cam grind question

More on the exhaust is because Ford Small blocks are soft on the exhaust side( befor porting..)and most cam grinds take that into consideration. as for p/v issues on the TW heads?? be carefull and I'm sure some TW guy will answer .. cool??

Just me...................

Thumper

I'd add more detail - it's not the small block that's the issue. It's that most of the early Ford heads (stock and performance) are intake biased. That is, they flow relatively more on the intake side than they do they exhaust side. Many cam manufacturers make up for that by offering cams with more exhaust bias - more duration to help out a poorer flowing exhaust port. Things have changed. Look at the flow characteristics of for example an AFR165 and you don't have much need for split pattern cams if the rest of the intake and exhaust parts are up to snuff.

However, it's not universal. A custom cam designer can model your set up and help you pick a cam for your parts.

Also, peak lift has nothing to do with p to v clearance. At peak lift the pistons are way down the cylinders. If someone is giving guidance regarding p to v clearance by suggesting limiting peak lifts, find another guru. They don't know what they're talking about.

Peak lift is limited by spring bind, spring force and in some cases by the flow characteristics of the head. P to v clearance is smallest during overlap when the intake is just opening, the exhaust is about to close the piston is passing through tdc at the end of the exh. stroke/beginning of the intake stroke. As such, all else equal, a cam with earlier opening intake timing, and/or later closing exhaust timing will have reduced clearance compared to another cam. Consequently, it's increased duration, overlap and/or smaller LSA's that reduce your clearance.

Hope that helps.

Keep the questions coming and we'll keep helping. Here's some bedtime reading for you - open all tabs and read. It'll really help you understand the role the cam plays. http://www.wighat.com/fcr3/

Thanks for doing your part to keep us safe -- we appreciate it; ESPECIALLY important to tell you this Thanksgiving season!!!

Let me know if I can help - M

PS - was flying home to K'ville,TN out of Ft.Wayne, IN last week. And in the early evening, the local IN Air National Guard boys were doing full after burner take offs. What a site to see - blue/white cone of fire the length of the plane out the back. Shook the whole building and we were inside the terminal. I think if I were on the other side and I just heard that coming at me, I'd simply put my gun down and say 'Sorry. I made a mistake. I don't want to play anymore. I give up.' What were they? Land-based, single engine was about all I could make out - darkness.

"feels like your teeth are going to fall out."

LOL!!! Actually, it hit me a bit lower; Uh, I needed to change my Depends!