For others that follow, there are some good points some of us made in another thread "$100 fueler" that might fit in here like using the AIC-1 to drive a AEM Boost Controler and getting more fuel using the USA head's Lambda valve with a RPM switch to triger more fuel.

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/463495-100-fueler-85-89-930s.html

AEM Boost Control Valve: http://www.aempower.com/images/products/Installation%20Instructions%2030-2400.pdf

:)

Can we keep this thread alive please, i was enjoying it :)

Guys,

I talked to Steve and my CIS is done and the "mystery cone" is installed. I should have it back next week and will post pics of it . I'm still putting the Old Sled back together so it will be a while before the engine goes in.
Unwired also anounced they were shipping the new units next week. I'll call Chris and see if mine is coming.

Cole

Sorry about going off topic here but I'm getting excited. The Old Sled is starting to look like a car again. Just finished sticking in the new Wevo, tube bushing, and PSJ joint coupling.
I'm fitting the new front bumper and lights. Glass and carpet next.


http://forums.pelicanparts.com/uploa...1239935269.jpg

http://forums.pelicanparts.com/uploa...1239935288.jpg


Cole

Some of the VW guys have added a boost modified fuel presure regulator installed in the return to the gas tank to bump the system pressure.

Interesting!

I like the idea of was to make the CIS safe with a manual boost knob. I like the MSD with boost retard so if boost is bumped, timming is pulled back accordinly.

With this idea, the fueling might bump with added boost.

RUF had what looks like an adjustable fuel pressure reg on the WUR of there 3.4.

I wonder if that was to buffer the WUR diaphragm so it would not get damage or some type of fueling strategy. Anyone know about the RUF system?

Great thread. I've been enjoying reading and following.

Was the IA fuel head modifications for US heads or was it applicable to the Euro heads, most specifically the Euro 930 head?

Also, is there a thread that details the IA modifications? I'm late to the party and have been searching threads but have yet to find an adequate description of the mods.

Thanks

Jim
1980 930
1995 993

IA can mod either head. Each head will then flow more fuel. I asked Stephen which head will flow more fuel when modified and he told me the USA one will.

There are no details on the modifications but I was told by Stephen they are CNC'd to flow more fuel.

Thanks for the info. I assumed they were modified by removing material from one or more passages but I'll have to think a bit why a modified USA header would deliver more flow than a modded Euro. I've never seen the inside of either but assumed the Euro header already had larger passages (ie modified).

Maybe someone with more experience can comment.

Jim

He was converting the Lambda heads to operate like a euro head.

The main reason these heads flow more it they are adjusted by the builder to do so. Thus, at every point along the arm travel they flow a given percentage of fuel, say 12%. Thus, if you set them correct at idle, they will be say 12% richer at cruse and 12% richer on full boost.

To compensate correctly for this change the WUR should be reconfigured so the arm will move said 12% less with changes in air flow.

This unfortunately this may limit the total amount of fuel delivered unless the control pressure it then lowered at higher rpm on boost like the Andial Fueler did.

The work around it to clamp the boost enrichment function on the WUR until later in the rpm range and try to adjust around idle and cruse AFR's.

Even without modifying the USA head there is more fuel to be had by 1) making sure you get full travel of the metering arm (reprofiled metering plate, Andial fueler, or lower CP/WUR) and or by taking over control of the Lambda valve with a different controller (Split Second w built in Oscillator).

In theory, a modified Lambda head that has the Lambda circuit manipulated should flow more than the modified Euro Head. However, not one that I am aware of has tryed this yet. :)

I'm pre-Lambda - 1980 Euro 930.

Thanks for the information. I need to think through your discussion of the fuel meter and WUR.

If I understand you correctly this mod was not made on Euro heads?

Jim

I have one and I was told the 6 metering slits in the steel cylinder the control plunger is inside of are CNC enlarged. That lets more fuel through to the top side of the differential valves for any given throttle position a little above idle speed.

