[6x400gmc]

Hello all,

After reading the 428 timing thread and Cliff's excellent post on what he does to HEI distributors, I thought I would post up my cry for assistance rather than clutter up those threads.

I have a 4" stroked, 4.15" bore 400 with a final displacement of 434. I have the XR-288-HR cam with 1.5 rockers. My heads are stock Edelbrock 87's, first design. I'm also running a 4 speed with 3.73's.

I have recently installed Edelbrock's pro-flo 4 fuel injection setup. It's complete with a Victor EFI intake, rails, 35 lb. injectors, TB, fourteen miles of wiring harness, all sensors, and a distributor. It's self learning, and you can tune it with an android tablet or your android phone.

I retrofitted my fuel tank with a Hyperfuel in-tank pump, plumbed the rails parallel with braided hose and AN fittings, and am regulating the fuel pressure with a vacuum referenced Hyperfuel regulator to 60 psi.

I was running a performer intake with an 800 Q-Jet with Cliff's recommended parts inside, and a stock distributor.

Why did I change?

1. The car used to run fine under cruising and light throttle conditions. When I would try to really call on the motor, I'd get to about 4500 before the carburetor would run out of gas and it would bog out. I didn't do this but once, and I immediately knew what the problem was - fuel supply. Not a reason to pull the engine and swap to EFI, but it helped the decision.

2. I wanted more hood clearance. I have a flat hood on my 75 Bird and while running the performer, Q-Jet, and factory drop based aircleaner I still had the lid crammed up into the hood insulation. That and I knew I was leaving HP on the table with the Performer intake as opposed to the Performer RPM I was running about 4 years ago (when I had a T/A Hood and shaker, and Larry's drop based aircleaner). Granted, it was a seat of the pants thing, but I could feel the difference. I lived with it because I had sold the TA hood and eventually wanted to go with a Formula hood. The overall height difference between a Performer/Q-Jet and the Victor EFI/throttle body gains you about 3/4 inches.

3. I AM NOT A TUNER. I call my dad the "car whisperer" because he can lay hands on anything and it runs. He's only been doing it for 40 years, and while he tried teaching me when I was a teenager, I was too interested in doing what ever idiot kids were into in the 80's. Where my Q-Jet always ran okay, I was never satisfied with how it started. Whether hot or cold, it always took more than I thought it should. My dad lives six hours away or I'm sure he would have helped me out with it.

My install. I didn't photograph much, and with PB down the tubes I'm not sure where I would host what pics I did take. Needless to say, it went like any intake swap does. All gaskets were provided and the bolt holes lined up. I had the engine out because I wanted to do a good clean up after I had a valve cover gasket dribble oil down the back of the motor, and some other things. It also made it easy to route the new fuel lines.

I mounted the EFI module to the left of the brake booster, kind of behind the fender. It's screwed into the firewall with some rubber isolators. The harness is very well made with thick loom and plenty of extra leads. Everything is clearly labeled. The sensor and injector plugs are all weather resistant with little gaskets. Though it's a ton of wiring, I managed to get it tucked and routed okay.

If you follow the instructions, initial setup and start is simple. Set the engine to 12 BTDC, line up the distributor, load a baseline map, hit the key. My idiot self had the 5 and 7 plug wires swapped at the cap because apparently I'm brain damaged. Even with that, It instantly fired. The third start is here:

https://www.youtube.com/watch?v=L1kNCXROdpU

That sucking sound you hear at the beginning is the idle air controller cycling open. It starts dialing back after the engine stabilizes to your set idle rpm.

How's it run? Idle's where you set it, +/- 50 RPM or so. I currently have mine set to 800 RPM, mainly because it sounded good. It will idle down to 650 but my vacuum goes to absolute crap. As a matter of fact, I lost a few of inches between the carb and EFI. I used to get 13 inches, now I only get between 9-10 inches. Here is an idle video. I'm having some weird readings come up on the "Long FT" window on the android display. Edelbrock is looking into that.

https://www.youtube.com/watch?v=gGdH_flHKRs

Driving for the first few minutes was interesting as the computer tried to figure out what was going on with this new motor. I'd say 5 minutes later and my part throttle around the block stuff was smoothed out.

After leak checking and so on, I headed off to the gas station and then around town. I tried exposing the computer to a wide variety of driving conditions, including a few full throttle pulls on some back roads. She pulled HARD all the way to 5500 where I have the rev limiter set, that works well too.

The EFI program comes with a baseline timing map, and I haven't changed it. This is what it is:

Initial Timing: 15 degrees
Simulated Vacuum Advance: 5 degrees (minimum 0, maximum 10)
Advance Starts: 1200 RPM, all in at 3000 RPM
Simulated Mechanical Advance: 36 degrees.

To be honest, I can't remember what my advance curve was with the original distributor, only that the initial timing was 16 degrees and the vacuum can was limited to 12 degrees.

