Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties DIY cam grinding

DIY cam grinding

Post Fri Jun 21, 2019 8:48 am

Posts: 8
Location: Tasmania Australia
Good evening Andre and all, in regard to the cam lobes l have, they were professionally made by a truly great engineer, John Trease, from Melbourne, Australia. John passed away late last year,RIP.
Ther were CNC machined from a bar of steel, professionally heat treated to be over 62 Rockwell,a must for these cam lobes. OEM, I believe are 60 Rockwell. Two programs for cnc had to be made, one for inlet, another for exhaust. The project took two years from inception to completion, learning, arguments and was expensive and labour intensive.
What l have is an old WLA engine ( l know they are all old but this is worn out and spins free with no valve springs) set up with a degree wheel off the sprocket shaft. It has no heads so l can use magnetic base dial gauge indicator off the barrels. I have recorded 3 sets of standard cams in good serviceable condition, all are really close. Allow a degree either way for all results. In answer to welding method to weld lobe to gears, using 1.6mm thoriated tungsten electrode in the tig and 1.6mm filler rod. 2 welds of 10 mm, one down each side. Can’t make photos happen so have write it all down.
With degree wheel set at 30*,l will use * to represent degrees, to coincide with timing mark and 0* is at piston top dead centre ,tdc. I put cam cover back on, just push on no screws, barrel base gaskets in place and set tappets at .006” inlet, .008 exhaust and take dial indicator readings off valve heads. Then take readings from valve at .010” lift all the way through to .010 before fully closed it gives me true duration of 240*.All literature tells me no valve lash is necessary but if l don’t set tappets this way the math don’t work out. Standard cam duration is 240*. I know it’s a lot of explaining but it was a lot more head scratching to work it out.
Front exhaust.

Cracks open, 53*bbdc. Start reading now.010” lift,42*bbdc. 030” lift 31*bbdc. 050” 23*bbdc. 100” 6* bbdc. .124” bdc. .150” 7*abdc. .200” 20*abdc. .300” 58* abdc. .312” 81*abdc(midway point, max lift). .010”20*atdc(closing, end reading here). Absolute close .000” 29*atdc. Gives duration of 240*. Now, when this valve, exhaust, is closing at .101” lift, crank at 15* btdc. the inlet valve just cracks open. So if exhaust valve closes absolutely at 29*atdc. This gives over lap of 44*. That’s for front exhaust valve. No matter how I try overlap for rear exhaust comes to only 42*. Give those figures tomorrow, it’s late, my rum and scoob are calling.
Hope you understand this rambling. Regards.
Hozay. Every day is Saturday.

Post Mon Jun 24, 2019 9:06 pm

Posts: 8
Location: Tasmania Australia
G’day Andre, sorry for delay, not my fault, that’s my excuse. You worried me asking if 76*abdc was midway point for front exhaust valve, l come up with 81* abdc. As I stated the engine I’m using is worn and figures may be off a little,hmm. Just to clear up the cam lobes were sent to a metal treaters for hardening and welded on latter, filler rod used was 1.6mm 309 stainless.
Figures for rear exhaust.
Cracks open 86*atdc. 010” 87*bbdc. 020”80*bbdc. 030” 75*bbdc. 050” 67*bbdc. 100” 51*bbdc. 150” 37bbdc. 200” 23*bbdc. 300” 16*abdc. 312” 37.5*abdc. (Closing). 010” 31*btdc absolute close 23* btdc. This gives duration of 238*. During this cycle inlet valve cracks open 65*btdc.

Figures for front inlet.
Cracks open 17*btdc. 010” 11*btdc. 020” 5*btdc. 030” 5* btdc. 050” 7.5*atdc. 100” 22*atdc. 150” 35*atdc. 200” 48*atdc. 300” 88*atdc. 312” 70*bbdc (Closing) 010” 40*abdc. Absolute close 46* abdc. Giving 243* duration.

