Tuneup differences between Fat and Fuel heads

Discussion in 'InsideTopAlcohol.com Tech Questions' started by greenracing, Apr 9, 2019.

  1. greenracing

    greenracing Member

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    Has anyone moved between Fuel heads and Fat heads on a blown alcohol setup and has a ballpark difference for timing and fuel? I've got a safe starting point for a Fat head setup and am putting together a Fuel headed motor with the 176cc camber heads. I'm assuming I can use more timing on the Fuel heads - I'm thinking around 30 would be safe, maybe 32 max? Will the Fuel heads use less fuel, or does the big chamber and more timing require similar fuel?

    Thanks!
     
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  2. KENNETH JORDAN

    KENNETH JORDAN New Member

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    subscribed
     
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  3. bruce mullins

    bruce mullins Top Dragster

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    keep your timing under 28.
     
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  4. greenracing

    greenracing Member

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    thanks Bruce!
     
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  5. quickcut

    quickcut New Member

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    Anyone else have any input to this ??
     
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  6. turbo69camaro

    turbo69camaro Member

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    Save yourself a ton on money and tail chasing .Get hooked up with Will hanna,Mike @ rage ,Randy Anderson,ETC and get your fuel system set up and flowed they will get you in the ballpark
     
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  7. Soldierboy0098

    Soldierboy0098 Active Member

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    On alky Fatheads max of 26 but it depends on your compression ratio for how much you will need to babysit the timing. Fuel heads like more timing because of the big chamber size. I have seen between 32 and 38 on a fuel head but they do not like high rpm's because the pistons weigh a ton.

    Also Turbo is correct for the $800 to flow a fuel system your money way ahead in getting it flowed as they will give you a good starting tuneup, flow your jets, and this usually includes one trip to the local track to help tweak it.

    Hope this helps,
    Trev
     
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  8. John byob

    John byob New Member

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    Trevor who mills fuel pistons down to take weight off of them. Met a racer years ago he took 200 grams of each blower piston fr his motor? Thx
     
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  9. Soldierboy0098

    Soldierboy0098 Active Member

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    Not sure on that one, I know people who mill the domes to get the compression down but the only people I can think of is the piston company for CP. They do a lot of lightening but not sure on a fuel head deal.

    https://www.cp-carrillo.com/pt-3507-pistons.html

    Hope that helps,
    Trev
     
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  10. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    I have found (was educated is more proper) the timing is relative to the bore size. Bigger bore = more timing. This is comparing fat head to fat head type of deal.

    Now the fuel head has more flame travel, so it needs more timing to start the burn a little earlier.

    You will hear of people running timing numbers well into the 30's with fuel heads. Most (not all) of that comes from the way these motors used to be ran before we got 44 amp mags. With the big chamber and weak ignition, it needed a lot of lead and a hot cylinder head to combust the mixture. Now we have an arc welder, so we don't need to start the burn as early and don't need 200+ head temp to help preignite the burn.
     
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