Cam timing slightly off- definite tell tale of a milled head?

[Jonohhh]

Last night I found that the cam timing seems to be just a little retarded. It does not seem to have skipped a tooth, as advancing one tooth would seemingly put the cam more advanced than the timing marks.


The timing mark is also very far from the pulley and getting a dead-on view of it is pretty difficult so it may be a little better or a little worse than photos show, but it definitely seems off.. although getting the crank exactly at TDC based on the FW marks isn't exactly a precise way to do it either. Does it look out to y'all, or within margin of error? I had the FW mark as in line as I could get it with the 0deg indicator.

Does that make it likely that the engine has had the head shaved at some point? I figured I'd check it while I had most of this stuff apart- the car idles pretty choppy and also doesn't pull very well up top, so that was the main motivation for checking in the first place...oh and that the timing belt was LOOSE to the point that I could almost push it all of the way off the tensioner with a single finger. That has since been sorted.

Are there any other telltales of a shaved head or block that are visible from the outside?



Sorry for all of the simple question threads lately.

 

[lookforjoe]

Do you have a pic of the flywheel TDC mark at the same position? That would help, since unless you pull the crank gear, the marker may have moved.

 

[Jonohhh]

Do you have a pic of the flywheel TDC mark at the same position? That would help, since unless you pull the crank gear, the marker may have moved.

Unfortunately I uh, didn't manage to get a look or picture of the crank timing pulley mark- to this point I've been relying on the flywheel only...and also my car no longer has the split pulley mark because, well the timing tab has been cut off for some reason, and the split pulley is no longer a part of the car.

However the car is in a million pieces and it has to come apart again because I made a pretty dumb mistake, so it'll be easy to repeat the test

 

[JimD]

Yes, a shaved head will create a variance in where the cam timing marks line up. My 1500 with a MWB performance head is off about 1/2 tooth. Mine can be 1/2 tooth off in either direction depending on how the belt is first placed on the teeth.

The shaved head will also affect the spacing of the holes on the back plate that has the cam pointer. Since it spans from the block up to the cam box, shaving the head lowers the cam box. Look and see if the lower hole has been elongated.

Also note that the crank timing marker "floats" and needs to be fixed into the proper position if you are taking things apart and reassembling them.

The flywheel mark can be hard to find, but it is typically a little dimple. This one is easy because the mark was painted prior to install. There are timing indicators on the view port at the top of the trans bell housing. This is just one more way to check your timing position.

 

[Jonohhh]

Yes, a shaved head will create a variance in where the cam timing marks line up. My 1500 with a MWB performance head is off about 1/2 tooth. Mine can be 1/2 tooth off in either direction depending on how the belt is first placed on the teeth.

The shaved head will also affect the spacing of the holes on the back plate that has the cam pointer. Since it spans from the block up to the cam box, shaving the head lowers the cam box. Look and see if the lower hole has been elongated.
View attachment 63244

Also note that the crank timing marker "floats" and needs to be fixed into the proper position if you are taking things apart and reassembling them.
View attachment 63245

The flywheel mark can be hard to find, but it is typically a little dimple. This one is easy because the mark was painted prior to install. There are timing indicators on the view port at the top of the trans bell housing. This is just one more way to check your timing position.

View attachment 63243

Awesome.

The back plate hole elongation/modification seems like a good way to check in my case.

My flywheel mark looks similar to the ones on one of the Wiki images...it took me a while to find which one was actually the right one. I guess I should also verify it with the crank sprocket mark.

My crank pulley timing tab is very much floating.... somewhere in southern California, probably in a storm drain, sewer, the ocean, or a landfill- being accused of causing cancer. It was cut off of the bracket for some asinine reason. Thankfully that seems like the least preferred to use based on the threads I've read


Thanks Jim!
I'll check and report back!

 

[carl]

An adjustable cam pulley would allow you to set the cam timing correctly.
The half tooth issue is a common complaint on 124s (and you have two cam pulleys to deal with). I guess at this point in Fiat life, most motors have had the head shaved for a rebuild or blown head gasket. I assume Fiat would have a service limit on shaving just for the cam timing issue.

 

[Dr.Jeff]

I've found the timing belt to be about a half tooth off on a couple of bone stock engines. Including one with a known history of never having any work done to the engine, a completely stock head and factory gasket that had never been removed since the day it was assembled at Fiat. In such cases the flywheel confirms that the crank is at TDC. So I'm of the impression that either manufacturing tolerances can allow that much variance, or maybe the pointer at the cam sprocket is off? I've not gone to the trouble to measure the cam lobes to verify it is in the correct position. So who knows.

 

[Longitudinal]

If you have everything in place and the marks are not a full tooth off, then yes, the only explanation is that the head was milled.

