My Cross Fire Mods...but will I need more fuel?
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
My Cross Fire Mods...but will I need more fuel?
I'm confused as to what I'll need to do once I get it running. I have a 1983 Cross Fire Z28 with the original 305 still in it.
Here is what I've done so far:
Ported the stock heads...I have the Renegade manifold which I ported paying special attention to the ports for cylinders 6 and 8 which required some work since the EGR passage is routed below them and there was extra material cast into the port area which would have restricted airflow. I'm also installing 1.6 ratio rockers and new valve springs and push rods.
On the exhaust side I got Hooker shorty headers and off road Y-pipe ans well as a Flowmaster American Thunder exhaust system.
My question is...with all of the extra air flow I have created, how will I know if I'll need more fuel? Will the stock 305 injectors work? What about a fuel pump? What about the ECM...will it need to be upgraded? I heard so many different things that I'm getting confused.
Any help? Thanks!
Here is what I've done so far:
Ported the stock heads...I have the Renegade manifold which I ported paying special attention to the ports for cylinders 6 and 8 which required some work since the EGR passage is routed below them and there was extra material cast into the port area which would have restricted airflow. I'm also installing 1.6 ratio rockers and new valve springs and push rods.
On the exhaust side I got Hooker shorty headers and off road Y-pipe ans well as a Flowmaster American Thunder exhaust system.
My question is...with all of the extra air flow I have created, how will I know if I'll need more fuel? Will the stock 305 injectors work? What about a fuel pump? What about the ECM...will it need to be upgraded? I heard so many different things that I'm getting confused.
Any help? Thanks!
#3
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
We have a chassis dyno here at school and a wide band O2 sensor. We're starting to put the engine back together, so it will be a little while. I have my stock throttle bodies ready to be rebuilt, but I have a feeling they won't provide the fuel necessary for the added airflow.
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Car: 2013 ZL1 convertible
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Transmission: 6l90e
Re: My Cross Fire Mods...but will I need more fuel?
well I have the corvette crossfire throttle body's with the DCS spring so you could adjust the fuel pressure. They are 350 injectors and should supply you with enough fuel.
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
Well, not good. I installed the throttle bodies I got from you and it has issues. Idle is fine but it stumbles and bogs down in low to mid range rpm. I tried putting my stock 305 injectors back in to see what happens, but I'm not sure it fixed it. Fuel pressure is at about 12.5 to 13 pounds. It seems like it's getting too much fuel yet. I thought of backing down the fuel pressure and see what happens. Do you have any suggestions?
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Car: 2013 ZL1 convertible
Engine: 6.2 supercharged
Transmission: 6l90e
Re: My Cross Fire Mods...but will I need more fuel?
Well, not good. I installed the throttle bodies I got from you and it has issues. Idle is fine but it stumbles and bogs down in low to mid range rpm. I tried putting my stock 305 injectors back in to see what happens, but I'm not sure it fixed it. Fuel pressure is at about 12.5 to 13 pounds. It seems like it's getting too much fuel yet. I thought of backing down the fuel pressure and see what happens. Do you have any suggestions?
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#8
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
We did a couple of pulls on the dyno yesterday and it was very disappointing...110 HP and 163 lbs of torque. We had the wide band hooked up to it and and I think it had read about 10.5 at the richest. It had a bad stumble. I didn't installed the 350 prom. Can I install that with my 305? I wasn't sure My heads have been ported, but we didn't go to extremes, just cleaned the casting up...nothing to resize the ports. I didn't sync the throttle bodies. It was idling too fast when we first ran the engine and we found the front throttle bodies was not coming back to rest on the idle set screw, so we adjusted the idle screw on the back one and the idle speed came down.
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Car: 2013 ZL1 convertible
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Re: My Cross Fire Mods...but will I need more fuel?
Also when you set your timing did you do it with the ecu wire disconnected.
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Car: 2013 ZL1 convertible
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Re: My Cross Fire Mods...but will I need more fuel?
