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Thread: Polished pirts and combustion chambe

  1. #1

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    Polished pirts and combustion chambe

    Has anyone gone through the time to polish the ports and combustion chambers?

    Is it worrh the time?

  2. #2




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    Geezer can talk to that - he has done them on many different Mitsubishi vehicles.
    Pennyman1
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    Living the D-50 lifestyle since 1980

  3. #3

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    Sonce i have a spare head i figure i go crazy on this one. Ive seen almost mirror finish combustion chambers

  4. #4

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    Go the full hog and match the volumes of the chambers and port match to the inlet and exhaust gaskets.

    The small amount of work I did to my old flathead got me up mountains in 2nd and 3rd rather than 1st

  5. #5

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    Go ahead and port match the intake side of the head to the manifold - but do NOT open up the exhaust ports. It will ruin your engine tune (there's a bunch of complex harmonics and exhaust gas pulsation going on just outside the exit of the exhaust ports - you get it wrong and it will result in crap fuel economy and loss of power) But do go ahead and and clean the ex ports up and polish the hell out of them. It will aid in gas scavenging If you have headers, get them thermally wrapped - this will allow a more aggressive engine tune. Hot gases move faster

    http://www.mightyram50.net/vbulletin...ll=1#post31683

    (links to some of my work)
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  6. #6

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    So here's the low down anyway of why you should do it. First up - labour. This is a long process (to do it properly). When you sit down and start working a head and manifold yourself and see how much time goes into it, imagine paying a shop? Most don't want to do it. You'll get it back and it will look 'ok' if you're lucky and the bill will scare you. Then there's the 'specialist' shops that do this stuff (and some of them have earned a shiteful rep - google it. Heads disappearing, overcharging, unfinished work - if you know a shop with a solid rep and are cashed up, that's fine...)

    For the most part, newer castings are easier to tidy up. All you're planning to do is take out sharp edges, radius transitions and get the port walls nice and smooth. The intention is to make every port behave the same way - same volume of gases in and out at the same speed. It's worth the effort to get the intake manifold matched to the head. As this is being done to a EFI engine you can polish the entire intake runner and ports without the need to worry about fuel molecule drop out like what allegedly happens with a carb'd motor.

    Be warned that this kind of work won't make power, so why are you doing it? It improves efficiency and will smooth out both idle and the engine power curve. Now you can meddle with your ignition tune to dial in hidden power. And this is easy to do on a stock OBD I and II ECU. You will know when you've got it right as the engine will pull through gear changes faster, your midrange torque will be beefed up and it will show an improvement in top speed.
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  7. #7


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    What Geezer said...
    lot of work, but IMHO Worth it.











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    Last edited by camoit; 08-13-2020 at 03:09 PM.

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    FYI I had my head (a new casting) given a Stage 5 port/polish etc.. by DPR Racing Development in Cali. Dan Paramore, the owner actually did alot of TRD stuff back in the 80's but was prohibited from any media about it. He did a fantastic job and Hot Ram runs great. he also did a match port to the Weber adapter.

  9. #9


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    My work was done by Dan Paramore! Small World!

  10. #10

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    Will it help if I split the intake and match the ports on the intake too?

    I'm doing it mostly to improve longevity and mileage.. not HP

    Also... this truck falls on it's face between 4200 and 5000.. not sure if this would help that

  11. #11

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    Key word here is 'efficiency'. If you can improve air velocity into the head it will help. All of the port work you're thinking about doing is aiming at making the engine more efficient. The story goes that 'the total power/energy created is greater than the sum of parts' when it comes to engine building. A port that isn't flowing right or a valvetrain component not working at its potential robs energy from the rest of the engine as everything else is trying to compensate. If you have a look @ LSRMike's pics you'll notice that the casting shrouds around the valve guides have been completely ground down to the gallery walls - this really improves velocity and flow into and out of the head but it requires the valve guides being removed. Is you coil in good condition, exhaust flowing nicely etc? What is your tune like? Might be another reason why it's falling on it's face...
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  12. #12

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    Everything is stock... all I know is that it has a fresh timing belt. I might pull the front of the motor off and see if the timing marks are lined up.

    The head work will also go with matching the intake, cleaned injectors and recapping the ECM.

