OldGray320i
OldGray320i Dork
2/9/20 5:48 p.m.

I was changing the timing belt oon the Miata,  using the two crescent wrench method to hold the cams. 

Exhaust cam torqued to 40 ft lbs just fine, but the intake cam had a e36 m3ty wrench and it moved. 

Go to pull the thing off, and as I wiggled back and forth,  I chingered the lobe a bit.  It's got a bit of an edge to it. 

How effed am I?

jimbbski
jimbbski SuperDork
2/9/20 5:53 p.m.

I can't see anything that would worry me if it were mine.

Patrick
Patrick GRM+ Memberand MegaDork
2/9/20 5:54 p.m.

Take any sharp or raised edges off.  Pack a rag around the lobe, file it gently, send it

Peabody
Peabody UltimaDork
2/9/20 5:57 p.m.

I'm in the camshaft business. I would run that on my own car.

OldGray320i
OldGray320i Dork
2/9/20 6:11 p.m.

In reply to Peabody :

It's got a tiny raised edge to it, should I smooth that down?

I thought I'd hosed myself badly, feeling better about it now...

codrus
codrus GRM+ Memberand UberDork
2/9/20 8:42 p.m.

I would take the cam out, clean it up, then run it.  You'll have to do the timing belt again.

 

 

Paul_VR6
Paul_VR6 Dork
2/10/20 8:26 a.m.

Make sure there are no raised bits, if there are then file them down. Do it in the head carefully, or out of the head more carefully (I've seen more cams roll onto the floor than I'd like to admit).

OldGray320i
OldGray320i Dork
2/10/20 8:28 a.m.

In reply to codrus :

Haven't put it all back together again... without yet googling,  remove the cam is unbolt the caps?  Accounting for valve spring pressure?

I know there's a cam swap of some sort that's supposed to be good, might be time to at least go research that...

CAinCA
CAinCA GRM+ Memberand New Reader
2/10/20 8:29 a.m.

I'd put a rag underneath it and then stone or file it smooth. 

Toyman01
Toyman01 GRM+ Memberand MegaDork
2/10/20 8:39 a.m.

I'd throw a rag around it and hit it with a stone just enough to remove any raised edges. A couple of pieces of tape, sticky side up, will also catch a lot of trash before it ends up somewhere you don't want it. 

OldGray320i
OldGray320i Dork
2/10/20 8:55 a.m.

So... I probably should do that, but as I searched the cam upgrade, apparently the MSM intake cam is a nice drivability  improvement and a drop in - runs on the stock ecu (?). 

How difficult is it?  IF I do it,  seems like shims are not anything to worry about (other than proper clearances), anything else to consider?

codrus
codrus GRM+ Memberand UberDork
2/10/20 11:15 a.m.
OldGray320i said:

So... I probably should do that, but as I searched the cam upgrade, apparently the MSM intake cam is a nice drivability  improvement and a drop in - runs on the stock ecu (?). 

How difficult is it?  IF I do it,  seems like shims are not anything to worry about (other than proper clearances), anything else to consider?

I have an BP5A (MSM) intake cam in mine.  It's not a dramatic difference, and I don't know that it's worth doing just by itself.

Cams are covered in oil, and that tends to grab little metal particles and hold onto them.  If I were filing/sanding/whatever a cam, I would want to hose it down with solvent to make sure I got rid of those metal particles, and I would not want to dump all that solvent into the oil pan.  Taking it out isn't hard as long as you're careful.  As far as cams rolling off the bench, I suspect that's more of an issue with OHV cams than OHC ones.  On OHC cams (at least Miata ones) the bearing surfaces are smaller diameter than the cam lobes, meaning it can't roll on them on a flat surfaces.

Swapping the cam is relatively easy.  Take out all of the cam cap bolts (do it progressively in mulitple steps, in theory it's possible to snap a cam if the springs are pushing on one and and the only bolts holding it down are at the other), take off the caps (gentle taps with a rubber mallet to get them to get go) and the cam lifts out.  If you're changing cams you'll need to check the valve clearances with a feeler gauge and possibly replace some of the shims.  The annoying bit is that dealers often don't have the shims in stock, and it can take several iterations to get it right.  If you do hose it with solvent then make sure to re-oil it shortly afterwards, they can rust very quickly otherwise.

Do not mix up the cam caps -- keep track of which cap goes where and put them back exactly the same way they came off.  If they have stamps in them then that's good, photograph them before you take it apart.

 

Peabody
Peabody UltimaDork
2/10/20 11:18 a.m.
Toyman01 said:

I'd throw a rag around it and hit it with a stone just enough to remove any raised edges. A couple of pieces of tape, sticky side up, will also catch a lot of trash before it ends up somewhere you don't want it. 

Magnet

OldGray320i
OldGray320i Dork
2/10/20 12:32 p.m.

In reply to codrus :

Well, it's got an exhaust, and I got the FM timing wheel (while I'm in there ), and the motor is unbuttoned now,  so that's the thought behind it (while I'm in there). 

The short research I did says 4k plus feels noticeably woke up,  and guys have scored the cams for $250ish.

If I can get the cam in all said and done for < $300, I'm ok with noticeably woke up. 

Put it this way - the exhaust woke it up in the +4k range,  going from an nb2 mani and sub $100 manifold back 2.25 home brew exhaust to a cheapish header and 2.5 mid pipe (home brew 2.5 muffler carried over) and that was just shy of six bones (and most of my motivation was for ground clearance, the extra pep was nice).

Noticeably woke up is of course subjective, and it's a Miata, so, never winning drag races (unless the other car doesn't run, and even then it's close).

I might still just touch the lobe and run it, but, if I'm in there...

Toyman01
Toyman01 GRM+ Memberand MegaDork
2/10/20 1:13 p.m.
Peabody said:
Toyman01 said:

I'd throw a rag around it and hit it with a stone just enough to remove any raised edges. A couple of pieces of tape, sticky side up, will also catch a lot of trash before it ends up somewhere you don't want it. 

Magnet

If fileing yes. If using a stone you need to catch that debris as well. 

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