kiwipathy Posted June 5, 2013 Share Posted June 5, 2013 Hey all, I'm new here but thought I'd share a mod I have done to my pathy. I guess you all know the VG33 is great down low but has absolutely nothing up top, so I decided to remedy that by turning my stock cam gears into adjustable ones like this: http://www.mygen.com/users/dbruce/myz31/cam_gear_instructions.htm When I got the engine apart and the gears on the bench I saw that the stock notches don't quite line up with the timing marks and that got me thinking, what if I swapped gears left to right? There is 40 teeth on each gear so 9 degrees for each tooth (18 deg crank). I measured the left gear notch to be 3 deg retarded (6 crank) and the right one 1.5 deg advanced (3 crank). So if you swap then left to right you end up with it 9 crank deg retarded on the right and 9 deg advanced on the left. If you skip the left one back a tooth (anticlockwise looking at the gear) that's 18 crank deg so they both end up 9 deg retarded, just like the max adjustment on the gears I linked above. I know that's quite a lot of cam movement but it has really woken my VG up! It actually goes when I put my foot down at 100ks now, instead of just getting louder. I hasn't seemed to lose a lot down low either, but I never really cared about that, I just want to tow my boat at decent speeds up steep hills, which is why I got the petrol one in the first place. So this mod probably won't be for everyone especially offroaders, but if you are keen its worth a go for the couple of hours effort, and completely reversible if you don't like it. I'd be interested to hear from anyone who tries it what they think. Link to comment Share on other sites More sharing options...
bushnut Posted June 5, 2013 Share Posted June 5, 2013 I'd really like to see before and after runs on a dyno. sounds interesting though. LOL! "it actually goes when I put my foot down at 100ks now, instead of just getting louder." 2 Link to comment Share on other sites More sharing options...
pathfounder Posted June 5, 2013 Share Posted June 5, 2013 From the link: """Regardless of what adjustment is used, the engine must be rotated by hand after installation to verify that the valves do not contact the pistons. Failure to do this is a recipe for a costly disaster.""" This is true, but I don't think 'turning it by hand' is an adequate test. It's possible for the valves to only touch the pistons at high RPM when the piston, rod and valves are stretching ever so slightly (a couple thousandths). It's enough contact that the valves will slowly work-harden the pistons, which could cause them to shatter. I would imagine that there was a lot left on the table in the making of the VG33 and that your perceived power gains are real. Link to comment Share on other sites More sharing options...
Nefarious Posted June 5, 2013 Share Posted June 5, 2013 the dishes in the vg33e pistons are massive. im sure theres quite a bit of room for those valves to move. i dont think vg33e is even an interference motor... if it is i think its semi interference... i doubt they would touch at all even rotating the crank with no timing belt attached. a vg30e on the other hand i would not do that with.. Link to comment Share on other sites More sharing options...
Rebelord Posted June 5, 2013 Share Posted June 5, 2013 Hmm those gear are interesting. I personally would like more low to mid range power. Doing 65mph with the trailer I'm usually at 23-2500 rpms. But going up hills it has to kick down and them im 3500+. But if I could have more mid power so it doesnt have to kick down. That would be great. 1 Link to comment Share on other sites More sharing options...
devonianwalk Posted June 5, 2013 Share Posted June 5, 2013 I would imagine that there was a lot left on the table in the making of the VG33 and that your perceived power gains are real. I agree. Tuned it back to keep it bullet proof maybe? Link to comment Share on other sites More sharing options...
JamesRich Posted June 6, 2013 Share Posted June 6, 2013 What did this do to your fuel mileage? James Link to comment Share on other sites More sharing options...
kiwipathy Posted June 6, 2013 Author Share Posted June 6, 2013 No idea about mileage yet, I've only had it running like this about a week. Will let you know though. No dyno results either, only the butt dyno tells me its better While I had the t-belt off and #1 at TDC I turned the cam slowly by hand, and it is definitely an interference motor! My take on this mod was instead of making it lug along at 2500 up hills, let it kick into 3rd (or even 2nd sometimes) and rev to make power to get me up quicker, and be more efficient doing it. Otherwise I'd probably get the 3.2TD version and just live with it being slow. Link to comment Share on other sites More sharing options...
nismotr Posted June 20, 2013 Share Posted June 20, 2013 Any update on this? I was genuinely curious about how this mod worked out for you. Link to comment Share on other sites More sharing options...
