L29 rebuild - give me ideas

Discussion in 'Towing' started by Philip Parker, Dec 19, 2020.

  1. andy396

    andy396 GMT400 Enthusiast

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    Retarding the cam put the peak torque lower in the rpm band. Being a truck application I’m guessing it was their solution for making an engine with nice low end grunt.
     
  2. Schurkey

    Schurkey I'm Awesome

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    Advancing the cam drops the RPM of peak power. Retarding the cam raises the RPM of peak power.

    I'm thinking that retarded cam timing is/was done for emissions-control reasons, not for "power".
     
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  3. andy396

    andy396 GMT400 Enthusiast

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    Oh yeah, right. Got that backwards. Thanks!
     
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  4. Christian Steffen

    Christian Steffen I'm Awesome

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    I have no idea what their goal was with the cam retard.. all it should do is move peak torque up in the band. As far as the new tune goes, it just affects airflow and timing, nothing else to really consider.
     
  5. L31MaxExpress

    L31MaxExpress I'm Awesome

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    Cleaner emissions and less dynamic compression to keep it from knocking on 87 octane towing on a long uphill pull.
     
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  6. Christian Steffen

    Christian Steffen I'm Awesome

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    That makes sense lol
     
  7. Philip Parker

    Philip Parker Newbie

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    Just an update on this build - here's where everything landed:

    I had to ditch the AFR heads due to a manufacturing issue and went instead with a pair of Brodix Race Right oval ports. Everything is put back together and the truck is running great. Just to recap the parts lit:

    Brodix Heads 270cc (I think)
    247/282 - .510 on both sides - hydraulic Roller
    Melling Lifters
    Comp Magnum XD rockers
    PAC 175-375 Dual Valve Springs
    Comp .135 wall push rods
    Melling high volume oil pump
    Milodon High volume water pump
    180 degree thermostat
    PSC Steering pump
    redhead steering gear
    Full disc conversion on rear brakes
    Updated steering cooler
    Stock manifolds that were ceramic coated
    Stock intake and injection
    ECU tune for cam and heads

    A Dozen new cooler lines, all new gaskets (be careful on head gaskets and make sure you get a Gen VI compatible one), no more leaks.

    Impressions so far:

    After getting my timing sorted the truck runs very good. It runs quieter than it did before with the non adjustable valve train. Getting the preload on brand new lifters took a lot of work and eventually they quieted down as well. We're at 6000 feet here in Colorado but the engine pulls much better than it did before, most noticeably around the 2500 rpm range. Idle has a tiny lump to it due to the cam but I have zero DTCs with the tune I got from Try Brown at Howell. Fuel trims and other compensations are like 2% - kind of impressive he was able to get it so close.

    I had to get low profile poly locks for the rockers to get the stock vlave covers to clear, as well as use 1/2" thick cork gaskets. Everything clears and nothing leaks.

    I also installed a new airlift 5000lb bag kit and a Redarc Proportional Brake Controller, which is a sweet piece of kit.

    The biggest surprise is how cool this thing runs now with the pump and thermostat. It was 85 degrees yesterday and I drove the truck around town for an hour, stop and go traffic. It never crept above 180 at all. No spikes at stop lights. The oil pressure when fully hot at idle is 20 psi. 40 psi while driving hot. 60 psi on cold startup.

    Next items are cosmetic or body related, but in general things turned out great. Thanks for everyone's suggestions.

    Philip
     
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  8. Philip Parker

    Philip Parker Newbie

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  9. Christian Steffen

    Christian Steffen I'm Awesome

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    Hell yeah that's good to hear, sounds like it turned out good! Hopefully you were able to return the AFR heads, what was wrong with them?

    Do you have a wideband o2 sensor? If not I would recommend one, just to keep an eye on things.
     

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