[Skip Fix]

Putting together a new 455 with an HR and have the new Comp "S" HR lifters . They are a littel snug in a few of the bores but do slide up and dwon easily once in. They are 0.001 larger using my Chinese mikes than my Comp solid rollers. What is clearance and what do you use to measure the bore-snap gauge?

[77 TRASHCAN]

I had a weird situation w/ a pair of roller lifters on my brothers SBC, recently. It acted like they wouldn't go into the bore...not the case. The ends of the lifter bodies somehow were burred on the edges. I cleaned them up, everything fit fine...

[Geronimo]

You can measure the bores using a small bore gauge and a 1" micrometer for the lifter body. I'd rather have them a little tight than too loose. .0015" to .0025" seems to be the normal range.

[mgarblik]

I have measured lifter bores a number of ways. Least accurate but cheapest is snap gauge and micrometer. A method I like better is to buy round gauge block the exact size you want the bore to be. They can be bought at Grainger, MSC, or my favorite, McMaster Carr for about $10.00-12.00 each. Then hone the bores until the gauge block just slides through the bore. A few year ago, I finally broke down and bought a dial bore gauge that will go small enough for lifter bores. It is a Starrett and not terribly expensive. It was an eye opener to see how tapered and out of round stock iron lifter bores can get on a 30-40 year old engine block. In my opinion, a good racing engine should have bushings, honed to .0015-.002 clearance and taper and out of round held to .0002. Not hard to do with a rigid hone. Does take some time though. Takes me about 3 hours to rigid hone 16 bushings to a proper diameter, straight and round.

[65nss4spdGTO]

Skip,

If the block was shot blast, it can leave a bit of a ridge at the top. You can soften the ridge with sand paper or a slight hit with a ball hone can do the trick.

Calvin Hill
Hill Performance
708-250-7420

[Skip Fix]

I don't think they shot peened it just tanked and clean up deck(previous owner had blos a head gasket) and of course assembled short block, heads on to finish with lifters pushrods and rockers. It slides OK once in but a few kind of snug dropping them in, and one is defnitely snugger than the rest. I'll see if there is one lifter a little smaller than the rest for that hole.

[74t/a]

I wouldn't want to run them any tighter than .0015, and even there you might "stick" a lifter. I have an abrasive brush that will go on my drill. Nylon bristles impregnated with and abrasive. You might could run one of those in there without putting contaminates in your engine. I wouldn't want to try though.

[Skip Fix]

I think it is probably .0015 or so. Once both sections around the oil band are in the bore it feels much better.

FYI the "S" Comp HR lifters with a .380 lobe are .100 form exposing the oil band of the lifter whre it can be seen at the top of the bore.

[74t/a]

I wouldn't be worried about the oil band....if you are. That is far enough that it won't sacrifice lifter stability.

What does worry me is the "probably" part. You really need to know what your tolerance is. Can you borrow a small bore gauge?

[Skip Fix]

I'll give a snap gauge a try. Tried to get my dial calipers in there but doesn't seem real accurate with the blades being perfectly centered-something that is also a little issue I think using snap gauges. My bore guage won't go that small.

Oil band should not be an issue for me but other guys using a bigger lobe might do well to check that. Solid roller Comp lifter has well over .300 before it is anywhere near the top.

[Skip Fix]

Looks like 0.002-25 and not round for sure.

[74t/a]

Unless they ground that cam on a small base circle, even a larger lobe would not come any higher out of the bore than that. The peak of the lobe cannot come any higher than the journal diameter because the cam will not slide in the block.

[Jack Gifford]

Originally Posted by Skip Fix

Looks like 0.002-25 and not round for sure.

Sometimes the snap guages are good enough to tell you what you needed to know!