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Thread: L29 head 454 MEFI tune

  1. #1
    Fuel Injected! roughneck427's Avatar
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    L29 head 454 MEFI tune

    took my flat bottom boat out with the stock tune and only 13-16 degrees of timing it turned only 4000rpm then bumped it up to 21-25 in WOT area and picked up some rpm to 4500 rpm whats a safe rule of thumb on the L29 heads?? I know regular bbc heads like 36 degrees or so the engine only runs at 160 degrees
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    On local pump gas 32* is as far as I get gains with. You upgrade the cam/springs? Truck engines dont rev much past 4500 usually, weak springs.

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    Fuel Injected! roughneck427's Avatar
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    Quote Originally Posted by mecanicman View Post
    On local pump gas 32* is as far as I get gains with. You upgrade the cam/springs? Truck engines dont rev much past 4500 usually, weak springs.
    Its an actual mercruiser motor so its a mercruiser marine hyd roller with springs already it is larger than a truck cam. Its abt the same size as a 70's 454 LS5 cam. It does still have a heavy marine cast iron L29 truck intake manifold im sure thats alomost past its limits. Eventually ill swap to a single plane with an elbow

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    Marine tunes are notoriously rich. Not sure why... maybe to keep exhaust or cyl head temps low??? More timing possible when mixture doesn't burn as well. I like to lean 'em out some to improve performance.

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    all that is changing now.

    if you had a car that ran nice and cold, but its main operating spec was climbing a hill while towing a trailer for 4 hours at full throttle and emissions were not a concern... that's how you'd tune it too. like a big RV. a bit rich, and conservative timing.

    the new marine inboards being sold are mandated to have cats, even with wet exhaust, and they are (afaik) mandated to have NB o2 sensors aiming for stoich during cruise conditions.

    NB o2 in a wet exhaust system is a nightmare, no matter which part of the pipe you put it in, you really need to build a trap system for it so it doesnt get soaked. honda did that with their outboards, and so did some of the yamaha 2-stroke stuff, and they were always the first thing to die, even with elaborate systems to avoid just pouring salt water over them. scary stuff, but good for a skiboat, once its on plane, it's pretty efficient, so stoich would be a good thing.

    im not even sure what they've done to mefi controllers to deal with it. we aren't getting stuck with them in canada until next year, but im curious to see how they figured 'er out. increases the price of a new boat by a couple grand apparently, since the cat plumbing is expensive stuff.

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    Fuel Injected! roughneck427's Avatar
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    I have over the transom headers and just shut the water off when I use my innovate wb O2 sensor clamp I have fuel dialed in pretty good so far

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    MEFI was designed to use NB O2 input since MEFI 1. Big money "upgrade" to have AS&M do a reprogram and add one wire to harness...

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    Ok slowly but surely been gathering parts to build my new motor larger forged domes -18cc and closed chamber heads CR will be around 10.25:1 and hyd roller peak is around 6k rpm 230 230 @ .50 .544 .544 on a 112lsa. i scored a single plane intake complete from ebay with a throttle body injectors and fuel rails. Im debating to keep the mefi3 being the tables only go to 6k and the cost of a mefi4. I have a set of LS1 coil packs a harness and an ecm already and trying to figure a 0411 conversion. The cam signal no big deal my 24x is my dilemma being its a gen5 motor EFIconnection setup is for a gen6 and in a vdrive boat my waterpump is driven off the timing cover and is a special unit. I have a donor timing cover to maybe use a L21 reluctor and weld a bung on the cover to mount my crank sensor. Another option i thought of i ordered it already is use a 24x gear from a LSX motor and retro fit it to my harmonic balancer and use it as a crank trigger. Any thoughts,inputs or easier solutions for a 24x setup?

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    I have been working on putting an 0411 onto a 6-71 409. I am using the vortec distributer with a 1" spacer to get the 1x signal. I have a friend in drafting and computer design who has scanned the 24x reluctor and the harmonic balancer. The plan is to split the reluctor into 2 pieces and add tabs that will line up with bolt holes on back of balancer. This is as far as it has gone as I am at the mercy of his busy schedule. He has the water jet or laser to cut it with so I guess I will wait.

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    MEFI 1 with O2?

    One Stated: MEFI was designed to use NB O2 input since MEFI 1. Big money "upgrade" to have AS&M do a reprogram and add one wire to harness...
    MEFI-1 never had O2 capability. It was planned but there were to many other concerns before this would occur. It was pushed off until the next level. O2 was mentioned within the MEFI-1 software but it didn't function.
    Az Spd and Marine is expensive for what you receive. I've heard of some poor cals from them.

    Marine was conservative with Spark and had a bit rich fuel. But the fuel samples taken explained why. Poor fuel quality. It was also to keep the pistons within the cylinder. Rich fuel is used to cool the pistons.
    Last edited by billygraves; 10-18-2014 at 12:38 PM.

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    Fuel Injected! roughneck427's Avatar
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    I have mefi burn already its not bad software my mefi3 tables go to 6k rpm only. A mefi 4 goes higher but for the price and what I have already its cheaper to do an 0411 now with a speed density open loop tune being I have water cooled headers no o2 sensors for me. UPDATE: I met a guy local that retro fitted a 24x reluctor on his 500 cid bbc it runs and was dyno tuned using cop ignition and a vortec distributor.He had a guy cut the centerpiece on his cnc water jet machine and tig welded it with zero runout he still has the plans for it ill be taking my reluctor over to him attached are some pictures.

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    Fuel Injected! roughneck427's Avatar
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    Well my reluctor,harmonic balancer, and belt pulley are at fab dudes shop hopefully it will be done soon. I scored a MSD 6010 to drive the coils im going to test the integrity of the reluctore running the tunnel ram then ill swap over to the single plane and 0411

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    The L21 24x reluctor is only $18 from GM.

    peace
    Hog

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    Steveo wrote:
    if you had a car that ran nice and cold, but its main operating spec was climbing a hill while towing a trailer for 4 hours at full throttle and emissions were not a concern... that's how you'd tune it too. like a big RV. a bit rich, and conservative timing.
    I have tuned RV's and tow rigs. And I have worked on both carburetor equipped and MEFI equipped marine engines. Unless engine configuration prevents it, I never choose to release a calibration that is so rich it burns your nose. That is rarely necessary when you have a degree of confidence in the owner / operator's ability to stay alert to the situation and in the system's ability to work consistently within design parameters. In this case (OEM Cals being so rich) fuel quality was suspect.

    Bill Graves wrote:
    MEFI-1 never had O2 capability. It was planned but there were to many other concerns before this would occur. It was pushed off until the next level. O2 was mentioned within the MEFI-1 software but it didn't function.
    Well, that's interesting. I can't remember whether or not my Chevelle used MEFI1 or 2 but it did attempt to enter closed loop once it was enabled in software.

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    Fuel Injected! roughneck427's Avatar
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    Quote Originally Posted by Hog View Post
    The L21 24x reluctor is only $18 from GM.

    peace
    Hog
    I would have used that but I'm limited with my camshaft driven waterpump and my motor plate in the front of the motor it being in a boat

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