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Timing problem.


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Hi.

Finally got my rebuilt engine back in the car.

The machine shop did the assembly and I did the rest.

Everything has been done according to the "Brown Bible" but it did not start.

The dizzy was set up to point at cylinder 1 at TDC

Tried out everything and finally I tried to move the ignition leads one step clockwise and the car started right away.

Can it be that the cam timing isn't correct or would it be impossible to start. It's a standard US engine with twin SU and Lumenition Optronic.

This is a bit strange or am I way out? it doesn't run smoothly.

Thanks.

SO

Edited by SOAA
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If you are standing on the left side of the engine compartment looking at the distributor, consider the oil filler cap to be about 12 o'clock. Is the #1 spark plug wire on the distributor cap about 7 o'clock ?

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Hi,

 

I had the exact same problem when I tried to start the engine after a full rebuild. It turned out that the distributor drive gear was installed at the wrong angle. That way the plugs were not firing at the correct moment.

 

Just a matter of taking out the drive gear and install it at the correct angle. Engine started instantly and runs very smooth.

 

Cheers,

Edwin

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Hi.

That can be the solution for me as well.

According to the installation instructions and illustration in section 12.41.05 sheet 8 in the Brown bible this isn't right.

I use to follow instructions carefully to get things right, so I must perhaps be bit more flexible attitude to it when it comes to old British cars.

 

Cheers

SO

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You can work with it that way, SO.

Just make sure that the rotor is pointing to 9 o'clock when the #1 piston is at TDC and the valves indicate it is in firing position.

The distributor cap may look odd with the wires clocked that way,but the engine won't know the difference as long you follow the firing order with the rest of the wires.

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Been done. Didn't help much. Still runs rough an noisy.

Will the engine start if cam timing isn't done correct?

It's not many to ask here in Norway who are good at these engines.

 

Still slightly optimistic ;-)

 

Cheers

Svein Otto

Edited by SOAA
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Been done. Didn't help much. Still runs rough an noisy.

Will the engine start if cam timing is done correct?

It's not many to ask here in Norway who are good at these engines.

 

Still slightly optimistic ;-)

 

Cheers

Svein Otto

 

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If you can start the car the timing can't be too bad. Have you checked the dynamic timing with a timing light? With the engine running at about 850 RPM mine shows about 11 BTDC... and this makes the car run smooth at idle and gives more than enough acceleration power...

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If it is a std cam it should be smooth,it will run out of timing but only just, check the ignition timing and that will tell you if the cam is out.

Edited by ntc
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It is a new standard cam from Rimmers. I will try to check the dynamic timing tomorrow. It runs rough with a knocking noise.

 

 

You have got the leads in the correct firing order: 153624 anti-clockwise looking down on the distibutor? That 'knocking' reminds me of my past errors...

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Time to check the cam timing on the rockers. When #1 is at TDC ( check via plug hole) on its firing stroke (both valves shut) then #6 should have its valves 'on the rock' ie inlet just opening exhaust just closing. If cam/crank have not been set up right then this state will not occur with the crank pulley marking of TDC at its zero position.

I would not run engine until you've checked this - the knocking could be combustion very early during compression trying to make that piston turn crank backwards...

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What would happen if the camshaft was 180 Deg out?

 

 

Nothing as such - - the crank rotates at double cam speed so by the time the chain has turned the cam 180 degrees the crank will be rotated through 360. Effectively the two are one and the same.

 

If you've done this without taking the distributor drive gear out then your ignition timing will be 180 out & it won't run. (unless you put the carbs on the exhaust manifold and reverse the starter motor ;)

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So we know the cam timing and ignition timing are spot on, that leaves mixture. Oil in SU dashpots? butterflies connected together ( throttle cable not opening just one of the pair?), manifolds tight against head ( no air leaks). etc.

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Went over everything again, valve clearance,static timing, plugs and all the rest and it fired up. It idles ok at 1000 rpm. When I get my new interior back in, I will take it for a spin.

The Optronic system is probably my main problem. Might have been bad earth and bad contact.

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