Questions on lifter bore correction

[Bill Diehl]

It depends on how far they are off and how many rpm you plan on turning.
Overall valve train geometry is everything at extreme rpm. Lifter bushings also allow you to control or adjust the oiling to the top end.

If the angle is not what the cam was ground for the cam timing is not correct nor is the valve seeing the proper lift either.

This is not to big an issue on inline valve heads but on canted heads it's very important as it will increase power and rpm substantualy.

[Jeff Stout]

For a stocker application can I change lifter diameter? I plan on correcting lifter bore and bush but having a hard time finding quality lifter in my diameter. .921

[FED 387]

Some Oldsmobile engines using .921 lifters 307 394 look into it

[Alan Roehrich]

Last I looked, Stock Eliminator rules require the stock OE lifter diameter.

[kansas stocker]

Alan is correct and it is often but not always checked.
Pete

[GallopinGhost]

Mike, thanks for the info. sounds like a good thing that guy brought his motor to you.
Bill, thanks. about 6500-6700 rpm. I'll look close at valve-train geometry for rocker arm location and push rod length. Just trying to plan for how much bang for the buck. I understand that it all really depends on the lifter bore location error though.

[SSGT Mustang]

I have always had the lifter bores corrected in my engines. You can use a lifter tru and install bushings with the stock lifter diameter. Then you hone them to fit the lifters perfectly. You can also replace the bushings if you need to down the road.

[SSDiv6]

Originally Posted by Jeff Stout

For a stocker application can I change lifter diameter? I plan on correcting lifter bore and bush but having a hard time finding quality lifter in my diameter. .921

Jeff, if your Olds 307 block has the .921 lifter, the block is for a hydraulic roller lifter, not a conventional hydraulic/flat tappet lifter.

According to the NHRA engine specs, the legal block for your HP rating, has the standard .875 hydraulic/flat tappet lifter and not the .921 hydraulic roller.

Also, the .875 Chevy lifter is not the same as the Olds/Pontiac lifter. They have different oil band locations.

[Dwight Southerland]

Caution on using anyone's fixtures. I bought a BHJ for a BBC years ago and after getting blueprints from Chev, found that the BHJ was out as much as most blocks. Then you have to wrestle with the assumption that the factory design and specs are the most optimum for valve train geometry. At least you will get them consistent.

[Bill Diehl]

Originally Posted by Dwight Southerland

Caution on using anyone's fixtures. I bought a BHJ for a BBC years ago and after getting blueprints from Chev, found that the BHJ was out as much as most blocks. Then you have to wrestle with the assumption that the factory design and specs are the most optimum for valve train geometry. At least you will get them consistent.

This is a good point, In most cases the factory design is not even close to optimum, as I said earlier specifically with canted valve heads

This was not brought up in the roller cam thread but it is a big reason why some guys are chewing thru lots of valvetrain parts..... did somebody mention.... "lifters"