The V8 Owners Forum -

Chaps.
I need some help!, I have fitted a new camshaft and followers, and while I did take care to align the timing marks, and set the piston to TDC, I did not check to see if TDC was at the firing stroke! ( duh! ) so at the moment I cannot get it started, and my niggle is that I had set TDC at the exhaust stroke.
My head hurts now, so any guidance or advice on how I can check on this before I start to take it bits again .
I also removed and replaced both cylinder head gaskets at the same time.

When you align marks on the camshaft sprocket and wheel you do not need to worry about No 1 at TDC on the firing stroke.

But, When you are setting the distributer then you do have to get no1 at TDC on the firing stroke.

Thanks for the reply.
I have set the dizzy at the firing stroke ( had the young un put her finger over the plug hole on CYL 1 ) and set the shutter wheel ( Malory unilite ) correctly.
However I did notice that the actual rotor arm does not point directly at a lead plug point on the cap, it sits between two positions when the shutter wheel lines up with the optic.
It should still attempt to fire up even with adjustment when cranking, but nothing resembling a start up, just a partial fire up with the starter engaged.
I am just doubting everything I have done so far.

The rotor arm will need to point pretty close to the cyl 1 tower on the cap.

Whether TDC is a firing stroke or not is dictated by cam position, so if the dots are aligned this will be correct.

stevieturbo wrote:The rotor arm will need to point pretty close to the cyl 1 tower on the cap.

Whether TDC is a firing stroke or not is dictated by cam position, so if the dots are aligned this will be correct.

Assuming the dots are correctly aligned, turn the crank until the timing marks on the pulley line up and then set the distributor so the rotor points to No1 plug lead and try again.

I have tried the crank at TDC and 6deg before, but what is throwing me is this optic on the shutter wheel, if I then line up the rotor arm with it pointing directly at Cyl 1, the gap on the shutter is no where near the optic, likewise if I line up the gap on the shutter wheel the rotor arm is nowhere near a single plug point on the cap, it sits midway between two positions, so is the rotor arm the the important one to position correctly, or the shutter wheel gap?

I have tried every which way on the distributor to position it both in fitting in the drive gear and fitting the cap so these two point correspond.

Is the optic fixed to the baseplate of the dizzy? Can you move the baseplate a small amount clockwise and anti clockwise? The baseplate is normally held in position by the vacuum advance unit. The baseplate can move away from it's correct position if it is not connected to the vacuum unit and this will result in the firing point occurring when the rotor arm is not opposite the terminal in the dizzy cap.

OR -- The shutter wheel has moved somehow on the dizzy shaft and giving the same result.

It's only a guess setting an electronic dizzy by eye to get the engine started, so set with a timing light when running.

The relationship between trigger point and rotor arm position is within the dizzy, and although you could have the plug wires 'one out' as it were, it's usually pretty obvious.

TAFF wrote:I have tried the crank at TDC and 6deg before, but what is throwing me is this optic on the shutter wheel, if I then line up the rotor arm with it pointing directly at Cyl 1, the gap on the shutter is no where near the optic, likewise if I line up the gap on the shutter wheel the rotor arm is nowhere near a single plug point on the cap, it sits midway between two positions, so is the rotor arm the the important one to position correctly, or the shutter wheel gap?

I have tried every which way on the distributor to position it both in fitting in the drive gear and fitting the cap so these two point correspond.

the rotor arm will install onto the shaft in one position only.

To alter this position you need to remove the dizzy from the engine, rotate the shaft/rotor arm so it locates in a new tooth in the drive gear in the engine and re-fit.

The other option, faster but not "correct" is to align the cam dots so engine is at firing stroke cylinder 1, and re-position the plug leads based on this new no 1 dizzy cap position based on where the rotor arm is pointing.

As Dave says, all this will let you get the engine started, timing must be checked and adjusted with a light after.

There is some movement available on the optic / baseplate, but not enough to align both points.
No Vac unit on this dizzy.
I have tried all positions on the set up with no luck, each one has the same result.
I am beginning to suspect the camshaft is the wrong type, even though the part number is correct.
The rockers are too tight at closed, and so are the pushrods.
I did get it to start, but I had to retard the dizzy so much while craning that I ran out of movement, so not able to check timing, and yes I have made sure that the plug leads are correct.
Frustrated

It still doesnt sounds like you're going back to basics as people have described.

