Never mind. Found what I was looking for. Now to find some injectors.
What would be the part number for 305 injectors?
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Never mind. Found what I was looking for. Now to find some injectors.
What would be the part number for 305 injectors?
5235279
http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers
Interesting information on the most recent set of 350 injectors (5235206) I sent out for service.
dave w
Absolutely! I don't know the state of mine. I pulled one out last night to get the numbers off it. They are a little rusty on the bodies.
I have no rich running trouble now. That's for sure. I even added around 2 turns out on the mixture screws. Note that my fuel economy is about the same. So I gained very noticable power for no loss in economy.
I did all the tuning after weeks of research and discussions on other forums, lots of trial and error, lots of testing and hard pulls, etc.
Having done this swap before, 305 injectors on this 305 would be BAD. Mine ran best on the stock 350 chip and 350 injectors. Had to correct the BPW in the chip and rework the VE table to make it run best. Also had to give it about 10* initial at the distributor.
I had a Mellings MTC1 204/214 @ .050, .420/.442" lift, 112 LSA, 107 ICL in my 1983 G20s stock 305 with a 92 350 TBI intake, TBI, exhaust manifolds and exhaust system.
The stock 305 injectors and stock chip are so lean even at 16 psi (the highest I could get the stock pump to output) it was too lean to be driveable.
I always used 6-14* on my setups, especially with a CAM. Makes it easier to start and also brings the fuel delivery in earlier to match the longer duration cams. It also makes the engine run better if the EST should ever go into limp home mode, disabling the ECM controlled advance.
My damper has not slipped. I used a piston stop to degree it. The timing marks line up correctly.
"Had to correct the BPW in the chip and rework the VE table to make it run best."
That's the key to tuning! There are slight tuning differences (VE ~ BPW) between engines, even when the engines are identical.
I posted a Base Pulse Width (BPW) calculator here: http://www.gearhead-efi.com/Fuel-Inj...BPW-Calculator
The BPW calculator is usually accurate within +/- 2 BPW for the 1227747 for a mild performace cam, and usually dead on calculation with a stock cam.
The only accurate way to tune is with data logs and wide band O2. Anything else is an estimate of what the engine needs. The BPW calculator would support my suggestion that a 305 engine with 305 injectors programmed with the stock BPW would be a good estimate to start with. The BPW calculator would support my suggestion that a 305 with 350 injectors programmed with the stock BPW would be rich.
Without seeing what the actual corrections are for a specific engine, I would expect the BPW calculator to be "Close Enough" as a starting point for most mild cam upgrades. I've tuned engines that required small fuel pressure adjustments, and small BPW adjustments, after using the BPW calculator, but I had data to show how much change was needed.
dave w
After thinking it over and over again, I agree that starting with a 305 chip and injectors is the way to start. What I end up doing later on will depend on just how it runs with the first chip. It's not a race car so I don't need every pony I can eek from it, but it does need to run well, especially at lower RPM's.