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  1. #1
    Fuel Injected!
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    Setting base timing for performance cam

    I am still gathering what I need for parts and information to swap a TBI into my carbed engine. I have an '83 305 with a mild Summit K-1102 cam (.420/.442, 262/272, 112*), stiffer springs, Edelbrock non-egr performer intake. Using an HEI distributor I have found that I need 20* base timing for best performance (no detination). At the factory 8* the engine will barely run. Summit recommends at least 4* more timing for this cam.

    I know the computer controller dizzy is supposed to be set at 0*, but I wonder if that will work ok with my engine. Is it possible or even advisable to add more base timing to make up for non-stock cams?

    Last question (for now :): Will 18inHg vacuum at idle work with the stock computer or am I going to have to get a custom chip or self learning computer?

  2. #2
    Super Moderator dave w's Avatar
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    I'm located south of you in Vancouver WA. I usually start with the factory TBI settings, and make adjustments from those settings. I've installed TBI conversions with a cam spec similar to the one posted above. The factory TBI settings will work, but ultimately a custom chip will deliver the performance the cam is capable of doing. I can, or other board members here can, program a custom chip for you. If you have the budget for a self learning computer, that is a good option. Most of us board members here take pride in our hard learned abilities to save on the budget and do our own chip. Sometimes it's a matter of time vs. money, the self learning computer can save time!

    dave w

  3. #3
    Fuel Injected!
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    Dave W,

    Thanks for the reply. All good to learn. My wife and I differ on what my budget is, but it is rather small at the moment :)

    I will end up needing a custom chip to remove the EGR at a minimum. It's good to know a stock chip will let it run, even if not optimally. Now to actually find one... I have a 350 PROM in my computer at the moment.

  4. #4
    Super Moderator dave w's Avatar
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    One of the important parameters (fuel) of the 305 and 350 chips will have the same setting. The important thing to do is make sure the 305 has injectors from a 305 if using a 350 chip for a 305 engine. Do you happen to know what the injector numbers are in your throttle body? Post back the injector numbers if you have, then we can figure out if you have 305 injectors. Usually the first 3 numbers on the injector are "523". Maybe you can get your engine running with what you have on hand?

    dave w

  5. #5
    Fuel Injected!
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    I will see what it there, but the throttle body and computer I bought are off a 350. The computer is a 7747. I have not opened it up to see what's inside it yet.

  6. #6
    Super Moderator dave w's Avatar
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    350 injectors / stock 350 chip on a 305 would be bad! 350 injectors / stock 305 chip on a 305 would be bad! 305 injectors / stock 350 chip / stock 305 chip, would be OK, but not great because of the cam specs.

    dave w

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