If memory serves, milling a certain amount off the bottom and top of the head and the bottom of the cambox brings you back to correct alignment. I think that amount is .040" off each surface. Also, you switch from a 1500 idler to a 1300 idler.

If you are observing slightly off timing marks, probably the best thing to do is set the engine at TDC using a dial indicator, then check cam timing.

 

[pro4art]

Very common to find the crank pulley pointer indicator is NOT indexed with the flywheel top dead center mark. Seen up to 5 degrees off when using the flywheel marks to get TDC. The sheet metal for cam position and the crank pulley timing pointer are parts that can be installed a little off, or in the case of ignition timing crank pulley, several degees off. Doing a cam belt on a street car, normally on the ones where the cam mark is 1/2 tooth off, I set it 1/2 tooth advanced rather than retarded. Retarded bothers the bottom end more.
I just worked on one of those X1/9's, that are seen often. Aftermarket crank pully, did start or run well. The crank pulley at TDC, the flywheel mark showed 10 degrees before TDC. Set the flywheel to TDC, used a baby Phillips screwdriver to lay in the grove above the transmission "O" degree mark, and the pointed end fits right in the flywheel mark. I just made a new mark on the crank pulley with a mini 3 angle file, and paint to highlight it. Eye balled some advance to the distributor, fired it up, and had 1500 rpm idle speed with timing set at 10 BTDC. Slowed the idle, reset timing to 10 BTDC, and trimmed the idle speed again, and rest ignition timing. Car has a 40/40 Weber DCNF, so balanced the 2 barrels with the air trim screws, they are never the same amount of air in each barrel at idle, adj mix. On this car, had to enlarge the very tiny accel nozzles to cure flat spots from idle.

 

[Dr.Jeff]

Very common to find the crank pulley pointer indicator is NOT indexed with the flywheel top dead center mark. Seen up to 5 degrees off when using the flywheel marks to get TDC. The sheet metal for cam position and the crank pulley timing pointer are parts that can be installed a little off, or in the case of ignition timing crank pulley, several degees off. Doing a cam belt on a street car, normally on the ones where the cam mark is 1/2 tooth off, I set it 1/2 tooth advanced rather than retarded. Retarded bothers the bottom end more.
I just worked on one of those X1/9's, that are seen often. Aftermarket crank pully, did start or run well. The crank pulley at TDC, the flywheel mark showed 10 degrees before TDC. Set the flywheel to TDC, used a baby Phillips screwdriver to lay in the grove above the transmission "O" degree mark, and the pointed end fits right in the flywheel mark. I just made a new mark on the crank pulley with a mini 3 angle file, and paint to highlight it. Eye balled some advance to the distributor, fired it up, and had 1500 rpm idle speed with timing set at 10 BTDC. Slowed the idle, reset timing to 10 BTDC, and trimmed the idle speed again, and rest ignition timing. Car has a 40/40 Weber DCNF, so balanced the 2 barrels with the air trim screws, they are never the same amount of air in each barrel at idle, adj mix. On this car, had to enlarge the very tiny accel nozzles to cure flat spots from idle.

That describes exactly what I was referring to in post #7. I agree the most likely reason is the timing cover behind the cam pulley is not accurate. Sometimes I find them roughly 1/2 tooth advanced, other times it is about 1/2 tooth retarded. But I don't think I've ever found one that was right on the money.

This reminds me also of how far things can be off with regard to the cam timing, ignition timing, carb settings, etc, and it still runs reasonably well (for a Fiat).

 

[Jonohhh]

So when the flywheel is in this position, the cam is in this position.

If I position the camshaft such that the mark lines up with the backplate, the flywheel ends up in this position:

Unfortunately, I don't yet have the gargantuan socket required to remove the crank pulley in order to see the mark on the crank sprocket.. The single missing slot on the crank tooth seems not to line up with anything useful that my car still has (the timing indicator)

I don't have the outer portion of the split pulley with the timing mark installed at the moment anyway. I could, but the tab is gone in my cars case.


I was kind of tempted to just advance it to see what happens. It has a lopey idle that I just assumed was normal, but I've heard other LJet X1/9s where that's not the case, and it has new plugs, wires, rotor, distributor cap, injectors, and correct fuel pressure. And unfortunately, it doesn't feel like it's cammed...in fact I've had to come to accept it's pretty meh up top (though for a SMOG motor it's fantastic) So

 

[Dr.Jeff]

That's exactly what @pro4art and I are describing. In my opinion I do not think that is a good indicator if the head has been milled or not. This sort of malalignment seems quite common on these engines. I'm of the belief it is more likely due to the pointer for the cam pulley being off. So I'd follow the suggestion given to set the flywheel at TDC, then place the cam pulley so the mark is 1/2 tooth toward the advanced side. And set up your belt there.