The lambda frequency or pulse valve is also removed and the banjo bolt that connected it to the lower side of the differential valve chambers gets a threaded plug. That fitting is just to the right of the large flare fitting fuel inlet line. The black cast iron euro, rest of world, and pre 1980 USA fuel heads do no have that threaded port.
The other end of the pulse valve was banjo bolted in tandem with the return line from the warm up/control pressure regulator and when the pulse valve is removed that port gets a shorter banjo bolt so only the return line from the WUR is connected to that return line port.

Lastly there are 3mm spring tension adjusters under the 6 - 4mm button head plugs on the top side of the fuel head next to the fuel injector line banjo bolts. These 3mm adjusters adjust the spring tension on the top side of the differential pressure valves.
They act as small fuel pressure regulators, one for each fuel injector so you can fine tune the amount of fuel going to each injector. Turning the 3mm screw clockwise increases the spring tension on the top side of that valve and that lets a little more fuel flow through that differential valve and on to the fuel injector.

The modified fuel heads have a dab of green or brown paint on each of the 6 - 4mm button head plugs showing that that 3mm differential valve flow adjustment under it has been changed or checked.

It's impossible to figure out how the CIS fuel heads work without seeing cross sectional diagrams showing all the internal passageways, valves, metering slits, and flow restrictors with arrows showing fuel flow direction.

Is there any spec that states what the stock (unmodified) flow rate should be out of the fuel distributer given s set system and control pressure? I haven't found it in the factory manuals but may be missing it. Also I don't have the little spec book which I need to obtain.


JFairman, thanks for your descriptions of thefuel distributor and the mods.

Jim

Jim,
I'm going to really confuse you here as I truly believe the 930 Euro fuel head will flow more than enough fuel to support 375- 425 Hp. Steve Weiner of Rennspor Systems says the issue is not a lack of fuel but the lack of air. The amount of air pushing on the metering plate determines the amount of fuel to the injectors. Steve had raced the old 934 and 935's when the 934 still used CIS. He has built high Hp 930's and worked on CIS for 28 years. He is also the first to tell you if your going to do a 930 build with 400 Hp + you want to go with EFI period.
I have an 80 ROW 930 and am in the middle of a getting the old sled back together after a tear down and repaint. I have been looking at the CIS threads for years. I personally believe you need to know what you have and what you want before you start dumping big bucks on fuel head mods. All the normal 930 updates, cams, headers, turbo upgrade, ignition system, larger intercooler, boost springs, etc are logical bolt on improvements that give you predictable, proven, instant performance results. The fuel system is a whole separate issue and needs to be approached from a complete systems point of view. CIS is an antiquated mechanical system thats 36 years old and has a bi metal strip as its only electronic facsimile. Air goes in an arm goes down a piston goes up and fuel goes out but not quite as simple as it sounds. Check filters, accumulater, pump pressures, return ck valve, system pressure, control pressure, fuel lines, WUR operation, AAV operation, and spray flow and pattern. All these things need to be in correct working order before you take another step. Next and most importantly what are your afr's from idle to full rpm and boost. This can only be done 2 ways; a dyno run or installing an O2 sensor and some lm1 type logging device. Now if you are running lean and can not adjust the system to safe afr levels you might want to look at a fuel head mod. There are a lot of guys out there running fuel mods that are washing the cylinders and running pig rich constantly and can only jack with the control pressure to try and get it under control. I don't know how much it costs to weld up and recut the metering slots but a new fuel head is probably cheaper.
I'm 66 have a junk pump and cancer, in 66 years I've made every mistake you can make and if you learn a little from each mistake the one that always comes back to bite you in the ass is I wish I had gathered all my facts before I did that.

Cole

Your post is not confusing at all... but from experience on more than one '87 930 with an innovate AFR gauge, I will say a stock USA fuel head will not give you enough fuel for over approximately 380 HP safely without doing some kind of adjustments to it.
The stock cast iron black painted euro head is supposed to flow enough fuel for 400-425 horsepower safely.
By safe I mean around 12:1 AFR at 6000-7000rpm while making 375+ horsepower with no detonation at 1 bar using 964 cams, headers, and a bigger intercooler.
Using SC or stock cams you probably won't be taking the revs quite that high because the power band runs out earlier than 964 cams.

