1st gen timing from scratch

[Rex Burkheimer]

A friend is installing a new long block in 1983 12A. He has installed the
distributor using all the standard 4-cycle reference points: rotate engine
until leading spark plug hole has compression pressure, continue until
timing mark lines up. Orient distributor base so that a distributor contact
lines up with the leading plug wire tower. Will not start.
So what else is there?
How do you determine the crank is at TDC to verify the pulley marks?
Anyone seen a step-by-step guide to timing a 12A from scratch?

--
Rex Burkheimer
Parts Plus Marketing Director WM Automotive Whse., Fort Worth TX
"I want to put a ding in the universe." --Steve Jobs

[David]

The leading and trailing plugs have a corresponding indentation on the
eccentric shaft pulley. The leading indent is the first mark ( CCW rotation
from the cabin). Line up the leading mark with the pointer on the front cover.
Next, align the small indentation on the drive gear of the distributor with the
raised point on the distributor body. Carefully install the distributor,
leaving room for adjustment in the screw hole arc. Tighten down the set screw
and try it out. If it starts, it can be timed using a standard timing light.
The lead plug to time is the front lower plug, set it's timing with the proper
mark on the pulley.
The Haynes manual covers this nicely, the trick is to get the distributor in
without moving it's drive gear a bunch. But due to it's layout the rotary is
relatively simple to time.

[Rex Burkheimer]

Thanks David, just what we needed. The only other thing I have been unable
to determine: The timing pulley can be installed in 4 different positions
with respect to the crankshaft. When I took mine off I did not mark it, so
I had to try all four positions until I found one that lined up with the
timing light marks. Is there a better way to do this when re-assembling the
motor?

--
Rex Burkheimer
Parts Plus Marketing Director WM Automotive Whse., Fort Worth TX
"I want to put a ding in the universe." --Steve Jobs

David <d...@dnx.net> wrote in message news:3B3161F4...@dnx.net...

[Rx7mania]

Before you remove the pulley from the RX you should stop the engine (manual
crank it) to TDC (on most engines this is how you do it) so when u
reassemble it you wont have that problem.

IN the mean time try this link. He is the GURU!

http://personal.riverusers.com/~yawpower/

He has links that also outline the advantages of setting timing to total
advance vs idle timing. Very informative man.

Good luck.

"Rex Burkheimer" <r...@wmautomotive.com> wrote in message
news:tj3up0s...@corp.supernews.com...

[David]

The 12A has equally spaced holes on the pulley. The later 13B came with a pulley
with holes that could only be mounted one way. If you have the exhaust manifold
removed you should be able to determine where the apex seals are in relation to
the housing. You'll have to do some trial and error thinking. It would help to
have another engine (especially out of the car) to compare it to. Better find a
good schematic of the entire cycle and give it a whirl. Good Luck!

[david hast]

Rex, just had a thought on the way to work today. The eccentric shaft has a key
way on the front end that secures the mounting point for the pulley. That may be
a good reference point for you. I have a couple of engines out of cars, so if
you get in a big jam I can probably help you out.
David

[Rex Burkheimer]

I'm familiar with the Yawpower site, and set up my own timing per his
instructions.

> Before you remove the pulley from the RX you should stop the engine
(manual
> crank it) to TDC (on most engines this is how you do it) so when u
> reassemble it you wont have that problem.

Well, Duh!
I couldn't agree more. But what if you buy a longblock from a company out of
state? Ships without pulleys.
If this were a piston engine, finding TDC would be easy, done it many times.
Do where do you suggest I mount the dial indicator to determine TDC on a
wankel?

[Rex Burkheimer]

Thank you, David. Is this engine like others, in that the keyway would point
straight up at TDC?
This would still require removing the front pulley, but it would give a
point of reference.

--
Rex Burkheimer
Parts Plus Marketing Director WM Automotive Whse., Fort Worth TX
"I want to put a ding in the universe." --Steve Jobs

david hast <d...@dnx.net> wrote in message news:3B334437...@dnx.net...

[Felix Miata]

Rex Burkheimer wrote:

> But what if you buy a longblock from a company out of
> state? Ships without pulleys.
> If this were a piston engine, finding TDC would be easy, done it many times.
> Do where do you suggest I mount the dial indicator to determine TDC on a
> wankel?

The keyway aligns with TDC on front rotor. The timing marker on the
front cover is ~90 degrees before and after TDC. Pointing the keyway at
the spark plugs means pointing the keyway at TDC. The worm gear driving
the distributor has only 7 teeth, so if you are off by 180 degrees at
the eccentric, installing the distributor puts TDC well away from the
center of the timing adjust slot. The 14 tooth distributor gear pitch is
coarse enough that most people can't get an engine to run if off by one
or more teeth. The distributor fires every 90 degrees dist, 180 degrees
eccentric, like a 4-boinger.

I rarely encounter any need to deal with this, as I learned very long
ago to never remove all four pulley bolts at one time. Unless installing
a different size pulley, or reattaching after cutting the A/C belt
pulley off, one should never have need to take the pulley completely off
its drive. Rebuilders shouldn't be removing the pulley either. There is
no reason that makes it necessary. To remove the outer pulleys, one can
remove the first three, then loosen the 4th. Once the 4th is loosened,
the extra pulley can be twisted out of the way and a removed screw
reinstalled before removing the last to totally sever the outer pulley
from the drive.

Once upon a time, Mazda pressed an alignment rivet into the eccentric
drive with a corresponding hole for it in the pulley so that
misalignment required one first remove the alignment rivet before
attaching the pulley wrong. Even before that, they either put obvious
alignment marks on both drive and pulley, or the holes weren't exactly
90 degrees apart and couldn't be installed incorrectly with all four
bolts.
--
Discipline your son, and he will give you peace; he will bring delight
to your soul. Proverbs 29:17 NIV

Team OS/2 *** Rotary ONLY since 1973

Felix Miata *** http://mrmazda.members.atlantic.net/ <- Not just a FAQ

[vox...@arvotek.net]

On Sat, Jun 23, 2001 1:46 PM, Rex Burkheimer <mailto:r...@wmautomotive.com>
wrote:

>Thank you, David. Is this engine like others, in that the keyway would
point
>straight up at TDC?
>This would still require removing the front pulley, but it would give a
>point of reference.
>
>--

Yeah !
The last time i did this, the key on the main pully, lines up with the
timing pin, and the tally mark on the ditributor lines up with the notch
on the Distributor shaft. Then in it goes.