304 EFI cylinder heads differences?

[adamRSLC]

A good friend of mine has a bit of a problem which i hope a few of the V8 brigade can help with.

He recently gave his heads to a reputable machine shop to be recoed and cleaned up , his heads were off a VT hsv 304 ( the sequental injected ones ) and were in imaculate condition with onle 50,000km's on them. When picking up said heads last week he noticed when he got them back that there was some corrosion around the water jackets and the head bolts that were also given to him ( he never gave them any) were very corroded .

Upon closer inspection when fitting the original head bolts to the new head they dont "mark" the head surface the same way as the corroded head bolts do .

My hope is that there some external/internal difference between the EFI heads that would lead him in some sort of direction . He will speak to the machine shop on monday but some proof /facts will always help an arguement .

adam

[Jim]

IIRC there is a notch on the intake port for the injector on the 304, which the 308 didn't have.

Sorry, not my area here, BigMuz will be along with some witty remarks on this.

[Bob Saget]

There is a difference from VN-VS to VT cycl heads but it's in the waterjackets, I don't know how to tell them apart externally.

[RVK 355]

The VT heads will have a heart shapped chamber, with a smaller CC then the earlyer EFI heads im led to belive

[director1356]

VT heads have a dimple (triangular in shape, on the intake side of the valve) between the valves to help raise the compression ratio slightly. Otherwise they're the same as VN-VS heads.

[bigmuz]

<Witty Remark for Secoh :D >

Externally they are the same I think. Chambers changed over time.

If they kept his ones and gave back another seth then his heads were probably more desirable. Go back and bust chops :D

[TK]

Yeah, they've done a change over for some other heads, common practice in big shops, they have reco'd heads on the shelf ready to go so when you bring in yours they give you someone else's thet they've already done.
Fine if you know your getting a 'change over' set of heads but in this case I'd be arcing up.
Biggest problem with change overs is if your heads are fairly good you may well be getting back heads that have been through hell & are on their last rebuild. Not as big a problem with iron heads but real bad with alloy.
Just a hint - jobbing shops (smaller shops) don't do change over shit, they'll rebuild your heads (or engine) so you know what you're getting back, it'll often take longer to get yours done instead of change over (& cost more) due to it being a one off job rather than a production run of crap.
Tell him to go see them & demand his heads back, then take them to a reputable jobbing shop & have them rebuilt properly.

Cheers
TK

[adamRSLC]

Thaks guys , thats a bit of info that can help us . Director1356 ill have a look for the dimples today , thanks again

adam

ps , The heads he was given back we think are VN/VR type.

[adamRSLC]

Had a look at the heads that were given and yes they are the correct VT heads , the combustion chamber is a different shape to vn/vr as director alluded too . Ill post up a couple of pics if their is interest.

adam

[BoganDAVE]

it is also a different volume, 58 compared with 62 cc chambers

[RVK 355]

just one thing, have you tried to swap heads from side to side to see if they do mark the same way as when you took them off?