LIfter ligtening?

Can't beat Jim Schmidt at this valve train game but wondering what can be gotten away with on factory lifter lightening. I had Peel's drilled out lower wall with 1/2" hole and survived horrendous test that about wore out and knocked the stellite bottoms off but no fractures. This implies still more to relieve somehow, but how much and where? Ken Canaga says he trims them but not revealed his recipe to me.

I lightened a set as per Dunstall's book one time and paid for it with a hand full of broken lifter, a ruined cam and a DNF. Then I went to BSA lifters. Jim

Ok Jim appreciate your sacrifice for us * but does that mean you had a bad lifter, mis judged what you saw done by Dunstall or that Dunstall was misleading innocents to destruction like hobot hobby? One thing I think I'd want is small drain holes in the factory lifter pocket aimed through bottom corners. I ain't out to "break" rpm records with Peel just survive as well as racers with Norton lifters.

For years I lightened lifters according to Dunstall's instructions. The only failure I ever had was when the Stellite foot came off one year at Daytona and trashed the cam, but the lifter body stayed in one piece. It also dinged the rods pretty well, but no other damage. I don't think lightening the lifter had anything to do with it. I think it was just a Norton quality control problem. I've heard of a few other instances of a lifter losing the Stellite piece. Although I've never had a stock lifter body break, I have found cracks in at least two during magnetic particle inspection. The cracks were in the open oval area, and I replaced the lifters rather than take a chance. I agree with Jim about the BSA lifters. I'm a real fan of them too.

Ken

I would agree with drilling through the corners to aid oil drainback.

The lifter I broke had been magnafluxed and relieved on the face like the picture in the Dunstall book. It may have been a weak casting- who knows- but it broke through the hole in the side and lost the whole bottom of the lifter. It was on a 2S cam in a fresh motor. It lasted 1 1/2 days of racing at Sears Point. I don't lighten them anymore. Jim

Ok then not much to gain for how much to lose messing with factory lifters. Nice to be reminded some factory items are good enough to race on reliably. I would like more bevel off the fronts for more oil drainage reserve if that didn't weaken them. Definitely an item that's been cryo tempered in Peel.

Slickest I've seen were the stock looking followers where the pushrod was planted immediately above the stellite surface; someone posted them on this forum. Everything above the stellite was more or less for guiding and no vertical loading. Really caught my eye.

Oh yes that is a clever way to lower mass with factory base line lifters but brings up the push rod length deflection issue using up the gain of valve control at hi rpm. If we stick with heavy weight Norton twins then we are stuck with heavy weight Norton twins eh. Just got to love their innate character and rev limitations.

Harlmut [sp] showed us his skeletal slab ladder like lifters but Ken Canaga said must be a special alloy milled from billet to get away with it.

Yep - my lifters were made from billet, hardened on the foot and ground. But then we found they have not enough surface on the foot for our radical cams - at least that was what the strobelight told us on the cam testrig. So we made bigger lifters with a rectangular flat foot - almost twice the length of the BSA lifters. Now the problems are solved and cams don´t show any wear so far, lifters had DLC and are spotless.

Cheers Hartmut

Alrighty Hartmut you have definitely moved several rpm limiting bench marks out of reach for most of us. What do you expect to red line your power plant wonder too? I'm trying to wrap up most a decade long Peel project so this post is what can or can not be done to matter with factory lifters, which appears better be very little. Peel engine is Maney race engine with JMS pistons/rods and welded nitrided smaller 5 lb lighter crank with dragster cam. Maney limits his 920's to 7200 which should be plenty for my sports bike spanking leaning hobby but i think the Drouin blower and engine is good to like 8000 for leaving a dyno bench mark and maybe 1/4 mile ET. I hope this means I can hardly ever go WOT and expect to go anywhere fast. Only Peels different handling behavior after loss of full tire traction makes over powering her worth while to me.

If you read Dunstall's tuning manual, he says to use lightened lifters only with the stock camshaft. If a hot-rod cam is fitted to the engine then he recommended stock lifters.....

That said putting a few small holes in the shoulders and towards the bottom to aid oil drain-back should not weaken the lifter that much if any, and if there is less oil in it then it should be lighter....

jseng1 said:

Stock Norton lifters weight a whopping 80 grams each. The BSA lifters weigh less that 1/2 of that so you save 40 grams each .

Click to expand...

Someone brought up the bucket tappets that Norton used on it's Domiracer project in 1961-62. I have an extra set of these for Heinz Kegler's works 88 racer and they weigh in at 37 grams each. I doubt if anyone would care to take on the expense of manufacturing them again now, but they are an interesting piece of Norton history.

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