i pulled the intake off of my crappy 305 because it kept bending pushrods and where the lifter sits in the block it is way bigger than the lifter, it is no longer a circle it is a oval i am just wondering what caused this i dont really care about the 305 at all i got a 355 going in its place i am just curious as to what caused this?

Got to be some poor machining or a bad casting IMO.

I've never heard of a stock or mildly modified street engine wear a lifter bore out of round in a small block!

It's common for racers to index and add bushings in stock blocks to make sure they are perfectly lined up!

I'm curious to see what CNC blocks or anyone else may have to say about this!

Sounds like an oiling issue maybe, but I can't say I've ever worn out a lifter bore that bad. I've worn them so you can feel just a TINY bit of wiggle at the bottom of the lifter, but never so bad it's flopping around in it's bore.

there are instances with chrysler and olds where they overbore to say .010 oversize and use an oversize lifter,,,, and that's right out of the factory. usually the olds blocks were stamped on that bore. don't think the chevy's ever did that though, at least not from the factory,, as far as i know. i'd have to side with damon on an oiling issue somehow.

really agressive roller cams can wear the lifter bores from the extreme side loading put on the lifters into the block. but i can't see that with a flat tappet unless it had a cam go flat and mushroomed the lifter bottom,, and the person took that lifter out through the "top" instead of pushing it through into the cam tunnel,, like you're supposed to in the case with a mushroomed lifter. meaning it flattened a lobe and smeared the bottom of the lifter out from the edge/corner. not a mushroom lifter type cam. just to clarify.

it could have "peeled out" some of the bore wall if that's the case. that's the only way i've seen what your describing with a flat tappet. jmo.
andy

i am just curious as to what caused this?

Friction :crazy:

Welcome to the site man.

Porosity in the casting or a defective lifter are the only things I can think of on a stock engine. I've torn hundreds down and never seen what you're describing.

yea i had no idea so i just figured id ask i should post a picture

YES!

If you would post a picture, it may help us to understand this better!