flier129

iTrader: (7)

Sold my NB to a local miata guy. He got a MSM cam so he installed it, put everything back together, and started turning the exhaust cam for timing. Turns out it was nearly impossible to spin the exhaust cam. He found the problem, see the attached picture.

The head had about 40-50 miles on it since it was rebuilt by a local machine shop. New valve guides, stem seals, head shaved, etc etc. The engine last ran spring of 2011 and seemed completely fine, no noises or anything unusual and it's just been sitting since then. The metal shaving in the picture looks fresh and the guy said that's the only shaving he's seen.

I don't know all too much about engine assembly and I'm hoping the machine shop I had the work done at can resolve the issue. I'm hoping the good ole boys that worked on it weren't too confused on the solid lifter design vs the rocker arms they're use to.

Any help is appreciated. I was about a month out from putting this engine in my car too

Braineack

iTrader: (62)

somethings wrong with the lifter...pull the cam and find out.

Miater

That's a first for me to see. Where's the rest of it? I didn't think there was enought room to loose parts in there.

vehicular

iTrader: (3)

That shaving looks like aluminum scraped out of the lash adjuster bore from the shim kicking out the side.

I have a dollar that says the machine shop didn't check the clearance after doing the valve job, and that valve is so tight that the cam physically smashed the shim out. That's assuming dude is smart enough to have put the cam in correctly.

flier129

iTrader: (7)

Ok more info.

My friend said he was able to turn the crank, but the exhaust cam didn't move so it sheered off the tab to hold the sprocket in place :( Or at least that's what I gather.

Machine shop says 90 day warranty on machine work, nothing past that, and that don't care how many miles are on it.

I'm agreeing with vehicular on this one, they didn't measure the shim clearances and it smashed it. My friend mentioned something about the shim being bent and shoved out, lol.

I'll try to get more pictures as well. It's still odd, it ran fine a little of a year ago.

Alta_Racer

iTrader: (4)

When the shim popped out, the lobe is in the well of the lifter and has jammed the lobe, that is why it wont turn. care must be taken unbolting the cam, to take it out, and not crash the lobe. Do not try to force the cam to turn! If you/he has access to the oem tool to change the shim, I would give that a try to get the shim back in place first.

You say he changed this cam that has the problem? Sounds like installer error to me.

flier129

iTrader: (7)

This is the exhaust cam, he replaced the intake cam with a msm. Yeah he should of stopped as soon as he saw and/or felt the cam sprocket not turning with the crank.

This might be far fetched but could it of happened from no oil on the lobes or lifter?

baron340

iTrader: (5)

I have no useful help on how to fix your solid lifter head. But I do really hope, for your sake, that head wasn't machined by the same guy in Maryville that torched my forged block.

flier129

iTrader: (7)

Haha, yeah it was done at Hitch's Repair. I'm not sure if it was the same fellow though. Hitch's was referred to me by the owner of East TN Race Prep, he's had lots of race engines worked on with them for the past 20 years. I think it's a hit or miss with them and I think around 2 years ago they had a terrible machinist working on miata parts

He pulled the cam and got the lifter out, says there's a scuff on the lifter's cylinder wall. He should have more pictures for me soon.

I'm putting money on tight clearances, that were obviously acceptable because it ran fine before, mixed with it sitting for a year and a half, and turning the cam over with it being completely dry.

olderguy

iTrader: (19)

Maybe he shouldn't have turned the cam backwards.

flier129

iTrader: (7)

More news! Lol

So he was able to turn the engine over, noticed it was kind of hard, figured it was on the compression stroke. Took out the spark plugs and turned it a full 3-4 rotations before he noticed the exhaust cam wasn't moving. However both the intake cam and the crank pulley were spinning. He also said the bolt that holds the exhaust cam sprocket was finger loose, which is confusing. I haven't touched the cam sprocket bolts since I got it from the machine shop.

So I don't think he ever turned it backwards, but it got wedged on that one shim then smashed that one shim and sheered off the tab on the front-end of the exhaust cam. The damage that's pictured and has been described to me seems forced, but I'm obviously not 100%

He's taking it to the machine shop, which thankfully isn't the same shop you used Jonathan. I figure they'll give him a good explanation on how it broke.

flier129

iTrader: (7)

Here we go, some video:



And more pictures. Looks like the camshaft lobe is broken for sure in the video.

flier129

iTrader: (7)

No one has anything new on this?

He said the first rotation was really hard, he just thought it was the compression stroke. But if the engine was broken from the start it would of never had a compression stroke cause the exhaust valves wouldn't of moved.

I think it broke on his first attempt of turning it and he just kept going even after resistance. The cause I'm thinking a mixture of too tight clearances set from the shop and dry cam lobes and lifters.

Braineack

iTrader: (62)

no, cause you haven't pulled the cam to show us pics yet.

Alta_Racer

iTrader: (4)

I can give a thought. Head was set on a table flat. Valves on that cyl were open and it bent the valve. when it tried to turn, shim popped out. The lobe got stuck in the lifter. The pin on the cam broke trying to force things.

Some people shouldn't work on cars.

Jdilla

I had this happen on my eclipse when it shut off at idle, sheered the cam pin right off the crankshaft. Make sure you cam bolts are torqued to spec

Jdilla

time to pull the head.....

flier129

iTrader: (7)

Machine shop claimed the timing was set wrong -_-. I think there would be more than just this issue if the timing was off that much, not to mention run as smoothly as it did.

Anyways, head is getting fixed and we'll be putting the engine in next weekend I believe. Lesson learned, double check all machine shop work within 90 days.

Alta_Racer

iTrader: (4)

Machine shop is wrong. Look for a better machine shop. Dont set assembled head flat on counter.

vehicular

iTrader: (3)

No quantity of incorrect cam timing will kick the shims out. Period. Find a new machine shop ASAP.