Putting 243s on a LQ9. Cam is a 226/236 .525 110 LSA. What is the largest valve size I can use without PTV issuses. Pistons are not fly cut.

 

A 230 intake lobe with .633 lift on 110 lsa had .052 clearance with stock valves on unmilled 243's with a .051 gasket

 

What is the clearence limit?

 

.080 intake is the standard. People do run less though

 

You MUST check for yourself, way to many variables.....

 

Something doesnt seem right there. I'm sure people have ran more duration with milled 243s and cleared just fine.

.052" With a stock gasket and stock heads with that cam doesnt make sense.

 

thats what you would think but i can tell you it is correct. the cam was bought from Ed Curtis and he sent the flycutting tools with the cam because he knew it was too close. he guessed .045, i measured .052. really makes you wonder what some people actually run doesn't it

 

See post #5.......

 

my question is why change valve size for the ammount it would cost to do it you could put a good down payment on a set of aftermarket heads

 

when talking about piston to valve clearance minimum are .080 int .100 exh, regarding to cam duration, lift and all that stuff, you can't make a rule for all cams, it also depends on cam architecture from factory, how lobes are located onto that cam from fac, you just can not figure or state all cams with same specs are gonna to show same clearances, as some said you have to check by urself, having or not head milled u better check it before u go with that cam.

 

So if I check my PTV clearance and its not enough, what can I do other than fly cutting? Push rod length?

 

So if I check my PTV clearance and its not enough, what can I do other than fly cutting? Change push rod length?

 

Fly cutting or changing the valve events are the only ways

 

you could either get thicker head gaskets or advance/retard cam (depending on what you need) changing push rod length won't work since they're hydraulic.

 

Thanks guys

 

Just to through some more variables at ya, went 240/244 613 596 109LSA +2 No flycutting, 64cc heads, GM .051 gasket, 2.04 Intake valve. about .063 clearance. STOCK Bottom LQ9!

 

Damn that cam is huge compared to what I'm running. Is that with flat tops with no reliefs at all?

 

STOCK BOTTOM LQ9 flat tops!! (I cheated tho, Trickflow 220 heads helped me a little)

 

DUH! I should have comprehended that when I read it. Thanks that info is what I was looking for. Still going to check when I do the swap.

 

Check out the LS2 GTO site if you want. LQ9 and LS2 are twins on rotating assembly.