OST-029: California here I come.....

[oldeskewltoy]

As I alluded too, the cams have arrived. They are a pair of Catcams 7105136 exhaust cams. As the box labels, and the cams indicate.



Since I'm setting the valve clearances, and the cams are more or less identical, I've labelled them "I", "E" so there can't be any mixing of one to the other. This will also help my client get them back in the right places once the head is bolted on.






These are a MILD bump in duration and lift over Bluetop cams.




Just a reminder... early TVIS cams are 240 total duration, 204 duration@ 1mm lift, with 7.5mm cam lift.



Ok, why go with such a "mild cam" a few reasons: 1) California emissions, that on its own can make or break this build. 2) My client is keeping the stock 9.4 to 1 pistons - he will be adding a thinner head gasket, and the chambers are smaller, but this engine won't be breaking past 10 to 1, so keeping as much trapped compression (DCR) is important. The ramp on this cam is pretty aggressive ("foot" is only 13 degrees) so even though the cam is "mild", it isn't as mild as the numbers appear...



The intake timing @ 1mm lift for this exhaust cam used on the intake side would be 4ATDC to 36ABDC. Now add in the head cut to the cam timing (albeit not a huge amount) will move cam timing closer to 2ATDC and 34ABDC... all with 8mm lift and all the "extra" duration from 1/2 lift on.

Only time will tell, but this should bring a nice LEGAL smile to my client


More to come......


EDIT - not thinner headgasket, so only compression bump is from 1cc smaller chamber (about 9.6 to 1)