Hi Everyone,

I'm trying to learn a few things about installing bushing in lifter bores. Could someone let me know what advantages and disadvantages to having bushing installed in lifter bores? This would be on a Hemi billet block build. Is there a difference with the oiling system? Meaning that the lifters oil easier with bushing? Can you run a engine at lower RPM with them compared to without them because of the oil? I got the new improved comp lifters. I read some place that you have run the engine at 1200 rpms to keep lubed it don't have bushings. I know there is a lot of experience on here with engines and was hoping someone could share their experiences. I wanted to run the engine around 900 to 1000 for street driving and 1200 seems way to high. Thanks for any help.

Not sure you need bushings with a Hemi billet block. Is there oil pressure at the lifter bores in that block? If that is a solid block then the only reason for the bushing is to provide a better wear surface than aluminum. But if this is a new engine then you could run the aluminum lifter bores for now and then add bushings in the future if the block is showing wear. Another reason to run bushings in a block like that is so you can install larger lifters or use Jesel lifters. But since you already have your lifters it doesn't seem like you would want to do that.

3 common reasons:
1. change the lifter diameter
2. correct tappet bore misalignment
3. use a keyed roller lifter with special bushings to avoid use of tie bars

A billet block is a solid block and has no water jackets and really is not a street piece - but if the block has drilled lifter oiling then yes you can bush it - otherwise its splash oiled and bushing has some advantages but if its new probably not worth it unless you are going with an exotic type lifter - if it is a lifter oiled block then bushing the lifters can be done for many reasons like push rod oiling - or the one reasons already mentioned.

I think the reason for bushing the bores has been missed. The main reason is oil control. A roller lifter requires far less oil than a hydraulic lifter so bushing a stock block reduced the flow and pressure loss around the lifters and sent that oil where it was needed most. Generally a bushed lifter got a very small oil hole drill into the oil galey to ensure some lubrication to the lifter. The "bronze" itself provides less friction than the cast iron so that's why they use bronze instead of just installing a steel sleeve.

Using a larger diameter lifter might be a reason in today's modern blocks but not "way back when" in stock blocks. There just wasn't enough material in that area to hog the bore out and bush it and have any strength left in the area.

Lifter alignment ... that may have been a bonus but I seriously doubt there be any performance gain - just how far out could they be ?!?!

just how far out could they be ?

Enough to eat a cam lobe every time it's built

OP says he has a billet block. Not sure what he means by that since the only billet blocks I'm aware of are Top Fuel type blocks. But if what he is saying is correct then the lifters bores would've been machined on a CNC rather than cast. So unless the CNC program was defective, the lifter bores should be in the correct location. Worth checking of course but a billet block shouldn't need bushings. My guess is that billet blocks already come with bushed lifter bores since the guys who buy billet blocks use 0.937 or 1 inch lifters. OP should measure his block first to see what size the lifter bores are since billet blocks tend to be custom made and the lifter bores are most likely not 0.904 diameter.

The same should apply to original iron factory blocks. While not "CNC" in those days, the machining process would still have been automated enough to ensure a high degree of accuracy. If the machining was "out" on one block, chances are it would have been out on the next fifty or so until a block hit inspection and the problem was discovered/resolved. Even then, there would have been a min/max tolerance - just like oversize lifters or bearings.. I'm still not buying the severity of lifter bore to cam alignment.

Factory blocks can be off far enough to cause problems. That has been proven multiple times. Even aftermarket blocks can be off far enough to eat parts and kill power. I'd be surprised if a billet block was off but it is something that should at least be checked with a degree wheel. Not sure any of that applies to the OP question though since he seems to be worried about oiling. From what I know about billet blocks they typically don't provide oil pressure to the lifters so there is no need for bushings to control the oil flow. I'd think the only reason to install bushings in a billet block would be to either repair the block, or to run a keyway type lifter.

You don't have to buy it, I'm not selling it.

If the alignment is correct (45° from vertical and parallel to the cylinder in both axes) the placement of the bore may still be off.
An error along the crank axis is harmless unless a substantial portion of the tappet face is off the cam lobe. Never heard of it.
An error across the crank axis will not be destructive (unless fairly large), but it will advance or retard the valve operation by changing the point at which the lobe's rotation reaches the tappet. Probably more common than suspected since there are no definitive symptoms except slight bump is the CCP/torque curve. If both banks are wrong in the same direction (block shifts in the fixture), move the cam to correct. Impossible to correct if the error is "handed" (left and right banks are wrong in opposite directions).
If the tappet bore alignment is tilted w/r/t the cylinder axis across the crank axis it will misalign the pushrod, and may not change the event timing points.
The dangerous one is where the tappet bore alignment is tilted w/r/t the cylinder axis front to rear, causing edge contact between the tappet face and lobe. The parts will eat each other, how quickly depends on the magnitude of the error, spring tension, etc. This was a big BBC problem decades ago.

Completely wrong. Machining is horrendous on old blocks