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Distributer Question

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Ray Smith

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Getting ready to attempt to start the BJ7 after a complete rebuild. When checking the #1 cylinder valve location it appears that the rotor is pointing to #1 on the compression stroke, not the power stroke.Could the distributor be installed incorrectly? The tech section of Moss catalog states that the right side distributor hold down clip should be at 3 o'clock when fitted correctly. My distributor clip appears to be at approx 5 o'clock. What is the procedure for relocating the distributor position?

The manual states the the rotor travels in an anit-clock direction. If this is the case does the engine also rotate in an anti-clock direction? Do not have the starter installed yet, so I can't crank the engine.

How much play should there be in the distributor shaft? I can rotate mine approx 30-40 degrees in either direction.

Thanks for taking time to read the above. Any other things that I need to check before attempting to fire the engine?

Ray
 
Re: Distributor Question

Hi Ray,
Just before the top of the compression stroke, about 10 degrees on the crankshaft, the rotor should be pointing toward #1 plug wire. At this same time, the points should be just starting to open. There is some range of adjustment by rotating the distributor base a few degrees. Make sure that the piston is on the compression stroke. Both valves for the cylinder will be fully closed. The engine rotates CW as viewed from the front.

If there is not enough range, by rotating the distributor body, pull the distributor up until it's drive gear just disengages & turn the rotor in the desired direction & re-engage the gear at a new position. A tooth or two or what ever is needed. Because the distributor is a helical drive, the rotor will rotate out of it's normal position as it is lifted up. You have to compensate for this when setting the new position so that the down, installed, position is where you want it.

It may take a few tries of repositioning the rotor & turning the distributor body to get things lined up so that the points are just breaking as the rotor comes into firing position. A test light, or ohmmeter is useful to determine when the points are just starting to open.

There should be about 15 degrees of rotor semi free rotation which is the centrifugal advance range. This rotation should feel spring loaded in the ccw (advanced) direction & be spring returned to the cw (retarded) position. The timing settings should be done with the rotor in the spring returned, cw, position.

If the rotor doesn't spring return or turns more than about 15 degrees, something is wrong with the advance mechanism under the breaker plate. If there is noticeably more than 15 degrees of rotation, something is worn or loose in the distributor drive or advance mechanism.
D
 
Re: Distributor Question

I agree with Dave - depending where the drive gear is, you can have the timing set anywhere.

The other thing before firing up is to get some oil pressure. Take the plugs out and spin the engine on the starter until there's pressure shown on the gauge. This is because if there's no pressure, it's better to find out when running at starter motor speed, rather than powered speed, and forces on the bearings are much lower with no BANG coming from the top end.
I have heard suggested that you keep it turning over like this until you flatten the battery, to make sure it's sort of run in, before starting with the plugs back in, but I don't know if this is necessary???
 
Hi Ray, welcome to the forum.There's lots of things to check before starting an engine for the first time. Hopefully all has been assembled properly. I'll start by repeating some errors others I've known have done. Maybe It'll help. Make sure the flywheel is mounted in the correct position in relation to TDC. If not, a vibration will be felt at medium to higher speeds. Second, as mentioned make sure you have oil pressure. I used a home made oil engine pressuriser. A contraction that utilizes an air compressor, a used pressue tank with oil in it. When connected to the engine there is no need to start the engine at all. Just open the valves on the pressure tank and allow the tank to build up about 40psi pressure then release into the motor. Watch your oil pressure gauge and once it builds up to about 40psi, shut it off. You now have all bearings pressurized and lubricated before starting. Works real well. Maybe you can borrow one from a local shop or car club member. Turning the motor over with the starter and plugs out is a good idea, also gives you a chance to check spark and timing. Work safely above all else. Make sure emergency brake is on, wheels chocked, and above all else transmission is in neutral. Sounds to simple but I know others have forgotten those simple checks and have regretted it.
Good Luck
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Thanks for the reply Dave and John,

Dismantled the distributor and found that one of the weights was not attached to it's post. That was causing the abnormal degree of rotation.

How do you determine if #1 is on compression or power stroke. Aren't the valves closed on both of these strokes?

Does anyone know where I can get a new set of return springs for the weights? One of the springs does not appear to have any tension. The dist is a dm25 on a late BJ7.

Cheers,

Ray
 
Ray, at rest one of the springs is intentionally left loose.To test compression stroke, remove plug,put finger "over" plug hole, Crank Engine, Compression will move finger off the hole.-FWIW---Keoke
 
Ray, setting up the Distributor. With #1 clyn on its compression stroke and the timing marks aligned,remove the distributor and look at the slot on the Distributor driving shaft.the big side of the slot,IT is offset,should face towards the engine block and the slot should match the hands of a clock when at the ; 20-to-2 position.If incorrect reset the driving shaft to this position.--FWIW---Keoke
 
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