You mentioned welding up the cnc machine widened flowtech/imagine auto modified fuel head metering slits.
The steel cylinder with the metering slits that the control plunger moves up and down in is removable from the bottom side of the fuel head.
I'd like braze them up and recut them to the stock width in the middle area and then gradually taper them wider right at the top of the cylinder where the piston will be at full throttle when you need the extra gas.

It seems like that would work well without a bunch of add on electrical and mechanical gadgets. It wouldn't be so overly rich in the midrange, but it would get the extra fuel flow from 5000 rpm on up where you need it on a modified higher output motor.

I spoke to a 930 tuner years ago that modified WUR's to be boost sensing and to operate at a lower on boost control pressure for more fuel (Rice Fueler). He made me aware that even with lower on boost CP settings the metering arm still dose not reach fuel range of travel. He found that on a dyno at full tilt he could push the metering plate down further with a screw driver and flood the car. Thus, I am suspicious that modifying the metering pin is of significant value.

Another way to test this the additional fuel delivery of the stock head and that we are not accessing it is to set the idle CO very fat. Then run the car up and you should see that the top end gets more fuel even though you thought you were at a limit. What this is doing is changing the position of the metering pin relative to air flow and allowing it to advance further. Until doing this no longer adds any fuel up top, we still have fuel delivery capacity left. Thus, if we can get the metering plate to not stall, we can get more fuel.

Steve Werner is the only tuner I have heard of that addresses this by relocating the hinge point of the metering arm. This allows the metering pin to travel further with any change in the metering plate position. If I recall correctly SW used to build a sweet 930 with gears, 3.5 twin plug w MSDs, 8/1 CR, ports, and .7 bar boost that was good for 425hp. Start to go much past that and the issue becomes premature ware and limited thermal reserve.

It might be helpful if we knew if we are talking flywheel HP or rear wheel HP.

I do not know if gross air flow is the problem at the HP levels we are talking about here. I think it is more how the metering plate responds to the air flow we have. :)

J,

I've kind of gone in a different direction concerning the fuel head. I have all the fuel system checks done injectors are out being cleaned and tested now. My fuel distributer is at Rnnsport Systems having a modification done to flow more air and assure full piston movement. Steve is also installing the velocity cone shown in the first part of this thread. I am installing a MSD 6AL Ignition, Boost Retard Module, and an Electronic Boost Controller. I will be running an on-board LM-1 and monitoring RPM, boost, vac and control pressure.
I am of the opinion that the fuel mod and adjustable BL WUR are more mechanical band aids to try and control mechanically created issues that are mechanically uncontrollable. With these add ons I think it is impossible to create an optimal fuel curve consistently across the RPM band. This is, by no means an attempt to disparage anyone or any of these devices it is simply stating a factual account of hours of forum posts. I have yet to see the thread that states this is what I did to my CIS and I have a perfect fuel curve across the RPM band consistently. I also don't believe we will ever see such a claim. CIS was a marvel in it's time but it's time has passed, kinda like mine, and unless you spend 10 grand on EFI you will never get there. I do think that to get the CIS as close to optimal as possible you must be able to do closed loop control of the CIS control pressure across the RPM band. I think from what we have seen so far the digital WUR is very close to achieving that goal. If you think about it you can buy a DWUR for about $500.00 less than the cost of the fuel mod and a BL adjustable WUR.
I also think Ignition timing control can add additional performance enhancement and detonation control but that's another story.

Cole

I very much agree with Cole's assessment. The DWUR, to me, appears to be capable of addressing all the shortcomings of the fuel delivery system. It has more refinement in being able to control fuel pressures across a broader MAP spectrum. One more input, such as Mass Airflow or O2, would be nice, but mapping the engine in temps around 70*F (mid point between 50*- 90* for Wisconsin driving temps) will have to do.
That being said, I would still carry a backup mechanical DWUR in the front bonnet as a spare until I am certain the reliability issue will not be rearing its ugly head at the most inopportune time. :)

Apologies if you have heard this from me before.

