monster81

...what size RRs r u running, 1.5 or 1.6 ?
should i stick with 1.5s, i heard the increased valve lift with 1.6s is a bit risky @ 6600+ RPM that there might be the posibility of valves smacking into the pistons !!!

RamAir95TA

iTrader: (2)

What are you doing running the 847 on stock heads anyway?

You won't have P/V issues with the 847 with 1.6 rockers, if you've got a stock bottom end.

monster81

hehe i know, but i loved the sound
and yes ive got a sock bottom end but with new rod bolts and will also get new main studs from ARP just for inssurance,,,
the reason why im a bit worried is cus im also having my heads milled to about 0.005-0.010 due to some scratches on the gasket surface of the head, im not sure if these scratches will cause any potential damage like water or compresion leak, scratches are not really deep but u can feel them by rubbing ur finger on them, should i be worried about this

RamAir95TA

iTrader: (2)

Even with the heads being milled, you still won't see an issue. Those scratches however need to be completely removed or you'll have plenty of compression/water issues depending on their location, size, shape, etc.

monster81

Great ,,,thanks man

myltwon

iTrader: (1)

with stock heads the gm847 will stop making power long before 6600rpm anyways

MadMike 97 Z28

iTrader: (3)

I ran the 847 with stock heads for a short period of time. The fact is that, that cam is not going to reach its full potential until you have ported heads and a bottom end that can support the rpms it will be capable of making power at.

but to answer your question I ran 1.52's, simply because 1.6's aren't necessary with such a big cam on unported heads. 1.6's will only cause strain on the valve springs with little to no performance gain.

TAEnvy

iTrader: (2)

Why did you get rid of the 847?