Si Valves

[Nighthwk12]

I'm building up some ported heads. I Am looking to run SI valves. I have a N/A set up. Running LS6 springs. I'm just worried about the valves failing because they are under cut. What is everyones experience with them?

Thanks

[blueguy]

I haven't heard anything great about them, why not run L32 valves?

[Nighthwk12]

The intakes are oversized. I was looking at ZZP valves too. I could run stock L32 valves for the exhaust?

[blueguy]

That's my point, is there any reason why you need a larger valve? I don't think it'll hurt by any means, but I don't think they'll be beneficial persay.

If anything, manley or LS1 blanks cut to fit?

[GTPpower]

Either stick with stock, or go with Manley or ZZP's. Unless you really want to spend some money.

[Nighthwk12]

The intakes are already over sized from the previous owner. I was probably going with ZZP's for intake just seeing if I could get away with not changing push rods by sticking with the SI's.

Where could I pickup stock L32 valves?

[blueguy]

Junkyard?

Morad's?

Classified's?

Car-part.com?

That's where I'd start...

[GTPpower]

The intakes are already over sized from the previous owner. I was probably going with ZZP's for intake just seeing if I could get away with not changing push rods by sticking with the SI's.

Where could I pickup stock L32 valves?

Why are you thinking that you need to change pushrods?

[blueguy]

Milling heads?

[GTPpower]

I didn't ask you.

[blueguy]

I didn't ask you.

Well I replied to you, because it was a logical response.

Get off your high horse, right about now.

[231FUN]

I didn't ask you.

[GTPpower]

Well I replied to you, because it was a logical response.

Get off your high horse, right about now.

Responses like that, are a great way to spread misinformation. Please refrain.

[blueguy]

Responses like that, are a great way to spread misinformation. Please refrain.

Please feel free to point out the misinformation.

[GTPpower]

How could I possibly know if it's misinformation??? The OP is the only one registered to this forum that knows.

That is why I asked. Calm down.

[Nighthwk12]

Why are you thinking that you need to change pushrods?

ZZP site states the valves keeper groves are at the LS1 position and states there will need to be shims or shorter push rods.

[GTPpower]

ZZP site states the valves keeper groves are at the LS1 position and states there will need to be shims or shorter push rods.

That is correct. If you go with Manley, they are the same size as stock though, so your pushrods will be fine stock.

[matt5112]

Oversized valves on a N/A build.

Sounds like a waste of money.

If the intake valve seat has been modified to accommodate a larger valve, you can no longer run stock valves. So that ideas out.

Whats next?

OP: To make power with NA, you're going to need an aggressive cam, and spin well past 6000 rpm. Wes Blair style. (that other company did similar numbers with no serp belt during dyno)

What intake valves are currently in the heads?

[darkhorizon]

Port heads and run stock valves so you can go turbo when you get bored of 120hp

[Nighthwk12]

I have a GT2 cam in the car now and a high stall convertor waiting for the spring. The heads were free, ported and over-sized intakes already, so no waste of money there. I do plan on using this set up as a turbo build down the road so ZZP valves or manleys are probably the way to go.