Camshaft Timing / Phasing

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  1. #1
    CelicaSupra.com Member drjim's Avatar
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    Camshaft Timing / Phasing

    Just curious if anybody has experimented with changing the cam timing and/or phasing on an otherwise stock 5M-GE.

    Way back in Ye Dayse of Olde, it was pretty common knowledge that advancing the cam *slightly* would make more midrange torque, while retarding it *slightly* would move the torque peak up a bit.

    And by *slightly* I mean a couple of degrees, max.

    Since all the engines I've dealt with used a single cam, changing the intake/exhaust phasing would mean regrinding the cam, while with our engines using separate intake and exhaust cams, it's quite a bit easier to change the phasing.

    Just thinking out loud here, feel free to ignore the musings of an Olde Farte.....

    - Jim
    1985 5-speed "Ms. Swan"

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  3. #2
    CelicaSupra.com Member AJ's Avatar
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    Doc, IIRC the exhaust cam 4 degrees advanced to increase overlap...

    Check out this camshaft page from Dimitri N. Elgin
    Elgin Cams
    Redwood City CA

    http://www.elgincams.com/campaper.html
    http://www.elgincams.com/c-toy.html
    Regards,
    Arch
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  4. #3
    CelicaSupra.com Member drjim's Avatar
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    Thanks for the links!
    1985 5-speed "Ms. Swan"

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  6. #4
    Founding Member pdupler's Avatar
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    I remember way back even before this forum, there were threads on the listserve discussing the the dowel pin adjustment. As I recall it allowed +/- 3 degrees, but Toyota didn't put it there for playing with, rather it was to compensate for machine work or product variation as the engine was serviced and repaired, i.e. so you could "correct" the cam position for instance if you milled the head or changed the head gasket. People did play around with the dowel pins seeking "more power" <insert grunting sounds> but I don't recall any results. Then at some point, somebody figured out that adjustable cam gears sold for another engine (was it the 2jz?) would fit the M engines too. It's been too long since I've read any of that but the threads might still be out there.
    Phil D.
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  7. #5
    CelicaSupra.com Member drjim's Avatar
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    Raptor lists their 5M gears as being the same as a 2J, but at $310 for a set of them, that's a bit much to just get them to "play" with.

    And Phil must have been reading my mind as I was thumbing through the TSRM and wondering about the dowel pin adjustment!
    1985 5-speed "Ms. Swan"

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  8. #6
    CelicaSupra.com Member supraz's Avatar
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    Sean Chung has done quite a bit of experimentation with the cam timing on the 5/6MGE

    http://www.celicasupra.com/forums/sh...ht=cam+overlap
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  9. #7
    CelicaSupra.com Member gamble's Avatar
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    Dustin has cam gears on his turbo'ed 6m setup, not exactly what you're looking for but it was the first one that popped in my head when i was thinking of who had them with good pics. Page 51 of his build thread if this doesn't work.
    http://www.celicasupra.com/forums/sh...l=1#post841907


    Here is a decent break down of cam gear tuning:
    http://www.enginebasics.com/Advanced...%20Tuning.html

    Here is the link to Raptor's for sale page on the 2j gears and relevant info for making them work for 5m's:
    http://raptorracing.com/toyota-mkii-...m-6m-cam-gears
    If you have cam work and if you've shaved material from your head and want dial your cams properly you're going to need cam gears.
    Please note that in order to use these on your 5m you are going to have to have them machined to fit. The bore on 2J cam is slightly smaller than the 5m so ensure you find a machine shop prior to your purchase. At this time Raptor Racing does not offer this service but it is something we are looking into.
    Honestly i'm not sure messing with cam timing is really worth it for an otherwise stock 5m unless you are stuck in some racing class that only allows minimal mods or something. If you are already doing mods that put you in the high octane fuel department you might as well go forced induction IMO

    If you are going bang for buck NA you are honestly best off taking that cam gear money and going 2jz, you can even get one with VVTI and play with cam timing like a modern(ish) car. Decent read on the VVTI setup here, though again mostly turbo based info since NA gets no love:
    http://www.kaizenmotorsports.com/blo...te-vvti-system

  10. #8
    CelicaSupra.com Member drjim's Avatar
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    Yeah, I suppose it would make a whole lot more sense to do an engine swap if I really wanted a serious boost in rwhp. Hi Perf parts for 5M's are just about non existent, and when you do find them, the price is outrageous.

    It was more an academic question than anything else. I was just wondering if anybody had done it, and if the engine responded well to it.

    I keep forgetting that even when these were popular cars/engines, there probably weren't very many people doing performance mods to them. They're NOT a small block Chevy, with decades of development time on them.

    Where you could get 50 different cam grinds for the SBC, you might have had two or three different cams when these engines were in their prime.
    Last edited by drjim; 11-29-2016 at 06:18 PM.
    1985 5-speed "Ms. Swan"

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  11. #9
    CelicaSupra.com Member Don L.'s Avatar
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    I did some testing with my 5mge with adjustable cam gears, and although the minor adjustments did make some differences, I just never felt it was significant enough to be worth the effort. I had stock cams and the engine always felt best with the cam gears at stock setting. fwiw, I wouldn't recommend using the dowel pins to create cam gear changes, the pins are (imho) resulting in too large a change in timing per dowel setting. To make cam gear changes small enough to be safe, gotta use the adjustable cam gears. I too got excited about the potential of cam gear changes, but maybe its best realized in motors with higher compression, race cams, etc.

    Don L.

  12. #10
    CelicaSupra.com Member SupraFiend's Avatar
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    I've experimented on them on a 6m thats fairly mildly built internally (stock cams, compression), but has all the bells and whistles on the outside. I found stock base timing made the most power (10deg on the distributor), and that the exhaust responded well to fairly extreme retardation (4.5deg) and the intake seemed somewhat happy at 3.5deg advanced. You can read about it more here...

    http://www.celicasupra.com/forums/sh...l=1#post680154

    In my case, my cam gears were at 0 when I dynoed but I later realized 0 was actually about 3.5deg retarded for both gears the way my head spacing worked out. Going to -4.5 +3.5 resulted in a much stronger midrange but my motor was consuming less air after about 5500rpm, though acceleration still improved. Every tune is a little different, I wouldn't even considering playing with cam gears without a good logging system like I have or dyno tuning. It made a difference, but overall a drop in the hat compared to fixing up the super inefficient exhaust system and horrible AFM and stock tune on BPU M motors.

    I've quite enjoyed building up my 6m and tweaking it every couple years to see how much more power I can get out of it. Its tons of fun as is, and I know there's plenty more left in it. But yeah, if you're going to do the "smart" thing, a 2jzge swap will pretty much start you right where a modded out 6m ends, and then you can play with it from there.
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