According to the WSM: 0.2-0.25mm Inket 0.3-0.35mm Exhaust (Same as a 328) Adjust by changing the shims. Shims should be marked underneath with what size they are BUT they often vary by as much as .02-.03 away from what the marking says. So you need to measure them with a micrometer to be accurate.
You are going to have to make your own call here. The 308QV/328 WSM does show the values that Iain listed, but every other piece of F documentation for the 4V models of that era (308QV OM, 328 QV OM, TR OM, TR WSM, etc.), regardless of version, shows the operating clearance specs as: 0.2-0.25mm Inket 0.33-0.40mm Exhaust Welcome to the (uncertain) F world
I see you can't spell inLet either Useful info. When I checked mine recently the exhausts were mostly in the 0.3 - 0.35 range. Certainly none anywhere near 0.4 - which would suggest that the Indi who did them last time used the 0.3 - 0.35 range
D*mn you cut-n-paste I even mangled the numbers -- should be: Inlet 0.20 - 0.25 mm Exhaust 0.35 - 0.40 mm I wouldn't sweat it too much either way. The "spec" is the target for when you have a chance to reset -- not the limits of certain disaster. There maybe is some logic to the US cars having a slightly larger cold clearance if the emission-based compromises they made increased temperatures in the exhaust somewhat (so more valve length growth to consider and a little more time on the seat for the valve wouldn't be a bad thing). Wouldn't surprise me if they just made the euro spec the same to not have different specs, but could just be a typo that has propagated without correction -- which is their usual response to typos
Back in the 'Old FerrariChat' somewhere I identified this internal descrepancy between 308QV/328 manual 's text on page B32 & Figure 27 on the same page(See 1st picture)!!! I next discovered that the 308QV/328 manual 's text was still specifying the same clearance as the 2V engine manuals. I cross-checked against the Mondial 8/QV WSM Page B27 Fig 41 (2nd picture) and it's text on page B26 which match each other AND also match my Euro QV OM. IMHO This makes it pretty clear that the the 308QV/328 WSM's text on page B32 is in error, but Fig. 27 on the same page is correct!!! BTW, I've found that the Mondial 8/QV in general has more recent & accurate information about the QV engine than the 308QV/328 WSM. Here's the relevant info from the Mondial8/QV WSM: Image Unavailable, Please Login Image Unavailable, Please Login
Interesting stuff Verrel. Fortunately (having just set all mine at 0.3-0.35!) I don't think this is too much of a problem either way. These clearances also appear to change very little over time. I suppose, if anything, a slightly tighter clearance will make the valve train run a litrtle quieter but I doubt its going to make much difference .
The 4V Exhaust valves run pretty hot, so will undergo max thermal expansion. So the key question is how much the clearance will decrease once things get thoroughly hot. Also, reduced clearance will increase exhaust open duration. I recently adjusted my valves, but don't remember what I set them to. IIRC thinking about there being a manual discrepancy at the time, but not what I did about it.
Reymund, Yes, JWise & I did the valves together while we had the engine out. Ian, When tuned for emissions, the mixture tends to be slightly lean which increases exhaust valve temperatures as there is less unburned fuel to cool the exhaust valves.
