Rise of the Phoenix

iTrader: (27)

Ok, since i found a guy who will inspect and pass my car, I'm for sure going the Super Victor/4150 TB route. I found a cam that I think will work very well. It is 236/248 .631/.631 111 LSA. Now the question is, will it clear my heads. My cam right now is 227/235 110 LSA and I have .069" intake clearance and .101 exhaust clearance. Here is something interesting that a guy posted in a thread I made over on another forum when I asked if that cam would clear: What do you guys think?

Fairly straight forward ....

Find your current cams tdc # on the ICL, multiply by the rocker ratio.
Now take the proposed new cams tdc # on the ICL, multiply by rocker ratio.

Subtract the difference between too. ......walla, new ptv number.....since you already know your current ptv.

This is just an example. .....
current 227 lobe on a 108 ICL @ tdc = 0.070" x 1.7 = 0.119".....this means your intake valve is open 0.119" at the nearest point in the revolution. ..aka; tdc.

New cam lobe 236, on a 106 ICL @ tdc = 0.089" x 1.7 = 0.151"

So.......0.119" minus 0.151" = 0.32"

So, you have 0.069" minus 0.032" = 0.037" of ptv with new 236 lobe on a 108 ICL.

Remember this ^^^^ is just an example.

You just need to find out what lobe family your current cam is and what your new one will be. Also, the same math will figure the exhaust lobe ptv too.

soundengineer

iTrader: (16)

that math doesnt work.....
it doesnt work that way...
you often dont make contact at TDC..

Rise of the Phoenix

iTrader: (27)

Either way, I'll clay it, but really don't want to have to flycut. Given my current PTV clearance with the current cam, what do you think?

soundengineer

iTrader: (16)

you are going to have more clearance on the Exhaust, and less on the inatke..

just plugging in the cam into a known ls1 engine model I have, with the specs you listed in your example, theres about .042 difference on the intake side(and this is assuming that the lobes follow the same pattern and they likely dont)

so .069 intake clearance.(which is already below the recommended minimum clearance) is going to be more like .025~0.27
which is WAY too close....you will have to flycut or you can expect piston to valve contact.

and of course...results will vary based on the ACTUAL real grind values and installed position

Rise of the Phoenix

iTrader: (27)

Thanks for all your help. In your opinion, do you think that cam would work well with a Super Victor/4150 TB? I don't even know if it's still available (found it in the classified section), but the guy says it is a custom Ed Curtis cam that was spec'd for a Super Victor intake setup, but for a 364ci, not 346ci.