[308] VH 308 - advise about head selection please

[uglyGMH]

Hey people...

I'm in the very early process thinking about a 308 build for a VH commodore and have question about what heads i should go with...

(think but need to confirm) I have just purchase a ex cop 308 short motor (VH commo - VT PREFIX) that has Aussie 4 speed bolt pattern - this 308 was stored for many years after it lost oil pressure and is a virgin bore... The Heads have bigger valves.... motor needs rebuild..

1st I'll start with what i want from the finished engine...

308 engine 300hp tops, will run a supra 5 speed gearbox - will re bore/hone, run new flat tops pistons and deck block to pistons...

I'm very open to what to do with heads... hear a lot of good stuff about VN style and i'm not to worried about pollution stuff... but mainly want to hear advice about heads...

look forward to ya feedback people but remember i'm not chasing big HP.... tops 300hp

 

[EYY]

VN heads will do what you're after with not much more than removing the casting flaws and blending the bowls. But it also depends on your cam selection and compression. A stock stroke 308 with flat tops and VN heads with a 286 and 10.5-11:1 compression properly set up and tuned will provide around 190-220rwkw depending on who tunes it and other factors such as auto/manual, exhaust, intake manifold, fuel type etc etc.

All still achievable with old style heads, but its much more difficult and you'll end up spending around the same money. Old heads - the intake manifolds/extractors are cheap, but it costs a fair bit to get them to flow well. VN heads - the intake manifolds are very expensive as are extractors. For each setup you'll need to spend money in different areas.

 

[Immortality]

Early style heads will get your 300hp easy enough with a little work.

I'd suggest heading over to the AV8 forum as there are some bloody smart engine builders there than can help you with exactly what you need.

 

[Bigfella237]

~ I have just purchase a ex cop 308 short motor (VH commo - VT PREFIX) that has Aussie 4 speed bolt pattern ~

Sorry to say but a "VT" prefix is just a plain old everyday blue 308, the only thing "ex cop" means for that engine is that it had the crap flogged out of it from stone-cold every day when it was new.

All blue 308 blocks after about November 1981 were Aussie bolt pattern, manual and auto.

I think you're confused with the high output "V5H" option 308, which had a "VZ" prefix and was only fitted to BT1 option (manual trans) cop cars?

Andrew

 

[uglyGMH]

Sorry to say but a "VT" prefix is just a plain old everyday blue 308, the only thing "ex cop" means for that engine is that it had the crap flogged out of it from stone-cold every day when it was new. All blue 308 blocks after about November 1981 were Aussie bolt pattern, manual and auto.

I think you're confused with the high output "V5H" option 308, which had a "VZ" prefix and was only fitted to BT1 option (manual trans) cop cars?

Thanks for clearing that up for me bigfella I didnt think about "V5H prefix"... I knew the VT prefix was VH or blue 308 motor and that's mainly what I was after... took the ex cop thing with a grain of salt but it would of been nice... engine was priced well to rebuild and shes a virgin bore...

Hey can you recommend any advice around heads.... cheers

 

[Bigfella237]

It depends on what you're after? If you want to keep the "factory look" then maybe get a pair of period-correct Yella Terra heads or similar and paint 'em blue.

Otherwise I'd go for the VN-onward design (and cam to suit as the valve configuration is different), either have someone do the work on a pair of standard heads or again, go to someone like Yella Terra. And obviously the exhaust headers will be different from the pre-VN heads as well.

Note that you'll need a standard pair of heads to start with/exchange for either option.

Or if money is no object, buy yourself a pair of alloy heads, there are a few different brands around, my market knowledge is a decade out-of-date but Yella Terra used to sell Dave Bennett heads, or COME Racing used to do them, or I think Harrop does them as well (there are likely other brands too).

It all depends how much you want to spend and how much HP you want to make. Getting power from an old Holden V8's is mainly about making them breath easier... big intake, big cam, big valves, big exhaust.

Also if the budget allows, I would strongly recommend going EFI. If using the VN heads you can go with a factory EFI intake for cheap, otherwise you can buy throttle bodies that bolt on in place of a standard carby (same manifold, same air cleaner, etc.) and they're pretty much self-contained and self-learning these days, not to mention virtually maintenance free!

Andrew

 

[Immortality]

Damn, all that to make 300hp......

Small valve early heads will do that easy enough with a little porting work without having to spend money buying other heads and everything else to suit.

Bigger isn't always the answer and you certainly don't need huge heads/intake and cam to the power he's after.

 

[gtrboyy]

Top end really depends on look you're after...stock look or modified.

Get the bottom end correct with stroker kit & mild cam it will make the torque you want mostly where you will use it...these days stroker kit is good value mod.
As a minimum if staying 5 litres flat tops,aim for 9.5-10.1 cr & suitable cam

I'd be inclined to keep all the stocko top end just get it all reco'd as quaddie/manifold & hei gear is good also not that hard to get performer manifold & & extractors cheaply particularly if 300hp is your goal I'd just want to get the power where you want it hence stroker.

 

[EYY]

Yella terra heads aren't great. Work with what you've already got if you're sticking with early heads.

 

[gemiracer]

Yella terra heads aren't great. Work with what you've already got if you're sticking with early heads.

What? They are probably the best pieces of gear you can buy for one of these old 308s