bobby daniels

No,,, it could help ,,but most builders I know check this !!!!!

Everything you can do will help alittle

Jersey Tom

The quality control on these lifter bores is terrible. Some blocks are fine (just luck) and some are crap. If the allignment is off too much the lifters drag on the side of the bore and wear out. It can also cause the tie bar to break when the lifter gets too much friction on it. Stock motors are not as bad as worked motors. The increased valve spring pressure and higher lift cams put more sideways pressure on the lifters and makes the problem more critical. At a minimum, the alignment of the bores should be checked. Boring them out and bushing them insures they are correct. A good machine shop that has experience with this can do it relatively cheaply. ($400-450)

rmbuilder

Jersey Tom has some very good points here. In the first link here Dave Reher expands on the severe tappet side loads generated by these blocks to the point of bellmouthing the bores themselves. The second is the link to the tappet bore sleeves.

http://www.rehermorrison.com/techTalk/28.htm

http://www.sdpc2000.com/cart.asp?act...=1625&pid=8374

http://www.cranecams.com/instruction...in/camfail.htm

fred castle

hi,

fred castle

hi, sorry for the mistake.i have been follwing this thread for a while and it is a problem of mine also. i contacted joe schubeck in Las Vegas and he has a new lifter ROLLER-X looks like the answer . i dont know if its on his web site yet. www.schubckracing.com

JOHN G

NEXT QUESTION. HOW DOES ONE VERIFY CORRECT GEOMETRY IN THE VALVE SYSTEM SPECIFICALLY LIFTER TO CAM ALIGNMENT? WE HAVE HAD INSTALLED LIFTER BORE SLEEVES AND STILL QUESTION GEOMETRY AND DON'T KNOW HOW TO MEASURE IT. IT LOOKS AS THOUGH THE LIFTER HAS CUT GROOVES AND EVENTUALLY CHUNKS OUT OF THE LOBES AFTER ONLY 8 HOURS OF RUNNING. THE FAILURES START FROM A GROOVE ON ONE SIDE OF THE LIFTER ROLLER AND TAKE OUT LARGE PIECES FARTHER UP THE LOBE. THIS SEEMS TO BE INCORRECT GEOMETRY BUT WE DON'T KNOW HOW TO INSPECT IT. THE BORE SLEEVES HANG BELOW THE LIFTER BORE IN THE BLOCK ON THE INTAKE VALVES APPROXIMATELY 1/8TH OF AN INCH. IS THIS RIGHT?? HOW DOES ONE MEASURE THE ANGLE OF THE LIFTER BORE WHEN DRILLING FOR THE SLEEVE?? OUR ENGINE BUILDER CLAIMS PARTS FAILURE AND SAYS USE ISKY CAMS THAT REED CAMS ARE SOFT. IS THERE AN OPINION ON REED VERSUS ISKY CAMS??

bobby daniels

I use a jig I have for small and Big blocks to locate and correct lifter bores as do most of the other I know ,its very easy to check
with this .
I've never found a reed or Isky soft they both work very well I like the Isky better But they don't have many good book grinds anymore but do great custom and the ones in the book do run
Yes the mk6 does have tons of improvments in it but the mk4 is still very very much in demand .

rmbuilder

The majority of component failures that occur, in situations other than max performance WOT conditions, are not due to a compromise in the integrity of the failed part. It usually occurs as a result of the part operating in conditions that are out of tolerance (spec) or incompatibility with related components. Under extreme conditions the importance of lifter bore axis indexing, correct spring rates, lubrication, and geometry become absolutely critical. It has always been my experience that if you examine the failed part as one component of the problem, rather than the problem, the solutions are a lot less expensive.
The cylinder case blueprints & dimensions for the Mark IV and Gen V big blocks are on pgs 110-113 of Chevrolet Power Factory Performance Guide which is available at most Chevy Dealers
This link shows one setup for the process
http://www.rottlermfg.com/catalogs/Rottler_F65.PDF