Jellybean Posted February 9, 2015 Share Posted February 9, 2015 Hi What is the purpose, why not just line up the dots on the cam and crank gears and call it a day Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 9, 2015 Share Posted February 9, 2015 Because an aftermarket cam isn't strictly timed to TDC. It is more important to accurate synchronise the moment of valve lift to a particular degree of rotation on the crankshaft as instructed by the camshaft manufacturer on the suitable cam card. That is done with a degree wheel & DTI gauge. Once that is set correctly a tuner can confidently adjust the power & torque curves of the engine by use of adjustable camshaft pulleys. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 9, 2015 Author Share Posted February 9, 2015 I think the Tomei Poncams are? PRESET VALVE TIMING http://www.tomeiusa.com/_2003web-catalogue/e087_cam_1j_2j.html#early2j Quote Link to comment Share on other sites More sharing options...
Digsy Posted February 9, 2015 Share Posted February 9, 2015 If the cams and pulleys have dowels or keys fitted then the closest you will get is within one tooth on the timing belt. Timing an engine manually is only relevant if you are using vernier pulleys or cams without dowels. During development its normal to leave the cam dowels out so engines can be built with precisely the same cam timing without production tolerances getting in the way. TBH a pre-timed cam with dowels should be pretty bloody close unless the manufacturer has messed up. However if you then want to swing the cam VERY close to the limits of valve-piston clash then knowing precisely what your timing is becomes more important. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 9, 2015 Share Posted February 9, 2015 Yes but regardless of how accurately Tomei has designed the cam and whatever the hell 'preset valve timing' actually means the fact still stands that what any engine manufacturer offers the general public as TDC on an engine and however accurately we line all those little dots up it is still not a very accurate way of determining the exact 0° position of a crankshaft, which is essential to the proper installation of upgraded camshafts. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 9, 2015 Author Share Posted February 9, 2015 If the cams and pulleys have dowels or keys fitted then the closest you will get is within one tooth on the timing belt. Timing an engine manually is only relevant if you are using vernier pulleys or cams without dowels. During development its normal to leave the cam dowels out so engines can be built with precisely the same cam timing without production tolerances getting in the way. TBH a pre-timed cam with dowels should be pretty bloody close unless the manufacturer has messed up. However if you then want to swing the cam VERY close to the limits of valve-piston clash then knowing precisely what your timing is becomes more important. Exactly what my mechanic said , I have vernier pulleys but they won't be adjusted ; I am running stock ecu They are 264 cams so engine is still non-interference Is it right in saying an NA engine requires more precise cam tuning , with forced induction , the air is forced in so precise cam tuning does not have to be as precise , oem tolerances are bloody close Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 9, 2015 Author Share Posted February 9, 2015 Yes but regardless of how accurately Tomei has designed the cam and whatever the hell 'preset valve timing' actually means the fact still stands that what any engine manufacturer offers the general public as TDC on an engine and however accurately we line all those little dots up it is still not a very accurate way of determining the exact 0° position of a crankshaft, which is essential to the proper installation of upgraded camshafts. I would hope Toyota did a good job of TDC for what's in it , I think it is easier to mess up TDC trying to out do Toyota, I would trust Toyota TDC than no matter what anybody says Quote Link to comment Share on other sites More sharing options...
Digsy Posted February 9, 2015 Share Posted February 9, 2015 (edited) Is it right in saying an NA engine requires more precise cam tuning , with forced induction , the air is forced in so precise cam tuning does not have to be as precise , oem tolerances are bloody close IIRC swinging the intake cam pivots the torque curve around roughly the mid point, so what you gain in top end you lose in bottom end. It could be that the top end performance is more dominated by the turbo so if you are only interested in top end power then a couple of degrees here or there makes very little difference. There ought to be a trade off with the bottom end though. Personally I would say that cam timing is equally important on NAs and turbo engines if you are interested in total performance. I would hope Toyota did a good job of TDC http://mkivsupras.co.uk/vbb/images/smilies/smile_new.gif for what's in it , I think it is easier to mess up TDC trying to out do Toyota, I would trust Toyota TDC than no matter what anybody says They're only indicators anyway. You can set TDC as accurately as you want but if you build with cam pulley dowels (which is what "preset timing" means) the engine will settle into own timing as soon as you put the belt on and turn it over. I'd expect cam timing using the stock dowels to be accurate to within a couple of crank degrees. Nowhere near as good as you can get it by timing it manually but also nowhere near as bad so as to risk jumping an entire tooth on the timing belt. Edited February 9, 2015 by Digsy (see edit history) Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 9, 2015 Share Posted February 9, 2015 I wouldn't be happy with that level of accuracy at all. And I'm a lazy sod hell bent on cutting every corner possible! These cams are supposed to the be all and end all. And you're going to set them by eye on a twenty year old engine? With your attention to detail this surprises me to be honest mate, your effectively hobbling the engine in my honest opinion. Quote Link to comment Share on other sites More sharing options...
