Outer Limits 4x4 Board

I am just about finished putting my motor back together after installing a 4.6l short motor. Motor is bolted back into the car and I just have to hook everything up tomorrow.

Is there any way to find TDC without removing the rocker cover? (which I have already sealed and bolted down).

pull the spark plug out of number one and put your thumb over the hole. rotate the engine until you feel pressure on your thumb when you get this you are tdc. apparently

Also a steel rod or long screwdriver down the plug hole and rotate till the timing mark on the balancer is lined up and the rod/ driver has popped up.
I have chewed 3 balancers out on my rangie so now i have loctited the b@stard on and check tdc using this method.

Also be careful you align the timing marks up properly.

If it's a tooth out you may have problems trying to get the timing spot on with the vac adv in the way, either hitting the timing cover or fouling on the thermostat housing where the top rad hose is located.

It took me about 3-4 hours one day to get it right The beer in the fridge was well worth it

Trav

Thanks everyone, will try this tomorrow.

G`day Adam , i only ever suggest .

Accurate way is a stop plug and degree wheel , this way you have true tdc and the timing can be set with a timing light if you choose .

When i swapped the 3.5 for 4.0 the timing tag on the 3.5 cover had to be bent to the right posy for tdc , would imagine a 4.6 would be the same though some are luckier than others .

I`d suggest it worth taking the rocker cover off , put a screwdriver/rod down cyl 1 watch the valves rock , hold pressure on the thing in the hole as you wiggle the crank back and forth because there is a void at tdc and you need to judge the centre of the void , then bend your tag to suit .

The best way to set the timing may be by ear or vacuum gauge , though a light may be in the paddock .

Also with the rocker cover off you can be sure oil is flowing , they have pretty low pressure so there won`t be much flicked about with the cover off .

I guess you know about running the cam in .

Good luck with it , peter .

Adam,

I don’t post here much but this may help

To check that the TDC marks on the balancer are actually TDC, use a dial gauge through the no 1 plug. Alternatively use an old plug and a manometer (water U guage).

Replicate the balancer marks up to 30 degrees BTDC. Disconnect the vacuum advance and run the engine up to 4500rpm and set the timing to 28 degrees BTDC. This will then automatically set your static timing

If you have got a hot cam you could go up to 34 degrees but that’s about the upper limit ………… the engine design was 28-30degrees.


Ian


90 V8EFI Truck Cab

Hi there,
as it is a V8 the piston during one rotation comes to TDC twice, and it fires just on one of this rotation, so you can be on the wrong side if you just check like this!!!
As you want to check your timing I assume the dizzy is already bolted on. so make sure the finger lines up with the contact for cyl. 1. Then you`re rite with this method.
Cheers

Thanks again everyone. I finally started it up last night and everything went well. It was real easy working out TDC on firing stroke with the "finger over the spark plug hole" method.
I was lucky in that the markings on the pulley were correct for TDC.
I have onlt set the timing by ear at the moment but will put the light on it as soon as I can.

Thanks Peter, I think I ran in the cam correctly, 10min at 1500RPM and dont turn it off.

Someone was saying something about 28degrees BTDC???? Is this in reference to using a timing light etc or is it just because it is at 4500RPM?

I thought at idle I should be setting it around 6deg BTDC!

I only ask this because with my old 3.5 motor I found that I did have to take it to about 26deg BTDC before it would run at it's best but I thought this must have something to do with how worn the engine was.

You are correct about 6degrees, or you can maybe go up to 10 or more, but test it on a steep hill to ensure no pinging.
28 degrees is total advance at 3000RPM plus and equates to around zero at idle, as the mechanical advance adds advance as the revs rise..

I suggest that if your 3.5 needed that then the mechanical advance mechanism was jammed. but its a wonder it started without kickback.
Regards Philip A