Anyone had issues with burrs in the lifter bores on GM Gen VI blocks?
 

I was dropping in my Morel lifters yesterday evening, and noticed that several of the lifters did not seem to slide smoothly in their bores - at least not as smoothly as the others. I could feel a little roughness when I moved the lifter up and down in the bore, and this would change if I applied pressure to the lifter in one direction. I put my finger down the bores, and it appears that it may be an issue with the oil passages as they intersect the lifter bores. I think there may be a very slight rough edge where they bored the oil passages. This did not present a problem with the stock lifters because they have a relieved area around the oil holes that prevents contact with that part of the bore. The Morels have a smooth face in this location. I had the lifter bore clearance checked previously, and they are in spec, and I did use plenty of oil and assembly lube, so that is not the issue either. Just to make sure I am not totally crazy, I dropped one of the Morel lifters into the bores on another stock Gen VI block that I had sitting around, and I noticed the same thing. FWIW, the intakes seem to consistently exhibit the problem more so than the exhaust.

Has anyone else come across this issue? Wish I had found this before the block was assembled, because then it would just be a simple task of knocking the rough edges down with some emery cloth. Not sure how I am going to handle this with the engine basically fully assembled. I guess more than anything I posted this to hopefully alert others to check this BEFORE you assemble your engine.

I'm going to have to mull this over and try to figure out a way to correct this issue without tearing the whole thing down. I think I can spin the engine upside down and work the burrs out so that the debris will fall away from the cam, but not sure how to keep the stuff out of the oil galleries.

Now you guys know why it has taken me a year to build a damned engine. I always seem to find weird goofy problems like this. It just seems to follow me like a cloud. :picard1:

Did you check them with a plug gauge? It will tell you if the bore is true. I've used like a hand reemer b4 to clean up. If you are gonna clean them up make sure the block is oil free as possible. Oil catches the metal. Also in the back of the block either side of the cam are pipe plugs. They are direct access to the oil galley that feeds the lifter and a dry block with a little compressed air should blow the metal out nicely. Hope this helps I know your pain. Put it together take it apart put it together take it apart. Story of my life at times.

it is not uncommon to feel some resistance when you put the lifters in the bore.remember that on lifters that are connected with tie bars you are lining up both lifters at one time and until you get them part way in the bore they are not completly lined up.once the lifter is all the way in and the wheel is sitting on the cam lobe move it up and down about .750 thousands,it should move freely in the bore if the clearance is correct.

Black, not sure what a plug gauge is, but he used a Sunnen dial bore gauge that had the three finger arrangement to measure the bore, after setting the gauge up on the mic measurements from the lifter diameters. Pretty sure he got a reasonably accurate measurement. He has been building racing engines locally for probably 35+ years and has a very good reputation among the local racing crowd.

Mike, I know what you mean about the tie bar making it hard to get the lifters to drop straight in at first. This resistance I am feeling is right when the lifter is near the bottom of the bore. Like I said, I can make it almost go away by pushing the lifter over to one side. When I pulled the lifter out of the worst one, I could just very faintly see a slight abrasion on the side of the lifter, so I don't think this is something that my imagination is conjuring up. Now the big question is if there is any way to correct this issue without pulling the engine apart again. That would mean another set of oil pan gaskets, timing cover, etc. :(

So I guess I'm the only sucker lucky enough to encounter this issue. :mad:

Although it sucks, it could suck way worse if you blew this off and led to something bigger.

If the builder/machining place/whatever, is close to you, i'd bring it down there for a second opinion before doing anything about it.

As far as how it feels, hard for us to answer without feeling it, but if you are seeing abrasion marks, like you say, then pretty easy answer to say....do not go further with putting engine together. Stop, and figure it out.

I just re-read your original post. One thought came to mind. Does your machinist have another set of morels laying around you could borrow for a quick test fit and side to side comparison with yours? Just a thought...

I have a friend who might have a set laying around, I'll ask him. I guess anything is possible, but I did try using several pairs of lifters in the offending bores with the same result, so I doubt if it is an issue with the lifters being off spec.

Talked to the local guy, and he advised that I tear it down and go through the bores lightly with a hone. Says he does that to all the blocks he builds. Sure wish I had known about this way back when I started with a bare block! Is that a "normal" step that I simply skipped in my ignorance? I went as far as getting the lifter clearance checked, which is more than a lot of people do.

He did say that if the lifter drops down onto the heel of the cam under its own weight then I am probably OK, but obviously wouldn't swear to it, nor would I expect him to. I have to say if it comes down to tearing this thing down to the bare block and starting from scratch I will be tempted to part it out, drop in a stock 454 and go boating! :party-smiley-004: :boat:

budman,measure the od of your old lifters and compare to the new morrels,use a good quality mic,when i installed the morrel,s they were .0002 bigger od,not enough for me to worry about.