307 Help
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5.0 and 5.7 Discussion, 307 Help in Cadillac Engine Technical Discussion; LOL. yeah it actually has one. i need an effiecent yet inexpensive & practical way to add some torque and ...
  1. #1
    FLEETWOOD4mTeamLAC's Avatar
    FLEETWOOD4mTeamLAC is offline Cadillac Owners Member
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    Question 307 Help

    LOL. yeah it actually has one. i need an effiecent yet inexpensive & practical way to add some torque and some horses. reasonably i can spend $150 (college student). i'm guessing that would only cover parts so i'll probably be doing the labor myself. i don't have pro mechanic tools so no engine swapping ideas. any suggestions...?

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    Night Wolf's Avatar
    Night Wolf is offline Cadillac Owners 10000+ Posts
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    Re: 307 Help

    impossible

    there are no aftermarket parts for the 307, they are dogs and very hard to get power....

    obvisouly you could try a 14" open element air filter, and maybe an after market muffler (since full exhaust will be too much money)

    otherwise it would be a small shot of N2O or something... but.. your outta uck with the 307...

  4. #3
    sizanjdf is offline Cadillac Owners Fanatic
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    Re: 307 Help

    for 250 Ill sell you a whole nother 86 fleetwood...come get it!!!

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    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
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    Re: 307 Help

    Check the threads for 307 power on the 5.0/5,7 forum. There is some stuff, and check the OldsFAQ too. Nope, Night is right, isn't a whole lot you can do. No magic tricks to make it gain an extra 100hp.... Well, nitrous isn't a bad idea.....

    Honestly, if you can get a 403 Olds for $150 and drop it in (direct bolt in, no mods) and that is a solid 100 lb ft torque increase, and that is very respectable in that car. that would be my choice to look for. But they only made 403's from 77-79. ALL 77-78 Toro's had 403's (these typically got best parts, but you will need the 307's oil pan) Wagons were common with 403's. The Trans AM's were a good place for 403's, and most 98 Olds had 403's from 77-79, althought I have seen 1 with a factory installed 350 (non diesel).

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    Caddy112 is offline Cadillac Owners Member
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    Re: 307 Help

    Are there strict emission standards in your state, and do you need an inspection every year? If so, then you're kinda stuck. If not, there are a few things you can do. I'd advance the timing as much as you can before it pings with premium gas, there's a way to do this without messing up the computer. You can hollow out the catalytic converter, and/or install dual exhaust. Unplug the blue harness on top of the carb, this controls the primary metering rods, and it'll run a little richer. Make sure the secondary butterfly spring tension is properly adjusted. Make sure there are no vacuum leaks anywhere. This will evetually clog the cat, though, so get rid of it if you can. Make sure the vacuum is OFF the valve on the passenger side exhaust manifold butterfly valve, the one that closes until the engine warms up. If that is closed, you'll have restriction. Constant vacuum to it will close it, no vacuum will open it. Other than that, you'll have to spend money. If you ever have to replace the transmission, throw away the 4 speed and have them put in a turbo 350 if you can find one. Made a world of a difference in my Monte SS when I did that.

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    N0DIH's Avatar
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    Re: 307 Help

    Open up the secondaries to allow full 800 CFM instead of the restricted 570 CFM. Connect a DVM to the O2 reading and dial in for .88v WOT. You will need adjust metering rods and secondary air door opening to vary this. As Caddy112 said, the secondary open rate is critical to lively performance.
    Make custom duals, no cats is very helpful. The pass side exhaust manifold exhaust plug (for the pipe that originally came from the drivers side) can be found at Detroit Diesel shops, as they took over ALL diesel support for GM. The Full Size trucks had true duals. You can run dual pipes fairly easily down one side of the car, and then add a second pipe and muffler from a 94-96 Fleetwood.

    I don't recommend axing the computer and messing up the carb by unplugging it, no performance will be gained, as the ECM will declare a problem and pull back timing to be conservative thinking something is wrong.

    But however a normal Q-Jet and std HEI distributor is much more tunable and can be very beneficial. Std Q-Jets on bigger engines are still reliable and ideal even down to the 10's in the 1/4 mile.

    Yup, I think the THM350 is a better trans overall, but you do lose OD. But shifting is MUCH improved and faster.

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    FrankieSixxxgun is offline Cadillac Owners Fanatic
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    Re: 307 Help

    If you want to go faster, you're better off leaving the engine alone and taking some of the weight out of the car. Pull all the sound deadening under the carpet and seats and ditch the spare tire.

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    FrankieSixxxgun is offline Cadillac Owners Fanatic
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    Re: 307 Help

    Hey, about unplugging the blue connector on the carb, that'll change the metering? I've isolated a lean condition causing my knock no my 307, only after the car goes into closed loop, and only at cruise throttle. Could that little solenoid that does the metering rods go bad and cause them to open less than they should? That's the only thing in the carb I didn't replace when I rebuilt it.

  10. #9
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    Re: 307 Help

    307's are VERY EGR flow sensitive, the EGR flow rate expected was dialed in closely to the ECM fuel and timing curves. Enough that it cannot NOT ping without sufficient EGR flow.

    The common problem requires removal of the carb, and to run an appropriate size drill bit down each EGR stack tube and clean out the carbon buildup.

    My "fix" was to clean them out, but you can also remove them (if intake is in bad shape, do not attempt) and to install 2 brass plugs in the holes and to drill a 3/8" hole in each. This improves intake air flow and eliminated the long term carbon buildup.

  11. #10
    FLEETWOOD4mTeamLAC's Avatar
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    Re: 307 Help

    THANKS...I have something to do now :-D. Hey sizanjdf are you serious about selling the 86? If so email me ALCeVilleaka2Ls@aol.com

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