I used the plumbing from the Andial Fueler and a Split Sec. Timing controller to make up what I called my electronic WUR. With this I did get near perfect AFR's at all points - curse or on boost. I was able to extend my gross fueling one more full point of AFR up top. Further, I was able to program in an ability to get the metering plate moving quickly with acceleration for less lag. From this I have to conclude that in theory the DWUR should be very effective and achieving its goals. It will also allow the increased flows of the IA head to be tamed. With my system, if there were to be a failure, you could just plug the WUR boost enrichment tube back in and be back to stock.

Having said that, I am back to being interested in taking a mechanical approach to extending the limits of the factory systems. If you have ever seen the AFR curves for a stock 930 that is well tuned they are actually pretty good. That is because the three systems that determing the AFR's are all ballanced to each other.

The stock fuel head, WUR, and more importantly the metering cone architecture is what determines the AFR curves. The motor was designed to make 300hp with some reserve built it. I think the fuel head can deliver about twice the stock fuel needs with adjustment. It has been done and 600fwhp has been had with CIS w/o additional injectors. Thus, I will boldly state that the fuel limit is near about 100hp per injector with approprate mods to the fuel head, WUR, and air metering systems.

Doing this is a mater of making compensating modifications to not just the fuel head but to the rate the metering plate advances (cone design or plate design) and the settings of the WUR (cruse and boost CP settings). No one seems to take a full view of these three systems and how they work together. They tweak one and maybe two and never get all three ballanced to work correctly togeather. I firmly belive it can be done.

Yes EFI is a better system and is the best way to acces power and drivability. However, at this point for me I would no sooner remove MFI from and 911RS as remove the CIS from a 930. That is just me.

I fully understand everyone has an opinion on 930 CIS, what can be done and what can't be done to improve it. I love the old sled and much like my lovely wife I accept its flaws and idiosyncrasies and still love it. I can't afford EFI, I would not spend the money for EFI if I had it. But I do want to get the most out of the CIS I have. To do this I have tried to logically approach the entire system by first making sure all the components that support the system work the way they were intended to. With that being done we are always left with the one variable everyone ends up with the fuel distributor.
In almost every discussion it is assumed that CIS will not provide enough fuel to support the HP the engine is producing. That opinion, in many cases, turns to which fuel head flows the most fuel. It is much more like some male ego thing about who has the biggest dick than it does having anything to do with solving any CIS issues. I would bet that 90% of us out here have never dynoed to actually prove we don't have enough fuel; I know I haven't, but I also don't know if that is even an issue with my set up. I would bet 90% of us have enough fuel available and have never done the necessary testing to find out; I know I haven't.
I have tried deligently to set a goal of having 11.9 - 12.1 afr's at 5600 RPM under 1 bar of boost with CIS regardless of what HP that ends up being. To put a system together that gives me the proven performance I can reasonably expect from the updates I have in a safe and reliable manner with no detonation. Untill I can read data that proves I cannot reach that goal with the set up have because of a lack of fuel I see no reason to do any fuel mods. After a lot of reading and several discussion with Steve Weiner, Bob Holcumb, Chris Fisher, and Chris Carrol I have come to the conclusion that I would modifiy the fuel head to get more air and facilitate full movement of the metering plate to allow full movement of the plunger and max fuel output. This has been done to make sure I am accessing all the available fuel from my fuel head without having to machining the metering slots. Once I have collected the data and definativly proven I have enough fuel I will be adding the DWUR to allow tuning of the fuel curve. I my opinion, presently, that's as good as it can be with CIS.

Cole

Cole,

For what it is worth, I very much like your approach. I am just not a big fan of jumping up to a modified fuel head. It takes a fair amount of work arounds to tame it.

I still have good hopes for the AMG/MBZ style metering plate for delivering a better fuel curve and more fuel up top. If it works, it would be such a simple, elegant, and efficient solution for all but the largest boost junkies.

Again, getting full range of movement of the metering arm is good for 'at least' one point higher AFR and from what I believe, even more. Andial, Rice, and others have done this by lowering control pressure. Lowering CP is one way but you should be able to also do this mechanically (hinge mod or metering plate mod).

