following our discovery that the 3vz-fe has backlash gears on the exhaust cams that allow the engine to run quieter i thought id peel the tops off the v8 and see if they did the same on that engine too...and yes they have! So for those messing around with the 1uz-fe it has backlash gears on the exhaust cams just like the v6's have.
Found this page ages ago, not sure if I posted it though, explains quite a bit on backlash and shimming of the Vee's.
http://www.autozone.com/servlet/UiBr...3d801882a9.jsp
you cannot have creation, without first a little destruction
Not too sure what you're speaking about on this one, are you just talking about the scissor gears to drive the second camshaft? If so then this is the same in all of the belt drive FE Toyota heads. The cams are too close together to use seperate cam gears and still have a large enough crank pulley to not over stress the timing belt.
surely you just mean Vee engines though josh? the 3s-fe and 5s-fe are twinks with separate pulleys no?
All of the belt drive FE headed engines I have seen use a single belt driven cam wheel and scissor gears to drive the other cam.
This is how the xS-FE, xA-FE, xMZ-FE, xVZ-FE, xUZ-FE all work.
This shows the 5S-FE cam drive arangement
Basically the reason for it is the cams are mounted very close together to get the narrow valve angle but still have direct actuation of the valves. Due to this mounting in order to run two cam wheels the wheels would have to be quite small. Then in order to drive the cams at 1/2 the crank speed the crank pulley would need to have half as many teeth as the cam wheels which would make for a tiny bottom timing pulley putting massive stress on turning the timing belt that tightly.
This is not how it works in the 1ZZ-FE and xNZ-FE engines though as they use a timing chain rather than a belt which allows them to run smaller pulleys and have individual pulleys for each cam.
shows how much notice ive taken looking at a 5s-fe engine! always thought they were twin pulley driven like the 3s-ge.....good info josh.
Reply With Quote
