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#1 |
Junior Member
![]() Join Date: Jun 2021
Location: Fort Worth, TX
Posts: 50
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TBI motor tuning
Hey all,
I have a TBI motor running a aftermarket EFI and mild cam. I'm working to get the tuning sorted out. I currently have an HEI distributor with vacuum advance, but have the option to change for a billet and let the EFI handle the timing control, which would make it more like an upgrade from the factory air/fuel delivery. My immediate question is where should I set the base timing, 0 as factory, or more like a typical SBC 8 degrees base? |
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#2 |
Senior Member
![]() Join Date: Jul 2015
Location: Warrenton VA
Posts: 1,051
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Re: TBI motor tuning
What EFI controller? The holley setups have you index the distributor a certain way, lock timing out to a certain number in the tune then verify it stays there at idle and revving it up. Once that's done you do all your timing curve adjustments through programing only. If you set it at 8, the EFI program thinks it's base line is "0" and puts in 8 degrees now your at 16 and having tuning issues.
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71 c-10 Long Bed, under the knife for a No Limit Engineering Wide Ride Chassis Pack and coil over static drop. 07 Silverado Classic 2wd 95 Camaro 427SBC/TH350 |
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#3 |
Junior Member
![]() Join Date: Jun 2021
Location: Fort Worth, TX
Posts: 50
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Re: TBI motor tuning
It is Fitech. Same basic principle. I'm asking if there is a known difference in the tbi vs carb motors calling for different timing for an aftermarket efi. Last distributor car I had was a 70s 2L BMW, so the SBC world is not stored in my brain.
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#4 | |||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,938
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Re: TBI motor tuning
Quote:
Gary
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#5 |
Senior Member
![]() Join Date: Feb 2022
Location: Ca
Posts: 496
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Re: TBI motor tuning
I beleive FiTech wants a 10 degree locked out setup. No vac advance, no mechanical. The spark control in their program will manage advance. I recall their max electronic advance is 22 degrees making total max 32. If you don't need 32 on top, you might be able to drop initial and let the computer manage srart up to a greater degree. I am unsure if their system adjusts startup advance.
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