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Thread: SBF 363 Issue - HP EFI

  1. #1

    Default SBF 363 Issue - HP EFI

    I've been battling a part throttle miss down low and getting the car dialed in has been a bear. Combo is a SBF, Dart 363, 14:1 on E85, AFR 220s, Wilson 4150 TB, ID1050X injectors, Super Victor port matched to heads, Custom N/A solid roller cam 264°/271° @ .050" with .748"/.707" on a 110°. Exhaust is 2"-3.5" Kooks long tube headers. Using a Holley Dual Sync Distributor. I had a Blaster coil and a Mallory 685, swapped them out for a new MSD 6AL & HVC-2 MSD coil to eliminate any issues from the previous stuff. Same issue. It was recommended to me that I just make sure I'm not 180° out because the car was running better when I disabled the cam sync sensor and went to Bank-To-Bank firing order. It was also recommended to double check the injector harness from the ECU to each injector. All wires checked out according to proper injectors.

    So I decided I'd pull the Dual Sync distributor and recheck to make sure I don’t happen to be 180°. Put the distributor back in, reprogrammed the dual sync cam and crank sensor to Digital Falling, and my issue wasn’t fixed as far as the car missing at part throttle. I then decided to double check everything again. Placed the engine at TDC #1 cylinder, verified with plugs out on #1 & #6 I was getting compression out the hole on #1 and not #6. It was correct. I had the valve cover off and also verified both valves closed at TDC number 1. Backed the engine off to 50° before TDC on my balancer. I unplugged the negative on the battery overnight and decided I'd let the ECU clear anything weird out as far as programming the Dual Sync again so I let it sit. Came back today and put the distributor back in. Plugged the harness for the Dual Sync in and moved the crank sensor to align with the rotor. Both lights on. Went counter-clockwise until crank sensor went out, stopped, went clockwise until light just came on and stopped. Locked down the distributor and then installed the cap. Installed #1 plug wire over the rotor and the rest in accordance to firing order. Checked Cranking Timing and everything checked out. Fired the car up and my valvetrain sounded like it was running dry, had a ton of noise. I pulled both covers and inspected everything, it all looked great. Fired the car back up, same crap. Gave it some throttle and checked the timing with higher RPM. Valvetrain noise was gone, timing checked out vs Static Timing in ECU I had set. I have repeated the process multiple times and still have ridiculous valvetrain noise that was not present before at idle. I'm stumped! I can't wrap my head around this. Thanks in advance. Mike

  2. #2

    Default

    Are you sure your cam is timed correctly?
    351W, 800HP stock shortblock assy

  3. #3

    Default

    You may be experiencing what engine builders call "camshaft chop". To tune a relatively small engine with that cam you should use the Injector End Angle table and tune that area of the Base Fuel Table in Open Loop.

    Or, you have lifter issues. Any builder would do a compression check and a leakdown test.
    Last edited by fastmanefi; 10-26-2020 at 06:16 PM.

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