SBM "MagnaVelocity" mushroom camshaft.

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My experiences with them goes back to the very early 80’s. But yes, they definitely go way back :lol:
 
Bewy said:
Do not see a mushroom cam + lifters as a cost effective deal, nor giving as much power as a roller using the aggressive lobes now available.
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My 1982 Direct Connection catalog says, "Comes very close to roller cam performance at about half the cost". For what I spent on my setup that's about right - it was cost effective for me in terms of power per dollar!
As already pointed out, the history of the mushroom lifter in Mopar engines is related to NASCAR.
 
If I remember correctly. You have to machine the under side of the lifter valley for the cam and lifters to clear.
 
tvt59 said:
If I remember correctly. You have to machine the under side of the lifter valley for the cam and lifters to clear.
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Not really machine, clearance. I did mine with a die grinder over 40 years ago. I changed then in the car after I made a tube out of aluminum and slid them in. Then I held them up with old wooden cloth pins. Low 10’s back in the 1980’s was pretty quick with stock rods and cranks, and TRW pistons and 906 heads.
 
I didn't have to touch mine, there was over .250 clearance at max lift. There are a number of threads on the Mini-Express over the years in various forums, and every one said they didn't have to back-spotface the lifter bores either...
 
If you read the DC (MP) Engine book, it's actually referred to as back-spotfacing, as I said. The spot-facing is on the underside of the lifter bore. That cannot be done with a conventional spot-facing tool - there is no room to come straight in from underneath.
So the .904 arbor is passed through the lifter bore, then the cutter (facing backwards, not in the usual forward direction) is attached to the arbor, then the tool is rotated while pulling, and the spotface is cut into the underside of the bore. :)
 
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