| Author | Message | ||
| Herbert E. Gault (Irfgt)
|
oops! It is a 3.25mm shim. I gorgot which one I took a picture of. | ||
| Herbert E. Gault (Irfgt)
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Here is a picture of a brand new valve shim with the markings of 3.35mm  | ||
| Herbert E. Gault (Irfgt)
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Having just accomplished this task I feel I can write about it with some authority. The shims are marked on one side when new as to what size they are and believe me it is a blessing to have them marked if you do not have a metric micrometer. A lot of the shims for the two valve engine are not easily found at the dealer or some other locations that I usually shop. You can also bet that the shim you need will be the ones that you cannot find so prepare to wait when you adjust the valves to order from where ever you can find them. Also The valve stem installed height is critical because if the valve is ground too deep into the seat there will not be a shim thin enough to realize the proper clearance. This was the case when I received my head back from the machine shop. They did not have the specs. for the installed height so they just measured the existing height and went from there. It worked well on all but a few of the valves which had to be removed by me after I installed the cams and found that there was not a thin enough shim to correct the gap. I had to remove the valve and grind the stem to put it in tolerance. No problem if you have access to a machine shop. I am sure that you could grind the back side of a shim to the correct size and be perfectly useable as long as no one ever tried to use the shim again upside down and provided it could be ground evenly. This may have to be done if the parts availability is not improved. I was lucky that I had a spare engine to draw parts from as a couple of the shims that I needed to adjust my valves were not available so I robbed them out of the spare. You are also going to have some extra shims when you adjust as they do not take any back that you do not need. I am also convinced that the shims can be reused provided they are not scored or have visible wear. When I worked on Fiats I kept a tray of every size available in what looked like a poker chip tray and would simply trade out the wrong size shim for the correct one and I would bet that is what any one else does that does a lot of these cars. Adjusting the valves is a simple job except for having the right shim when you need it. I guess that is one of the things that annoyed me when I did my engine in that I spent thousands on parts and when it came down to a $5.00 shim to finish the job there was none available. This is one area that I did not expect to have a problem with. | ||
| Craig Dewey (Craigfl)
|
Are the shims marked as to which side is "top"? If they are, they may only be surface hardened on that side. If not, they're probably surface hardened on both sides and can be flipped. The problem I always had with these shims is that you never had the right size and you needed to buy an assortment to be sure you had the right thickness. | ||
| Steve Magnusson (91tr)
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And why not flip once? -- is not the top of a new shim identical to the bottom? | ||
| '75 308 GT4 (Peter)
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Okay. In my case, I don't have a surface grinder at my disposal, so I'll go ahead with new shims. I didn't think you could flip shims over. | ||
| Steve Magnusson (91tr)
|
Peter -- I think you've misunderstood Karl D.'s message a bit (i.e., removing material from the shim surface in contact with the thimble{cup} is OK as the shim surface characteristics are not that critical for proper function on that side of the shim); however, for those of us without "easy" machine shop access I'd agree that buying new probably makes more $ sense (and really isn't a big expense). Still, I'm too frugal to not reuse shims when possible -- the "when possible" is the tricky part. The best way I've found to state the confusing "F shim reusability rule" is: Each surface of any shim can be used only 1 time in contact with a cam lobe. It's not hard to distinguish a used side from an unused side (which is necessary on older cars where many shims may have already been flipped over once). I know others have disagreed on this (i.e., they'd say reusing even a used side is OK), but IMHO there is benefit to presenting only a "fresh" (i.e., non-work hardened) shim surface to the cam after shim replacement. I'll probably be doing a lot more "swapping" now that I have 48 options rather than 16. | ||
| '75 308 GT4 (Peter)
|
There are many publications out there advising not to grind the shims at all (even when you say that it's safe). For what's it worth, you might as well change it if its the wrong size (sure I'd like to save a buck if I can, but something so critical like this I wouldn't even think about it, just change it). | ||
| KARL DASTOLI (Luch)
|
Just another note - and I agree - the clearance becomes tighter...but more important, your car is 15 yrs. old and you should make sure your timing belts have been changed as they may have become brittle. Also if you change your shims, you can have them surfaced ground on the cup side (ie underneath) because they are nitrided and will not effect their performance. | ||
| '75 308 GT4 (Peter)
