Thread: 4BD1 injection timing

Quick question.

1. When installing the pump, It is done at TDC and the advance line/pointer in the inspection window lined up. Then timing is set by turning the injector pump left or right?

2. Or do you install the pump at 10-13 degrees and the advance line/pointer in the inspection window lined up.

Reason I ask is when I first rebuilt the engine, and reinstalled it I did #1 (according to the manual) but found Id loose power on any slight incline. I then rotated the pump (pulled top away from block) and this fixed the problem.

Just want to make sure that it is set up correctly.

When I checked the timing according to the manual below. I found that when fuel appear at the top of delivery valve holder #1, the timing mark was some distance to the right of the 'TDC' mark. I assume this is after TDC and incorrect?

Thanks for the help.

Having another look at it. I think ive installed it correctly. As both inspection plate pointers line up on TDC. I also remember lining all the letters up during assembly.

So only real question is now. Is the timing right with the IP pulled away from the block and fuel showing past the TDC timing mark?

R & R the IP when #1 is at TDC, on compression stroke (both valves closed).

Note because of the helical cut gear teeth, the camshaft of the IP turns slightly as you remove it. You need to have the timing gear at the same location before replacing the IP to allow for the reverse rotation. The marks should be lined up when the IP is back in place.

Also note that the Vee belt pulley that drives the coolant pump and alternator is fitted to the hub with a rubber insert, to make the assembly into a harmonic balancer, it is not unknown for the pulley, with the marks, to have moved out of the correct position.

Regarding the old posts about the alignment of the timing marks on the idler gear, the reason that it tales 102 revs for the marks to re-align is because the gears on the camshaft and IP have 50 teeth and the idle gear has 51 teeth (the pinion on the crank has 25 teeth. So for one rev of the crank, the idler, camshaft and IP rotate by 25 teeth. This is exactly 1/2 turn (25/50) of the camshaft and IP but 25/51 of a turn of the idler gear. BTW this is waht is called a "hunting tooth" and is purposely done to spread tooth wear uniformly.

Originally Posted by Bearman

10 degrees btdc I am pretty sure John.
Just checked my book and that figure is for the 4BD1T. It says 13 degrees for a NA 4BD1

Brian,

What year is your manual from? - my October 1988 manual says 13 degrees BTDC for a turbo engine (non boost compensated pump).