Keys to getting big cam to idle?

S

S351 R

Member
Joined
Nov 3, 2002
Got a 427 sbf with large hyd roller (242/254@.050, 585/585 112LS). Running FAST Classic.

I can get it to idle at about 1250 but slightest closure of TB blade sends it hunting badly. A rough idle is fine, just dont want the 300 rpm up/down with borderline stall

Pls clue me in on best parameters to play with, i.e. idle timing, throttle follower, etc. and what those targets should be.

FWIW it draws about 12" vacuum or 60 kpa @ 1250rpm. I have gotten other two FAST combos to idle well, so the basics I got. Just not sure how to tame big cam now.

Thx
 
I did at first when it was on the engine dyno but abandoned it once I got SD to work for the dyno.

Surely I don't need AlphaN with at least 10" of vacuum, right?

One interesting thing is that after turning off engine and reconnecting and reading a dashboard, Actual A/F is still reading something (once 11.76 and 13.20) When not running, shouldnt this be 15.95. Is there raw fuel somewhere?
 
Try a 13.0ish afr around idle, and set correction limits to 0 in the idle cells to start with and adj the ve #s in those cells to correspond with your target and see if that is more stable.
 
Looks like I got it to idle ok at about 1000-1100, in open loop at about 13.5 with 24 degrees of timing. It liked the lower timing down from 30-36 everywhere else. I shakes like a cammed motor would but seems stable enough and recovers fine from throttle blips.

Now to post another thread on driveability... Much thanks for the inputs.
 
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