I am degreeing a SBC Chet Herbert solid roller , and all the info I have is it's .5oo" lift and 300 deg duration. I also want to check opening and closing events, so I can put the info into an engine program and check corrected CR. If valve lash is .018", do I correct it by the rocker ratio? This would make the Intake Opening @ .020 actually at .032". I need numbers at either ,o20" or .050" to work in the program.
Just measure at the lifter from .050 get max lift on the lobe multiply by the rocker ratio to get max lift.
to degree cam I check events using zero lash not sure if that answers your question, your program didn't specify?
No, it didn't; I always****umed it was zero lash and is checked on the lifter, not the valve. I did some research in books and they say " always check on the lifter". I'm probably overthinking this. Any way, what I have is Int. duration = 283@ .020" and 247@ .050" ; Ex. duration = 286@ 020" and 249@ .050". 66 deg. overlap @ .020" and 30 deg. overlap @ .050". I'm going to load this into the program and see what it says. Thanks.
I measure base circle and max lobe with cam out, install cam with thin oil on the intake and exhaust of #1 lobes, install lifter, push rod, rocker****embly with head torqued down. Adjust to zero lash, with dial indicator on valve adjust screw locate start and end of ramps, adjust degree wheel and "dial in" cam. if I want to see what lift at valve is I adjust lash and check at the valve spring retainer. This of course is on an early Olds engine, not small block chevy and no computer. I can see that with sbc and for sure if heads are off, check at lifter
I see what you're saying. I started to think about doing that to get effective valve events; I'm not ready to install the heads yet and I was thinking that if I corrected lash at the valve by the rocker ratio (.018/1.5), I could get a better number for the computer program. I'm also getting ready to curve the distributor and I like to see corrected CR before I set total timing. I know this is only a starting point, but you have to start somewhere. BTW , that .008" lash correction amount to an avg. of 6 crank degrees @ .020" at the lifter. Thanks for you're input.
You are mixing two different things here. Your opening and closing event are measured on the cam lobe and valve lash or rocker ratio have absolutely nothing to do with it. If you want to know where you are as far as your opening event at a certain opening value it is when the cam lobe reaches that value, and not the valve itself.
Adjusting the lash to give a pseudo cam change is a old racer trick. I'd imagine this exercise will give you great insight on the how, why, WOW of its workings
Do everything off of the lifter. I generally use .050 lifter rise to get my events (IO EO IC EC). Measure the base circle and subtract from the total measured height to get max camshaft lift. That number X rocker ratio minus valve lash =gross lift with a checker spring. Everything changes when you use real springs and pushrods.
As above..At 300° adv the 247° & 249° @ .050 is ball park, I've almost got that in a hyd cam but after the .050 the roller probably ramps up quite a bit more..post what you get for Hp/Torque..
In '63 I bought my first solid roller cam directly from Chet Herbert at his shop here in California. He let me use his valve spring base cutter on my heads so I could run his valve springs and gave me specific instructions on how to degree the cam off the lifters. My cam was a #70 for the 327 in my '55 C/Gasser and Chet told me it would only work with a 4-speed and 5.57 gears. His roller lifters were held in position by 1/4" square hardened stock run through the oil galleys and secured with the pipe plugs. He also instructed me to put 3 pipe cleaners inside each push rod to control the oil flow to the rockers. I dumped the Hays clutch at 8000 rpm and power shifted at 8500. Chet was an extremely intelligent self taught engineer and was credited with the first high performance roller cam shaft for racing. So as others have said your dial indicator should be set on the lifters and with a degree wheel determine your cam position. With my engine I ran it 4 degrees advanced. Your results will vary.
Yeah, I get that; when I started checking, I realized that if added .008 " to the lifter position, I had to move the crank 6 deg. It made me wonder if it should be done that way, but I see that it shouldn't be. That's what I'm doing. I had to make a*****on to put on the lifter so the indicator would stay put. Good suggestion posted earlier. I'm getting another set of event numbers at .050" tomorrow. Will do after I get the new numbers tomorrow. The program doesn't have any appropriate cyl. head flow files for SBC. I've used it on Harleys and if you put in good data, it usually comes close to actual dyno results. Thanks to all you guys; your replies keep me on track.
I had to smile when I read this; I knew there had to be someone else out there. I bought mine in '68, only didn't get to use it until now. I installed the lifters with the key stock last spring when I****embled the short block, but about a month ago I bought a new set from Herbert to use newer technology. No Balls I guess. I forgot the pipe cleaners until I read your post. I would have loved to been able to use the stuff when I bought it. Uncle Sam got in the way. I have my cam advanced 4 deg also. What kind of times did you run? Thanks for your comments.
Joel, The best run with the small block was 11.21 @ 121, that was a t LIONS in '66. We later installed a 427 with a Herbert roller and ran in the 10.80s @ 129. There's a story of my '55 under "White Lightnin'" here on the HAMB. I still have a #50 cam in the shop and plan to use it in the near future. Have fun with your build.
Here's the result after making the*****ons to give the indicator stem a solid place to sit. The checking points seemed to repeat much better. Duration 246 Deg. both In. and Ex. with 28 deg. overlap. In. CL=106 deg and LSA = 109 deg.. The cam is installed 3 deg. adv. Corrected CR is 8.9
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