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-   -   12A rebuild (https://www.nopistons.com/1st-generation-specific-16/12a-rebuild-72475/)

regar 06-02-2009 07:47 PM

Last weekend I got serious and started rebuilding my stock 1980 12A. We went as far as torquing down the tension bolts. Later I was reviewing what I had done for the day and realized I had neglected to apply a layer of hylomar to the permeter of the housings according to the Haynes manual. So I'll probably tear down the engine and add a layer of sealer like I should have the first time.

My other concern is about the water seals. I bought new water seals form Mazdatrix,both the orange set and the black set. My question is, why is the groove in the housing so much larger than the seal? Am I missing something here? Do I have the wrong seals? I need help.

My next concern is about timing. I've installed rotor number 1 with one apex pointing north and rotor number 2 pointing south. I'll install the distributor with the tally marks aligned. Will this insure the timing to be correct or at least close enough to get the engine running?



Thanks for your help


Lynn E. Hanover 06-03-2009 10:05 AM


Originally Posted by regar' post='922346' date='Jun 2 2009, 05:47 PM
Last weekend I got serious and started rebuilding my stock 1980 12A. We went as far as torquing down the tension bolts. Later I was reviewing what I had done for the day and realized I had neglected to apply a layer of hylomar to the permeter of the housings according to the Haynes manual. So I'll probably tear down the engine and add a layer of sealer like I should have the first time.

My other concern is about the water seals. I bought new water seals form Mazdatrix,both the orange set and the black set. My question is, why is the groove in the housing so much larger than the seal? Am I missing something here? Do I have the wrong seals? I need help.

My next concern is about timing. I've installed rotor number 1 with one apex pointing north and rotor number 2 pointing south. I'll install the distributor with the tally marks aligned. Will this insure the timing to be correct or at least close enough to get the engine running?



Thanks for your help




The seals are much smaller than the grooves in width but also taller than the groove in depth. So when the stack is torqued up they nearly fill the groove volume left. The design is to allways allow some volume left over when the groove is closed up. This to prevent a hydrauliced seal where too much seal fills the groove and then some, and part of the seal extrudes out of the groove and interferes with the sealing process.



For the distributor just complete the build. Turn the crank until the pointer is over the TDC mark on the pulley. Install the distributor with the rotor pointing at the number one leading plug wire. This will get you close enough for the engine to start.



Then time with a timing light.



Lynn E. Hanover

regar 06-03-2009 10:50 AM


Originally Posted by Lynn E. Hanover' post='922367' date='Jun 3 2009, 08:05 AM
The seals are much smaller than the grooves in width but also taller than the groove in depth. So when the stack is torqued up they nearly fill the groove volume left. The design is to allways allow some volume left over when the groove is closed up. This to prevent a hydrauliced seal where too much seal fills the groove and then some, and part of the seal extrudes out of the groove and interferes with the sealing process.



For the distributor just complete the build. Turn the crank until the pointer is over the TDC mark on the pulley. Install the distributor with the rotor pointing at the number one leading plug wire. This will get you close enough for the engine to start.



Then time with a timing light.



Lynn E. Hanover


regar 06-03-2009 10:57 AM

Thanks, Lynn.

One more question.

Since the seals are now compressed, will they be junk when I disassemble the engine to add sealer around the perimeter of the housing?






Originally Posted by Lynn E. Hanover' post='922367' date='Jun 3 2009, 08:05 AM
The seals are much smaller than the grooves in width but also taller than the groove in depth. So when the stack is torqued up they nearly fill the groove volume left. The design is to allways allow some volume left over when the groove is closed up. This to prevent a hydrauliced seal where too much seal fills the groove and then some, and part of the seal extrudes out of the groove and interferes with the sealing process.



For the distributor just complete the build. Turn the crank until the pointer is over the TDC mark on the pulley. Install the distributor with the rotor pointing at the number one leading plug wire. This will get you close enough for the engine to start.



Then time with a timing light.



Lynn E. Hanover



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