timing a 4.2

[joe johnson]

its an 82 inline six. I am running the howell tbi and need to retime the engine.
I have been told to set the timing with the vacum advance removed and the engine at idle. I have also been told to do it the same but with the engine at 1600rpm. Which is correct?

[SavageSun4x4]

Timing:
Set it at idle, check it again at full advance [1600 rpm]. If you don't have total timing at the number of degrees you want, add/sub at idle.

If you were racing I would tell you to set crankshaft timing at TDC off of number one piston on a warm engine, in gear by pushing the car forward untill TDC the gently move the car to the timing mark you want, say 6 degrees. Then turn distributor untill No 1 piston fires [just ask your buddy to hold the spark pulg untill it fires]. Now go set the advance curve using weaker/stronger springs, lighter/heavier weights untill you get the amount of advanced timing you want at the rpm you want full advance.

[danno]

Joe,

Straight from the Howell installation manual:

"There are no idle speed or air fuel ratio adjustments on the Howell EFI kits. Only initial spark timing is adjustable. Our recommended setting for good emissions and driveability is 6-8 degrees BTDC, at idle with vacuum advance disconnected. This setting is higher than the original OEM recommendation."

INSTALLATION MANUAL MODEL JP-1 EFI KIT FOR JEEP 258 CID (4.2) 6 CYL ENGINES 1972-1991 (http://www.howell-efi.com/technical_support/jeep_kit.pdf)