:)

Keith,

I wanted to tell you how much I appreciate the thread and your input. I talked with Rice and found him to be very CIS savey, Nice man and lots of experience. I have a couple of his articles around here some place I'l scan and post them later. Some good food for thought in them.
I can appreciate all the hard work that has gone into the many different devices made to elevate the CIS's capabilities. My thing is they all seem to be directed to more fuel and I am not convinced it's really not an issue in most applications. The average mods most of us have done to our cars might yield another 25-75 HP and that doesn't seem to me it would require more fuel than these fuel heads can provide as they are. I see the IA mod threads and they seem to cause more richness and drivability problems that they are worth. I want 11.9 - 121 afr's at 5600 on full boost but not at the cost of street ability and black smoke in the mid range. We even have people re shimming pressure regulators to lean them out. I think lowering system pressure is going to bite you in the a-- elsewhere.
Modifying the air metering unit is limited by the casting and not understanding the complexities of the inner contouring. Don't mind experimenting with the velocity cone and metering plate but hesitate go any deeper, machining etc.
My theory is KISS "keep it simple stupid" I use the MSD to get a good, clean, hot multiple spark and the boost retard to dial up more initial advance to get her launched and then back the timing down when boost comes on to stop detonation. Use a DWR to manipulate the afr curve and cut back the mid range richness and pour the fuel to her on the big end. Once the system has been tuned you can build multiple maps to load for any type driving you want to do.
KISS !!!

Cole

Well guys I got the fuel head back today. The air mods is done and Steve assures me the control plunger has full travel. I noticed some machining on both the top and bottom profiles of the venturi "cone". It wasn't opened up to a larger diameter, it looks like the angle was changed. The velocity cone is installed and shes ready to rock and roll. Here are a couple pics.

http://forums.pelicanparts.com/uploa...1240973064.jpg


http://forums.pelicanparts.com/uploa...1240973079.jpg

Cole

Cole,

Two thoughts.

First, I belive the new metering plate is not suposed to be put on top of the original. It is a replacement. That dose not mean it may not work. Just not as intended.

Second, what dose Steve mean by you have full pin travel? Dose this mean he has blueprinted the castings under the head? Dose it mean the new metering plate will no longer stall so you get full travel? There not being anything keeping the pin from reaching full travel is usally not the issue, keeping the metering plate from stalling is.

The best. :)

Just my thought...
If the origonal metering plate was not there it looks like there would be about a 1/4" air gap all the way around that smaller diameter convex one.

There's not alot of air being sucked through there at starter motor speed and I don't think the metering plate would move one little bit to turn the pumps on or send any fuel to the injectors with just that smaller diameter convex curved one in there. The intake air would just flow around the disc and through that huge round air gap not moving it at all.

I don't think you would ever get the car to start without the factory disc in there along with the smaller diameter convex one.

The fuel distributor sends absolutely no fuel to the injectors until the metering plate moves downward around a millimeter or two - while pushing the control plunger upward in the fuel head less than a millimeter.
I have checked that with the injectors removed from the ends of the metal lines so there was no resistance to fuel flow from the fuel head, and no fuel dripped from the lines while the pumps ran and the metering plate was at rest.

When the fuel head is removed from the cast aluminum air flow meter housing you can see the counterweight on the arm in there over to the right side, and also see and feel where it comes up and contacts two little lumps of aluminum on the inside of the casting that act as stops when the metering plate is pushed down as far as it will go.

I havn't tried it, but you could easily get a small cut off wheel in there on a die grinder and grind some aluminum off those two raised contact points or counterweight travel stops.
Then the counterweights could go higher before hitting the inside of the casting so the metering plate can go down farther and push the control plunger higher in the fuel head.. possibly exposing more of the metering slits in the control plunger cylinder and sending more fuel to the injectors.

I'm not taking a chance of screwing mine up by trying that though..
I would like to try one of those convex discs on top of the metering plate.

I went to a lot of work taking the metering assimbly apart to blue print of my metering arm travel so the pin could travel as far as possible. Did not help one bit that I could verify.

