Hi guys



I built a half bridge 12A



I assembled the engine, and place the distributor as recommended by the FSM



I cant get the engine to start, wont even try



I know timming on a hb is a lot different, but how should I place the distributor? one or two teeth advanced and once it starts try to find the proper timming?



Any input would be great



Thanks in advance

 

Make a mark (vertical line)(magic marker) on the distributor in line with the number one Housing leading plug wire tower.



Alighn the rotor button with that line. Insert the distributor, noting that since the gears are cut on an angle the rotor button move away from the mark as the distributor body seats. Try again, leading the twist so that the distributor is seated and the rotor button is still pointing at the mark.



This will be good enough for starting. Tightn the clamp screw gently. Install the cap and wires.



The engine needs to spin fast to start. They leak down quickly and have low compression, so little heat of compression. Heat of compression is needed to vaporize the fuel. Otherwise you get no explosion, just s fluffing sound and no start.



Check for spark on all plugs.



You might want to mix up some starting fluid. 25% motor oil. 75% fuel. 3 or 4 squirts down each carb throat will do. Lots of smoke at first. The oil helps new seals trap some compression.



You can push start it in 2nd gear. Air cleaner in place to prevent fires.



Lynn E. Hanover

 

Thanks for your input Lynn

Quick question



I follow your instructions with the pulley at TDC? or since its a halfbridge, I should use a more advanced timing mark on the pulley?





Thanks again!

 

looks like you took apart your timing pulley and when you put it back together, got it all lined up the wrong way. when this happens, the timing is way off. your gonna have to find top dead center, without using your pulley as a guide. follow lynn's suggestion.

 

Did you take the front pulley stack apart?



The actual ignition timing is of no importance. The engine will start and run with anything from zero to 35 degrees of advance. For the street a total advance of 24 degrees is plenty. Check the advance with the RPM about 3,500. Well outside the advance curve.



Early front pulleys had 4 symetrically spaced 8MM studs or bolts to mount the stack onto the hub. This allowed for a wide range of assembly options. Four possible and only one usefull. Later pulleys have one bolt hole out of locus a few degrees. This is so the pulleys can only be installed in the correct orientation.



If you are not sure the timing marks are in the correct location, remove all of the spark plugs. On the front housing only, turn the engine "Clockwise" looking at the front of the engine, until a apex seal is centered in the top (trailing) hole.



With a magic marker, mark the inner shieve Next to thr front cover and right under the timing pointer. The little wire thing. Then turn the engine backwards until an apex seal is centered in the lower (Leading) plug hole.



Mark the pulley as befor. Half way between those two marks on the pulley is TDC within a degree or so. Close enough.



If there are no marks (Griives) on the pulley in the area of TDC, the pulley may have been assembled incorrectly.



Make a wire "C" device to measure the actual diameter of the pulley shieve next to the front cover. C=PiXD Divide the answer into 360 to find the degrees per inch. Lay out points along the pulley in the direction of rotation, if none exsist, for timing like 20,24,and27 degrees. Mark the pulley and file a small groove into the shieve with a 3 cornered file. Apply a drop of colored paint to identify each position. Write on the core support what the paint dots mean.



Easy........Lynn E. Hanover

 

Your help is priceless Lynn, thanks again



I rebuilt the engine a year ago and I cant really remember how I assembled the pulley.



I will double check, follow Lynns instructions and get back to you guys.

 

First of all, Im sorry. I stated that you need more advanced timing and I should have said retarded



I found a few pics.



This is my pulley, I think you cant assemble this one wrong because you have to match that hole







I made timing marks

 

The pulley looks good. I would use a different color for the preferred timing mark, like red or yellow.



Out in the sun at the race track it gets real hard to see those marks. And the stock piece of wire pointer is no help. I sight past one side of a water pump stud to be consistant. If you use a smaller racing pulley then there is much room for error in setting timing. Some folks pull that wire out and tap the hole for a 6-32 screw. The grind the top surface flat and paint it orange or yellow. Much easier to see.



Picture was my last racer.



Lynn E. Hanover