  13. #13

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    Your timing marks will be right or this would be a no-go situation. Experiment with the ignition timing - the factory tune nerfs the engine (it's only intended to meet emissions requirements) I did a write up as a supplement to engine tuning for injected trucks -

    http://www.mightyram50.net/vbulletin...th-ECM-control
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  14. #14

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    Geezer is a maniac. I love it.

    I remember when you ported and polished your oil pump. Bad ass meticulousness and precision.

  15. #15

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    Well.... my porting tools should be here this week.

    I'm gonna port, polish the chambers and mirror finish the valves.

    This will be on a 1988 2.0L head that is going on my 2.4.

    Since i have tons of time slips from last year, it will be fun to see if I pick up anything after all this work.

    Before I add the turbo, I want to make sure it runs awesome in N/A

    I'm tempted to look for a larger throttle body... not sure what to grab from though.

    I'm going to try and make my own header later when I can actually get to a welding shop for some flat bar.

    I'm in no hurry to get the head done... I'll try to take pics as I go.

  16. #16

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    You'll probably go over the head a second time once you get the feel for it. Visually inspect every port to figure out which one you should/can use as a bench mark and match the other ports to that. Remember that the more material you take out of the mouths of the ports will change the heads' characteristics from torque to higher rpm flow. If you're not going to go for oversize valves, don't go crazy on it. The trickiest part will be the valve bowls and the transitions behind them. Keep us posted with your progress!
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  17. #17

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    Does anyone have an option to cleaning the head versus taking it to a machine shop to go in a cleaning tank?

    The head will end up at the machine shop to get it planed flat.... but it REALLY needs a bath now...

    I heard that oven cleaner on aluminum is a no no as it can change the colour of the metal.

  18. #18

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    Soda crystals (laundry Isle) are decent for cleaning out emginrs

  19. #19

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    Non caustic oven cleaner and a paint brush to break it all up - worse case scenario use an old tooth brush to get into the tough stuff. Strip the head first and make sure you separate and ID valves and springs so they go back where they came from. This will also help if you run into a problem and something is showing unusual wear (valve stem, seat etc). A pressure clean afterwards and it should be squeaky clean. Do the rocker cover and intake manifold as well. There is an oil gallery that is plugged up next to #4 exhaust port. Take the bolt out and flush it with brake/carby cleaner and then force compressed air through it so there isn't any gunk waiting to ambush you when you put it back together.

    *yeah don't use acid based alu cleaner/wheel cleaner - it will stain the metal badly. And definitely DON'T use anything caustic or you won't have a head to bolt onto your engine
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  20. #20

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    I suppose a trip to the car wash for the head won't hurt either.

    I'm going to install new springs since the head has unknown mileage.. pricey.. but worth it to not break a spring.

  21. #21

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    Intake ports are almost done
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    Last edited by camoit; 08-13-2020 at 03:10 PM.

  22. #22

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    Transitions look good, casting seam on the intake gallery walls are nicely levelled out, valve bowls look like they have a good radius - good stuff

    Stick your fingers through the valve seats and feel for any sharp edges. Are you port matching to the intake manifold? You can cheat a little and just add a taper to the port so it acts like a velocity stack to ramp air speed. How long has it taken you so far?
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  23. #23

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    I am going to split the intake as I bought a gasket set anyways. I will match where things touch.

    I was thinking about tapping and sealing off the EGR in the head and intake. Since I don't drive this very often in the cold I really dont need the intake heated anyways nor do I need the EGR.

    My old Big Block Mopar picked up over a tenth when I blocked the heat cross over ( but that was in a 12 second car) so I know keep the intake cooler is certainly worth some HP.

    I am really curious just to see what the port matching and cleaning up of the ports will reward me in power. I don't expect much, maybe 5 or 8 HP... but in this little truck that is a ton.

    Then, when it gets the Sniper system and a little boost next year it might be interesting.

    I'm going to make an injector pulse wave modulation circuit and will try cleaning the injectors myself too.

  24. #24

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    Does anyone feel that I should take more material off near the valve guide?

    I have been using my finger a ton to ensure there is no sharp edges and everything has a smooth transition

  25. #25

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    looks fine to me for a daily driver.

    race car you would get rid of as much as possible and just put new cut down valve guides in each season

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