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Thread: 3sgte 3sge cam timing question?

  1. #1
    Forum Member Grease Monkey
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    Default 3sgte 3sge cam timing question?

    Hi all,

    After a year of head scratching and ghost vacuum leak chasing ive finally got my freshly rebuilt gen 2/3 3sgte frankenstein (st185 block with a st205 head) running... Just...

    I have low vacuum tho, around 12hg!!! After checking EVERYTHING im now thinking it may have something to do with my cam timing/specs...


    I running a gen 3 3SGE intake cam and a HKS 256 exhaust cam with a JUN valvetrain. Pretty mild...


    Both cam notches are lined straight up to the 2 notches on the head along with the crank at 0 tdc. Timings at 10 btdc.. Still idles rough/misses/runs like sh*t...

    Stock gen 3 3SGTE intake cam is 240deg/8.7mm (7/53)

    Stock gen 3 3SGE intake cam is 252 deg/9.8mm (7/65)

    What im asking... is in Homer Simpson terms... whats the diffrence between (7/53) and (7/65)??? Extra 6 degrees either side? or is it 3 degrees (2 crank rotations per 1 can rotation)... Am confusing myself...

    I think its saying the 3sge cam opens and closes 6 deg before and 6 deg longer than the 3sgte cam. So the extra 12 deg of overlap would explain the low vacuum... Am i on the right track?


    Basically can someone smarter than me tell me do i need to retard OR advance the 3sge intake cam a little from those numbers (7/65) to line it up properly (zero the centreline) instead of using the 3sgte cam marks?

    Thinking retard it slightly? to say 3 degrees to start to pull more vac? (have adjustable pullies)...

    What's bending my head is do i want the intake to open/close sooner? (advanced) BUT surely advancing would increase the overlap?

    Retard intake, 3 degrees then advance the exhaust the same sounds about right in my head? Am I way off?

    Stock gen 3 3SGTE exh cam says 236deg/8.2 (50/6)

    HKS is 256/9.0mm Says "duration at 1mm lift 216 deg" (all the info i can find)


    Thinking the exhaust can wont make as much of a diffence to the idle as much as the intake cam?


    Has anyone else ever swapped Gen 3 3sge/3sgte intake cams and had to play with the timing marks to get the engine to run properly?


    To confuse things even further I'm running a skinny 1mm HG and a skimmed head so i realize both cams will be slightly retarded? (like me) anyways maybe 1 deg so will take things into account soon as someone helps me get my head round this.


    Sorry for rambling, my ineptness and daft questions, just hope someone can help me out again cos im so close to getting this car running right again. Wanna play with the cams but dont wanna bend any valves before asking about those numbers!

    Thanks yet again for everyones hell. Going to play with the Gt4 tmrw so looking forward to hearing any replies/tips I get.

    Cheers

    Chris
    Last edited by Blackcountryboy; 08-01-2018 at 03:23 AM.

  2. #2
    Fustrated DYI mechanic Automotive Encyclopaedia Omegaman's Avatar
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    Default Re: 3sgte 3sge cam timing question?

    i know nothing about yr cams.
    But on 18rg cams, i took the time to buy a cheap degree wheel and dial indicator.
    I then place all to top dead ctr and used the dial indicator to find true highest point on the cam lobe.
    This is done for both intake and exhaust cams.
    Try this method as the degree wheel will show any overlap. grab a white wheel as u can use a marker as u go.
    i bought this for being cheap at the time.
    https://www.ebay.com.au/itm/0-10mm-D...YAAOSwoydWnejW

    Honestly, i had no power at top dead and to factory sec's, Found my overlap was out by a few deg's.
    see youtube vid's , they helped heaps.
    good luck

  3. #3
    Forum Member Grease Monkey
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    Default Re: 3sgte 3sge cam timing question?

    Hey, I've got a dti gauge in the garage I'll try your advice dude, thanks again.

    Your Car looks amazing BTW :-)

    I retarded the intake cam 3 degrees and advance the exhaust can 3 degrees. Gained 3hg so from 12 to 15 but still ran like crap....

    Decided to pull the timing belt today to do the valve stem seals...Exhaust were a piece of piss. Intake seals are a NIGHTMARE... Gave up on those by 3pm as it was getting dark.

    What I did notice was cylinder 2 which has had a ghost dead miss for.ages (spark, fuel, 150psi compression but wouldn't fire???).one of the exhaust valve buckets had spat out a SHIM!!!

    Tested all the exhaust cam clearances before I took off the belt off 7 within 0.25-0.35. The offending valve, I couldn't get a 0.05mm feeler in.

    I'm confused tho how the cylinder could make 150psi compression and have a spat out shim?

    Maybe explains why that cylinder no matter what wouldn't fire? Thought after months of hunting it was something to do with the centre intake manifold stud leaking oil into the 2cnd cylinder stopping it firing. Glad I took the cams out just hope its done no damage.

    Anyone else had a similar thing happen?

    Thanks

    Chris
    Last edited by Blackcountryboy; 11-01-2018 at 02:35 AM.

  4. #4
    Forum Member Grease Monkey
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    Default Re: 3sgte 3sge cam timing question?

    Still only pulling 11-13 hg. Do I need to retard the 3sge intake cam 6 degrees to the left to march the lobe centrelines?

    Read the 3sge is 119? But it needs to be 111-113? In homer terms someone explain this to me?

    Am lost... Again... Anybody?

    Waiting for payday to order a degree wheel (skint). Untill then I just wanna inprove the running. Loads of people ive read on the Mr2oc/Mr2aus forums have done this cam swap. Some one must know? One guy said "straight up" someone else says 6 degrees but not sure which way, thinking must be retarded to increase overlap?
    Last edited by Blackcountryboy; 19-01-2018 at 09:17 PM.

  5. #5
    Forum Member 1st year Apprentice
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    Default Re: 3sgte 3sge cam timing question?

    You need to verify that the cams are set correctly, as already suggested. 256* cams should not have that low of a vacuum. Spreading the LSA between the intake and exhaust should improve your vacuum reading. I would suggest that you verify the cam center not at max lift, because it is to easy to be off by several degree with that method. Set up the lobe center using 1 or 2mm on both side of the lobe. Davew7

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