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True, I've been reading up for my rebuild and its been noted that you can take your readings, turn the cranks over one revolution and the readings could be different by a thou' or more. | ||
| Herbert E. Gault (Irfgt)
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The only problem with that is that what does a person consider tight and what was the exact reading of the valve in question and at what temperature was the work done and what criteria of how loose or tight did the feeler gauge feel under the lifter, and how worn was the feeler gauge? There are so many variables plus the factory tolerance of plus or minus.002 on each valve that saying a valve was tight or loose could be only an opinion rather than a fact. I would be willing to bet that if you carried your car to someone else for a valve adjustment tomorrow they would find some out of adjustment. I am not being anti-adjustment but I believe it is being over sold. | ||
| William H (Countachxx)
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I would do it in a hurry, take it to a good shop. if your valves hit the pistons u could b writing a check for $12k plus labor for a new engine. These r essentially detuned race engines & therefor require lots of maintenance & TLC | ||
| Kenneth Butler (Mondialman)
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I noticed a huge difference after my valves were adjusted; it probably hadn't been done for 38k miles. It ran smoother with (seemingly) more power. Or was my mind just trying to justify the expense? | ||
| Craig Dewey (Craigfl)
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Thanks for the follow up.... I was wondering if the valves would really get out of adjustment. You saw all the differing information and it was difficult to sort out. It looks like what you are saying is that the factory orginal adjustments have changed in 30K miles to a tighter situation. Looks like I'll be checking mine too!! | ||
| Justin Kerns 86 328 GTS (Kerns)
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Just to follow up in case anyone is still interested... I had the valve adjustment done and they ended up adjusting 15 valves. They said 12 of them were "tight". So I feel better after having done it, although my wallet does not! Better safe than sorry. | ||
| Justin Kerns 86 328 GTS (Kerns)
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Hmmm. Seems like there are some differing opinions on this topic. But I do agree that burning a valve should be avoided, so I will check them. Thanks to everyone for your input! | ||
| CraigFL
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Ang & Rocco.... Are you saying that you have definitely seen valve clearance tighten after 30K miles on 328s where you have done the original clearance adjustment. Also, I absolutely believe that the clearances must at least be checked,because as everyone has already said, it becomes VERY expensive if the valves burn. Checking them is a pain but not in the wallet! Justin, In spite of all the discussion, you do need to check all the clearances to be sure. | ||
| ANGELO ALBANESE (Lbanez)
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I agree with Rocco,as time goes on , the valves hammer into the seat and clearance between the shim and the cam decrease, creating less valve clearance, this could cause a burned valve and a loss of performance, premature valve opening, loss of compression,at 30K I would not think twice about it ,peace of mind alone is worth it, you can't run down to your local PepBoys and pickup a motor and toss it in.....pay now or really pay later.......Ang | ||
| rocco
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as the engine gets older, the valve clearence becomes tighter. the valve seat moves up higher in the head. thats why its important to do the adjustment. I have yet to find any engine with a perfect adjustment. | ||
| irfgt
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I work on many engines that have shims such as Jaguar, Toyota, Fiat, and the Cosworth Vega and as a rule the valves remain within tolerance indefinately. If something wears enough for the clearance to change enough to cause a problem then you were going to have to take it apart anyway. I am currently overhauling my 308 engine and after I adjust the valves I have no plans to ever adjust them again. | ||
| CraigFL
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I also have a 328. My experience with this type of valve train system (OHC, hardened shims), although not Ferrari, is that I've never had to adjust the system - ever. As long as I didn't remove the camshaft and do any valve work, the system always stayed in the spec limits. I've purchased many spare shims for my cars in case I had to do it but they remain unused. I too would be interested if the Ferrari is the same. | ||
| Justin Kerns 86 328 GTS (Kerns)
|
I am the very proud new owner of a 1986 328 GTS. In my researching of the service history, I have found that everything looks in order with the exception of the valves having never been adjusted. The car has 30k on it and has had 30k service sans valve adjustment (VA). I have inquired in a couple of places, including my local Ferrari dealer, and have been told that as long as the oil has been changed religiously and the engine runs fine, there is no need for the VA. The car runs very well, but I am still nervous about it lacking any recommended service. Should I pay the who knows how much money and have it done anyway? Or am I just a paranoid 1st Ferrari owner? |