Even with a dramatic lowering of Control Pressure using the Andial Fueler frequency valve I still believe the metering plate stalls. This was supported by Lee Rice of the Rice Fueler who told me that even w lower control pressure he could run up a 930 on a dyno and flood it by pushing down the metering plate w a long screw driver. I just believe the MP stalls due to the design of the cone it rides in.

As to the metering plate, it sure would not hurt to try. If the AFR's do not look right then it could be experimented.

I believe why the new plate has the increased clearance around it is that the added profile above the plate pushes down on the plate and the way the air is accelerated over it also helps move it. Thus, to slow the plate down at idle and off idle the diameter had to be reduced to dump some air at first.

A side thought, with the plate moving less at first, the metering pin can be readjusted. This will give more fuel up top when the arm moves to its furthest position. This can be tried w/o the plate by setting idle fat. Such adjustment translates to more fuel up top.

Another way to say it, if we set the head adjustment to full rich, then trimed the MP plate back to spill air so a proper CO could again be reached, we would get more fuel up top.

I can not wait to see how the new plate works. Wish we could do AFR's w the stock plate then the modified plate.

Good stuff. :)

Keith & J,

Steve does not, understandably, reveal all he does. I respect his position and therefore would not reveal anything even if I knew without asking Steve's blessing first.
We are dealing with two different issues here.
No# 1 I ask Steve to do his magic on allowing the unit to pass more air. I do not know what he did except you can see where the inside and outside of the cones castings has been machined. The diameter of the opening was not enlarged but the angles were either cut back or the angle changed. He also does a modification to the metering plate arm assy. although it does not appear to be repined to a different position. One of the benefits of doing the air mod is it allows full travel of the plunger and give full fuel availability to the injectors.

No. 2 I gave Steve the velocity cone and the metering plate that came with it. I asked him to look at it and give me his opinion as to it being of any value to the system. His opinion was that the height and shape of the velocity cone would possibly be a benefit to better air flow/distribution and plate movement. He could not flow it without having to make a special fixture to get it on his flow bench so we will just have to wait and see what it does.

I am sure the cone mounts on top of the metering plate. I got the metering plate with the velocity cone. I also called one of the originators of the cone and ask specifically if you use the cone on top of the plate and he confirmed that you do.

Cole

Cole,

Thanks for sharing.

Interesting stuff if he is re-profiling the cone the metering plate rides in. If so, that would be the best way to reset the AFR curves. Only other builder I have heard of doing this deep may be Scargo for the NA CIS motors.

I have been wrong before and will be again. If you talked to the makers of the velocity plate then you must have it right.

Hope everything works out well.

The best. :)

"you can see where the inside and outside of the cons castings has been machined"

Hi Cole, I know that you said you wouldn't mention what all he did to your CIS housing, but I'm really curious what you meant by "cons castings"

I don't think anyone ever modified the pivot point of the arm inside the housing.

If you ever remove the housing from the intake manifold and look in there you will see that the cast aluminum arm is pretty elaborate and precise and then there is another hinged smaller arm on top of it for the CO adjustment.
At the far end of the arm there is a counterweight so the arm and sensor plate actually balance in there.

Here's why I don't think anyone ever changed the pivot point of the arm, and it would be practiaclly impossible unless you redesigned and refabricated the whole thing...

When you look at the cast aluminum arm and the bosses in the upper half of the housing that the bearings are inserted into, and the counterweight you can see it would be next to impossible to move the bearings and pivot point of the arm without destroying the housing and the integrity of the arm.

When you look at the housing while installed in the car you can see the bosses where the bearings are installed for the arm.
They are just to the right of the Bosch part number plate that is rivetted on the front, and a little to the left and below where the steel banjo fitting fuel return line is mounted on the fuel head.
There are steel caps about the size of a dime over the bearings with snap rings to retain them.

It would take so much fabrication to change all that, no one could make money doing it for such a small and possibly imagined gain.

It is possible he ground some metal off of the two internal cast aluminum lumps that act as stops the counterweight comes in contact with at the end of it's travel. That would take about 3 minutes at the most.
If the metering arm does go all the way to those stops then grinding some metal off of them would let it go farther.

