Hi ,

I am thinking to get a larger valves ..... something like (2.02,1.57) or (2.055,1.60) ...... but without porting my heads .

I mean get larger valves on stock heads ...... is that OK ??? is it worth it ?? can I expect more power ???

I want the car for street not for drag

Thanks

 

Larger valves will not help you if you do not open up the seats to match them by porting them. You might pick up some slight gains by having the stock seats machined with a nice 3-angle valve job and have the valves matched to them.

-Tony

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Nine Ball:
<strong> You might pick up some slight gains by having the stock seats machined with a nice 3-angle valve job and have the valves matched to them.

-Tony</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks

but can you please give me more expline ???

and do you see that this job is wrth it ??

and do you have some examples ?? I mean do you know cars that did this job ??

Thanks again

 

With a light port job to smooth out the valve bowl areas, and a 3-angle valvejob, you should pick up about 20 rwhp with no other changes. I'd rather go all-out on the heads and do it once though.

Tony

 

Thank you Tony , now I got it <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Well , I wish to read from guys that did this and tried it , or guys know someone did it , to see what is their reviwe !!

 

Fahad,

Just some additional explanation of what Tony was saying...

I'm new to the LS1 so I can't give specifics on it's particular issues, but in general...

If you go through all the expense of having the valves installed, seats cut (or replaced with bigger seats, depending on how big you mean), valve bowls ported (to match the bigger valves), etc...... You may be better off just buying a set of fully worked stage-II type of heads.

You may end up with the same cost (or close to it) and better power gains.

Gordon

 

Thanks..Gordon

Now I got it about valve bowls ported but did you know what is that mean 3-angle valve job

And I mean who tried it or if you know someone did it ...

Thanks ..

Fahad ,

 

Fahad,

A 3-angle valve job is a common mod for hi-performance use. The standard cut on a valve seat & the back side of the valve (where the valve contacts the seat) is 45 degrees. This is fine for a "grocery-getter", but the sharp edges of the single cut, actually hurt the flow of air past the open valve & seat.

A 3-angle cut would have an additional angle cut abouve & below the actual seating cut of 45 degrees. For example ... 25 to 35 degrees on the chamber side & 70 degrees on the port side. This has the effect of smoothing & rounding the edges of the seat & valve back side. Hence.... more air flow.

This procedure is always beneficial, on any performance engine.

 

No benefit with 5-angle over 3-angle. Just alot more work, and possibly harder to match components fit-wise with that many cuts.

-Tony

 

Hmmm..... I was gonna mention the 5 angle (and even 7 angle) thing in my post above ...

When you are all out racing - for the big fame & money.... it does make a difference. However it's a high $$/gain ratio, as with any top level racing.

The idea is just more cuts above & below the actual seat cut ... making the angle past the seat and back side of the valve more & more rounded (less sharp edges).

On our street cars & the levels of flow we are dealing with, it's not a very good trade off for the cost.

Also, in order to get all those cuts in, the actual seat has to get narrower and narrower.....shortening the life of the seat.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Hmmm..... I was gonna mention the 5 angle (and even 7 angle) thing in my post above ...

When you are all out racing - for the big fame & money.... it does make a difference. However it's a high $$/gain ratio, as with any top level racing.

The idea is just more cuts above & below the actual seat cut ... making the angle past the seat and back side of the valve more & more rounded (less sharp edges).

On our street cars & the levels of flow we are dealing with, it's not a very good trade off for the cost.

Also, in order to get all those cuts in, the actual seat has to get narrower and narrower.....shortening the life of the seat.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

May I ask one question about 3-angle thing? - SLP (and some other places) offer 5-angle valve seat treatment. However it appears that performance gains are negligible, if any. Can anybody clarify, if 5-angle is really beneficial over 3-angle?