Non-standard cam timing - how to? - Alfa Romeo Forum
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(Post Link) post #1 of 10 Old 19-05-17 Thread Starter
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Non-standard cam timing - how to?

I posted here just under a year ago about a complete rebuild of a 3.0 24v V6. I'll update the post soon as the engine is just about finished.

However, I spoke the engine builder today and he's timed my cams using the standard settings, and that's not what they need. They are a 'custom' piper regrind and need none standard timing. He called Piper before he fitted them and I think they though he was taking about the cam they offer on their website which is a drop in replacement.

So he needs to time them. He's a perfectly capable chap but not had much experience with these engines. He suggested I get some vernier pulleys. Now I know these aren't needed as the cam pulleys on the V6 don't have any key and just bolts to the taper, so in effect are infinitely variable.

His comment to me was 'However to achieve the other setting will require Vernier cam gears.
There is no way to turn the cams with thee standard gears removed.

So can anyone help me (and him) by explaining how you tune the cams without the pulleys on? I sure this must be able to be done somehow but have never done it so don't know exactly how!

I would be very grateful for any advice.

BTW - this is what the engine looks like at the moment




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You can turn the cams with a 25mm spanner, there are flats on the cam for this purpose. You can even do this with the belt on, so long as the bolt holding the pulley onto the taper is loosened and the pulley has been tapped free.

What is that flywheel on the floor? Looks nice and shiny

What car are you putting the engine in?
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Thanks very much! I'll pass his on to him.

Well spotted on the flywheel. It's a 6.5 kg solid flywheel to fit this engine. I asked TTV to make it using a standard GTA solid flywheel as a pattern. They made it for me but now offer it on their website along with a 8kg version (as per the standard GTA flywheel). AHM seem to sell them too now on their website. Not cheap though!

Having these made too. With have 45mm Jenvey ITBs and a DBW actuator form a BMW M3 to control them




The engine is going in this chassis. Bet you can guess what it is

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Ohhhh. Stratospheric.
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Quote:
Originally Posted by lphuk View Post
Thanks very much! I'll pass his on to him.

Well spotted on the flywheel. It's a 6.5 kg solid flywheel to fit this engine. I asked TTV to make it using a standard GTA solid flywheel as a pattern. They made it for me but now offer it on their website along with a 8kg version (as per the standard GTA flywheel). AHM seem to sell them too now on their website. Not cheap though!

Having these made too. With have 45mm Jenvey ITBs and a DBW actuator form a BMW M3 to control them




The engine is going in this chassis. Bet you can guess what it is

Does it have the same out-of-balance factor as a GTA flywheel? Or have they made it perfectly balanced so that you can get the whole bottom end balanced as one assembly?

Will be awesome on those throttlebodies. What exhaust manifolds are you using?
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(Post Link) post #6 of 10 Old 19-05-17 Thread Starter
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The one they made for me was made slightly out of balance and then I had the whole bottom end balanced dynamically. There was extra material on the back that could be machined off to help balance things. Should rev very nicely with the slightly lighter flywheel but still be driveable.

Going with the standard ex manifolds. The engine is a CF2 so has the pretty good tubular stainless manifolds that I'm told should be good for more power than I'm expecting. Have upped the CR to about 11.2:1 by milling the head and added some cams. Used uprated PAC (Catcam) valve springs too. Similar specs to the stuff Jim K has done.

The TB setup will look something like this. They will be available for sale once we know they work. Probably won;t fit under the bonnet of any Alfa though!

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Ohhhh. Stratospheric.
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I timed my ahm regrind cams with a degree wheel and dial gauges measuring lift...

It's Slovenian language so that wont help you much. Basically i needed to get max lift at 107 degrees and to know where your max lift is you measure it 5 degree before and after 107 and compare the number on dial gauge, pointer must be at same number!

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(Post Link) post #10 of 10 Old 22-05-17 Thread Starter
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Thanks for the replies and advice. Much appreciated.

When I have the engine finished I'll update my old post (about a year ago) with the spec and also cost - which have got a bit out of hand......
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