Scott Posted February 10, 2015 Share Posted February 10, 2015 Stump up for the adjustable pulleys and do it right. I probably didn't do the best job, but I did it as well as I could. Cams in, adjustable pulleys on. Everything set to TDC, belt on. Rotate the crank a few times, get everything back to TDC. Big ass DTI put in cylinder 1, rotate a couple of times to find peak, loosen cam pulleys and rotate camshafts so that line hits TDC. Tighten everything up, rotate crank a couple of times and check the peak against TDC again. Probably not the best method, but it's all I had and I guess it must be better than not doing anything. Quote Link to comment Share on other sites More sharing options...
Scott Posted February 10, 2015 Share Posted February 10, 2015 Scratch that, I just had a look at my cam card out of curiosity and that's not what I done at all. Well.... I did, but then I used the clock on the valve to fine tune where the top of the cam was on both sides. Do you have a cam card? Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 I wouldn't be happy with that level of accuracy at all. And I'm a lazy sod hell bent on cutting every corner possible! These cams are supposed to the be all and end all. And you're going to set them by eye on a twenty year old engine? With your attention to detail this surprises me to be honest mate, your effectively hobbling the engine in my honest opinion. I am not installing them , will have a word with my Mechanic Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 They're only indicators anyway. You can set TDC as accurately as you want but if you build with cam pulley dowels (which is what "preset timing" means) the engine will settle into own timing as soon as you put the belt on and turn it over. I'd expect cam timing using the stock dowels to be accurate to within a couple of crank degrees. Nowhere near as good as you can get it by timing it manually but also nowhere near as bad so as to risk jumping an entire tooth on the timing belt. Sorry I am a bit confused , "preset timing" the engine will settle into own timing as soon as you put the belt on and turn it over Do you still need to time it manually? "preset timing" not just overwrite this? Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 10, 2015 Share Posted February 10, 2015 Put it this way, the stock camshafts have preset timing. Meaning they will only mount to the stock camshaft pulleys when the dowel pin is located in the hole in the pulley. The stock timing marks are sufficient to ensure that a timing belt cannot be fitted a whole tooth out either way. And that is a fine way of keeping a stock engine running within stock tolerances. But that method does not take into account any changes that may occur in the engine over two decades of use. Is the distance between the crankshaft pulley & the camshaft pulleys still the EXACT same as it was the day the engine rolled off the production line? If not then the orientation of the camshaft pulley is going to be ahead or behind where it should be, depending on the history of the engine, in relation to the crank shaft & pistons once the timing belt is fitted & tensioned properly. If you were going to use the stock cam pulleys with the new cams then the preset timing is really all you could go on to time the cams, but you are fitting vernier pulleys because vernier pulleys are part & parcel of cam replacement as they allow the timing to be dead-on, and for future alterations to be untaken with the correct information regarding previous adjustments to hand, not just to be within a tooth either way. Sorry I know I sound like I am ranting and that is really about as far as my knowledge allows me to tread but you have practically all you need to do the job 100% properly, it would be a pity to miss out on the true capabilities of the upgrade just to save a bit of time/money now. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 Thanks Damien , I am not trying to save time or money just going by what my mechanic said ; he was going to set them up as if I was using stock cam pulleys and to the OEM TDC tolerances (Using the Oil pump/ ignition marker) , set my vernier pulleys to 0; I have a stock ECU so not too sure if you can advance the timing or retard it unless you have a mappable ECU ; maybe his reasoning behind it I am just looking for advise on what he is doing is correct, so far you guys are giving me some Q's to ask him But I am still not 100% clear. He has built a few 2JZ's, I dont have a clue about fitting cams so just learning as I go, I have a general interest in how to do things and I like to quiz him about his reasoning as to why he is doing it this way (I am a nightmare customer ) I have Stock ECU, Vernier pulleys and the Camshafts ; is the route he is taking correct ? Worse comes to the worse I will just not fit the cams, as you said I like to do it right As for Camcard, I have some documentation with the Cams , I presume it is in there, nothing has Cam card written on it I have confidence in my mechanic , seeing the engines he built and his experience with 2JZ's Maybe he is covering up his experience in installing Cams but who in Ireland can you get to install them, I am not too sure who to trust Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 10, 2015 Share Posted February 10, 2015 I would go the extra mile and check the timing against a degree wheel and dial gauge, and if they are out buy vernier pulleys and adjust them. If the head has been skimmed they will be out, as cam centreline to crank centreline distance will have changed. As the belt is a finite length this means the timing will move. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 She is still a closed block , never opened Will ask him to check it against a degree wheel and dial gauge Just read By GSC ( Manufacture of Cams in the US) , install the cams straight up off the factory timing marks; they normally recommend doing this then fine tuning on the dyno and see what the graph tells you Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 10, 2015 Share Posted February 10, 2015 The cam card refers to the information given for the opening & closing positions of the valves once the new camshafts are installed. For example, on my BC 264's the intake valve should open at 1° before TDC and close at 39° after BDC. The camshaft position is measured at .050" valve lift. Fifty thousandths of an inch, about 10 sheets of paper. Can you honestly say you'd have a definite knowledge of where the valves are opening & closing by simply installing the camshaft at TDC and leaving the vernier pulleys set to zero? You are basically putting all your faith the all the things you had absolutely no part in the design or building of. All of the above is just to get the camshafts dialled in to the manufacturer's specs, dyno tuning would alter the pulleys by as little as one half of a degree to get the best compromise between idling, low end torque and top end power to have the very best set-up for your specific car and driving wants. If I didn't think it was necessary I wouldn't have bought the kit to do it properly. I DETEST not being able to use what is to hand to get something done. But when I go to Westward engineering to have the final tune-up done there will be no doubt about the whereabouts of the pistons or valves at 7,000 rpm even after an adjustment. Quote Link to comment Share on other sites More sharing options...
Scott Posted February 10, 2015 Share Posted February 10, 2015 10 sheets? You're buying card, not paper 4 thou each on a good day, ours is cheap 0.0035" stuff Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 10, 2015 Share Posted February 10, 2015 10 sheets? You're buying card, not paper 4 thou each on a good day, ours is cheap 0.0035" stuff Peasant! It makes it harder for the customer to tear up the invoice! Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 How do you adjust the cams if they are out? Chris suggests using the vernier pulleys , so what is the difference install the cams straight up off the factory timing marks and adjust the pulleys on the dyno? If you still have to adj the vernier pulleys on the dyno, will your work with the degree wheel and dial gugage not be a waste of time? Maybe I am missing something Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 10, 2015 Share Posted February 10, 2015 If you want to make sure the timing is exactly as the cam designer wanted you probably need degree wheels. If you want to experiment on an engine dyno you definitely need degree wheels. Experimenting needs a proper understanding of the potential for valve to piston, or valve to valve clash. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 10, 2015 Share Posted February 10, 2015 That is the reason for the vernier pulleys, to get the cam exactly zero'd in relation to EXACT TDC which is done with a degree wheel & dial gauge.. A properly 'zero'd' cam may have the vernier adjustment sitting a few degrees either side of the actual zero mark on the pulley, that is the idea behind them, to know the value of the adjustment required to get the cam into the proper/desired position. If you just set them up with preset timing, valve events could be a few degrees early or late in relation to crank position from then on & any adjustment done later on a dyno will always have an inherent degree of error and no real data to take away from it to work with later. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted February 10, 2015 Author Share Posted February 10, 2015 Thanks Guys , Degree Wheel and Dial they will be, even if I need to get somebody else to do it I have asked around , I am sure with the amount of rallying over here and the usual guys racing in Mondello ; somebody somewhere must know how Quote Link to comment Share on other sites More sharing options...
Scott Posted February 10, 2015 Share Posted February 10, 2015 I struggled like you wouldn't believe to get a degree wheel. Ended up having to import one from the US. It's actually a good exercise if you want the experience mate http://www.mkivsuprastar.com/mkivsuprastar/Pics/SingleInstall/c1f9ecaacfbe1de924ed9146ebc8a737.JPG Quote Link to comment Share on other sites More sharing options...
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