Start from scratch, align everything as it should be aligned, put the leads in the correct order and it will start unless there are other problems.


Setting the timing for it to start should be very simple as long as you follow sensible procedure.

The fact you needed to rotate the dizzy by some margin, simply means to me you are not following all of the steps outlined.

And not quite sure what you're meaning by the camshaft being wrong ? wrong in what way ? The chances of that really are slim

I have gone back to basics time and time again, both at TDC and 6deg before, and it still will not start and idle enough to continue.
To add insult to injury, I now have no oil pressure, or not full pressure when priming manually.

The engine ran very well until I began this work bar a slight miss on idle, this I think was the result of a loose bolt on one of the cylinder heads.

That fact that I have to rotate the dizzy so far when it has been set at both TDC and 6deg before, with no positive signs of starting tells me that something is not right somewhere, and it leads me to the rotor arm and shutter wheel.
If the profile of the cam is not the same then surely this will affect the valve clearance / opening and closing.?

Forget the shutter wheel and forget the rotor arm positon and forget piston position at this time Taff.

You fitted a new cam. As said before!! Are you happy that the cam cog and crank cog timing marks were facing each other when you pushed them (with the chain fitted) into positon

This would have seen whatever marks there were on the cogs facing each other. ie bottom cog mark at 12 oclock and top cog mark at 6 o clock.

Did this happen ??

If it did, then you have the cam timing correct

To set up the dissy just remove the near side rocker cover and turn the engine by hand with a ratchet and socket until you see the inlet valve start to open. Then continue turning until the inlet valve is closed. ie rocker has come up and then stopped.
Look at the crank pulley and timing marker. You should see that this is indicating very close to TDC.

Rotate the engine a little more until you see the crank pulley line up with the marker to show TDC. This will gicve you No 1 at TDC on a firing stroke.

Re fit the dissy with the rotor arm facing number 1 segment / plug lead connection. You may have to pull the dissy out a few times and rotate the rotor arm a few degree's each time so when the dissy drops back in the rotor arm moves to the right positon. I think its around 30 degree's between dissy engaging the cam drive cog to where it finally rests when pushed fully home. Once you have the dissy fitted with the rotor arm facing number one plug lead segment in the dissy cap you will be very close.

This should see the engine trying to fire at TDC if you crank it over. So before you crank it over apply a bit of simple visual logic and try to add 10 degree's of advance by rotating the dissy anti clockwise by 10 degree's to give you a starting point to work from.

TAFF wrote:There is some movement available on the optic / baseplate, but not enough to align both points.
No Vac unit on this dizzy.
I have tried all positions on the set up with no luck, each one has the same result.
I am beginning to suspect the camshaft is the wrong type, even though the part number is correct.
The rockers are too tight at closed, and so are the pushrods.
I did get it to start, but I had to retard the dizzy so much while craning that I ran out of movement, so not able to check timing, and yes I have made sure that the plug leads are correct.
Frustrated

Despite my previous comments regarding the setting up of the dissy etc.. Your comments regarding the cam choice with respect to the rockers being too tight when closed as well as the push rods are confusing ?

What is the difference between the cam you removed and the new one that you fitted?

I have assumed that you replaced a standard cam with an identical replacement item?

If you have a full hydraulic cam setup and have replaced the old cam with a new stock cam then there should not be an issue with regards to lifter pre load settings. But if you have fitted a cam with a higher lift that your valves and springs cannot cope with you may have bent some pushrods??

Can you please tell us what cam you have fitted and also tell us if this is a direct replacement cam for the old one ?

Perry

Thanks for all the advice chaps.

Yes I did fit the cam and pointers correctly with the piston at TDC.

I have set number 1 firing point by the blowing the finger off the plug hole, and watched the inlet valve close, however I do have to rotate the crank a fair bit to reach the marker ( the scale is just out of view when the valve shuts )

The piston is definitely at TDC, I have used scale to measure the lift in the bore.

The cam is a standard like for like replacement 3.5 carbs.
I think I will remove the front cover next weekend and have another look.
I need to check the oil pump out anyway.

I will keep you informed of my progress.

Thank you all.