We did a couple of pulls on the dyno yesterday and it was very disappointing...110 HP and 163 lbs of torque. We had the wide band hooked up to it and and I think it had read about 10.5 at the richest. It had a bad stumble. I didn't installed the 350 prom. Can I install that with my 305? I wasn't sure My heads have been ported, but we didn't go to extremes, just cleaned the casting up...nothing to resize the ports. I didn't sync the throttle bodies. It was idling too fast when we first ran the engine and we found the front throttle bodies was not coming back to rest on the idle set screw, so we adjusted the idle screw on the back one and the idle speed came down.
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
I'm not sure that dyno is all the accurate, but the one instructor insists it is. That's why I put my stock injectors back in. What is the size difference in the 305 to the 350 injector? I'll try driving it tomorrow and if it's still giving me problems I'll try adjusting fuel pressure and go from there. I need to be able to drive it back to my garage where I keep it from here at school in Blairsville, which is about 3 hours.
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Car: 2013 ZL1 convertible
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Re: My Cross Fire Mods...but will I need more fuel?
I would stick to the 305 injectors for now. recheck your timing with the power wire disconnected. the ecu should get it to run right. unless the throttle bodies are not in sync.
#13
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
I set the timing yesterday to the stock spec for the engine. The emissions label under the hood says base timing with the wire disconnected is 6 degrees. The only problem is my class is over and I don't have a place to work on the car here. I thought the throttle bodies were in sync.
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Car: 2013 ZL1 convertible
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Re: My Cross Fire Mods...but will I need more fuel?
they were in sync when they were installed on my engine but maybe they moved when I unbolted them from the top plate. never know just throwing some ideas your way. 6 degrees seems low. did you try to bump it up to 10 or 12 to see what happens could lean it out.
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
Maybe it does need more timing since I changed the manifold and ported the heads. I also installed 1.6 rockers which I was told would giving me about .030" more lift. I also replaced the valve springs and push rods.
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Car: 1983 Camaro Z28
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Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
No code...no check engine light. I replaced the coolant temp sensor, so that's not it.
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Car: 1982 Z-28
Engine: 5.7L Crossfire
Transmission: TH-350
Axle/Gears: GM Posi, 3.73
Re: My Cross Fire Mods...but will I need more fuel?
Since you are using a stock 305 cam, stick with 305 ECM and injectors. Also stick with factory 13 psi fuel pressure setting.
You really should get a dealer service manual. It has all of the procedures for setting the TBs - doing it correctly is very important. If everything is in good condition, your engine should have a good idle.
Leave timing at factory spec, the ECM controls timing and takes the 6* initial setting into account when calculating timing. If you change too many things at once, you will be chasing your tail figuring out what to do.
I think you need to get all of the TB settings in order first. Then work on other stuff.
You really should get a dealer service manual. It has all of the procedures for setting the TBs - doing it correctly is very important. If everything is in good condition, your engine should have a good idle.
Leave timing at factory spec, the ECM controls timing and takes the 6* initial setting into account when calculating timing. If you change too many things at once, you will be chasing your tail figuring out what to do.
I think you need to get all of the TB settings in order first. Then work on other stuff.
#19
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Car: 1983 Camaro Z28
Engine: 5.0L 305 Cross-Fire Injection
Transmission: 700-R4
Axle/Gears: 3.23 Limited Slip
Re: My Cross Fire Mods...but will I need more fuel?
I do have a dealer service manual. Hopefully other things I have done haven't affected the way it runs. I ported the heads, but didn't do anything to enlarge the ports. The main focus was to remove the roughness...I did do some work in the bowl area of the intake side and gasket matched the area where it meets the head. I installed 1.6 rockers and replace the valve spring and pushrods.
The throttle bodies that are on the engine now have been modified the make fuel pressure and idle speed adjustable. I installed my injector in those throttle bodies. I'm thinking of putting my old throttle bodies back on since they are unmodified and the engine ran fine with those and I'm sure they were in sync...then I'd know where I was at.
