[Alfar7]

Regarding 750 camshafts not just Veloce

xxxxxxxxxxxxxxxxxxxx
Verzonden: donderdag 18 december 2014 9:18
xxxxx@yahoo.com'; 'AlfaR7@aol.com'
Onderwerp: Alfa 750 Cams

Dear Dave,

Please find copied in in this email the email address of Richard Jemison – Scuderia Giallo and a Guru on tuning alfa engines J. I have been reading the Alfabb for quite some time and the community refers to RJ for Cams/head tuning etc. He is able to supply modern design camshafts for our old cars.

I have been in contact with RJ for about 6 months now, actually just shaved the cylinder head to his suggestion. Next up is cutting the seat, rebuilding the lot and fitting the cams Richard supplied.

@ RJ - David (Dave) Mxxxxxxx owns a 750 with some some mild tuning, a head shave etc. and was looking for cam advise.

@ dave – are you the same Dave Mxxxxxx that did a series on restoring a Giulietta in the early 2000’s? I think we have actually been in contact before. My father had just purchased the 101 sprint and we needed to do some reading.

Good luck guys!

All the best,

Arno
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I got this mail from a customer in Europe regarding another Alfa owner`s cam question about 750 Veloce cams.

There seems to be some either misinformation, or assumptions on cams for these motors.

Published info on the 750 Veloce cams (10106 03200 00) which were used in the Veloce and S.S. with different lash and lobe center settings. (.019/.021 and .011/.019 lash settings and 104.5/106.5 and 99.5/105.5) The later on the SS resulted in massive overlap of 80 degrees. resultimg in poor idle and no low RPM torque.)
Basically the cams were 9.0 lift (.354) with "0" lash duration at .050 of 245 degrees.

I just finished a "Re-constructuin" of a `58 750 Veloce for a Florida customer. He had a set of "NOS Veloce cams" which did have correct markings and did fit only one side of the engine to insure correct placement (single LC mark on each cam).

However even new, as they were, there was a discernable step in the seating/closing ramp area that wouldn`t comply with the lash settings as factory specified, leaving adequate lash oiling.. This ridge was both visable and feelable and I pointed this out to him and sent the cams for full profiling on the CamDoctor.
Results are below. Note that the Exhaust cam was the larger cam of the pair?? Opposite what has been proven with modern cam designs for these engines.
Specifications are lobe lift at "0" lash
The Specs given for a "Veloce" cam are from a used original and reflect expected wear from old cams (nose wear)

750 V NOS 750V int. NOS 750 exh RjR1299 int RjR11i exh RjR45
Lift .349 .356 .362 .364 .358 .415
duration at:
.010 327 326 340 300 304 282
.020 274 276 286 276 268 268
.040 253 254 258 256 248 250
.050 245 246 250 249 241 244
.100 218 218 221 220 213 220
.200 162 168 170 169 163 176
.300 88 100 106 101 98 128
.350 32 46 52 50 91
.400 57
BCs 1.040 1.040 1.030 1.030 1.030 1.020

Cams were made without the big closing ramps for lash settings of .010/.012 and profile changes (removal of excessive early duration) to improve Torque and more "open valve" duration for better overall breathing/power. Lobe settings were set up at 108/108 initially as this is a street motor only with 10.5 to 1 CR.

The RjR45 is a cam designed as an intake cam for those who want more lift but great torque and HP increases.

Hopes this helps you "Mouse motor " owners.

 

[Alfar7]

CatCam issues V6 12V

From an Alfa owner that had his car modified in Europe.
His issues are not atypical unfortunately.
Engine is 3.0 V6, 11 to 1 pistons, individual throttle bodies.
Complaint was extremely noisey engine. No power below 5000 RPM.
Cams:12mm Catcam
camshaft details | CAT CAMS performance camshafts

In a message dated 12/22/2014 6:27:04 P.M. Central Standard Time, xxxxxxx@msn.com writes:
Hi Richard,


Nice speaking with you today. Thank you for your words of wisdom.


