decking heads

[Karl Von]

Hi All

While I am trying to find time to dig into the clutch problems on my 1100 Sport, I have been thinking about another project I have been putting off. I have a 74 Eldo LAPD with a Cali 2 motor in it. It needs new gaskets from the Cyl base up and while I am in it, I was thinking about small ways to get a little more power out of it. I dont expect a road burner just a little more juice.

 

I have a set of med valve heads and 36 dellortos from a Cali 1100 Carb, I was thinking about installing a hotter cam and using the med vale head and 36's. I was also thinking about decking the heads to get a little more compression. Has anyone tried this on a guzzi and if so how much can I go without having to worry about the push rod length and the valves hitting the piston ?

 

thanks

[pete roper]

The Cali II motor with the smallvalve heads has pistons to suit those heads. If you stick the mid-valver heads on to those barrels and pistons you substantially lower the compression ratio. No amount of decking of the heads will return the CR to anything ine its original without changing the pistons.

 

Best bet would be to buy an 88mm Gillardoni kit for a Mk III Lemans. This will slip right on and will work very satisfactorily with the mid valve heads and you'll effectively get a 950cc Mk III LeMans motor which will give you considerably more poke thn thr original Cali donk especially if you carb it up a bit. Unfortunately 36mm PHF Delortos are getting hard to find.

 

If you consider the fact that you'll save money by not hving to do any machining to parts and can defray the cost by on-selling the Cali Barrels and pistons you'll find that the cost won't be exhorbitant.

 

pete

[motoguzznix]

Karl

 

Using the med valve heads is possible, but you will need pistons too, as the flat topped Cali 2 pistons will lower the compression ratio below 8:1. This will upset any gains from the bigger valves and Carbs. Any piston from a stock 950 as SP3 or Cali3 with med valve head (Cali 3 used both, depending on the year of production), will do.

 

But there is a better (cheaper) way to get power from the Cali 2:

Keep the heads and pistons, put 36 mm Carbs on it and rework the intake port of the heads slightly to make them flow. You need only to modify the port from the manifold flange inwards as the Cali 2 port diameter at the flange is 33 mm instead of 36.

 

Next step is to raise the CR slightly: When the heads are off, clean the piston top carefully and fix the cylinder barrels to the block (with base gasket). Measure the deck height of the pistons with the piston at TDC. They are always somewhat below the cylinder top gasket surface. Measure both cylinders as exactly as you can. Bring the cylinders to a machine shop and let them shortening the barrels at the base gasket surface the same amount as measured before. This brings the pistons to the top of the bore at TDC. Every 10th of a mm shortening will raise the CR to 0,1. Ready.

 

Replacing the camshaft brings the biggest gains, ecpecially in the lower rpms. The original Guzzi cam design is not benefical for high VE. Use Dynotec 8206, HMB 8.1, or Scola OSS. These are designed to be used with the small valve heads. Use them with the springs recommended by the manufacturer. I'm not sure if Scola offers springs to suit the cam, but the V11 Springs will work well. V11 Springs requiere the use of the upper and lower collars too. Preload at closed valve should be 36 mm. The standard Cali 2 springs are not adequate for one of these cams, the usable max rpm will be below 7000 rpm.

 

Edit: Sorry Karl, I overlooked you were talking about decking the heads, so I suppose you know about the proceidure described above. Also LM3 piston/barrels will benefit from the decking proceidure and contribute to some HP more than the Cali 2 parts. The cams mentioned above will also bring big gains with the med valve heads, if not more.

Note: The cam is the worst in the Cali 2 engine configuration. The cam replacement shows bigger gains than extra 100 ccm capacity in any Guzzi engine like the Cali 2.

[Greg Field]

If you really want low- and mid-range grunt, get LeMans pistons, and use them with the small-valve heads and larger carbs and a B10 cam. There's a local guy for whose Eldo we did this. I do not think we even had to fly-cut the pistons. C/R is high, but it runs well on premium. It lifts the front wheel if you want it to. What Pete says about PHFs is probably true in Australia but not in the US. We can still get them new from several sources, or at least we could last time I checked, which was in November 2006.

 

As for valve springs, the V11 ones do work. A tip, though: Those same springs were used on all the hydro Calis and are being replaced with softer springs in the warranty cam update. All those V11 springs are just being tossed in the trash . . .

[Karl Von]

I have the rest of the 1100 Cali Carb motor. It is locked up and have not looked inside to see what the issue is. I know the stroke on the Cali 1100 is diffrent from the 1000 motors, but would the cyl & pistons from the 1100 Cali work on a Cali 2 motor or would it be like the diffrence between the Eldo & Ambo where the bore is the same but the wrist pin location on the piston is diffrent as well as the crank.

 

There is a set of Cali 3 cyls & pistons on Fle-Bay I will keep a eye on. This is going to be a low buck build up just for fun. I got the 1100 sport & centauro to really go fast on.

 

thanks for the info guys.

[Baldini]

Not sure if this is relevant to what you're trying to do but I run a Tonti on T3 cases using SP barrels & flat top pistions with LM11 heads & (36) carbs. I don't know the CR but it must be low. I love the motor, it's so easy to ride, pulls from any revs & very untemperamental. It has std T3 or LM11 cam. doesn't rev out much & probably doesn't produce a lot of HP, but it makes up for it in torque & usability. Is thirsty tho. Probably not the ideal engineering solution, but easy cos I had the bits & works great for me.

 

KB

[motoguzznix]

I have the rest of the 1100 Cali Carb motor. It is locked up and have not looked inside to see what the issue is. I know the stroke on the Cali 1100 is diffrent from the 1000 motors, but would the cyl & pistons from the 1100 Cali work on a Cali 2 motor or would it be like the diffrence between the Eldo & Ambo where the bore is the same but the wrist pin location on the piston is diffrent as well as the crank.

 

There is a set of Cali 3 cyls & pistons on Fle-Bay I will keep a eye on. This is going to be a low buck build up just for fun. I got the 1100 sport & centauro to really go fast on.

 

thanks for the info guys.

Karl

 

Cali 3 heads and pistons existed in small and medium valve configuration. Depends on the year of production.

There is a difference on the wrist pin location between cali 2 and Cali 1100. I did not try this yet, but for proper installation the pushrods should have the correct length. And the deck height has to be checked...

CR will be lower than on the Cali 1100 because of the smaller capacity, bu not too much.

[Karl Von]

Karl

 

Cali 3 heads and pistons existed in small and medium valve configuration. Depends on the year of production.

There is a difference on the wrist pin location between cali 2 and Cali 1100. I did not try this yet, but for proper installation the pushrods should have the correct length. And the deck height has to be checked...

CR will be lower than on the Cali 1100 because of the smaller capacity, bu not too much.

 

I checked on the Cal 3 and it had 30 dellortos, so it would be a small valve, the same as the Cal 2. I have also been looking into change the cam as recommended. I think trying to use the Cal 1100 cyl & pistons is out due to the wrist pin location.

 

thanks for the info