Results 1 to 7 of 7

Thread: Lumpy cams

  1. #1
    Forum Member 1st year Apprentice
    Join Date
    Aug 2018
    Location
    Wellington
    Posts
    12

    Default Lumpy cams

    Hi

    I have a 4age head 20v and a 7afe block, im looking to make put some lumpy cams in the motor but im unsure what cams will be the right ones, can anyone explain how i would go about doing this? is it as simple as getting different cam duration's for the intake and exhaust?

    Thanks

  2. #2
    Junior Member Backyard Mechanic
    Join Date
    Jul 2012
    Location
    QLD
    Posts
    231

    Default Re: Lumpy cams

    To my understanding the lumpy idle is not a condition caused by a mismatch in duration, but a high duration, mismatched to some extent or not. Look for some 280 plus duration, but dont go too high as a 7a wont spin as fast as a 4a at the limiter.

  3. #3
    Toymods Events Secretary Too Much Toyota trdee's Avatar
    Join Date
    Jul 2007
    Location
    NSW
    Posts
    10,243

    Default Re: Lumpy cams

    lobe separation angle is more the thing here. you probably want to do some reading, plenty of tech articles out there
    1988 AW11 9A-GTE - Turbo Missile | 2004 Elise K20A - N/A Screamer | 1984 MA61 1JZ-GTE - 80s cruiser
    Quote Originally Posted by Rex_Kelway View Post
    .....and the within first laps everything that made the AW11 great hit Rex as if the 'Gods of driving fun' had all Jizzed on his face.....
    Quote Originally Posted by JustenGT8 View Post
    Mono blocs mate....as close to yours as a Ferrari is to a Fiesta

  4. #4
    iconoclast Backyard Mechanic Youngy's Avatar
    Join Date
    Dec 2005
    Location
    NSW
    Posts
    312

    Default Re: Lumpy cams

    And also talk to a cam place like https://www.kelfordcams.com/

    Which if you're in NZ are same time zone.
    Oh really...

  5. #5
    Fustrated DYI mechanic Automotive Encyclopaedia Omegaman's Avatar
    Join Date
    Oct 2005
    Location
    Sydney N.S.W
    Posts
    852

    Default Re: Lumpy cams

    Do some reading from camtech site. They have standard recommendations for mild, street and race.
    https://camtechcams.com.au/


    from site

    Description:
    272 Degree 8.6mm Lift. Slight lope at idle, good mid range power, suitable for std or slightly modified engines. RPM RANGE 3000-7000

    Description:
    280 Degree 8mm Lift. Rough idle, strong mid range and top end power, suitable for engines with limited modifications and increased compression ratio. RPM RANGE 3500-7500

    Description:
    280 Degree 8mm Lift. Rough idle, strong mid range and top end power, suitable for engines with limited modifications and increased compression ratio. RPM RANGE 3500-7500

    Description:
    290 Degree 8.6mm Lift. Rough idle strong mid range and top end. Suitable for modified engines with increased comp ratio. RPM RANGE 4000-8000

  6. #6
    Forum Member 1st year Apprentice
    Join Date
    Aug 2018
    Location
    Wellington
    Posts
    12

    Default Re: Lumpy cams

    Hi, plans have changed, iv decided to turbo the 7age, probs run between 200-300 hp with a rev limit of about 7000 maybe 7500 on good days, im not to fussy about low end power as Gas prices have gone up, Im after instant power but doesn't need to be to aggressive til turbo/ vvt kicks in but still have a bit of go from a 20kph roll start race.

  7. #7
    Learner / modder / Backyard Mechanic PrettyCoolWagon's Avatar
    Join Date
    Aug 2009
    Location
    Victoria
    Posts
    404

    Default Re: Lumpy cams

    For turbo, you don't need bigger cams.
    For example toyota kept the same sized cams in the supercharged variants of the 4AGE engines. All you need is flow and the 20v head flows very well from factory - it's proven.

    Especially if it's a street vehicle you say you are 'after instant power' which is really 'torque'

    The 7A block & vvt will give you torque. More important than cams is turbo selection.
    A TDO4l will suit, they're plentifull and affordable.
    OR..
    If you willing to spend a bit more $ for earlier spool and broader power band, go for the disco potatoe Garret's GT28RS ball bearing turbo - there's 2 versions. One of them has a larger exhaust housing, so the power band is higher in the rev-range and a higher peak power figure is attained. My 2cents worth = the smaller version suits a street driven vehicle, ..but it's entirely up to you.

    With the vvt working properly (they wear out and develop a ticking sound like a diesel engine), you'll have an excellent street engine with a good balance between torque and peak power.

    NOTE: When researching 7AGE there's talk about weak factory conrods, machining oil-squirters in the block and adding hardened steel dowels into the crank where the flywheel bolts up. All those mod's a for high powered race-cars - you don't need them, even if you're doing a few track days.

    There's very little evidence of broken factory rods, ..but still the rumour persists. The weak point is actually the bolts, but they can only be called weak in light of fully dedicated race builds at sustained 8000rpms with poor oil conditions and excessive frictional heat at the crank and connecting rod. (which is why race builds run forged rods and dry sumps)

    The street build I've outlined will be good for occasional track days. The 20v head flows really well from factory which is critical to boosted applications.

    If you want to maximise the camshaft operation (which is where power & torque can be adjusted and improved) ..just get adjustable cam-pulleys.
    4AFE/gearbox issues, 4AGT/ZE replacement changes to fully blown 7AGTE project...
    https://www.facebook.com/gerard.mang...1485304&type=3
    The Corolla 4WD fan club: https://www.facebook.com/Corolla.Ae95.4wd?ref=hl

Similar Threads

  1. GT4 got lumpy idle need wiring info please
    By shrike in forum Tech and Conversions
    Replies: 4
    Last Post: 18-11-2010, 12:05 PM
  2. cams
    By Toyota 20v in forum Tech and Conversions
    Replies: 8
    Last Post: 25-01-2010, 04:55 PM
  3. 4A-G & 4A-F cams
    By TE35 in forum Tech and Conversions
    Replies: 5
    Last Post: 24-07-2007, 09:24 PM
  4. Lumpy Idle and Lack of power
    By AJz in forum Tech and Conversions
    Replies: 23
    Last Post: 02-02-2006, 07:47 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •