tomulrich

iTrader: (2)

Please post specs on your BIG cam (240+ duration) you are running. Also post any issues you may have had with idle.....specifically surging.

I would also like to know what your manifold pressure is at at idle (RPM)


Thanks for the input. Trying to diagnose a problem.

tom Ulrich

Adrenaline_Z

Comp Cams 292H-10

Intake/Exhaust: 292 degrees @ 0.006"
Intake/Exhaust: 244 degrees @ 0.050"

(all specs @ 0.050")
IVO: 16 BTDC
IVC: 48 ABDC
EVO: 56 BBDC
EVC: 8 ATDC
Overlap: 24 degrees

Intake Centerline: 106 degrees
LSA: 110 degrees

Manifold pressure @ 800 RPM (200 ft. elevation): 6 in./hg.

Cons:

No assist for brakes. Very choppy idle. Low RPM power is weak (*until about 2000 RPM).

Keep in mind this is not an LS1 engine, but certain characteristics will apply.
Hopefully it will spark an idea to help you out.

tomulrich

iTrader: (2)

Thanks adrenaline........everyone please post same specs........

My cam is a 250/256 113 lobe seperation.

My vacuum is 8in./hg
I am being told that this may be the cause of my surge.....I have a 427ci motor.....

Tried everything...and 2 tuners tried as well.......still real bad surge

SAM98WS6

242/250 109
Dont know the vacuum but I can check it.
Surge at 2000rpms only...just have to stay out of that rpm...which is tough...
VERY choppy idle

blacktransam

iTrader: (13)

yeah i'll have to check vacuum.. i know my brakes only give me about one soft step.. but my cam in my sig and its in a 346..

Cal

iTrader: (1)

Any time you have a cam with 240+ degrees duration you're going to get some surging and bucking, and I don't think there is any way you can tune it out. Smaller LSA's make it worse also. Mine runs rough and surges/bucks at any rpm less than 2000. At first I hated it and tried to tune it out, but I'm pretty much used to it now.

BADSZ28

iTrader: (39)

Cal: are you cam only?

Cal

iTrader: (1)

Home ported heads with stock valves and stock compression ratio (heads not milled.)