11-06-2007, 04:32 PM
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All in all, pretty easy so far, as you can get to both sides of the manifold and its a simple profile to match. I do however think the taper from 46 to 41.5mm which takes place at the front half of the manifold is drastic enough to have more clearification as to where the center line lives and where exactly does that dia. relate to the old dimentions.
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I think JimK has written the tao of Alfa cylinder porting.  Hiis diagram intentionally provides a relative increment of taper because head porting is about half science and half art. IMHO it's more important to focus on the smoothness of the taper rather than trying to locate an exact point for its start. My take on laminar flow is that it is a generalized phenomena and so the fact that a taper happens is probably more important to flow than the exact point of its start. Thus (again in my opinion) in his diagram, Jim gives us a general idea of where to make the port changes. Implicitly, a few mm's either way shouldn't make that much difference. It goes without saying, however, that once you've decided where your particular taper begins that it pays to be consistent when you work on the other ports.
Thanks for posting your progress. It looks like you are doing some good work!
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Jim
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'70, 1750GTV, 2nd series
'62, Lancia Flaminia Zagato3c, 2nd series
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11-06-2007, 05:28 PM
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I totally agree with the things you say, regarding smoothness,consistent tapers and such and I HOPE what you say about a few mm's +- and there impact on flow is equally as true. being that this is such a new process /program, to me, I just want to make sure I can blame someone else if I get 114 HP on the dyno  .
I think I will be able to get the hang of this 'feeling' for flow, at least in a meta sort of way, once I get to the actual head until then or in spite of my perception of the information, I only have the numbers..
I am looking for just this sort of input however, its going right into the soup!
Thanks.
ps. eddy is the real name, shelf the pete thing. |
11-07-2007, 07:46 PM
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I totally agree with the things you say, regarding smoothness,consistent tapers and such and I HOPE what you say about a few mm's +- and there impact on flow is equally as true. being that this is such a new process /program, to me, I just want to make sure I can blame someone else if I get 114 HP on the dyno .
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Eddy,
Your head is definitely going to flow more air than one with a typical 3 angle valve job and stock ports. It will also (probably) flow less than a head modified using a flow bench. JimK developed his particular head design using a flowbench and, if you get close to what he did, you'll have a satisfactory result. That's one of the best things about his books. But there are also as many different approaches to porting Alfa heads as there are people doing the work.
I'll admit to being a little biased in favor of Jim's approach because when I got his first book I was surprised to find that my most recent (and successful) head porting attempt was, in fact, pretty close to what he'd published. That head worked really well. Before I started that head I read about everything I could find; various hot rod magazines, David Vizard's head porting book. Some conversatiions with with Alfa legend, John Shankle, helped as did the guys in the hot rod machine shop I used who had a lot of experience porting Chrysler Hemis. That's the fun thing about doing this: there is informaton out there that you can use and, also, there are people who know things who are usually willing to help if you ask the right questions.
Come to think of it, I have a friend with a blown up Sperry Stage 5 head. I'll see if I can get him to get me those measurments.
It'd be interesting to compare the two designs.
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Jim
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'70, 1750GTV, 2nd series
'62, Lancia Flaminia Zagato3c, 2nd series
Last edited by 180OUT; 11-07-2007 at 07:58 PM.
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12-20-2007, 11:08 PM
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How did your porting project turn out? Do you have the new head on your car. . . .????
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Jim
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'70, 1750GTV, 2nd series
'62, Lancia Flaminia Zagato3c, 2nd series
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12-21-2007, 10:36 PM
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No I had a little detour with the spica that was in the 74. I had to spent the extra scratch on putting in the 40's I had and that pretty much put the other head on hold. The up side- crazy fast ! so much fun over 2500 rpms I can hardly stop smiling, in fact I picked it up today and the only thing crazier then the fun was the bill! (well worth it)
I have 11mm cams and we lightened the flywheel 4 or 5 lbs. super mid to high range, but I couldnt get the vilocity stacks in and the K&N filter was too shallow, so I might be missing some low end, but fun enough!
As for the new head, I have one (again) ready to go, but its from a later model spider and the manifold hits a part of the casting so that needs to be ground off also it has the intake ports stepped for the bosch injection so I have to see if the port dimentions will work.
