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VVT, VTC... so what
Topic Started: Apr 8 2006, 04:48 PM (1,156 Views)
ocphangaz
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Datsun Taikor
all the new hype of VVT and VTC in modern cars left oldskools felt left out.

but we do have something up our lil old datsun's sleeve... MAT!

Mechanical Advance Timing!

compared to VVT, VTC, VTEC. they change their valve lift timing or change the valve timing phase or the timing itself (VTC in nissan)

our datsun have that capability to change the timing automatically depending on how agresive we press on the throttle. using the vacuum tube from the carb to the distributo, it can advance the timming up to 20 degrees!

im not a real expert on VVT, VTC or VTEC... but MAT ideas is almost the same .
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ficxky
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Administrator
yeap. i try oledi. its seem load of power after connect that tube from vacuum pump to my carb ( tercabut oledi before )
but pick up a bit slow. left by your car few second before can catch you back everytime i brake or slow my car.
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cookie
Datsun Taikor
kekeke I know what r u refering too my car got that stuff :lol:
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ocphangaz
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Datsun Taikor
i'm on 5th gear all way... damn that saga with 5 indians inside just before the pantai exit... dowan bagi jalan.. bagi half jalan, when i pecut he masuk balik the right lane X(
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ocphangaz
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Datsun Taikor
where were you cookie monster? wanna see your carb mod.. maybe get some ideas from you :P
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abubu
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Datsun Taikor
i only feel the work of the MAT once...when i drove frm mlk to jb, after 1 full hour of 120-130kmh driving..woosh, my datto tails benz,beemers and smokes saga's n wira's too...somehow the throttle feels diffferent and response is almost immediate! syok la tht moment! but i left my car at JB for 3 weeks with my friend while im bek in hometown..my housemate has 4 other cars at home to choose from so he doesnt bother about my car..he jus starts it 3 days once and aft i come bek to jb, the syok throttle response is gone :(
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ocphangaz
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Datsun Taikor
put some carb cleaner... i think there is some gunk build up in the carb after idle for so long.

the one you mentioned is not from MAT, but from the secondary jet opening (ie extra intake.. became something like 2 throttle)

the secondary venturi have 2 butterfly... one controlled by your foot... another controlled by the amount of vacuum created by your engine. the higher the CC of engine, the lower the RPM required for the secondary butterfly to open. (purposely created by datsun for economy and drivability)

safe to say, the secondary second butterfly opens at 3000rpm, below that, even you press the throttle all way down, it'll only run on 1 jet.
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Datsun Taikor
ocphangaz
Apr 9 2006, 10:22 PM
where were you cookie monster? wanna see your carb mod.. maybe get some ideas from you :P

my car slow bai but I got the electrical ignition where it operates via vacuum advance my timing until 20++

idle timing 19++ :lol:

come lar...... hope can make it for next TTT :(
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cookie
Datsun Taikor
something to spice u all :huh:

Posted Image
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abubu
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Datsun Taikor
i c i c..so how can u feel the MAT leh...sorry arr me noob here know ntg wo...sifoo all must teach me ya..thx thx :D
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abubu
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Datsun Taikor
btw, how to get the secondary jet open again ah..wah tht feeling really nice...lol..my car damn powerful lah :lol:
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Datsun Taikor
abubu
Apr 11 2006, 03:46 AM
btw, how to get the secondary jet open again ah..wah tht feeling really nice...lol..my car damn powerful lah :lol:

is it due to one vacuum hose :huh:
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abubu
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Datsun Taikor
dunno lehh...how to unleash my car hidden power ah..lol...bro ocp..share share abit..lol
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ocphangaz
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Datsun Taikor
vacuum is for the timing only... cookie,, your idle at 19, how come full advance only 20? should be more than 30... the mechanical advance is about +20 degrees advance. i think your vacuum hose got leak..

for the secondary jet... you can try is pop open your airfilter, see the carb.. start the engine, push the throttle from the carb... if the top butterfly open (rev above 3k) that means it is working. below 3k, even the throttle butterfly valve open, the secondary's top butterfly have not enough low pressure to open. the vacuum is dofferent from the MAT

MAT is using the vacuum or low pressure to activate from the primary venturi, while the secondary jet is the vacuum only in second venturi to open the second valve...

meet up at next TT so i can explain... hard to explain here because Hitachi306 is a bit different from normal carb.
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ocphangaz
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Datsun Taikor
i'll bring a spare working carb for you guys to see.. so no need to open hood :P
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