Dak

Just started my car for the first time today since my rebuild. Seems to run good but the idle is alittle lopey. Idle is around 8 or 900rpm with a touch of brap. I used Pineapple racing templates for the intake and their EP2A(Med streetport?) for exhaust. Opens earlier and closes just a touch later. Also 6-port sleeves are removed. Intake opens alittle sooner as well. Has a RB lightweight steel flywheel if that matters. Probably about 20 miles on the engine. I kinda like it but wondered if it is normal or should it be smooth like the stock ports? Thanks.

peejay

Depending on how much ignition timing you have at idle, that's kinda normal.

Sgt.Stinkfist

iTrader: (6)

A ported 6 port w/o aux sleeves will idle kinda.... iffy. Mine seems to be happier and smoother idling @1000rpm, below that its a little choppy

bumpstart

no.. idle should be 15" Hg + at 1000- 1100 rpm for most mild 6ps.. , built plenty

( assuming its not early open inlet ports to any massive degree )

Tem120

iTrader: (5)

what is the relation there ? more timing is more unstable ? or visa versa ?

bumpstart

idle should be smooth-ish fast with a slight , rhythmic miss now and then
( its not carrying the fuel through at correct airspeeds so the mixture gangs up on the walls and causes a lean then rich miss )

possibly wants more timing,, usually around 5 to 10 BTDC at 1000 rpm ( should be around 15 " Hg )
but about 25 BTDC under load, WOT, 3500 rpm up ( with an adjustable ecu )

Dak

I am using the stock ecu. I will double check the timing. Will also bump the idle up to 1000rpm. I would like to evuntually get a tunable ecu so I can fully utilize my porting.

peejay

FWIW, I've never been able to get a street or stock port engine to idle acceptably well below 1000rpm, mostly because I tend to lock the advance out on such mild engines and run them at about 22-25 degrees of timing. I usually idle my street port engines at 1100-1200rpm and they do stutter/miss at idle.

More advance increases manifold vacuum which increases exhaust gas pull-up with makes the idle rough.

Oddly enough, on my current bridge port, I was able to get the idle down to 600-700rpm. Idled dead smooth, although it was only 2" of vacuum so throttle response off-idle was soggy to say the least. Also the alternator doesn't really work below 1200-1400 or so, but it was fun to experiment to see how low I could go.

HellaRotor

this is good stuff