I will try to measure the intake runner length as soon as I can.


Let me know when you would like me to send the stock Verde camshafts, and can you please provide your address again.


Best,

xxxxxx

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In a message dated 12/27/2014 5:49:22 P.M. Central Standard Time, deriko@msn.com writes:


--------------------------------------------------------------------------------
From: AlfaR7@aol.com
Date: Tue, 23 Dec 2014 08:10:31 -0500
Subject: Re: Camshaft Inquiry
To: xxxxxx@msn.com

While you have the cam cover off check the lash on one intake and exh. That needed to be known as well. If exh lash is over .008 they are easy to tighten up. Intake should be .012 - .014(max) they require removing to change shims.

The cam selection really is a matter of what "real" clearances exist for lobes using a realistic base circle.
The 429 is a proven lower lift lobe design. The exh lobes for the V6 are on pg. 17 The 82 is my "race" exh. You can see it has far less early duration but more "open valve" duration than the CatCam. You have no torque due to excessive overlap due to too much early "off the seat" lift duration on intake and exhaust cams, incorrect tight lobe separation angle (106/106) and just too much exhaust lobe ffor the engine design.
For an exh lobe I would suggest probably the RjR61 or 61+3(6). If we used the RjR82 exh I would change the LCs to 110 int / 112 exh to keep torque high.

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In a message dated 12/23/2014 1:58:51 A.M. Central Standard Time, xxxxx@msn.com writes:
Didn't know if you still needed it, below is the part # and spec sheet on my cams.


http://www.catcams.co.uk/acatalog/1030322.pdf


I'll pull off the covers tomorrow to get the pictures you requested.


So you think the RjR429 would be a good choice for me?

Best,


xxxxx xxxxxx


Sent from my iPad

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On Dec 22, 2014, at 6:02 PM, AlfaR7@aol.com wrote:


I found your cams on the CatCam website so I don`t need that info. When you look at duration the RjR429 is probably more intake cam than you are currently using, just less lift. (at .040 260 deg compared to CC`s252)

Their (CatCam`s) 11.5mm lift cam set shows 110-110 Lobe centers. Too bad they didn`t use that on this cam set.

Lash per their specs should be .008 exh and .014 intake. I bet lash has been set to Alfa specs (.020 int and .009 exh.) Rocker lash should be .008 at the cam follower not under the rocker, (Typically the settings for such intake cams would be .012-.014)

camshaft details | CAT CAMS performance camshafts


Attached you will find a PDF file with the cam profiles.
You should measure the base circles of the existing cams, both an intake lobe`s and an exhaust lobe.

A picture of the engine might help, as well as a picture of the cams from several angles with the cam cover off. This way I can see any modifications for cam lift at the cam bores.

With your engine upgrades you should be making well over 300 HP. Have you had the motor Dynoed?
You should to establish a baseline map.

Also please scan the cams data sheet and email to me. I need to see what I can determine from the little info given buy the builders in Europe.
Is there a part #?

See the RjR429 intake. That is a 11.2mm lift cam that when compared to the stock Verde (same as all 2.5V6s) or the "S" cam will show this to be basically a high torque/HP intake with more later duration than most early race cams. Difference is the new cam designs make good low end power, not just at high rpms.

Thanks,
Rj
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Hi Richard,


Hope you had a good holiday.


Was able to take the cam covers off today. My best measurement of the base circle was 25.40mm, the runner lengths are approximately 4 3/4".


Can you tell me which cylinder(s) lash measurement you want. Engine is currently at TDC. The exhaust valves on #1,2,4, and 6 have probably 1/8" of clearance between the cam and end of the lifter/rod. Don't know if it's supposed to be that wide open..? Seems weird to me.


Can send my Verde cores anytime, need your address please.


Here are a few pics, let me know of you need more.


Best,


xxxxx xxxxxx

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xxxxx:

Re: Pics
You do have serious issues. The cams are by lobe shape (even with no other info), old school race cam designs. (high overlap, no power except at high RPMs.

Re: Measured data:
It appears that the cams are very small Base Circle cams as well (1.000 inch) (25.4mm ) or less in order to fit your unmodified head. However I can`t imagine the cams not having clearance issues in the "seal to keeper distance" as valves open. I will not build cams with Base Circles this small unless demanded and then under protest, nor use 12mm in a head that has not been extensively modified including deeper spring pockets and approiate short guides and correct spring design for both intake and exhaust (they are different). Obviously these were not designed by anyone knowledgable of these V6 12V engines.

The clearance you gave (appx 1/8 inch) on the exhaust is a real problem. They must not have changed or done any valve adjustment. Be sure the cam followers are not showing any wear. If so they cannot be used, particularly on new cams!

As I mentioned in an earlier email, the Exhaust lash is measured at the interface between the heel (base circle center point) of the cam lobes, and the cam follower, should be .008, and NO larger. However, these very small base circles would be best set at .006. (and lets use inch measurements from now on as it`s the US standard., and the way I specify clearances)
If it is more unlock the adjustment screws and close the lash to .006. (I hope you have room to do this with such small base circles!)
There is a solution to dealing with lifter clearances on small base circle cams. You put a intake type adjusting shim on top of the exh valve and then set lash. The shim should have a minimum thickness if .080 to take the stresses of the ball end of the adjustment/lifting screw.

On the intake side measure clearances with a feeler gauge set between the heel of the cam lobe and the cam follower. The "CatCam" specification was .014, however with such small base circles as in this set, they should be no more than .010. I suspect again that these cams were "built on order" from someone trying to get more lift without correct internal modifications in the head!)

FYI: you will have to turn the motor over by hand to get exh lobes in position to reset lash. While turning it to do that you will have the opportunity to measure intake lash during that process as the intake cam lobe`s heels are in the correct position as you move the motor.

If the intake lash is over .014 you will have to pull the cams and using the correct shim, close intake lash to .010.
Let me know what you find lash wise on all of them! IF when you reset lash and when turning the engine over by hand you feel heavy resistance, that would be lack of clearance beween the seals on the guides, and the keepers in the spring retainer. Do not continue to turn the motor as you will destroy the seals.

Do not run it as it is either!

My address is below, however send the Cams to my West Coast Wife!

Send Cams to:
XXXXXXXXXXXXXX
xxxxxxxxxxxxxxxx
xxxxxxxxxx xx
xxxxx

My address:
Richard Jemison
xxxxxxxxxxxxxx
Pensacola, Fl.
32514

 

[Alfar7]

Re-building a head for improved street performance

Hello Richard,

I hope you are well and thank you for all your guidance.


Richard, i'm just about to start the head work on my to be Fast street Alfetta GTV 2.0, using your cams (RJR472/785) and i was hoping you could please take a minute or two and answer the following questions i have about porting just so i have a better understanding on the work that i will be doing.

These questions I have posted on the Alfabb (Post 27 on the following link) but i haven't received a proper response as yet. If you like, the link is:

http://www.alfabb.com/bb/forums/engine-rebuilding/249506-2l-head-still-good-2.html





Bowl work
First, unshrouding the valve seats. So the bowl should be shaped to initially match the flow line of the 30 degree seat on the inlet and exhaust. Could you please confirm how far the 30 degree cut into the bowl should go ?
From the pics I posted on post #18 (see attached) it seems to me that this has already be partially done around the exhaust valves.

Secondly, unshrouding the spark plug. Is this something I need to do? I think I read somewhere this is normally done when using extended tip plugs which doesn't make sense to me.

Now, with the combination of the two steps listed above, will this have much of an affect on the compression ratio?

Lastly, once the 75 degree cut is made to open the seat and throat, the area to the side of the ports from the guide to seat base should be opened so you should end up with a straight direct path to the seat from the inlet.
Now, as mush as I understand by opening this area it will reduce obstruction of airflow, I thought that area was narrower to help increase air velocity. Could you please explain what I missing in this concept?

Thanks as always for the great help.


Regards,

Rob.

First: From the pics you sent (and those you posted here earlier) this head cannot be used.
The valve seats have been cut way too deep and your valves will require very small BC cams just to fit.
As well the shrouding of the valves will never flow effectively. Find a unmolested head to work with or you will be wasting time and be disapointed in the performance as well as not being able to find shims thin enough to assemble the head.

To be clear, toss this head!

Secondly; Terminology. Bowl is the area under the valve between the head of the valve and finished valve seat back to the area of the valve guide.
Combustion chamber is just that, The valves should sit with the seats edge even with the combustion floor.

The first step in re-working a head is to open the seats (widen the inside diameter of the opening)
To do this you use a 75 degree cutter and cut the seat away until what is left of the original 30 degree valve contact area is no more than 2mm(.080) smaller than the OD of the valve you will sit on the seat (intake and exh) .
Note: I said 2mm(.080) This will leave a 1mm (.040) seat width on the valve /seat. This is still, to me, too large, but it is 1/2 of the stock seat. I cut my intake seats to leave a finished seat of .5mm(.020) and exh to have a seat of .75mm (.030). Typically in an unmolested (never worked on) head you will find the seat`s surfaces are proud (above) the floor of the combustion chamber, and when finished the target is for the seat to have the outer edge flush with the combustion chamber floor. So if the seat is proud of the CC floor you should open the seat a bit more at this point, as the 30 degree seat will be wider when shortened to match the floor. Matching the exhaust seat to the floor is important to flow! You do not want a raised seat lip for gasses to be obstructed by on their way out.

Now you remove the old valve guide so porting can be done.
You will find that the 75 degree cutter ( if you opened the seats enough) will have machined away some of the bowl area.
The intake and exh runners should be ported so there is a straight wall from the original opening in the head to the seat area on the sides of the port. The top should be raised and curved to inprove flow into the valve area. The area around the guide is the most congested and needs opening.Leave the original radius at the bottom for better flow into the chamber. You can clean off the ridges.

Note, when the finish 30 degree cut on the seats is done (and this is not until after the new short guides are installed as the insert position is always slightly different and the seats must match the angle of the valve)They should be seated in the spring pocket with only 2mm of the guides main body left above the floor. (to center the spring pan) This leaves adequate clearance for correct space for high lift cams up to .500 lift with greev viton seals on the guides.
Don`t think about using Teflon seals or the guides they fit on!!)
Once the finished 30 degree seat is done, the sharp edge between the 75 deg cut and the 30 deg seat can be touched with a 45 degree stone to break the edge. If you left too wide a seat area on the valve you should use the 45 deg stone to cut back the seat until a correct width seat is left.

Forget anything you have heard about a 3 angle cut! Gasses don`t follow small radiuses at these nearly supersonic flow speeds. Only area counts!

 

[Daywalker]

Hello Richard,
what will be the better choice for a Street Car, Motronic Pistons S4 Spider or Motronic from an Alfetta.
Regards

 

[Alfar7]

Motronic Pistons

These were not used in Alfetta series cars. Only Spiders from `91-`95.

 

[Alfar7]

Valve seat design

I got this inquiry today, and such suggestions bear watching. The only way to get improved flow is larger internal seat opening.

Sharper angled seats if opened correctly cannot take the stresses of the valve seat angle IF the seat has been opened to get the resulting area needed to get max flow.

Any seat design that uses old school 3 angle seats cannot result in as good a flow level as the one I have described in the info below.

At speeds involved with the intake and exhaust gasses, don`t be fooled by the concept that the gasses will follow a rounded shape. That just does not happen. Volume of the opening is what counts.

A proper seat design opened to the max will not take the outward forces exerted by a 45 degree much less any angle sharper (50 or 60) unless more seat material is left (reducing flow).

I'm building up a new engine for my car and considering going to a 50 or even 55 deg intake seat angle. Would clearly require new valve seats and additional machine work on the seats and valves, but the racing companies I work with at my day job swear by the flow improvements.


Has anyone tried this? Any thoughts?


Kxxxx
#95

You can`t put larger seats in a two liter head without moving the sparkplug`s location.

If you want the best flow retain the 30 degree seat, cut the 45mm oversize valve from 45 degree seat to 30. Open the seat with a 75 degree cutter which will open the seat internally,including the entrance at the bowl. The 75 degree cut should end at the valve seating surface leaving only a seat width of .030 wide (intake) and .040 wide ( exhaust but using a stock valve size (40mm)
No 3 angle mess, just the 30 to 75 degree cut.
Using a 45 or greater angle will cause splitting of the seat due to seating forces forcing the seat open.

The info above is the way to get flow!
Rj

In a message dated 10/31/2015 12:20:24 P.M. Central Standard Time, alfaracing@yahoogroups.com writes:


Hello

 

[horsewidower]

The Coanda effect is a well known, well documented physical phenomenon. Air does follow a rounded surface, it was known all the back in the 1800s. It's used in many facets of motorsports, including head porting.

https://en.wikipedia.org/wiki/Coandă_effect

I do agree with Richard that you don't want to use a 50* to 55* seat on a street engine.

Bob

 

[Alfar7]

Comment

The Coanda effect is a well known, well documented physical phenomenon. Air does follow a rounded surface, it was known all the back in the 1800s. It's used in many facets of motorsports, including head porting.

Bullsh!t. At high speeds liquids (and air is a liquid) will not follow much of a radius at high speeds. It separates from curved surfaces at a relative slow speed.

That`s why airplanes and race car wings stall at too large of an angle of attack.

If your shop tells you a 3 angle cut helps, find a different shop.

Alfa heads have had awful seat designs for ever, 30 or 45 degree seats to a 90 degree inside of the tube section. They were of thick tube sections, and any cut that opened the seat any improved the flow. Even 3 angle cuts that opened the seat very little, but measuring flow has become quite precise with today`s devices.

Steve ask a question that I`ll share regarding 3.0L 12V Alfa
motors, that are by design under 7200 RPM max motors due to exhaust valve train weight and rocker rate that multiply spring forces by 40% and cause lots of exhaust lobe wear as the lobes & followers are far smaller than they should have been for this push rod/rocker design.

His question in short does my first post on 45 degree seats apply to the 3.0 heads & valves that use these angles.
My answer in short is no if you are using stock valve sizes on the stock seats which will have adequate material for the 45 degree cut on seat and valve, with the interior of the seat opened with a 75 degree cutter to the inside of the 45 degree seat with a .030 wide seat. That .030 horizontal measured seat will measure at "45degrees" .060 edge to edge. And the 75 degree cut should open the seat right up to that inner 45 degree surface.

As an addition while doing the valve job if you look into the valve seat you can see and feel with your finger a significant left turn and curve in the port. At a minimum you should reduce that curves radius (to nearly straight if you are doing it properly).

 

[horsewidower]

So we should throw out scientific fact, and follow your opinion?

I would agree that it's propensity to follow a rounded shape is determined by the shortness of the radius and the velocity of the fluid. And, we strive to get as close to a straight shot as possible to the back of the valve.

I think your argument is about the degree to which a fluid will follow, is limited.

I'll leave this be, as your "Bullsh!t" response tells me that you aren't interested in a discussion. You've already formed your opinion.

 

[horsewidower]

Ed, that's simply not true.

Nevermind.

 

[hunttheshunt]

RJ is right ! Coanda effect is limited to specific flow velocity.
And as soon as you lose it, you´re running into stall effect.

 

[alfaparticle]

Ed, that's simply not true.

Nevermind.

Apologies. I deleted it.

 

[Alex]

As a layman, I am struggling to understand something. Intuition tells me that any fluid or gas will behave in a certain way when passing over a single surface, but surely, in the case of valves, we are talking about the behaviour of gases when forced between two surfaces i.e. the valve seat and the valve itself. Surely this act of 'guiding' or 'compression' between the two solid surfaces will have an additional effect on how the gases flow?