Figures for rear inlet.
Cracks open 63*btdc. 010” 57*btdc. 020” 49*btdc. 030” 44*btdc 050” 36*btdc 100” 20*btdc. 150” 7.5*btdc. 200” 5*atdc. 300” 42atdc. 312” 66*atdc (Closing)010” bbdc. Absolute close 7*abdc.
Hope these figures help, however l feel accuracy may be an issue. It is what I have to work with. Soon I shall try this on a fresh engine, the one I’m making these cams for and compare results, I shall post what I find. From memory l think hardening cost $150 for 16 cam lobes. Once welded in place cams can be sent for regrinding for even hotter performance.
Hozay. Every day is Saturday.

Post Tue Jun 25, 2019 4:43 pm

Posts: 14
Location: Dresden, GERMANY
81*ABDC! Thats the info i needed. Thank you, Hozay! Thank you for measuring!

There was a misunderstanding about "welding on lobes". I thought you have added some material on the lobes by welding. Which I have tried without success because of the hardening. Just hardening a lobe and welding it to a gear is not a big deal.

I know such a project takes years. For example it took thousands of youtube lessons to try to learn integral and differntial calculations to calculate the shock (change of valve acceleration) for every degree in the cam lobe. Until today i am still trying to understand the whole issue...

May be you can tell a bit about the specs and the experience of your racing sets or post a picture. Would be interesting.

Meanwhile I have regrinded 2 old sets. IN and EX 284*@0.010" with 0.358" (9,1mm) lift and a mild valve acceleration. One set is already running quiet well in a big port stroker and the other set I have sold. No feedback yet. So an exhaust lobe center at 81* abdc means that the EVC of these regrinds are at 43*ATDC. Nice to know. If I loose torque someday, at least I know where.

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Post Tue Jun 25, 2019 7:30 pm

Posts: 3434
Location: Central Illinois, USA
I'm still in awe.


Post Fri Jul 12, 2019 9:42 pm

Posts: 8
Location: Tasmania Australia
Just testing to see if it works
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Post Tue Jul 23, 2019 1:31 pm

Posts: 8
Location: Tasmania Australia
Hello all. Andre, it is with cap in hand l must apologise to you and all reading for the last couple figures l posted. They are a bit all over the place. ( I tried to delete them but couldn’t work out how ). You had correct figures in the first place. Let’s blame it on the medication. Having set up a fresh built engine with an excellent set of factory cams and bushes. I repeated the tests and figures come out just as all the texts say. Figures are at 0.010” lobe lift.
Front Inlet open 15*BTDC. close 45*ABDC
Rear Inlet open 60*BTDC. close 1*ABDC
Front ex. open 45*BBDC. close 15*ATDC. Midway point of 76ABDC, which is what you said.
Rear ex. open 90*ATDC. close 30*BTDC
Not having grafted lobes on cams before or had any regrinding work done it’s all new and exciting. Have a road legal WLA hotted up a little, gets to over 80 mph by the speedo with standard cams. The first set is for that baby, yes sir.
These are the specs I am using to set up four sets of lobes onto four sets of cams (16) so l had to keep trying till the figures came out true, seems doing test work on a worn out engine just don’t work. But the little jig l made to turn engine over(see above), works a treat. In the interest of saving WL cams from being destroyed, some Sportster cams can be used. Number 3 cam( front inlet) from sportster with same spindle as WL will work though timing marks on gear face need to be altered to same as WL, about half a tooth, then weld on new lobe using new timing marks. Some Sportster number 1 cam (rear exhaust) have a spindle same as WL 3 cam, that is it has no oil pump tangs. This also could be used as a WL 3 cam, once again it has only one timing mark so new marks must be made.
The inlet lobes I have are 298* duration, 0.370 lift, exhaust are 290* duration, 0.350” lift. There’s more to this rant but it’s 5.30 am and lm a worn out engine
Hozay. Everyday is Saturday


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