Schubeck Lifter Update - Page 5

Cam · 08-19-2007, 08:41 PM

I hate to ask a potentially dumb question but here goes; Assuming your cam is optimized and your not trying to reduce net duration by increasing lash, except to ensure the valve is closed on the base circle why have any lash at all? Trying to keep cylinder pressure longer by delaying the valve event at super low lift then wacking it open at a more aggressive point in the curve?
It would seem that more lash would result in greater damaging harmonics from impacting. Everythng gets hit with a more agressive hammer. With the Schubeck lifter cermic puck there seems to be no practical limit ( stock diameter single springs, <500 pounds over the nose) to spring pressure when lash is very tight. But hit them once too often and they will fail with predictable results.
Cam

Aubrey N Bruneau · 08-19-2007, 11:23 PM

Has anybody here, other than myself, ever used the solid version of the Schubeck lifter ?
SURELY there HAS to be SOMEONE who has them in a 375HP 396 or the like ? no ?
I've been running mechanical cams in various engines, since 1977. All came from the manufacturer with a recemmended lash setting... generally in the .016" - .026" range. The "rule" as I have discussed on hundreds of occasions, is that you can tighten as much as .004" to MAYBE .006", or loosen .002" - .004".
I can't help but become concerned that if a person were to tighten lash on a mechanical lobe that has say, a .020" "ramp" off the base circle, to .004" or .006"..... that besides the obvious loss of cylinder pressure at anything below 6000 RPM, there would also be a concern of the valve practically never sttling on the seat.

Would take a different lobe design for sure.
On a hydraulic profile.... ABSOLUTELY.... if you were to back the lash to even .010", it would smash the hell out of everything.
On an even remotely traditional mechanical flat tappet cam lobe, there HAS to be some form of mechanical "cushion". Tight-lash cams are the latest though. Some have as little as .012". But that's as tight as I've ever seen.

"Starter to turn the engine over when setting valves" ?????????!!!!!!!!!!!!!

Jeff Lee · 08-19-2007, 11:43 PM

AS I stated in my argument that NHRA should allow AFFORDABLE solid lifters in lieu of $800 quasi-hydraulic lifters, a Schubeck "hydraulic" lifter typically has only +/-.015" plunger travel as required by NHRA. In affect, it is a solid lifter. Remember, this isn't anything like the solid cams / lifters of yesterday. Glued on glass puck...

Cam,
Setting at "zero" lash opens the possiblity of the valve not seating. I've tried it. The engine sounds like it has 7.1 compression, and runs like it also! At least that's my experience. Even my 1st Stocker 390 AMC engine had "real" Comp Cams hydraulic lifters. I initially set the lifters at minus 1/8 turn lash - like a street / bracket car. It was embarrasing the way it sounded. Re-adjusted to +.003"-.005" and it sounded like it picked up 100 HP at idle.

Jim Hanig · 08-20-2007, 12:25 AM

Aurbey I was taking about lifter clearance in the bore ,not valve lash . I have ran subeck lifters for several years and have not had another failure . I ran them with 190 420 seat open never saw much in 220 450, till i installed 7/16 120 wall push rods and Holroy studs and rockers. Be careful with the tool steel as they will flatten the cam also but much slower. Again good luck. Jim Hanig

08-19-2007, 08:41 PM	#41
Cam Junior Member Join Date: May 2004 Location: Prince George, BC, Canada Posts: 83 Likes: 2 Liked 0 Times in 0 Posts	Re: Schubeck Lifter Update I hate to ask a potentially dumb question but here goes; Assuming your cam is optimized and your not trying to reduce net duration by increasing lash, except to ensure the valve is closed on the base circle why have any lash at all? Trying to keep cylinder pressure longer by delaying the valve event at super low lift then wacking it open at a more aggressive point in the curve? It would seem that more lash would result in greater damaging harmonics from impacting. Everythng gets hit with a more agressive hammer. With the Schubeck lifter cermic puck there seems to be no practical limit ( stock diameter single springs, <500 pounds over the nose) to spring pressure when lash is very tight. But hit them once too often and they will fail with predictable results. Cam

08-19-2007, 11:23 PM	#42
Aubrey N Bruneau Member Join Date: Sep 2003 Location: South Eastern Alberta, Canada Posts: 311 Likes: 6 Liked 7 Times in 3 Posts	Re: Schubeck Lifter Update Has anybody here, other than myself, ever used the solid version of the Schubeck lifter ? SURELY there HAS to be SOMEONE who has them in a 375HP 396 or the like ? no ? I've been running mechanical cams in various engines, since 1977. All came from the manufacturer with a recemmended lash setting... generally in the .016" - .026" range. The "rule" as I have discussed on hundreds of occasions, is that you can tighten as much as .004" to MAYBE .006", or loosen .002" - .004". I can't help but become concerned that if a person were to tighten lash on a mechanical lobe that has say, a .020" "ramp" off the base circle, to .004" or .006"..... that besides the obvious loss of cylinder pressure at anything below 6000 RPM, there would also be a concern of the valve practically never sttling on the seat. Would take a different lobe design for sure. On a hydraulic profile.... ABSOLUTELY.... if you were to back the lash to even .010", it would smash the hell out of everything. On an even remotely traditional mechanical flat tappet cam lobe, there HAS to be some form of mechanical "cushion". Tight-lash cams are the latest though. Some have as little as .012". But that's as tight as I've ever seen. "Starter to turn the engine over when setting valves" ?????????!!!!!!!!!!!!! __________________ Aubrey N Bruneau 6409 C/S 62 BelAir sport coupe, 409 HP 409 Last edited by Aubrey N Bruneau; 08-19-2007 at 11:26 PM.

08-19-2007, 11:43 PM	#43
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 2 Times in 2 Posts	Re: Schubeck Lifter Update AS I stated in my argument that NHRA should allow AFFORDABLE solid lifters in lieu of $800 quasi-hydraulic lifters, a Schubeck "hydraulic" lifter typically has only +/-.015" plunger travel as required by NHRA. In affect, it is a solid lifter. Remember, this isn't anything like the solid cams / lifters of yesterday. Glued on glass puck... Cam, Setting at "zero" lash opens the possiblity of the valve not seating. I've tried it. The engine sounds like it has 7.1 compression, and runs like it also! At least that's my experience. Even my 1st Stocker 390 AMC engine had "real" Comp Cams hydraulic lifters. I initially set the lifters at minus 1/8 turn lash - like a street / bracket car. It was embarrasing the way it sounded. Re-adjusted to +.003"-.005" and it sounded like it picked up 100 HP at idle. __________________ Jeff Lee 7494 D/S '70 AMX

08-20-2007, 12:25 AM	#44
Jim Hanig Senior Member Join Date: Aug 2006 Location: Pukwana SD Posts: 858 Likes: 555 Liked 97 Times in 47 Posts	Re: Schubeck Lifter Update Aurbey I was taking about lifter clearance in the bore ,not valve lash . I have ran subeck lifters for several years and have not had another failure . I ran them with 190 420 seat open never saw much in 220 450, till i installed 7/16 120 wall push rods and Holroy studs and rockers. Be careful with the tool steel as they will flatten the cam also but much slower. Again good luck. Jim Hanig