[VintageLambo] Re: Engine manual, Camshaft timing

Laust: Thank you for clarifying the settings. For those who are interested in this discussion, the minimum piston to valve clearance recommmended is 0.10in. for the intakes and 0.12in. for the exhausts as per the Crane Cam website to be checked 15 degrees before and after TDC in the overlap zone; presumably for Detroit iron. Regards, Nash --- In VintageLambo@yahoogroups.com, "lgpdk " wrote: > Nash, > > That is right, I used 6 cam degrees (=12 crank degrees). I ran the > simulation for the standard cam setting for the engine and was > encouraged by seeing the shape of the curve being close to what has > been published. At that time I was also encouraged to see that the > peak HP was close to 350 HP. I then increased (and decreased) the > cam timing individually, I think up to 8 cam degrees and found that > the 6 degree advance on both cams provided the best result without > almost no side effect, except the risk of valve piston interference. > I then calculated difference in valve piston interference (0 to 6 > deg cam advance) to be 1 mm. With that knowledge I measured the > actual cam – piston clearance (I have forgotten what it was) and > decided that it was safe to take 1 mm out (and I stand by a prior > statement that a final .060" clearance should be safe). I used cam > centers as the parameter to adjust, which takes the valve-lash > uncertainty out of the measurements (you don"t have to question what > valve lash is assumed for the quoted 32/64 inlet opening/closing). > In the case of the inlet the cam center would be (32+180+64)/2-32 = > 106 ATDC. Since the cam top is flat, the center is found as the > angular mean between same height between a rising and falling edge. > Using cam centers pre-supposes a symmetric motion as a function of > cam (and crank) angle, which I strongly believe is true and > certainly did not have contradicted in the results I got. > Since I did many things to the car I cannot separate this effect > form others, but I certainly am very impressed with its low-end > torque. It effortlessly and smoothly motors uphill (around Laguna > Seca Golf Club) in 5th gear with four people at 1000 rpm. The > smoothness I am sure is helped by the fuel injection which does not > require high air-flow to get good fuel spray. > > Best regards, > Laust > > > --- In VintageLambo@yahoogroups.com, "nashbap " > wrote: > > Hello: > > > > I recently finished reviewing the engine rebuild manual on the 400 > GT > > site and was extremely impressed with it. Jack, this is excellent > > work. Congratulations and Thank You! Laust, your work on the > Espada > > is equally impressive. It takes courage to do the changes that you > > effected. > > > > You mention that you have advanced each cam by 6 degrees (approx. > 4 > > vernier holes). I am thinking of trying out the same on my Espada > and > > I just want to verify that you are referring to 6 camshaft degrees > > and not crankshaft degrees. If this is the case, then am I correct > in > > assuming that the intake now opens at 44 degrees BTC as opposed to > > the factory setting of 32 degrees, the exhaust closes at 20 > degrees > > ATC as opposed to 32 degrees and the resultant valve overlap > remains > > the same? Also, are you using 32/76, 64/32 as your starting point > for > > the 6 degree change? > > > > Jack, on page 61 of the engine rebuild manual I notice that the > valve > > depression for #6 intake is greater for the Espada and Jarama > engines > > as opposed to the 400 GT by 0.90mm. However, the settings for #4 > > exhaust, #8 exhaust and even #9 intake are exactly the same. Why > > Lamborghini recommends a different setting on only one camshaft is > > peplexing. Any suggestions? > > > > Thanks. > > > > Nash Bapasola > > 72 Espada II