As for your crank pulley and missing pointer, that is more for ignition timing. You can use the marks on the flywheel to set the ignition timing and not need a pointer on the front of the block.

 

[Jonohhh]

Thanks for the suggestions and info everyone! It sucks that there's not a dead reliable set of timing marks on these things, at least not a set that's convenient to use!

I'll advance it a tooth and see how it does.

 

[kmead]

Thanks for the suggestions and info everyone! It sucks that there's not a dead reliable set of timing marks on these things, at least not a set that's convenient to use!

I'll advance it a tooth and see how it does.

Honestly I think it is fine as is.

Most of the time when you shave the head you also have to change to the 1300 tensioner pulley which is larger in diameter to take up the slack.

Turn it through two revolutions and verify all the marks are in the same places.

Have a read through here: https://www.midwest-bayless.com/Fia...81-85-fi-10-bolt-w223-degree-cam-rebuilt.aspx

 

[fiatfactory]

So when the flywheel is in this position, the cam is in this position.
View attachment 63342

The mark you have highlighted with the yellow paint is not the flywheel TDC reference point.

SteveC

 

[Jonohhh]

The mark you have highlighted with the yellow paint is not the flywheel TDC reference point.

SteveC

Hold up a minute. OMG

Now that you say that, I've gone back and zoomed in really far and can now see this mark on the flywheel that looks much like the one on JimD's photos, except just not anywhere near as obvious.


I can't even see that with my eyes given that I can't get all that close to it and my eyes suck....

Is that it?!

The silver paint to the right is where the previous owner marked one of the protruding clutch dowells as the timing mark.....which the timing was set off of when I got it. I guess I made a similar mistake but marked something else instead.

 

[fiatfactory]

I don't think the silver paint was intended to mark the clutch cover dowel (yellow arrow) but perhaps the small drilling dimple (the red arrow) is the timing mark

or the silver mark has got absolutely nothing to do with TDC, and was just a mark put there by the PO to mark the clutch cover to flywheel as a reference for re installation?

the dimple you've marked with yellow paint actually looks to be a balance drilling in the pressure plate , not actually the flywheel at all.

SteveC

 

[Jonohhh]

I'm trying to remember if I've always been mistaken about this, or if this is a mistake I made just now when trying to check this for the first time after not needing to look at the flywheel for a good while.


I do remember setting the ignition timing at some point with a mark that was definitely smaller than the huge hole (likely for balancing as you say), now that you mention it. It's been over a year since I last looked at it.

Also, the PO (or their mechanic) put a very distinct mark on the camshaft pulley one tooth offset from the correct timing mark, for whatever reason. I never worked that out.

I'll check the ign and cam timing next time ai can get to the car, and try to verify the correct timing mark on the flywheel. I absolutely cannot see it with my eyes so I'll get rid of all of the current marks and make a new one once I can identify the correct one.

Anyway, all that's clear at the moment is that I'm a moron and that this poor engine has had one hell of a time with the timing seemingly being set at probably 20ish deg base timing. I would say I'm surprised there was no detonation when I was using 87 octane during the gas prices surge, but I guess I shouldn't be surprised given the CR.

 

[kmead]

I'm trying to remember if I've always been mistaken about this, or if this is a mistake I made just now when trying to check this for the first time after not needing to look at the flywheel for a good while.


I do remember setting the ignition timing at some point with a mark that was definitely smaller than the huge hole (likely for balancing as you say), now that you mention it. It's been over a year since I last looked at it.

Also, the PO (or their mechanic) put a very distinct mark on the camshaft pulley one tooth offset from the correct timing mark, for whatever reason. I never worked that out.

I'll check the ign and cam timing next time ai can get to the car, and try to verify the correct timing mark on the flywheel. I absolutely cannot see it with my eyes so I'll get rid of all of the current marks and make a new one once I can identify the correct one.

Anyway, all that's clear at the moment is that I'm a moron and that this poor engine has had one hell of a time with the timing seemingly being set at probably 20ish deg base timing. I would say I'm surprised there was no detonation when I was using 87 octane during the gas prices surge, but I guess I shouldn't be surprised given the CR.

You might consider contacting MWB for a new crank pulley end timing quadrant.

If you remove the crank pulley you can verify which of your marks is correct as there is a definitive mark on the front main seal cover which Hussien I believe showed in one of his images.

 

[carl]

And don't forget the scenario where the flywheel can be installed 180 degrees out and you can spend an awful lot of time looking for the flywheel timing mark that is actually sitting down near the oil pan.