugely restrctive, you will be hard pressed to make power over 4500 rpm with a 355 and the standard EFI manifold. Just recently I rebuilt and tuned a 304 Walkinshaw(twin throttle group A manifold), mild cam stock heads, it made 187 rwkW with a very flat torque curve, a few months earier I tuned a 355 stroker. It had a larger cam, crane 386 which is a popular choice for the Holden V8, with a standard manifold the most it could muster was 165 rwkW at 4500 rpm, the power stays at that untill 5800 rpm and you can clearly see the manifold vacuum building up and the dyno datalog.
There are manifolds available, JHP make a big throttle body manifold, previously STARR Performance manifolds, and C.O.M.E. and Harrop. A budget option is a 4 BBL manifold, and a twin throttle adapter, or a 4BBL throttle body such as the Holley one.
I have used the C.O.M.E. crankshafts in numerous vehicles without a problem and can reccomend them for cost effectivness, the Harrop and crankshaft rebuilders products are possibly better but unless you are reving the engine over 6500 rpm or adding forced induction I wouldn't bother.
The most important things for you are camshaft selection and compression ratio, these must be selected so as to work most efficiently with the weight of the vehicle, gearing and use.
The engine will require retuning and larger injectors if you've done it right.

Cheers

Joel

thanks for the advice Joel, what would you reccomend for a camshaft spec and preferred compression ratio?

I am wanting the torque to come in low and max revs not to go past 5800

[GASDRX]

Great points by ZAPPA and some of PGS.
I think joel had a typo, 386 cam most defiantly 286 crane which would be way too big for a 4wd unless maybe for out back challenges. Stay away from solid cams for your application.
355 with 10 to 10.5 comp and leave cam or just a couple up from standard. Best bet as Zappa stated is the hydralic roller cam. If you put one from a vt into yours that would be great but need machine work to fit roller lifters.
For torque wise the standard manifold would be fine but power no.
What exhaust are you running? Good extractors and twin cats are a must.

With the higher petrol prices make the combination more efficient. 355 and compression and good exhaust.
Fit a big cam and watch the fuel gauge go down

[PGS 4WD]

Yes sorry "286". You should see how many typo's I catch before I post! Fat mechanics fingers.
10 to 10.5 would be fine, I'd lean towards 9.5 to 10 myself unless you are prepared to buy premium, If running duel fuel then it's best to aim for 10 to 10.5 as LPG and premium have more similar ignition timing requirments and the octance rating to cope.
You can buy a roller camshaft and lifters to go straight in, Crane is just one company that makes them to suit the low lifter bores, they are similar to what the small block chev uses with tied pairs of lifters.
They are certainly the bees knees but somewhat dearer. As they have much faster valve opening rates and more lift over the same duration when compared to a flat tappet they, will make more power /torque.
You can often afford a slightly larger cam in an auto (5 degrees more) in a heavy 4wd as they won't stall, but if you have to winch and traverse at low speed (rock and stuff) with a manual I'd suggest keeping the camshaft under 218 degrees at 50 thou as bigger cams are prone to being unstable at low rpm. Wider lobe centres will produce less peak torque and power but a broaded spread of power that often suits a heavy vehicle, around 112 would retain suitable idle quality and vacuum. Tighter LCA's would result in rougher idle and a narrower power band it makes a bigger peak figure that might look cool on a dyno figure but honestly could be quite crap to drive in a heavy 4wd....better in a Commodore with ratios and stall converter.
Also wider lobe centres tend to return better economy as they are efficient over a larger power band and have less valve overlap.

Joel