LS6

Greeting

I wonder that a 5.3 head can have 2.165"/1.6" (intake/exshust) valves?

The 5.3 heads is a killer mode with proper porting!!! I'm trying to see the results with real big valves, but will the head accepted with minor modification or not?

Isolde

iTrader: (4)

I'll bet not. GM had to move stuff around to fit those huge intake valves, hence the offset rockers.
Further, you never want the port to be the flow-limiter. It's supposed to be the valve.

LS6

Then what is the maximum valve sizes it can be installed on the 5.3 for the intake/exshust?

LS6

from the search, I found the maximum is:

2.08"/1.6" (Intake/Exhust)

Can any one confirm it is or did some installed? and does it require the valve seat to be changed or the original seat can accomodat the larger valves?

Thanks

1madss

iTrader: (10)

The 2.08/1.6 are what they are putting in the Stage 3 heads for larger bore (4.00" and up) motors. These are going to be too big for a 3.9" bore. I had 2.055/1.6 valves in my old MTI Stage 2 heads, but to be honest I don't think they made any more power on my LS1 than the 2.02/1.55 valve heads.

I believe that they largest that the stock seat can take is a 2.02 Intake.

1CAMWNDR

iTrader: (21)

That is not correct. The valve is in the same position. The rocker is offset to move the pushrod and rocker bolt away from the wider intake port.

You can have the stock seats removed and larger seats put in, probably even for a 2.165" valve. But will the valve hit the block, and if not will it be shrouded by the cylinder wall negating the $$$ of the mod?

LS6

Thus, it can have the 2.165"/1.6" valves on the 5.3 head
The 5.3 will be fitted on the 6.0 Liter engine, where the bore is 4.0". I had the idea since the LS3 has a 2.165"/1.6" valve that many had installed on 6.0 engine...

LS6

I hope porter co. will drop in with advice

LS6

any advice

nastychevelle

iTrader: (7)

Physically, they will fit the head has a 3.78 bore for the 5.3. 2.165 + 1.6 = 3.765. But, even if you put them in the head, it would be shrouded because the valves would be so close to the chamber walls. If you had the chambers opened up i would see this being beneficial. But then again, if your going to be doing all that work why not just start with a bigger chambered head?

chrisfrost

iTrader: (8)

Hello , the biggest valves I've heard of in a 5.3 head is 2.00" in and 1.60" ex .
Any increase in valve size requires different valve seats , think about it , You could put 10" valves in with 2.00" valve seats and You'll still have 2.00" valves . The valve seat is the restrictor when talking valve sizes , the inner diameter of the valve seat . If they made narrower valve seats using more durable materials they could "effectively" increase the valve size just by installing valve seats with a larger inner diameter .

nastychevelle

iTrader: (7)

LS6

You have a point...

From experimental, valves when upgraded in term of bigger size, you see improvement in the power and evident in the response with the engine is under load, although I'm refereeing to increase of + 0.02 inches (2.00" to 2.02").

If 2.165" / 1.6" of valves would fit on the 5.3 or LS1 (5.7) heads or LS6 (5.7) and require valve seat change with no problem of champers interface, then I would like to go with.

racer7088

Those size valves would be hitting the bore at 3.780

1CAMWNDR

iTrader: (21)

I think he understands they will not fit in the small bore of the 5.3.......right? OP, what bore motor are you using? It seems he just wants to know if he can use the 5.3 heads with the larger 2.165" valve.

racer7088

Valve spacing is around 1.915 on normal LS1 heads so you could do it if you put in bigger seats but you'd only have .030 or so between the valves and there might not be enough metal in the heads to take them out that much to match. On a larger bore they would not hit but 3.780 bore would not happen.

Prorac1

iTrader: (4)

OP said that this was going on a 4.00 bore 6.0. Eric L

racer7088

The LS3 heads have different valve location and spacing. Valve spacing is wider (about 2.010) and intake valve is closer to the bore than a normal LS1 head.

chrisfrost

iTrader: (8)

Ok guys , hears the scoop . I have a pr of 706's and a pr of 862's , both heads used on 5.3L engines . There is 1/32" on either side of the in and the ex valve seat to the edge of the combustion chamber. Between the valve seats there is 1/16" . So if You were to but the valve seats right to the edge of the combustion chamber , You would have .060-.065" extra because I don't believe You could safely put the valve seats much closer together without much risk of cracking the aluminum between the seats . Maybe You could take a little of that area , but not much . Lets say You could take .020" from between the valve seats and .060 from the edges , that's .080" . And You're talking a difference of 2.165 minus 1.89 equals .275" . So I would have to say , no way would those valves come even close to fitting . There are other issues than that , to move the valve seats closer to the chamber walls would require moving the centerline of the valves/seats which I doubt You could find any machinist that would do that .....etc Good luck with which ever direction You end up going

LS6

Gents

Your experience contributed well. It is always good to take other opinion

It looks like 2.08" & 1.6" hallow valves. Will this require to replace the original factory valve seat to accommodate the new seats?

Thanks