lifter bore problem

hello all i have been have lifter bores that are galling , this is leaving metal on the sides of the lifter itself from the bore . i have replaced the lifters and after just one run the lifters are getting metal on them again , the new lifters are the good crane ones . this is happining on the left bank exh only at this stage . note this is a cast iron standard hemi block with dart 96 billet heads, stage 5 rockers . could this be lack of oil as the exh push rods have a larger angle and put more load on the side of the lifters . looking at the idea of installing bronze sleaves into the lifter bores , is this a good idea ?
also i need to go to the next size up on the piston bores at the moment we are at 4.280 . is it ok to go larger with the standard block and to what size . this is a blown alcohol funny car that runs in a braket type class that runs around the 7 to 7.5 range .
thanks

 

Your lifter bore problem may simply be that your wearing them out. They are not round anymore and too big.

 

have you changed the rocker shaft on the left bank exhaust recently?

 

The oil galley going through the lifter bore on a stock iron block is huge and I have always felt that the edge of the galley had the potential to snag a lifter unless it was a full body roller style. Also depending on how high lift you have, some lifters will actually go high enough in the lifter bore to uncover/ unseal the lifter galley enough that there is a slight oil pressure loss. Bronze bushing an iron block is never a bad idea if for no other reason than that it can correct factory tolerances (or lack of them) for keeping the lifters at perfect alignment. For the type of racing you're doing, another. .030 overbore (4.310")shouldn't be a problem on a steel Hemi block, they're cast quite a bit thicker than a wedge block. I would check to see if you can get .040" over (4.290") rings though, just to get as much use out of the block as you can.

 

lifter bore

Another possibility to add to your thought, I had the same problem once after a cam regrind. The base circle was reduced causing the lifter oil slot to drop below the bore deck on the heel of the cam. Bronze bushings were the cure, they dropped slightly lower into the lifter bore, but still cleard the cam.