ALFAGTV6.COM

P.Webb · Post by **P.Webb** » Mon Dec 06, 2004 7:16 pm

You can mill to 0.060 (1.5mm) before any relief is needed and that's around the edge of the piston, not the valves.

Reliablity is fine so far on my car. You can just have a machine shop take 0.040 (1mm) off the surface and reinstall. I've taken my car to 7200rpm no problem. I asked an experienced Alfa GTV6 racer about this before I did it and he assured me it was fine.

Something I forgot to mention, and this is gonna make everyone shudder but it's perfectly safe and a common practice.

You need to leave the woodruf keys out of the cams. When you mill the head, the cams won't time because you decrease the distance between the pulleys. Time the cam pulleys with an interferrance fit and crank down the nuts.

-Peter

Greg Gordon · Post by **Greg Gordon** » Mon Dec 06, 2004 7:20 pm

Peter I don't think 2.5 heads on a 3.0 is such a hot idea. First of all the 2.5 heads have smaller valves which would offset any gains from the compression increase. Second I don't think you can bolt 2.5 heads onto a 3.0. I have not tried it but I don't think all the holes and passages will line up.

Regarding supercharging, more compression is counterproductive. With turbos there are some cases where more compression is better but that's not the case (within reason) when dealing with a roots type blower.

P.Webb · Post by **P.Webb** » Mon Dec 06, 2004 7:27 pm

Greg, they will bolt on. We played with it at Besic's this summer.

Neglected to mention putting the 3.0 valves in the 2.5 head. Some slight machine work to set the seats and hog the ports out.

Agreed on forced induction. Noone has mentioned super/turbo charging yet. If this isn't a naturally aspirated motor, disregard everything I said.

-Peter

Greg Gordon · Post by **Greg Gordon** » Tue Dec 07, 2004 8:32 am

Peter, just to clarify Murray did mention forced induction on the first page of this thread, I try not to bring it up first since it could be considered unethical.

Regarding the 2.5 heads on a 3.0, are you sure all the cooling and oil passages lined up? I seem to remember they are different. I don't have a 3.0 head off a car here for me to look at but looking at the gaskets I would say they are different. If not, would that mean you could mill a set of 3.0 heads and bolt them onto a 2.5? What do you think?

Murray · Post by **Murray** » Tue Dec 07, 2004 1:01 pm

No Greg and Peter I made no mention of forced induction in my initial post.First I'm going to rebuild and then I'll dyno it to compare to my recent results.If I can pull 140 Whp out of her then I might be satisfied short-term if not then I'll consider going with a SC.Engine came out last night - not a bad job but man do I wish I had a heated garage to clean this thing up.I'm going to go through a lot of degreaser before I'm done.

Greg Gordon · Post by **Greg Gordon** » Tue Dec 07, 2004 2:24 pm

Hi Murray, 140 whp is possible with nearly stock components. I know of one ITS racer in Texas that gets that with 9.5:1 compression via milling the heads, Total Seal rings, a good valve job, ballancing and headers. I suspect he may be using 164S cams too.
Supercharging was first mentioned in this thread by you on the first page about 3 posts up from the bottom. However there is absolutely no need for a supercharger to get 140 whp.
Good job getting the engine out, now you are commited!

Post by **Zamani** » Tue Dec 07, 2004 4:58 pm

I read on the alfaracing groups, there is another SCCA GTV6 racer who has some special cams, and 10:1 J&E pistons. He claims 200 whp on the dyno. He says the cams made a HUGE difference. The cam design came from Richard Jemison (also on Alfaracing group).

This is his website:

http://www.realemotorsports.com/

He also has a CF driveshaft fitted on his GTV6.

