Questions on lifter bore correction
 

I'm trying to justify the cost to have this done on my block. 383 big block mopar, stocker.. I've heard costs are $500-700. If correcting the angle and location is worth 20 hp, then fine, if it's getting 3 hp, I'll spend the money somewhere else. Also, when this is done, is the oem angle kept....?

I'm on a budget and want to qualify with a little headroom, not kill it. thanks.

Re: Questions on lifter bore correction
 

$ amount sounds about right.
I have done BBC and SBC,using BHJ fixtures, didn't have mopar fixtures,BBC and SBC you would really be surprised most of the time how far out they are,first tried taking them to .875 and would have 1/3 to half that wouldn't clean up going from .842 to .875 so after a few times of that just went ahead and bored for bushings.
You can install fixture on block and check lifter bore location,with go-no go gauge.
you can also degree cam on every lobe and check for cam timing variances,if shows differences though are lifter bores or cam if off????, but will not show if correct angle and squareness to cam.
Usually lifter bores are corrected to where they were supposed to be from factory.
Have never done a Mopar or done A-B testing on lifter bores, however one time dynoed BBC a guy had had machined elsewhere and assembled himself,wanted dynoed because didn't run right, ended up completely re machining all of it,had to square deck up,rehone,redo lifter bores that had been done, went from .842 to .904 to correct them,rebalance rotating assembly, gained 50HP first pull when went back on dyno.
Mike Taylor 3601

Re: Questions on lifter bore correction
 

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.

Re: Questions on lifter bore correction
 

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

Re: Questions on lifter bore correction
 

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

Re: Questions on lifter bore correction
 

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

Re: Questions on lifter bore correction
 

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

Re: Questions on lifter bore correction
 

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.

Re: Questions on lifter bore correction
 

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.

Re: Questions on lifter bore correction
 

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.