not too sure what you mean by back cutting the valves can you explain p ----- Original Message ----- From: "Scott Cable" <s2cab...@yahoo.com> To: <kr...@mylist.net> Sent: Wednesday, June 22, 2005 5:06 AM Subject: KR> Performance Valve Jobs
> Netters, > I've been doing some flow testing on a Super Flow 600 flowbench for a local area speed shop. > This shop mainly does allot of work for the local guys running at the 1/4 mile speedway. > Because of the racing rules that state you are not allowed to add foreign material, or grind inside the ports, we're pretty limited as to what can be done. The rules also state that any cut over 60 degrees must be concentric to the valve guide and may only extend 1 inch below the valve seat. Since most valve jobs only reface the 45 degree seat, and "perfomance valve jobs are 3 angles (30, 45 & 60 degrees), there are some opportunities here. > If you add a 15 degree cut to blend between the combustion chamber and the 30 degree cut, and a 75 or 80 degree to 1 inch below the seat, you now have a 5 angle valve job. > Add a 30 degree back cut on the valve face also. > The end results were no less than astonishing. At the upper end of the valve lift spectrum, the ports flowed over 10% more, at the lower end of the valve opening (.050) the head flowed over 200% over thee 3 angle valve job head! > Using the formula for horsepower: HP= CFM * .2527 * # of cyl. > The SBC engine was dyno tested before the teardown at 525 hp. > The port actually flowed at 260 CFM max. Which directly corresponds to the above equation. > With the 5 angle valve job, and the back-cut valves, the same port flowed a maximum of 292 CFM! Which by the above equation = 590 HP! > I can't wait to finish these heads, re-assemble the engine and get it back on the dyno. > There are still a few more tricks up my sleeve here that will surely put this engine well over 600 HP. > So if you're looking to get some additional torque and horsepower out of your engine, consider having a 5 angle valve job and back-cutting the valves. > Good Luck and as always, your results may vary..... > > > > Scott Cable > Jamestown, ND > s2cab...@yahoo.com > > --------------------------------- > Yahoo! Sports > Rekindle the Rivalries. Sign up for Fantasy Football > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.323 / Virus Database: 267.7.8/22 - Release Date: 17/06/2005 > > -- I am using the free version of SPAMfighter for private users. It has removed 21009 spam emails to date. Paying users do not have this message in their emails. Try www.SPAMfighter.com for free now! -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.8.1/28 - Release Date: 24/06/2005