Murray · Post by **Murray** » Wed Dec 08, 2004 3:09 am

Greg yes I'm now committed.Talk and supposition replaced by actions ! I am very hesitant to shave the heads to change CR.because I don't want to end up having to play with the cam timing-offset keys etc.I'm reasonably confident that I can get a good bump in horsepower just by taking the steps you have outlined.I looked into the exhaust ports last night and am very surprised that my engine has been performing as well as it has (130Whp.).The back side of the exhaust valves are a mess.Looks like oil leaking by the seals has been baked on to the stems and formed a gooey mess.Glad I decided to open her up.
Boy Zamani I'd like to know some of that guy's secrets ! Got to be a little more than cams and 10:1 CR.Must be a blast to drive.

P.Webb · Post by **P.Webb** » Wed Dec 08, 2004 5:07 am

If you shave the heads you leave the keys out instead of using the offset keys. Not a big deal. Alfa stopped using the keys in the 24V 3.0 anyway.

Greg, what would you gain with a 3.0 head on a 2.5 besides the larger valves? I'll see if I can drop one on at Besics shop next time I'm down there.

-Peter

Murray · Post by **Murray** » Wed Dec 08, 2004 5:23 am

So Peter are you saying that the press fit of the cam sprocket onto the shaft is sufficient to keep everything in position without any doubt ? If so any idea why Alfa keyed this interface to begin with ?

P.Webb · Post by **P.Webb** » Wed Dec 08, 2004 8:00 am

Yes, and you don't have to use a press to put the pulleys on. The taper is sufficient to keep the pulleys in place by just cranking down the nuts.

When you go to pull the pulleys off you're existing cams, you'll notice they don't come off easily. You'll need a puller and they come of with a big pop. After you remove the pulleys, for your own peice of mind, put the pulley on without the key and install the belt. Turn the engine with the plugs in using the 19mm cam bolt. The engine should turn without any slippage. If it will turn the engine with full compression without the keys, there's no way the pulleys are going to slip.

Alfa eliminated the keys on the later 3.0 24V engines. No idea why they used them earlier. Belt and suspenders?

-Peter

Murray · Post by **Murray** » Wed Dec 08, 2004 8:41 am

Thanks Peter that makes the option of shaving a bit off the heads viable now.I think I'll give it a try.

P.Webb · Post by **P.Webb** » Wed Dec 08, 2004 8:56 am

Below is a posting from Hans Milo to the Alfa Digest earlier this year. He references the keys and the shop manual which recommends leaving them out to time the cams... I don't have the shop manual (Cardisk) handy right here but I'll post the referenced page later tonight.

-Peter

----------------------------------------------------------------------------------

Fellow Alfisti -
there is indeed a method for fine tuning the V6 cam timing for the 12 valve
version.
On page 00-27 of the Milano shop manual, paragraph 5, we are told "If the
notches on the camshafts and those on the related camcaps are not aligned,
carry out the adjustment operation by proceeding as follows."
Then it tells how to remove the pulley from the hub (3 bolts) and how to
pull the hub off the camshaft, with tool A.3.0521. The hub will come off the
cam with a fairly serious 'pop', because of the Morse taper fit that holds
them together.
Then it says to remove the "related tongue", which we call the woodruff key,
and rotate the camshaft until the notches line up, and then put in a new
o-ring and tighten up the big nut that holds the hub to the cam, followed by
the 3 small bolts that attach the pulley to the hub.
The 'related tongue' cannot be used because its groove has disappeared, and
it is superfluous in the first place because it's the aforementioned Morse
taper fit that fixes the pulley/hub to the cam.
I've used this method a number of times and it works, provided the mating
surfaces are really clean.
Using loctite on the mating surfaces would provide no benefit, but eventual
disassembly
would be practically impossible.
Please excuse the verbosity; the family tree has many preachers.
hth,
Hans

ps. the belt stays on the pulley during the entire process, and after the
hub is bolted back into the pulley, turn ONLY the cam until the knotches
line up .

Greg Gordon · Post by **Greg Gordon** » Wed Dec 08, 2004 3:04 pm

Peter, the advantage of 3.0 heads on a 2.5 would be bigger valves. not that I think it would be worth the trouble, just wondering.

P.Webb · Post by **P.Webb** » Wed Dec 08, 2004 7:06 pm

As promised...