 

[hunttheshunt]

In my understanding of intake air flow of a naturally aspirated engine one first at all should forget the imagination that air flow happens always with pure laminar flow and simply straight-lined. Think much more about tumble and swirl and you´ll be in fact close to real conditions.

And these thoughts even don´t include reverse flow, steadily changing pressure ratios and valve head movement including changing valve seat gap.

 

[DPeterson3]

While not speaking directly to the points in debate here, it might be entertaining to go find one of the detailed histories of the Rolls Royce Merlin engine. When WW2 intruded upon English destiny, RR was immediately faced with the need for massive improvements in their aircraft engines. In the histories I read, it is told that the first person they hired to achieve this was an aerodynamicist. His contributions to airflow management more than doubled the power output from essentially the same sized engine.

It didn't come down to simply making bigger pipes to feed more air.

 

[Alfar7]

moving this thread

Gordon/papajam , would you please move this thread to my tech thread:
http://www.alfabb.com/bb/forums/eng...-repair-diagnostics-rebuilding/331266-technical-questions-rj-s-suggestions.html
Thanks

 

[Alfar7]

Clutch non-release/dragging problem

In a message dated 11/1/2015 8:08:35 P.M. Central Standard Time, gerald writes:
Hello Richard. I have a head-scratcher here. I finally got the gearbox back in along with updated engine mounts and such and went for a test drive yesterday. The good news is that the reverse shudder I was experiencing is completely gone - smooth as silk. And the drive-train in general is smooth. Now for the puzzler -


Shifting a very low RPMs is not an issue and the clutch engages nicely when pedal 1/2 way depressed as expected in both forward and reverse. When I am running at >2000 RPM I step on the clutch and the clutch does not disengage, ie. no "neutral"... the engine breaks the speed of the car. This happens in first, second, third, reverse...have not tried 4th because I can't start the car in 4th.



Thoughts on what this could be from and how to fix would be appreciated. Let me know if you need more info.


Best regards,

I suspect that there is a clutch release issue, and it would seem to follow that the issue is likely the clutch plate.
Quite often disk that have broken wafer springs will sling a piece out which causes it to still not be released. Or a warped disk.

This isn`t uncommon as stresses on the clutch disk if the trans is allowed to hang when it is stuck in the clutch on removal or insertion.
You should check all of the clutch parts. The arm often fails that pushes the clutch MC. Both the MC and slave can fail internally. How much movement is there at the slave?
The clutch should release normally higher that 1/2 distance if all were normal....
Feel free to call. Cell 850-516-XXXX
Rj

 

[papajam]

Gordon/papajam , would you please move this thread to my tech thread:
http://www.alfabb.com/bb/forums/eng...-repair-diagnostics-rebuilding/331266-technical-questions-rj-s-suggestions.html
Thanks

Done. Threads have been merged.

 

[ALF750]

The man was Sir Stanley Hooker (not Sir back then). He wrote an autobiography 'Not Much of an Engineer' titled after what one of the RR engineers said he was when he first arrived. Hooker was a Uni thermodynamicist/mathematician seconded to RR for the war effort. He improved the design of the Merlin intake and supercharger system, and developed it throughout the war increasing efficiency so that greater boost was available while keeping intake temperature and power consumption as low as possible. He stayed with RR into the jet age but left in the 1960's I think. When RR almost went bust in the early 70's due to the Trent problems he was asked to come back and sort it, which he did.
Maybe relevant to this thread - intake flow is oscillatory, and possibly supersonic, or at least transonic....normal rules no longer apply.

 

[Alfar7]

Intake speeds

intake flow is oscillatory, and possibly supersonic, or at least transonic....normal rules no longer apply.

Intake speed flows can reach just under supersonic. At "supersonic" the flow stops.

This is the basis behind "SIRs" (single inlet restrictors) used to control airflow to engines now commonly used in SCCA and other groups to limit and equalize engine power / output in "class" racing.