PRO-FLO Shutter Wheel

[John 69 Camaro]

I have an Edelbrock 3500 Pro-Flo in a 383 Stroker and when I removed my GM HEI Distributor Cap I was examining the position of the narrow Shutter Wheel Tooth in relationshiop with the Rotor. I found that when the Rotor was pointing at the #1 Cylinder, the narrow Shutter Wheel Tooth wasn't positioned inside the Half Effect Sensor. I rotated the engine and when the narrow Shutter Wheel Tooth is inside the Half Effect Sensor the Rotor is pointing at #8, which is one cylinder off.

Unknowingly, I've been running the car like this for 2 years. It has power, doesn't miss and generally runs okay; however, for these past 2 years I have been experiencing instances of irratic idle and TPS fluxuation. I have a Comp Solid Lifter Flat Tappet Cam with a .555 Lift, 262 @ .050 Duration, and 110 lobe Seperation, so I was attribuating these issues with the size of the cam.

Do you think the Shutter Wheel allignment is causing these issues? How could it be that the engine is running decently so to speak, with this misalignment? Since the injectors are not in sync with the spark, wouldn't I experience power loss or hesitation, etc.? What would be the usual symptoms caused by this misalignment? I guess I don't understand that this misalignment isn't causing significant driveability issues. Any help will be appreciated.

Thanks, John

[JRouche]

WOW.. I am surprised it was running so well, or at all. Did you change the spark and fuel maps dramatically to get it to run. I have the 3500 also, just a 350, but it has a funky idle too. I just thought it was the cam, RPM cam. Im really surprised its running actually. JR

[John 69 Camaro]

I took it out this past Saturday and jumped on it in 3rd (700R4) and it hit 5000 pretty fast topping 95 when I shifted into overdrive. My setting are pretty basic except for a few Fuel & Spark map changes under 2000. Last month I pulled the Throttle Body and removed the IAC and did a thorough cleaning to include the inside of the Intake. I installed an Accel Brute Thunder Coil and new Cap and adjusted all the valves. So far the idle has been good and the TPS is maintaining 13 degrees, so I'll keep an eye on how long they'll be constant.

I spoke to Edelbrock today and from what I was told it really doesn't matter where the Shutter Wheel is positioned because fuel will be in the intake runners waiting for the intake stroke. They feel I'm about 90 degrees off optimal Injector Pulse but also feel that shouldn't cause any degradation; however, they do recommend setting it up IAW the instructions. I'll probably keep it where it is until I need to pull the Distributor for something.

How ratical is your Cam and what is your vacuum at idle? It is my understanding the Pro-Flo is designed to work best with a Cam that has a Lobe Seperation of 112 and makes at least 10 inches of vacuum at idle. Anything less will cause some tuning challenges.

John

[JRouche]

First off its nice to have another guy using the Pro-flo, I may need to get some tech help from you.

I have the RPM performer cam. Its basically the same setup they were using as an advertisement when it first came out, that 420hp 350 they built. RPM heads, cam, same headers. The cam is a 7102. So its a mild cam. Has the 112 degree lobe separation. Havent put the vacuum gauge to it yet but the brakes work LOL. Is your cam a deeper cam? Meaning more overlap?

So get this, I bought it in 1996 or so and have yet to drive it!! lame huh. I have been working on this project car for so many years now its just pitiful. On the suspension now. And I have driven it, around the block LOL The suspension wasnt complete yet so I couldnt take it on the road. Everything on the car is new, everything. So I need to break it all in. The cam is broke in.

So get this, I have some taylor ignition wires, they are thick, I think 10mm. Anyway, my old craftsman timing light cant even get around the wire, the pick up. So I cant get a constant read on my timing. I bought a new light, its back burnered till I wrap up all this welding for the suspension. Im close, I think, should be a fun street car.

Im getting there, just a slow road. Thanks for posting. When I get back to the engine Im sure to have questions for you. JR

[John 69 Camaro]

My cam is a little more radical then your using. I have around 6-7 inches of vacuum at idle in gear but so far I haven't experienced any braking problems. I have a 11 inch single diaphram booster and I believe my master cylinder has a 1 1/8 bore.

By no means am I an expert on the Pro-Flo as I am still learning this system. I spend a lot of time reading stuff on it and do speak with the Edelbrock Tech guys from time to time. The majority of my experience with this system is trial and error with a whole lot of luck. When you get your project finished and need any information I'll be glad to give you a hand. Good luck on getting it on the road.

John

[ErikSOCAL]

I got my pro flo running in time to get it running and into storage! haven't messed with it in a year but I've found some good info on the following sites:
Chevy Talk. There is information to adapt a wide band O2

This site is probably the most comprehensive and beyond most (me).
Note the MAT sensor location, I have heard that from at least 3 people running pro flos. it needs to be moved for proper temp readings
http://sonic.net/~mikebr/efi/main.html

Also, the distributor conversion leaves something to be desired, many have recommended making the swap to the mallory pro flo specific distributor.

[John 69 Camaro]

Thanks for sending the site. I'll need to spend some time and go through the entire project.

My Air Sensor was located inside the Air Filter Housing and I was getting high Air Temperature readings at idle, traffic, and hot start-up. The temperature was so high I would get hesitation and backfire until I got moving. Once moving the outside air would come through my Cowl Hood and all would stabilize. This past November I relocated the Sensor between the Radiator Support and Grill. So far it seems to be working but the true test will come this summer when the outside temperatures hit the 80's & 90's.

I was looking at a small Cap Mallory because my HEI fits pretty tight near the firewall. I believe the Mallory like the HEI uses a Half-Effect Sensor and Shutter Wheel, so why would that one be any different than the HEI? I still don't understand how my Crank Position is being properly relayed to the ECU, since my Shutter Wheel isn't aligned properly with the Rotor. I don't think it creates a major problem with the pulsing of the injectors but it would with the Spark. Mine is obviously firing right; I just don't understand why!

John

[John 69 Camaro]

I just spoke with the Edelbrock Tech about what fires the spark. He said the ECU sends out the signal based on the Shutter Wheel passing through the Half-Effect Sensor. If the Distributor Cap Wires are properly routed the spark with firing based on the Rotor position. The importance of proper alignment of the Shutter Wheel is related to the proper sequential pulsing of the Injectors not the spark. I guess that make sense because my spark is firing properly. If I want to sync my Injector pulse to my spark I'll need to set the leading edge of the narrow Shutter Wheel Tooth in the middle of the Half-Effect Sensor and re-rout my wires on the Distributor Cap. John