Fiat SOHC, wiped cam edition!

Working on the Yugo today fixing the temp gauge and wiring a tach up. Fired it up for a cooling system and tach check. Noticed it was making a bit more noise than usual, especially seeing as I had just reshimmed the valves a few hundred miles ago and it was full of fresh 15w50 M1. Removed valve cover. The lobe closest to the belts on cylinder 1 (cant remember port order, intake?) is wiped down enough the chamfer on the edges of the lobe at its tip and then some are gone.

How berkeleyed am I? Oil in the cam box is glittery, hopefully not so in the sump. It was making 32 lbs at idle when I started it.

It's because of the new oil doesn't have zink in it.

Not my problem, only ever ran 10w40 QS defy, 1200 PPM zinc, and then switched to M1 15w50 which is 1300ppm zinc IIRC, due to not liking the pressures I got on 40wt. Zinc related cam problems is and always has been primarily a small block chevy issue because they have crap valvetrain geometry thatreally stresses the cam. An OHC engine, even this one with 9000 RPM valve springs, isnt that hard on oil.

M1 15w50 has lots of zinc http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2365763

9000RPM springs? what is the seat pressure?

In reply to Onetrillionrpm:

They're stock dual springs, IDK what the pressure works out to. Known good to a lot more than the stock cam makes power, I've heard 8-9k. They tend to drop valves before floating them, to put it one way.

http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf

Its a suitable oil for flat tappet applications. M1 15w50 is more or less a streetable race oil.

stan_d wrote: It's because of the new oil doesn't have zink in it.

There are at least five problems wrong with that statement.

• It's spelled "zinc".
• The active material is the phosphate, zinc is merely the first word in the chemical name for ZDDP
• Motor oils do still have some ZDDP in them
• We have better compounds for combating camshaft wear than ZDDP nowadays, anyway. In most cases, increasing ZDDP levels to the old figures makes cam wear worse.
• Cam wear is not ordinarily a problem on OHC designs that have bucket followers literally twice the diameter of a pushrod engine's lifter and much reduced loadings on that interface thanks to wider lobes, lighter valves, lighter valvesprings, and no leverage ratio in the rocker working against the cam.

What Knurled said, just to reinforce things.

Is the cam a re-grind?

the fact that it was only one lobe sounds like either a bad shim or a bad cam. If it had been the wrong oil or too much pressure, all of the lobes would have shown wear

Stock Yugo 1.1 carb cam AFAIK. I used used shims, but they were in good shape. My best thought is that's the farthest from the oil filler, so when I changed the oil before starting it after sitting all winter, the way the cam box is baffled, it probably only had a few drops of residual oil from last year on it. Whereas the others were drowned in the good stuff. It cranked a lot before I got it running and I didnt fill the filter, so it didn't build pressure for a while.

For those that do not know Fiat SOHC and DOHC engines.. the shims are ontop of the followers. This is unlike Alfa what put them under the followers.

It is very possible what you say is true.. but I know with several stock DOHC fiat engines that have been left to sit for literally years.. starting them up caused no cam wear issues

The question still stands, can I get away with replacing just the cam, re shimming and changing the oil? Or am I gonna have to roll in new bearings at a minimum?

I only had the cams out of a Fiat engine once. I want to say there are no real bearings on the cams, but that they have polished journals that ride in polished supports

Bearings as in lower end bearings. I mean, like a teaspoon of hard metal powder has run through it and who knows how much the filter actually got. Though I do only run the NAPA gold filters(top tier wix) on this engine.

Need an EFI 1500 from an Exxy? Free for pickup in the PNW.

In reply to turboswede:

As much as I'd love to visit the PNW, road trip isnt really an option right now, let alone 16mpg truck road trip, as I dont think a SOHC will fit in the trunk of a 99 Prizm. And upgrading from the 55hp 1116 would hurt the "ultimate slow car fast" character.

Kenny_McCormic wrote: In reply to turboswede: As much as I'd love to visit the PNW, road trip isnt really an option right now, let alone 16mpg truck road trip, as I dont think a SOHC will fit in the trunk of a 99 Prizm. And upgrading from the 55hp 1116 would hurt the "ultimate slow car fast" character.

actually the SOHC would probably fit in the trunk of a Prizm :)

If you need a cam let me know, I have a few running around. A few spare motors too...

In reply to JThw8:

Well maybe layed down it would, but then where would I sleep? Expect a PM soonish.

In reply to Kenny_McCormic:

A Fiat SOHC will definitely fit in your trunk. Free is free, you can sleep in your car!

Well, the car gets ~30mpg the way I drive it, 5000 miles roundtrip from MI to OR, 5000/30=150gallons 150 gallons*the current national average of $3.50=$525 of fuel, it would take me no less than 4 days driving flat out, at which point speeding ticket prices come into play. This doesn't account for food, and how mind numbingly boring driving alone for 4 days would be, at which point a friend is needed, at which point the car becomes too small for both of us to sleep in.

I think I'll try throwing a cam at it and flushing it out really good with cheap 15w40 diesel oil.

I don't know anything about Fiats but some mercedes engines use oil fitting to the cams that can either plug or brake and take out a cam lobe. Check the oiling to the cam before you do anything. Verify that oil is getting to the cam, not just oil pressure.

It was getting plenty of oil, cam is oiled by bearing ooze out, it puddles completely submerging the follower because the drains are ~1/4" above follower level.

I may not be of any help. I can tell you this. Its not your oil. Its more likely you installed the shim upside down.

They have sides? I was under the impression they were through hardened and finished properly on both sides, the painted on numbers being the only reason to put them in one way or another. I put all mine in markings down, unless shiny and successfully used on both sides, in which case they went pretty side up.

Kenny_McCormic wrote: Well, the car gets ~30mpg the way I drive it, 5000 miles roundtrip from MI to OR, 5000/30=150gallons 150 gallons*the current national average of $3.50=$525 of fuel, it would take me no less than 4 days driving flat out, at which point speeding ticket prices come into play. This doesn't account for food, and how mind numbingly boring driving alone for 4 days would be, at which point a friend is needed, at which point the car becomes too small for both of us to sleep in. I think I'll try throwing a cam at it and flushing it out really good with cheap 15w40 diesel oil.

I'ts only about 1400 miles roundtrip to NJ....I have motors, lots of motors

Bring the truck, some $$ and a tow dolly and take the whole lot for the right price.

But seriously, I'd toss a cam at it and try again, you should be ok.