Hey guys, I got a little tired of seeing the argument of " sure its safe, but I didnt measure..blah blah blah"...so while I was doing my heads cam swap I made sure to try and check everything and being as safe as I can. So I went with an MS4 cam, 239 intake duration, 242 exhaust, .649 intake lift and .600 exhaust 111.5 LSA and swapped over a set of ported 706 heads and I used my old stock head gasket for the test, light tester springs and such...anyways on to the results. Drum roll please I had NO clearance at all on exhaust side...let me say that again...NO clearance, I actually had slight contact with the piston. intake I had .020 on intake side. I even re-done the test again to make sure I had everything lined up and checked correctly (cam timing and such) everything checked out and I recieved the same results the second time. So it looks like Ill be getting some fairly large reliefs cut. I really hope this ends the silly debate about this cams clearance and how important it is to measure and degree before completing swaps

 

Did you check the clearance with the stock ls1 heads?

 

Were the heads decked?

 

That's backwards. Intake should be closer than exhaust

 

Whats chamber size on the heads? Stock or decked?

 

Heads were bone stock truck 706 heads when I done this, no I did not try on the 241s, I was under the impression they are identical to the 706 besides a smaller chamber for higher compression

 

I done the check on piston one first time and piston 2 the second, the pics are from piston 2 (front passenger side) am I wrong in assuming the ptv clearance are the same between 241s and 706s? If so then I would highly recommend everyone whom purchases this size cam have flycuts, now granted I also know that not all engines are the same and some may have .020 and .040 but for me that's way too close even for normal driving in my opinion.

 

Why would you think that?

 

Well I'm guessing I'm wrong but on the setups I've measured it's always been intake tighter than exhaust. My assumption was it was partially due to the valve sizing.

 

Check your dot to dot on install! Good news is with over 5,000 ms4s in the field when everything's right you will have absolutely no issues at all!

 

what are you using for your "clay"? looks like silly putty..... it looks to have molded accurately im not debating that. just curious as is looks soft and shiny. I use modeling clay, firmer than play dough and other similar stuff. holds up better for measuring.

 

Yes sir, dot to dot all lined up! Also thank you guys for your help and professional manner in choosing this cam, I'm sure I'll love it. With that said I'm sure many of people have used this cam with no issues at all and I'm not debating that in the least, my only reason for the post was to end the debate on what this cams actual clearance is, and that it should be checked, degreed and measured for ANY cam, not just this one. However I do in my own opinion suggest that people who buy this cam concider flycutting to be extra safe, also so they can have less worry about hitting 7k on the Rev

 

The container says Modeling clay, however the brand is PlayDough, so I am going to assume it is regular play dough which is one of the many factors that led me to test twice to make sure on two diffrent pistons.