Air fuel ratio's are set from the factory (and are unchanged) at:

Idle: 13.4
Cruise: 13.9
WOT: 12.8

Nothing is pinging (especially at WOT) and the engine doesn't feel lazy, so I've run with the factory settings. I do have some dyno time scheduled with Lee for later this month so I'm sure we'll get things dialed in there.

My final thoughts on the system:

Best money I've spent in a while. I've got about 300 real miles (freeway, around town, neighborhood, parking lot, WOT, etc.) and it runs smooth. Acceleration is smooth, no hiccups anywhere. It starts every time I turn the key whether it's 45 degrees out (the coldest start I've performed so far), or heat-soaked in a parking lot after an hour of driving.

My questions:

1. Do my timing numbers look right? I ask because of Cliff's post from his HEI thread, "The numbers we've seen work well for Pontiac engine builds are around 10-14 degrees initial timing. 20-24 mechanical advance, and 10-15 from the vacuum unit." doesn't equal what I've got going on.

2. Can I get my vacuum levels up? I get about 10 inches at 800, and while the car is high-idled during warm up I get 13 inches at 1000.

3. Where should I set my idle?

4. Anything else look out of wack?

Thanks for reading this long-winded post. I'm not the greatest into putting my thoughts into written word, but I did my best. Please let me know if I need to clarify anything.

Britt Bettell

[JLMounce]

I really despise the "self learning" marketing claims on these systems. The system can't learn the engine, only the values you give it. It's kind of a messy interpretation of what is actually happening.

That said, I think there's certainly room for improvement here, but just like doing it with a carb and standard distributor, you're going to have to play around (or better yet schedule dyno time) to find what the engine actually wants.

My understanding with the first generation edelbrock heads is they like a bit of timing in them. Up to around 40 degrees. Without a dyno spitting out numbers, you would tune that the same way you would before the switch. Get out a stop watch to time runs in a loaded gear like 2nd and add timing until you either hear it start pinging, or the car stops getting faster. Then back it down a degree or two for safety.

You can now also change your initial timing settings as well. You may be able to add a few degrees there which should help with idle vacuum.

Same deal with the AFR's. I can tell you that the idle AFR is a bit rich and you're losing some vacuum there as well. My 462 with a somewhat similar HR cam likes about 14.1 for idle AFR. To set that, dial in a bit less fuel incrementally and watch the vacuum changes. Again, same thing as pre efi, tune for highest vacuum by changing initial timing and AFR values. Cruise can likely go leaner as well.

[amcmike]

Originally Posted by JLMounce

I really despise the "self learning" marketing claims on these systems. The system can't learn the engine, only the values you give it. It's kind of a messy interpretation of what is actually happening.

That said, I think there's certainly room for improvement here, but just like doing it with a carb and standard distributor, you're going to have to play around (or better yet schedule dyno time) to find what the engine actually wants.

My understanding with the first generation edelbrock heads is they like a bit of timing in them. Up to around 40 degrees. Without a dyno spitting out numbers, you would tune that the same way you would before the switch. Get out a stop watch to time runs in a loaded gear like 2nd and add timing until you either hear it start pinging, or the car stops getting faster. Then back it down a degree or two for safety.

You can now also change your initial timing settings as well. You may be able to add a few degrees there which should help with idle vacuum.

Same deal with the AFR's. I can tell you that the idle AFR is a bit rich and you're losing some vacuum there as well. My 462 with a somewhat similar HR cam likes about 14.1 for idle AFR. To set that, dial in a bit less fuel incrementally and watch the vacuum changes. Again, same thing as pre efi, tune for highest vacuum by changing initial timing and AFR values. Cruise can likely go leaner as well.

^^^this.

Start with the AFR first, and then play with the timing.

[6x400gmc]

"To set that, dial in a bit less fuel incrementally and watch the vacuum changes. Again, same thing as pre efi, tune for highest vacuum by changing initial timing and AFR values. Cruise can likely go leaner as well."
I can actually do this directly by setting the target AFR in the menu. Presumably the EFI will adjust the fuel trims to meet that.

Britt Bettell

[JLMounce]

Correct. Assuming the distributor is setup correctly and your timing marks on the balancer is accurate, you just make the changes via the software now. A good way to test that is to get out the trusty timing light and have somebody bring the engine up to mid revs. Check what the computer readout is displaying as the commanded timing value vs what the timing light is showing you.

I haven't seen the Edelbrock software first hand, but it probably has something that accounts for timing drift as rpm increases. It could be called something like VR timing, may have a timing setting at a higher rpm, like around 4000-5000 etc. If you have that setting available, make sure you establish it based on the information above for that specified RPM. That'll keep things as accurate as possible.

Road tuning does change from the old days though and a lot of people get hung up on that. You aren't doing anything with the software that you wouldn't do with a standard carb and distributor. It's just nice that you can do it all from the software without having to open the hood!