101 Cylinderhead height ????

[Superleggera]

Anyone who can tell me the minimun height of an 1300 series 101 cylinderhead.
I´m suspect mine to be machined one to many times.

The messurement in the Giulietta by Anselmi is for an 750 head which is at least 10 mm lower than a 101 head.

Or even someone could take a look in their workshop and tell me the height of their 101 head.

Thanks in advance
Björn in Sweden

[divotandtralee]

750n=4.055" 750v=3.995" 101n/105n=4.410" 101v=4.35"

[Superleggera]

Quote:

Originally Posted by divotandtralee 750n=4.055" 750v=3.995" 101n/105n=4.410" 101v=4.35"

[AlfistiSA]

Hi Bijorn

I ran it through my conversion program for you.

750 Normale = 4.055" = 103mm

750 Veloce = 3.995" = 101.5mm

101 Normale = 4.410" = 112mm (also 105 cars)

101 Veloce = 4.35" = 110.5mm

Ciao
Greig

[Andrew]

To get from inches to millimeters, multiply by 25.4

Andrew

[divotandtralee]

I'm having a nervous breakdown...please don't ask me to convert anything to anything because t's all relatively the same. signed: Stephen Hawking's worst student

[divotandtralee]

Ah..HA! I snapped out of it. The MINIMUM height is the question. I gave you the MAXIMUM. Now, that is a head scratcher! I would attempt to guess a minimum equal to .010" (.254mm) OFF the Veloce thickness or twice resurfaced at .005". It's obvious to me the Veloce head has less to give up than the Normale. When you shorten the head, you make it more prone to warpage which exacerbates the first problem in the first place which probably was warpage. This is one of the reasons I DO NOT take a normale replacement head down to Veloce specs when building a Veloce motor. Once the head is shaved there is no going backwards and these pieces are getting to hard to come by. I think the people who race these things probably have a better sense about how thin to go since they are more apt to do it on a regular basis. I'll ask my Alfa machine shop.

[divotandtralee]

Here is what my "head"man says--

"Well, sir, that depends on the piston we're using. On 101 and
105 1300's about a millimeter off the thickness shouldn't make trouble.
Beyond that the little chamber made littler by the milling starts to get
cozy with the base of the piston's dome. On the 750 series head 1mm
removed is a lot. It is best to cut the pistons at the base of the dome
to provide clearance. This operation does not provide a " free pass". Again,
depending on the piston, much milling will force the valves against the
outside of the pockets in the piston, forcing them to claw away at the
piston as they open and close. For that, one can alter valve timing
events and further mess things up. In short, heads are not millable into
perpetuity; if compression enhancement is the goal, buy nice pistons. If
the head is on its ninth valve job, look for a head in better condition."

I would add, anytime you change the thickness of the head and change pistons, you show "clay" the pistons to check the clearances or give it to someone who can. I promise to keep quiet now as it is time for my medication.

[Gordon Raymond]

Just for what it is worth, which isn't too much, the largest problem is running into a head that has been cut so the valve seat edges (intake) get close to the casting surface, or worse, one cut not parallel to the cam journal bottom centers.
Custom pistons can correct many problems, by a cut at the base of the dome, sometimes even the top of the dome, and always the valve fly cuts to provide 1.5 / 2 mm clearance there with NEW seats & valves. Now that said, the piston needs to be a custom forging, like a JE to have enough meat above the top ring groove when this area is thinned. If the engine has old seats and old valves, there will be some recession into the chamber that vanishes when either new seats or valves are used. With the single plug heads there needs to be some above-the-dome room for the plug. If the head is cut to the point where the seats are near the chamber edge, seats don't have much material at the lower edge for support or heat transfer, (think hot spots). With any of the scarce heads that show a warp, I have a skilled aluminum head restoration friend that works on vintage Ferrari heads. He presses these flat with often no need for even a clean up cut. For a head cut at an angle, well, good luck. Some can be recut flat if there is enough material, and custom pistons used. Expensive! Machine work on factory cast pistons is limited as they are somewhat thinner,not as tough, and have less material that can be safely removed than most forged pistons. All just my opinion.