I will go at it in a few months.
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12-22-2007, 01:22 AM
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Quote:
Originally Posted by peterosefirepit
No I had a little detour with the spica that was in the 74. I had to spent the extra scratch on putting in the 40's I had and that pretty much put the other head on hold. The up side- crazy fast ! so much fun over 2500 rpms I can hardly stop smiling, in fact I picked it up today and the only thing crazier then the fun was the bill! (well worth it)
I have 11mm cams and we lightened the flywheel 4 or 5 lbs. super mid to high range, but I couldnt get the vilocity stacks in and the K&N filter was too shallow, so I might be missing some low end, but fun enough!
As for the new head, I have one (again) ready to go, but its from a later model spider and the manifold hits a part of the casting so that needs to be ground off also it has the intake ports stepped for the bosch injection so I have to see if the port dimentions will work.
I will go at it in a few months.
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Glad to hear the car ran good and you liked the new changes. Thanks for picking up the car this afternoon, the steak and lobster dinner went down well tonight with that bottle of wine
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Anthony Rimicci | 64 Giulia Spider | 65 GTA | 68 GT Jr.
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12-22-2007, 09:33 AM
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What 11mm cams did you guys use? I ran 11.1mm Pittatores for years and found that they worked well with Spica FI. I noticed that Pittatore has a website now and so I'm wondering if they're again producing cams for old Alfas?
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Jim
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'70, 1750GTV, 2nd series
'62, Lancia Flaminia Zagato3c, 2nd series
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12-22-2007, 09:54 AM
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the cams are IAP . I had pittatore cams in the past and these pull much harder in the midrange, but I will have the gurus play with the timing after a few weeks, just to see what we can dial in.
Anthony, glad you guys had enough to cover the bar tab!!
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02-12-2008, 08:44 PM
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well Im back on this head and the time off did not do wonders for my hand work, it seems that my horz. dimention at the manifold and head joint is a little wide. about 1.5mm too wide in fact. No excuses, I rushed it, nuff said. Now what? do I match the rest to this one, or can I add some weld? I am still about .5mm shy at the floor ceiling dimentions, should I keep those (-) numbers to compensate for the larger horizontal dimentions... ? I was going to make a silicone positive of the tract/port to use as a guide in order to check the rest and also use to match the volume of each port cause I heard that was also important, and also since it is really kind of a PITA going off of a mic to inside calipers etc.
THanks
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02-12-2008, 08:55 PM
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the pic show the casting that had to be removed to fit the manifold. the other shot shows how I ground the port with the guide in place in order to not gouge that boss area. I will ( I think) have enough guide left to cut in the new seats then I can remove the old ones and finish off the seat to bowl area. I know this is not the 'way' to do it but I really just felt like getting dirty.
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02-18-2008, 04:47 PM
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Hi Eddy and Jim:
Very interesting thread. I am so glad you saw the BMW P/N error, thank you for relating this to us!
I am planning a 2L motor myslef and after seeing your dyno results for the
46mm intake 38mm exhaust valves, I had planned to go this route. Now you have me thinking about 47mm intake valves.
In the past I know you have said that a "39mm" exhaust valve (1mm less then stock)is actully the perfect size and would scavange the least.
In your opinion do you feel that the combination of going with a 47mm intake valves and 39mm exhaust valves will still be the way to go? This would of been a very intersting read on the dyno compared with the dyno results for the Intake 46mm, Exhasut 38mm in the book.
I am at a crossroads....
Quote:
Originally Posted by Jim K.
Well, I'll be damned!! All the proofreading and one more mistake found...you are right, the valves are NOT from the 325 but the 525/528/728/730 series, BMW P/N 11341257592. The ones you got from the old 2002ti and used in the 316/318/320/520 are also 46mm but they're too short (103.8mm, BMW P/N 11341254625)and the wrong shape for best flow. If you really want the best, go for the 47mm valves from the new 525i/735iL engines, BMW P/N 11341705560. Both these are 106.5mm long and if the machine shop doesn't butcher the seats and sink them in, you end up with best flow + good CR and no problems with valve clearance shims.
Jim K.
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Last edited by RossoGTV4Me; 02-26-2008 at 10:40 AM.
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