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Discussion Starter #1
Gentlemen -

I am rebuilding a 3.0 engine out of a well-maintained, wrecked 91 164L.
Since there's no discernible wear on the liners in the ring area, I'm reusing
both the liners and the pistons, but, I would like a little more compression.

This engine will be used with an early version of the L-jet system, (1982),
so I will have to be the knock sensor, and the ignition system is independent from the L-jet. And we have 93 octane readily available.

The question is; how much can be heads be milled to raise the CR to something reasonable?
I would appreciate experience-based advice only, please.
thanks,

Hans
 

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My advise is don't do it. The power gains going from 9.5:1 to 10.5:1 with L-Jet are minimal. It creates a cam timing problem, makes the head weaker and more likely to warp. It's also non reversable. Alfa 3.0 heads are not too common any more. It's not like heads from a Chevy V6 that can be replaced with a quick trip to the salvage yard.

Greg
 

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After reading Greg's post, if you still insist on milling the heads, I've milled mine years ago by 1.6mm (about 0.065") and got a measured CR of 11:1. This was on the 75 (Milano) Jetronic engine. Be more careful with later 164 Quadrifoglio Motronic engines which had stock 10:1 by way of higher dome pistons.
Jim K.
 

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Richard Jemison
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Mill It!

Actually 3.0 heads are readily available.
But the (164) heads are done very sloppily by the factory regarding intake track and bowl finish. The valves are overly large so that`s no issue (porting is same as 2.5)
The heads can easily be milled more tham .070, but .050 off of the 3.0 heads with std. 9.0 pistons will give you 10.24 to one compression.
Head chamber volumn after removing .050 is 58.5 cc. Piston dome volumn is 16 CC. with top ring height, bore to piston clearance, gasket thickness & diameter of the firering etc. the compression ratio calculates to above.
Adjustable cam sprockets solve all timing issues.
 

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Discussion Starter #5
milling 3.0 heads for more compression..

I appreciate the quick response - it sounds to me as if Richard has been there and lived with the consequences.

I had no idea about what the safe amount would be, other than don't do it.
Fifty thou sounds about what I'd be willing to risk.

Contrary to an opinion voiced here about compression increase, it is one of the most cost-effective means of increasing performance.

And finally, milling the heads causes the timing belt marks to line up about a half a tooth off. The simple fix is outlined in the Milano shop manual, group 00, Complete car, page 00-27: "Secure tool A.3.0521 to hub and withdraw hub itself from toothed pulley, RECOVERING THE RELATED TONGUE".

Actually, the manual is wrong here, since the tool pulls the hub from the cam, not the toothed pulley.
In the next step, one turns the offending cam so the marks do line up, and then the hub is tightened to the camshaft WITHOUT the TONGUE, which we call a woodruff key.

In short, since the cam fits into the hub with a morris taper fit, the key is superfluous, so it's used here as a security blanket.
ciao,

Hans
 

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Just to clarify, I didn't say it wasn't "cost effective". I said the gains are minimal with L-Jet. That's true, they are, and I have a car here set up this way with the addition of "S" cams. I suppose the word "minimal" is relative. The term "readily available" is highly relative also. These heads are not common by any normal automotive standard.

Greg
 

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Richard Jemison
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Adjustable Sprockets

Actually, the manual is wrong here, since the tool pulls the hub from the cam, not the toothed pulley.
In the next step, one turns the offending cam so the marks do line up, and then the hub is tightened to the camshaft WITHOUT the TONGUE, which we call a woodruff key.

In short, since the cam fits into the hub with a morris taper fit, the key is superfluous, so it's used here as a security blanket.
HANS:
In theory it is better than practice. I`ll stick to the easily built adjustable sprocket.

Secondly many cams are off when degreed in the motor. All performance cams need to be degreed, so lining up marks are best left to the 4 cyl bunch where intake & exhaust are on separate sticks!

Rj
 

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I think if you have the 2-piece cam pulley found on older V6 engines, you can slot the holes for the 3 bolts. Makes it somewhat adjustable within a small range.
 

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good day

isn't it a idea too make the conectingrods 1 mm longer by puting in new small end buches but making the centre to centre dimension 1 mm longer.

then you get the same as milling off your cilinder heads but not the decrease in hight and soforth the problem with timing.

my two cents.

Han
 
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