The throttle bodies that are on the engine now have been modified the make fuel pressure and idle speed adjustable. I installed my injector in those throttle bodies. I'm thinking of putting my old throttle bodies back on since they are unmodified and the engine ran fine with those and I'm sure they were in sync...then I'd know where I was at.
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Car: 92 Formula WS6, T-top
Engine: 5.7L T.P.I.
Transmission: 700r4
Axle/Gears: Limited slip, 3.23 10 bolt
Re: My Cross Fire Mods...but will I need more fuel?
I was looking into this earlier tonight, and I'm not sure I understand. What's the difference between CFI and TBI? Looks like about the same setup, but I know there has to be a difference. Does it have to do with the shape of the intake passages?
#23
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Re: My Cross Fire Mods...but will I need more fuel?
crossfire injection is just a name GM came up with for The system using twin independent TBIs on a crossram intake manifold-Single TBI used on many 2.5"iron duke"starting in '82 uses basicly the same TBIs as CFI,except 1-11/16 bore instead of 1-13/16 bores on CFI.
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Car: 1983 Camaro Z28
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Re: My Cross Fire Mods...but will I need more fuel?
CFI is Cross Fire Injection, which is a form of throttle body injection or TBI. It uses two single bore throttle bodies which were used on GM's 2.5L engines. The throttle bodies are arranged to where one sits closer to the right side of the engine closer to the front and the other sits on the left side closer to the back of the engine. The throttle body on the right was suppose to feed the left bank of cylinders and vise versa....hence the name Cross Fire Injection.
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Car: 92 Formula WS6, T-top
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Re: My Cross Fire Mods...but will I need more fuel?
CFI is Cross Fire Injection, which is a form of throttle body injection or TBI. It uses two single bore throttle bodies which were used on GM's 2.5L engines. The throttle bodies are arranged to where one sits closer to the right side of the engine closer to the front and the other sits on the left side closer to the back of the engine. The throttle body on the right was suppose to feed the left bank of cylinders and vise versa....hence the name Cross Fire Injection.
Last edited by TheExaminer; 01-06-2015 at 07:10 PM.
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Car: 84z28, 2--1983 TA's
Engine: 305 H.O
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Re: My Cross Fire Mods...but will I need more fuel?
Going to keep an eye on this thread as I may end up referencing back to it. I'm rebuilding a 305 to go back under my CFI and changing maybe to vortec/hooker headers. Not sold yet on Renegade and as of this moment.
#27
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Re: My Cross Fire Mods...but will I need more fuel?
We did a couple of pulls on the dyno yesterday and it was very disappointing...110 HP and 163 lbs of torque. We had the wide band hooked up to it and and I think it had read about 10.5 at the richest. It had a bad stumble. I didn't installed the 350 prom. Can I install that with my 305? I wasn't sure My heads have been ported, but we didn't go to extremes, just cleaned the casting up...nothing to resize the ports. I didn't sync the throttle bodies. It was idling too fast when we first ran the engine and we found the front throttle bodies was not coming back to rest on the idle set screw, so we adjusted the idle screw on the back one and the idle speed came down.
#28
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Re: My Cross Fire Mods...but will I need more fuel?
We did a couple of pulls on the dyno yesterday and it was very disappointing...110 HP and 163 lbs of torque. We had the wide band hooked up to it and and I think it had read about 10.5 at the richest. It had a bad stumble. I didn't installed the 350 prom. Can I install that with my 305? I wasn't sure My heads have been ported, but we didn't go to extremes, just cleaned the casting up...nothing to resize the ports. I didn't sync the throttle bodies. It was idling too fast when we first ran the engine and we found the front throttle bodies was not coming back to rest on the idle set screw, so we adjusted the idle screw on the back one and the idle speed came down.
#30
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Re: My Cross Fire Mods...but will I need more fuel?
those are some pretty healthy dyno #s in reply 28-better than the original flywheel rating -getting close to getting the renegade on? I might do a few tweaks to my crossfire this yearrobably upgrade the fuel pump again as the one I installed about 6 yrs ago seems to be losing pressure...might put my SLP headers back on too(edelbrock TES on now)
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