I've changed heads on my car (off goes the ported LT1 castings, on goes the Canfields) and with no other changes, the engine then ran rich at idle (12.x AFR) and lean at WOT with up to 15.x psi.
I bought a MAF Translator and installed it and by setting the MAFT to 5% lean, I got the rich condition taken care of (now runs about 15.3 at idle and cruise) but because boost maxes out the MAF early, the MAFT can't compensate for WOT so I'm still lean. So lean in fact that it almost dies at WOT when I get up to 13.x PSI.
Example: I just took it out with a fuel pressure gauge, taped to the windshield so I could monitor Fuel Pressure at WOT. After warming up the car, I slowed to 20 mph on a deserted part of the highway, put the tranny in 3rd and floored it. It ramped up fairly quickly and while I watched the FP gauge hit about 5x PSI, the car fell on it's face because of running too lean. I let off the gas, pressed in the clutch and the motor caught on again and idled normally. I pressed the memory button on my AEM boost controller and it revealed I'd hit 13.5 psi at the max and that's when it had fallen over.

What fuel pressure should the rails be seeing at 13 PSI? Someone had posted once that for each pound of boost, the Fuel pressure should increase by some amount. I don't remember what that figure was but is there a stated/known relationship for boost/FP?

 

base FPR +1psi FP for every psi boost.

Assuming you are using the typical 43.5 PSI for an LT1, you should be seeing 57psi with 13.5 PSI boost.

 

I'll have to test it a couple more times to see if it's exactly 57 at 13 psi.

I'm just puzzled that nothing else was changed other than the heads and I've seen the behavior (rich idle, lean WOT)

Can you envision the new heads flowing so poorly at idle that it show's rich and conversely, flowing so much more at WOT that it runs rich?

I'm waiting for my AKM cable to show up so I can reflash my PCM to see if it makes any difference.

Thanks for the tip on the FP/PSI

 

I would expect different heads would change everything.

Your fuel presure regulator should simply maintain a 43.5psi difference between the fuel rail and the manifold at all times.

If you have 10psi boost in the manifold, you'd need 53.5psi fuel.
If you have 10 inches of vacuum you need 38.5psi fuel (2 inches = 1psi).

 

You got canfield heads, correct? What heads did you have before? Those LT1 Canfields flow like beasts up top, I will guarentee you need a re-tune with those deads. Different flow numbers = different tune

 

Yes, Canfields. That's good to know(about the canfields flowing well). I'll see if Bryan Herter (PCM4Less) will send me a changed tune.
On the old heads, Ported LT1 castings with LT4 sized valves flowing 275/195 on I/E. I went with the Canfields for the thicker decks since I was pushing water on the LT1's at 12 psi.

 

any idea who they were ported by? There was a place (trying to recall name) that got 330s out of the canfields. People have sent stock castings to them and got 300s, only problem is they are super $$$.

 

I got them from some guy on this list I think in the classifieds. He said they were ported. I didn't think they looked ported to me when I got them but maybe. Let me seach and see if I can find the link.

 

Here's my thread when I first got them. Look at the pictures.
Opening one end and exposing the passenger side head ...


Full view of the passenger side head..


Intake port side... Looks like the original sand casting surface in the ports to me...

 

Here's the ad that I responded to when I bought them. The flows are portrayed pretty much the same as the castings I removed....
https://www.camaroz28.com/forums/sho...heads+for+sale

 

Nu-tek was really bad about charging people and not producing results at the end. They are probably just slightly polished instead of actually ported. Ported they should do over 300 cfm on the intake side and probably 220s on the exhaust.

As far as your fueling question goes... The intake runners on the Canfields are probably quite a big larger than the standard LT1 intake runners. That allows them to flow huge amounts of air up top but will hurt low speed velocity especially on a low compression application.

 

The intakes dont look ported to me, I still see the rough casting marks on the walls.

 

Exactly! I'd ported my own stock heads back in '99 with a porting kit(carbide bits and sanding rolls) That took forever with an electric drill as the power tool and I highly recommend this kind of activity for punishing prisoners, war criminals, etc. I know what a ported port should look like. Unfortunately, I took the seller at his word when he stated they were ported. Live and learn...


___Right now, the car is running perfectly. I had a host of small issues that, taken singly, might not have been of much consequence. But compiled all at once, the car has been less than perfect. Now, several cubic feet of cuss words, weeks/days/hours and many hundreds of dollars later, it's perfect. I had the weird behavior after the heads swap of running rich at idle/cruise but runnning lean (and erratically at that, meaning mostly lean but occasionally perfect) at WOT during high boost. Next, going down the road at cruising MPH, it would sometimes either die or stumble heavily, only to pop right back and run like it should. Last/most recent issue was it suddenly ran pig rich on a drive(10:1 on my wideband gauge, no matter what RPM/MPH/Gear). I pulled over, killed the barely running motor, got out under the hood, didn't see anything amiss, went back to start it. Dead battery...

Here's what I had to address.

• Dying while driving = Replace Jegs/Summit Opti with an AC Delco Opti
  
• Running pig rich = Replace Battery w/new $89 one. Only to find out Alternator(original 14 yr orld) was also toast. Bought one for $139 +core from closest parts store(27 miles away from car stranded on side of the road) put it on.
  
• Stumbling heavily during driving then recovering = I datamastered a log and found that it was throwing up to 5 degrees of Knock retard, spontaneously, while in the middle of cruising on cruise control at 55 mph. The Battery/Alternator replacement might have fixed this or the next issue fix below might have. The issue hasn't returned since both fixes were applied.
  
• Running rich at idle and Lean at WOT = One ground wire from the PCM was not noticed during my reassembly of the motor into the car. When looking around for burnt thru wires(my first suspicion when the car started running pig rich above) I found this nifty ring connector wire end dangling underneath one of my exhaust manifolds. I traced it back to the PCM harness, found it reached perfectly to the factory ground post on the passenger side fender and I attached it.

I'd bought a (used) MAF Translator to 'band aid' the Rich/Lean issues and it was set to 5% lean for non-WOT and it put it perfectly in the 14.7 to 15.x at idle and cruise. Ever since I connected the 'lost' PCM ground wire, it ran WAY too lean with the MAFT in the circuit. I took the MAFT out of the circuit and just plugged the normal MAF connector to the MAF and, viola! She runs perfectly on the AFR targets on idle/cruise/WOT w/boost.

At some point, I'll either pull these Canfields and have them REALLY ported or buy some nice ported AirFlowResearch Heads.

 

I think part of your issue is still running a MAF to be brutally honest. I think a speed density setup would be more able to get you close to where you should be with the tune.

 

I'd considered a SD tune awhile back but after reading a lot here on this board, it sounded like there was unexplained behavior around a barometer setting or something like that? I'll look for what I'm referring to and update this post.