By Ryan Hogan

318/360 Magnum , JTEC Fuel Sync Instructions

This article is geared toward those with 318 and or 360 based engines using the JTEC controller, but is applicable to any Magnum engine any time the distributor is removed from the engine (maintenance/replacement, upgrades, etc) 

On most legacy small block V8 engines, (Small Block Mopar/LA, SBF, SBC, BBC, BBM, BBF), the distributor would normally control ignition timing. 
On a Magnum, the distributor controls injection timing. The ignition timing is entirely computer-controlled. 

When the distributor is removed and replaced in these engines- and even more so when an aftermarket (performance) camshaft is used- the distributor must be synchronized to properly time the injector pulse with the opening of the intake valve. Failure to do so will result in increased emissions, poor low speed drivability, misfires, and rough engine operation. 

When the distributor is re-installed you need to get the sync close enough to start the engine so you can get it dialed in from there. 
Bring the #1 piston up to top dead center (T.D.C.) on the compression stroke. Line-up the T.D.C. mark on the damper, with the “0” mark on the timing tab, on the timing chain cover. 
The slot in the top of the intermediate shaft must be positioned so that the slot runs from an 11:30 o’clock to a 5:30 o’clock position when cylinder #1 is at TDC compression stroke. Once the intermediate shaft is correctly in place, the distributor can be installed.
Install the distributor so that the rotor is lined with the small notch in the plate that covers the top of the distributor base.
This mark will time the injectors to pulse close enough to get the engine started and run. Proper final synching should be done with a dealer’s scan tool DRBIII or Snap-On Scanner. You can use other scanners, but this info is specific to Chrysler DRBIII/Witech or Snap-On scan tools. Setting the sync using an ohm meter IS NOT RECOMMENDED NOR ACCURATE. 
Using a scanner, the idle is brought up to 1000 rpm. This reduces fluctuation in the sync value. The below values are a recommendation on our experience, but it is not an exact science. Once you are in this sub-mode, you have to loosen the 13mm nut that holds the distributor down and adjust- by hand- the indexing of the distributor. Once you reach the desired value (there will be some fluctuation), secure the nut to hold the distributor down, exit the sync test and you are set. 

FRP recommends the following for a 360ci engine
210/220* @.050......+4
220/230* @ .050.....+6
230/240* @ .060.....+8 to +10
If you have a 318, please add approx 2 to these values. 
If you have a 385-408ci stroker application, add 2-4 degrees 

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