Valve Timing Overlap

[r_speedfreak_r]

Hey all

I own an r33 gts-t and i just got a new set of adjustable cam gears on the way from just jap & being a 3rd year mechanic i know how they work and all but i'm trying to find out how much overlap can be obtained before piston to valve clearance is compromised. I appreciate all inputs but i'd rather get a response off people who can give advice off facts about r33 skylines rather than just enthusiats working on there interpretation of valve timing in general. Sorry if that sounds rude.

cheers

[The Dan]

Hey all

I own an r33 gts-t and i just got a new set of adjustable cam gears on the way from just jap & being a 3rd year mechanic i know how they work and all but i'm trying to find out how much overlap can be obtained before piston to valve clearance is compromised. I appreciate all inputs but i'd rather get a response off people who can give advice off facts about r33 skylines rather than just enthusiats working on there interpretation of valve timing in general. Sorry if that sounds rude.

cheers

around 8 degrees is the maximum that I would allow. You will not need anywhere near that though. You should only be aiming for about 2 degrees on the exhaust side. And if you have VCT on your 33 then the inlet cam gear is already adjustable and the aftermarket one will not fit.

[r_speedfreak_r]

i didnt know skylines had vct. i never even bothered to look. obviously they dont all have them because there normally sold in sets. when i get them i might just adjust it 2 degrees on each cam so theres 4 degrees extra overlap, take it for a spin then change to 3 degrees on each side and see which i prefer. i've already spent the money i might as well get as much power out of it as i can. Kadenacy affect is a great thing i think

[Duncan]

only series 2 33 have VVT. but you really need to set it on a dyno how are you going to feel a 1o difference on the street?

[The Dan]

only series 2 33 have VVT. but you really need to set it on a dyno how are you going to feel a 1o difference on the street?

1.5 has it also. And I agree, needs a dyno to be set correctly.

[NateR31]

isnt the exhaust cam gear already adjustable

[The Dan]

isnt the exhaust cam gear already adjustable

No it's the inlet cam.....as stated above.

[NateR31]

No it's the inlet cam.....as stated above.

im pretty sure the big VCT gear is the way of making any adjustments, and when i got my pfc tuned, my tuned was adjusting the timing on the zorst gear

[kjb_r33]

My 93 series one has it as well, varies inlet cam through 20 degrees under the right conditions

[r_speedfreak_r]

I dont see how having less overlap can make the car go slower. if anything it'll just be rougher at idle. I have a series 1.5 so thats a real bumma. i'll see how its mounted maybe i can remove the vct on the inlet and put the adjustable ones on. i relise you'd know more than anyone 3lit3 it just seems weird thed sell them in sets specifically for my car. i'd much rather it be symetrical thats all

[NateR31]

I dont see how having less overlap can make the car go slower. if anything it'll just be rougher at idle. I have a series 1.5 so thats a real bumma. i'll see how its mounted maybe i can remove the vct on the inlet and put the adjustable ones on. i relise you'd know more than anyone 3lit3 it just seems weird thed sell them in sets specifically for my car. i'd much rather it be symetrical thats all

i dont think you can just remove the VCT gear, it has its own oil supply and other things

[Craved]

if you disconnect the solenoid that opens the oil feed to the gear it wont move and remains closed

just a thought

[r_speedfreak_r]

really you can remove anything. its fitting the new cam gear back on thats the challenge

[rob82]

Hey all

I own an r33 gts-t and i just got a new set of adjustable cam gears on the way from just jap & being a 3rd year mechanic i know how they work and all but i'm trying to find out how much overlap can be obtained before piston to valve clearance is compromised. I appreciate all inputs but i'd rather get a response off people who can give advice off facts about r33 skylines rather than just enthusiats working on there interpretation of valve timing in general. Sorry if that sounds rude.

cheers

They are a wast of time on a standard car.

[DJRIFT]

im pretty sure the big VCT gear is the way of making any adjustments, and when i got my pfc tuned, my tuned was adjusting the timing on the zorst gear

i think you may be confused there. The cam angle sensor wich adjusts the timing is on the exhaust side but this adjusts ignition timing not the cam timing. the cam gear sits in behind this and isnt related to it.

[Munna1]

All R33 GTS25-T have NVCS on the intake side

from winkipedia

Nissan Variable Cam Timing (commonly known as N-VCT, VCT or NVCS) is an automobile variable valve timing technology developed by Nissan. N-VCT varies the timing of the valves by rotating the cam shaft(s), valve lift and duration are NOT altered. The system is implemented with an electric solenoid which is controlled by the cars ECU. Some Nissan engines only have N-VCT on the inlet cam (such as the RB25DE/DET) while ot

hers have it on both the inlet and exhaust cams.

People have had mixed results with the standard turbo still in place. You only need to replace the exhaust cam gear and -3 to -4 seems to give the best results but not always as every engine is different.

cheers

[r_speedfreak_r]

All R33 GTS25-T have NVCS on the intake side

from winkipedia

Nissan Variable Cam Timing (commonly known as N-VCT, VCT or NVCS) is an automobile variable valve timing technology developed by Nissan. N-VCT varies the timing of the valves by rotating the cam shaft(s), valve lift and duration are NOT altered. The system is implemented with an electric solenoid which is controlled by the cars ECU. Some Nissan engines only have N-VCT on the inlet cam (such as the RB25DE/DET) while ot

hers have it on both the inlet and exhaust cams.

People have had mixed results with the standard turbo still in place. You only need to replace the exhaust cam gear and -3 to -4 seems to give the best results but not always as every engine is different.

cheers

cheers thanks heaps