pedro a

hi there do anyone have pic of how to pin the Tll.help thank

mazdaspeed7

Its basically just reaming out some of the tension bolt holes to fit extra dowel pins. But most builders like to keep exactly which ones work and dont work to themselves.

Lynn E. Hanover

The use of extra dowels and, or, oversized tension bolts is usually reserved for boosted engines running high boost numbers and perhaps using dog ring transmissions in drag racing.



You may have noticed that over the years Mazda has moved the engine mounts from the front cover to the center iron. I have seen race engine where the engine is supported by only the rear iron.



The engine is not very stiff in bending, and is not rigid in torsion. So with only 2 dowels in the stock engine, at high boost numbers the torque generated is twisting the engine by pushing the rotor housings in the opposite direction from the crank. The rotor housings are prevented from turning only by the dowel tubes. Add to this the shock loads of the dog ring shifted transmission and you might see a dowel tube shear off, or the hole in the rear iron (usually the upper dowel hole) breaks out the iron. Both dowels are equilly stressed, but the upper hole has less material around it, so it fails first. In later engines, Mazda added more material around the upper dowel hole. At high boost, a preignition event or a series of detonation events can produce enough torsion to fail the top dowel, or dowel hole in the rear iron.



Adding dowels helps spreads the torsion load out around the rear iron, and reduces the problem.



The rotor housings are flexible, and high boost engine will have the spark plug side of the housing scrubbing on the irons and failing seals. Dowels are added here to make the housings more rigid in the plug area to prevent flexing (the plug side is being pushed out from the rotor face).



Generally, NA, or unboosted engines don't make enough torque to need extra dowels. However you can destroy one with preignition and, or, detonation.



Lynn E. Hanover

FJDRX7

Here you go, come down to Killeen , i show you what you need

Liborek

Extra dowel on intake side???

13BT_Starlet

I know right , Why on the Intake? It should be on the bottom of the housing before the exhaust port around to bottom of the leading plug every other hole end up with 3 xtra dowel pins.

ArmyOfOne

Well while we are on the subject here. Where can I get pins that are long enough to go through from rear iron all the way to the front?