MY1PATH Posted June 20, 2013 Share Posted June 20, 2013 THe vg33 has no top end because it has baby cams. So letting it breathe later just shifts the bottom end upward. (retarding the cams)throw some 3.0 cams or euro cams in there and it will have the same effect while running stock cam timing.My euro cams are advanced ~3 degrees and they still make peak torque at 4800 rpm.Hmm, I should play around with my cam gears and see If I can squeeze another 10 ponies out.... Link to comment Share on other sites More sharing options...
fixinto Posted June 24, 2013 Share Posted June 24, 2013 (edited) the dishes in the vg33e pistons are massive. im sure theres quite a bit of room for those valves to move. i dont think vg33e is even an interference motor... if it is i think its semi interference... i doubt they would touch at all even rotating the crank with no timing belt attached. a vg30e on the other hand i would not do that with.. My 1996 VG33e is an interference engine. http://www.gates.com/part_locator/index.cfm?location_id=3598 Edited June 24, 2013 by fixinto Link to comment Share on other sites More sharing options...
Nefarious Posted June 25, 2013 Share Posted June 25, 2013 Interesting. Well I know most vgs are but when I saw the size of the piston dishes I couldn't see much chance of contact but I guess it still is. Link to comment Share on other sites More sharing options...
Arrow Posted July 9, 2013 Share Posted July 9, 2013 Hey guys, I have a curiousiy based question in regard to swapping the cam sprockets... How do you unbolt them?! When I replaced my water pump / thermostat / timing belt / bypass hose I tried to unbolt the sprockets since it would have allowed me to remove the back timing belt cover which would in turn give me easier access to the bypass hose that was shot and leaking... But the only way I could figure to unbolt the cam sprockets would have been to have the "special tool" that Nissan shows in the FSM that uses the holes in the sprocket to hold it stationary while you unbolt it. IF that is what needs to be done then can anyone point me in the right direction as to where I could possible purchase one of those tools? Thanks! Link to comment Share on other sites More sharing options...
SteeevO Posted July 9, 2013 Share Posted July 9, 2013 This is a great post! I don't think I've ever seen a thread on this on any of the nissan 4x4 boards! .. or I've just been sleep'n. good stuff. Link to comment Share on other sites More sharing options...
R3DN1CK Posted November 6, 2014 Share Posted November 6, 2014 Hmmm. I'm digging the fact that this is working. What was the premise for the experiment? I mean, where did the eureka moment to swap sprockets happen? Link to comment Share on other sites More sharing options...
fixinto Posted November 7, 2014 Share Posted November 7, 2014 i think when i read in the timing belt section it said the cam gears were cut at different degrees from left to right and dont mix them up. /shrug. sounds like it worked out pretty well for you though. pat Link to comment Share on other sites More sharing options...
ejin4499 Posted November 20, 2014 Share Posted November 20, 2014 Anyone that tried this ever get any gas mileage results? Link to comment Share on other sites More sharing options...
R3DN1CK Posted November 21, 2014 Share Posted November 21, 2014 Any update from Kiwi? Link to comment Share on other sites More sharing options...
Quaintbucket Posted November 24, 2014 Share Posted November 24, 2014 I will assume his pathfinder exploded. I would like to know tho... sounds interesting but won't work for my pathfinder considering what I use it for. Link to comment Share on other sites More sharing options...
spddm0n Posted May 16, 2017 Share Posted May 16, 2017 Interesting...bringing back this thread. I'm currently looking at putting VG30E cams in my VG33E (Xterra actually) and using an adjustable timing gear to dial it in. Anybody else do this? Does anyone have any recommendations on best adjustments (dyno verified) for the cam gears? Link to comment Share on other sites More sharing options...
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