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lost a falt tappet could use some input

1658 Views 41 Replies 13 Participants Last post by  CFMCNC
had built a 454, 8:1 comp, 781 heads with 2.19 valves. stock guts
got a lunati flat tappet .531/.542, 220/227. and used Melling lifters.

took it to the dyno and as soon as we fired it up we noticed the rockers were banging the valve covers(cast aluminum mickey Thompson with the drippers)
pulled them off and ground and rinsed them.
but when we pulled them off notices some smoke/steam/vapour coming out of the crank case, figured it was moisture.

rockers were still banging so we cleaned them up some more. still vapour coming out. we could actually feel the covers banging.

we had hit lunch so I went and picked up some super thick cork valve cover gaskets, installed then as ran for a couple minutes and could hear banging, double checked rockers were lashed properly, fired up and still could hear the clattering coming and going so we killed it and pulled intake, sure enough at least 3 lifters were totally fucked.

this must have only been total 10 minutes run time, and when we pulled the covers off the first time it could have only been a minute. so I feel like whatever was wrong was totally wrong from the instant we started it.

couple of theories,
1 the aluminum flakes from the rockers banging the valves covers instantly started to chew lifters, which would be weird as its aluminum.
2 I put the rear cam plug in to deep, I checked when I got home and the cam gear was up against the block but the distributor also has some pretty good wear on the teeth.
3 typical flat tappet failure, even though I used moly(isky rev lube) and made sure everything rotated(lifters) when I put it together also used driver BR30 oil

will post all the pictures soon.
looks like the crank main journals need a polish at least, block needs a hone, and new rings and bearings all around
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if the cam was being held forward by the plug it could have contributed to the lobe wear
ya that what my machinist figured, but the cam sprocket looked to be rubbing against the block as it should when I pulled it apart
also how far in should that plug be? he said the edges of the plug pretty well flush with the block, mine were maybe 1/8 or so in
What do you think is happening to the lifter and lobe when the rocker hits the valve cover?
If the lobes got hot enough to cause smoke from crankcase it ran awhile......
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A few of the failures look at the exhaust valves then see if its weird the dont have the same heat spots.

And you can see how far my cam tunnel plug was pushed in.


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And here are a few more of 1 lifter about to go plus wear on the distributor gear that Looks a little intense to me.


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I would go with that cam plug is way too far in. Just looking at the pics of the lifter on the cam, it's way off center and basically rode the edge of the lobe. Explains the dist gear wear, as well. If you did that much damage in 10min, have your machinst check your work before you button it up. Everyone makes mistakes, but motors aren't cheap anymore. FYI, go roller, spend the $$$ once. It's 2023...
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They always shit right away if they are going to, well most of the time, plug is in way too far. I wouldn't recommend melling lifters for that application. What was the spring pressure during breaking in. And did you check lifter rotation?
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It sux brother. It really is worth the money to go Hyd. roller as suggested if possible.

Gaterman lifters, and I will ship to Canada. If I can help let me know.
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Just me but I would completely disassemble that engine, clean up and smooth ALL casting flash, thread chase and CLEAN, CLEAN, CLEAN ALL bolt holes in block. Bolt holes in deck look no Bueno and that block has a shit ton of sketchy looking flash. One little piece of that breaks off and you have a expensive boat anchor.
Are you positive no valves were kissing valve pocket in exhaust side? Maybe just the pic but it almost looks like a shiny witness mark in pocket.
Cam pushed forward too far which probably caused distributor issue as stuska said.
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Had a small block that did exactly like this one. It was the rear plug pushed in too far. Replaced cam and lifters and new rear plug just flush with block and never gave another issue.
Not worth running a flat tappet cam any more. Hydraulic roller is the way to go.
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This has nothing to do with it being a flat tappet (even "in this day and age") or the break-in. This was strictly an assembly error; the cam moved one way or the other, some of the lifters contacted the lobe next door taking the edge of the lifter off, once that happens it's game over. Edge loading is the quickest way to fail a cam.

The cam plug is in too far. Is it far enough to cause a problem? It could be or it might not be, often times it will have some brown/blue heat marks on it from the rubbing, but this may not have run long enough for that to show. It could also be that the cam moved back too far if the timing chain set up used a thrust bearing/bushing and it did not get installed. Yes, believe it or not, I have seen this. A good friend made that mistake somehow and we caught it on the dyno. In this case, the new tight chain kept the alignment decent enough for the engine to run ok - though I did notice a bit more spark scatter than I like to see - but it was a warmed over stock 383 with no trick parts so no one got too excited. But as time went on there were some misfires at high speed and the timing scatter got much worse so we took a good look and while the distributor was being checked out I had a look into the valley (Mopar RB dist hole is huge) and found the issue. Attached are a few pics for you.

In your pics I can't tell which is the front of the block, that will tell you which way the cam moved too far. In any case, you should run a cam button and set end play before putting the cam plug in and the plug goes in just flush. It also looks like yours was hitting the sides of the lobe and the rough cast radius took the edge off.

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They always shit right away if they are going to, well most of the time, plug is in way too far. I wouldn't recommend melling lifters for that application. What was the spring pressure during breaking in. And did you check lifter rotation?
You can see the lifter rotation in the pics.
Are you positive no valves were kissing valve pocket in exhaust side? Maybe just the pic but it almost looks like a shiny witness mark in pocket.
I see that also.
hey guys thanks for the replies it sure sounds like I fucked it up by installing that plug to far in, even thought the cam gears up against the block when I pulled it apart it must have been bumping, I will check for marks on back of cam and plug today.
I don't remember the block orientation when I took the pictures but I will go put the cam back in and drop a few lifters down and see.

I have thought a lot about a roller set up, but honestly with the price of them up here after exchange and everything I could afford to do this 2x before the roller is worth it. a frigging roller cam alone is close to 700$ all on its own.

the Melling lifters I use my machinist has used a bunch and hasn't lost any of them.

I will have to double check but I think the spring rate was 310ish and 340ish open.

I checked the lifters all rotated prior to buttoning top the motor.

I will double check for exhaust valve contact, some of the pistons sure did look dirty and maybe a little oily(#5)but that. could just be residual from assembly, it really didn't run very long at all.

so far it looks like the rod journals are ok and will only need bearings, the front main journal on crank is the worst and rear main barely looks touched im guessing because of the extra clearance, I built this thing as tight and close to factory spec as possible and it looks like if I had everything opened up and ran a 20w50 most the the garbage would have just washed right through lol.
hopefully all it needs I a polish on the main journals and I can go with .011 under mains and standard rods again. and it looks like it will need new cam bearings.

also the head bolt hole in the deck look crappy because they have silicon sealant in them that pulled out a bit when I pulled it apart.
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im not totally against the roller but I still feel like a flat tappet is more in my affordability range( even after a failure).
but I might get jones cams to price me out one and see if it wouldn't be to bad after getting shipped to Canada with his god flat tappet lifters and such, and probably a better cam since it would be a little more custom tailored.
I will also say I used sky rev lube(the moly stuff) on the lifter faces and cam, and I even primed the motor with intake off so after giving it a bit of a rotation I would reach into the cam valley a bit with a little brush and paint any that got wiped off the lobes.
my machinist says he has been using the driven assembly grease on all the flat tappet stuff though and hasn't had any issues.
he also doesn't push that cam plug in to far ether though.
im wondering how that grease would work compared to the moly stuff though?
Cam thrust would not wreck just a couple lifters, there would be marks on the side of the lifters and lobes.

My guess is pushrod length and or rockers were out of travel (coil bind?).
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