There is no way to tell though unless the car is wide open on a chassis dyno at 6500 rpm and you tried to push the sensor plate down farther with a screwdriver or whatever like Keith said someone has done.

thanks for the pics and information...
Jim

I forget how large the pivot pin is? Is is large enough to substitute a smaller pin and just add offset drilled bushings?

I like extending the cone or adding profile on top of the MP for and easier way to increases travel.

The Andial Fueler and BL's modified WUR both lower control pressure so the metering plate will advance further. This indicates it dose not bottom out on most 930's so adding range by blueprinting the casting is not of much benefit if the arm is going to stall any way.

Again, I suspect one relatively easy test to see if it still has range left is to set the CO as fat as possible at idle and run it up to red line watching AFR at a peak rpm point like 6600rpm. If this helps the AFR, then the pin has not bottomed out. If the AFR stays the same, the pin may have bottomed out.

Here's a diagram showing the arm, the pivot shaft, and the bearings.
http://forums.pelicanparts.com/uploa...1241050425.jpg

I took one of Cole's pics and drew a red arrow pointing at the cast boss where the pivot bearing is installed.
This is the back side of his CIS housing.
http://forums.pelicanparts.com/uploa...1241050674.jpg

Just thinking out loud.

I would love to see a picture of metering plate pushed to the end of travel where we can see the cone.

The distance between the pivot center and the point where the metering pin is located is a very small distance. Thus, a small change in that distance should make a big effect.

If the distance from the pivot is say 1.5" and we can relocate the pivot 3/8's of an inch further away, we change the ratio by 25%. That would be a lot. 3/16's would be about 12.5%. Thus, the metering pin would move about 12.5% further with the same amount of movement of the metering plate.

Remember, if we do change this ratio, then we will see a like change at all points like with the IA head. That is, if we set the CO correctly at idle, we will be 12% richer at cruse, and 'up to' 12% richer at red-line.



????

J,
When I referred to cone, I noticed I left out an e in my fat fingered spelling of cone's. I am actually referring to the venturi portion of the metering casting, that is what it has previously been referred to as. It appears the exterior leading edge and both profiles of the interior trailing edges have been machined. I also motioned it did not appear that the arm pivot point was changed. I looked at this because Keith had previously motioned he thought that may have been a path that would be taken in this mod.

Cole

As I look closer at the drawing it looks like it would not be hard to weld or bush and re-drill the hole the pivot pin is located in to relocate it. The stock pin, bearing, plate and circle clip could then be reused. Look across from 27 to see the relative size of the pin hole. There is a lot of room to re-drill the hole in any direction. The stock retaining plate dose not have to be centered to the hole.

If the pivot has been relocated, removing the circle clip (23) and retaining plate (24) should reveal such.

:)

Steve at Rennsport is who dose the pin relocation mod. Never heard of anyone else doing such.

Dose it seem any machining done might have only been to make air flows through the metering opening flow a little smoother?

Sound like not reprogramming or extending of the metering cone has been done then.

Shucks. ;)

Keith.

These are not the best, hope they will do.

Cole

http://forums.pelicanparts.com/uploa...1241054314.jpg


http://forums.pelicanparts.com/uploa...1241054338.jpg

To me it looks like as the end of the metering plate starts to get a little past cone area, air starts to spill over and around the plate and its rate of movement will slow dramatically.

I thought is the metering cone is designed to take us up to about 300hp plus a little margin. After that the metering plate hits an area in its travel is was not designed to reach. At this point the plat starts to stall or at least slow forward movement movement.

Wow, sorry for the wrighting and spelling, I was distracted and rushed. http://forums.pelicanparts.com/support/smileys/wat6.gif

Keith,

If that's actually the case the velocity cone with it's indented center, added height, and rolled outer edge may be intended for overcoming that exact condition.

Cole

If I remember correctly, the added cone there to take advantage of the high velocity air passing over it. In theory, the cone adds spoiler effect to the metering plate, increasing downforce exerted on the plate to force it further in its travel. In theory......... :)
I never saw any scientific proof to support this theory, but it sounds good on paper.

btw, that cone is mounted properly. It only covers part of the metering plate.