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Post by blck87gtconv on Feb 15, 2004 3:43:59 GMT -5
When you adjust the timing of the cams.. the valves will open and close sooner or later than is layed out by Toyota. The duration is not effected, as the lobes are not rounded off more by this mod. They are also not sharped more, so the duration is not insufficient, either. Duration will insure that more air is let into the intake, and that more exhaust is ejected.. if not more, then easier, because of the longer time the valve is left open. This, in theory, allows for easier breathing of the engine which, in turn, results in a theoretical increase of power. Although the idle may be effected, it just may be what some are looking for. The question isn't about duration, however. The question is will advancing or retarding valve timing do much at all? Also.. cam gears. If the are larger, or smaller than stock, and the teeth are the same as stock to match the timing belt.. what will the effects be? 1. If they are smaller than stock, then the cam shaft is making more rotations than it was designed to, because each tooth effects more of an angle of rotation of the camshaft than the stock setting. Will this not eventually result in a cam timing that is just entirely off? The timing belt will pull the same number of teeth/second.. and there are fewer teeth to pull on a smaller gear than a larger one, thus resulting in an eventual over-advancement of the valve-timing. Correct? Or am I missing something. The reverse is true for larger than stock cams. Larger diameter means more teeth required on the circumference of it in order to stay matched up to the timing belt, which cannot be changed, for it must match the water pump, oil pump, and all of that good stuff. Any thoughts? -Jason
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Post by Jeremy on Feb 15, 2004 20:45:04 GMT -5
Aftermarket adjustable cam gears are the exact size of the originals & they have the same amount of teeth they are just adjustable. so if they are the same size there is no way they could turn more than stock to cause a cam timing that is way off. by advancing the cam timing, it makes the valves open sooner than stock, doing this will result in very little power gains on a NA engine, enless it is heavilly modified. & is being tuned. the Cam gears are really useless on a stock 3S-GE.
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Post by allblackalltrac on Feb 16, 2004 15:29:57 GMT -5
Just a few more things to keep in mind when planning on installing adj. cam gears...as mentioned before, cam gears - and cams for that matter should be installed after all other mods have been performed ie. CAI, headers/DP, cat-back, AFM mod/FPR, coil, plugs, wires. Sometimes installing cams might nessessitate the need for a head re&re with larger valves, larger port openings, porting of the bowls, head decking, lifter conversion.....but cam upgrades is a whole other topic in it self. One thing to also keep in mind is adj. cam gears should be installed before cams and cams should be one of the last upgrades to be performed on a motor. Usually adv. the intake cam a few degrees will yeild a few hidden HP and retarding the exh. cam may and may not yeild a bit more. Most cars respone well by just adv. the intake cam a few degrees and leaving the exhaust cam alone. A few precations to take into account when adv/retarding cam timing:
-use only premium gas -dialing/degree'n in cams using adj. cam gears CAN only be done safely on a dyno -the dizzy runs off one of the cams, so when dialing in cams the ignitin timing should be reset after a change has been made -do not tolerate any detonation
OK so you got all the mods done to you motor that can be done and your ready for adj. cam gears...apart from the obvious while your in there you might as well go ahead and change that timing belt & idler pulley at the least. If you want you can change the water pump, oil pump, cam seals and front main seal as preventative maintence. Ok so you got all your parts and your ready for installation, you get all your new goodies installed and your good to go right? Wrong. Dialing in cams is best done using a timing wheel and a dial indicator...however most of us dont have these tools, thats ok cause all you really need is to get them dialed in as close as possible to get you to the dyno. Camshafts/cam gears should be set at 0 degress or what ever the manufacture recommends, so check your BGB or Haynes manual. Ok so you got it all installed and you safely made it to the dyno without any problems. When degree'n cams you should adv/retard in 2 degree increments, continue until you see the power drop off and back off a tad and set it. Remember to re-set your igniton timing between changes. Try to shoot for the best performance instead of peak HP. Power under the curve is better suited to keep the gains in a more useable power band, across the rpm range opposed to the high end. A gain of 4-6hp from 2500-5500rpm is better than 10hp from 5800-6200rpm and will get you down the track faster.
Happy tuning.
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Post by Jeremy on Feb 17, 2004 9:28:59 GMT -5
nice write up very informative
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Post by 86er on Mar 29, 2004 12:02:27 GMT -5
So, if we are just advancing out timing with the distibutor, will the ecu ajust it for us, back to a safe level, or will it alow us to runn outragious amounts of advance?(on race gas 106oct)
-Andy.
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Post by blck87gtconv on Mar 30, 2004 22:04:00 GMT -5
As long as you do it right, you can advance is as far as it can go. -Jason
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Post by 86er on Mar 30, 2004 23:03:03 GMT -5
And on premeum, how much is that?
-Andy.
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Post by White87GT on Apr 10, 2004 14:24:55 GMT -5
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Post by 86er on Apr 10, 2004 22:12:19 GMT -5
What gas(LOL) is that with?
-Andy.
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Post by White87GT on Apr 10, 2004 22:31:46 GMT -5
What gas(LOL) is that with? -Andy. Premium. Dont advance the timing without using the absolute highest octane level of gas that you can find
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Post by 86er on Apr 11, 2004 14:58:59 GMT -5
Yeah, that is what i'm running right now. The car needs some advancing, so i'll tune it later.
-Andy.
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Post by Jeremy on May 2, 2004 1:17:31 GMT -5
I have the FX16 advanced 18 degrees & run 91 only & it has more get up & go by alot & I have never heard the slightest bit of ping or detonation even with the AC ON
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Post by 86er on May 6, 2004 10:13:32 GMT -5
Damn, but that is with the 20v4age though, they car run insane amounts of advance without even breaking a sweat.
3sges cant do that man.
-Andy.
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Post by Joel87GT on Jul 26, 2004 20:52:37 GMT -5
Since adj. cams have the same circumference, R squared equal to stock OEM cams. Isn’t the sole purpose of adj. cams is to make do w/o timing gun thats only 39bucks at autozone? Actron Inductive Timing Light Model CP7504. I'm 17* BTDC with 91 octane on 3sfe and taken it to 20BTDC w/o any sluggish idle at 800 rpm. My 4g operates in 130F* driving conditions. Had to adjust T/B idle to stay at 800rpm turning it clockwise to close. Dunno after reading this thread, and looking from a common 4g driver - Highschool, college or hobbyist prospective. It be allot of prerequisite just to install adj. cams esp. with all crankshaft, cams seals, belts etc. Don’t you think investing in a inductive timing gun for 40 bucks be better?
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Post by garbled on Jul 26, 2004 23:24:13 GMT -5
The point of an adjustable cam is to allow you to advance timing by very small amounts, and each cam independant of one another. IIRC this is impossible on a 3sfe, because it has a single cam gear that drives both cams.
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