J-Rat

iTrader: (2)

CAS is stabbed when the yellow mark is aligned with the timing pin. You then line up the timing dot on the CAS (or take the cover off, and mark that stuff right like I do). So in theory the CAS is stabbed at 5 deg ATDC.

There isnt a mark on the pulley of a stock TII, that has a TDC mark.

Not to mention the fact that TDC, although the given standard of measurement (for timing), isnt really an applicable term for the rotary. There isnt a top of travel, so to speak, since the rotary is not a reciprocating motor. I belive for simplicity, the chose to adopt that standard.

Jarrett

Ary'01xj

Ok guys, since you guys know so much more than me, how do I do this?? I have my distributor in hand, my pulley in hand, and there are no marks on the pulley. Also, as far as I can tell, the holes are not staggered(measured with calipers), well I guess they're staggered, but it could go on two different ways. I'm not above removing stuff to check and see what's up inside the motor. It's currently out of the car, and I'd like to do this before I reinsert it. Thanks

Edit: there is an indicator peg on the front plate...

ary

J-Rat

iTrader: (2)

So let me get this straight. There are no timing marks on any part of your pullies>?

Ary'01xj

Not that I can see. There are two marks on the back of the pulley, but they look like someone took there pinky finger, dipped in paint, and touched the back of it. They're also right next to eachother, so I don't think they have any relevance. On the other hand, I might just have the wrong pulley. It fits on the eccentric shaft, but it rubs on the front plate. so either I'm missing a spacer or it's the wrong pulley(engine has been dissassembled for over a year and I didn't take it apart, my uncle did. Thanks for your help.

Ary

Hot_Dog

You wrote: "TDC is when the trailing (yellow mark) on the pulley is lined up with the pin..." That is not TDC, that is 6 degrees ATDC. TDC is when the top apex seal is midway between the two spark plugs holes.

Larry Mizerka
90 RX7 GXL
02 RSX-S

J-Rat

iTrader: (2)

Where are you getting 6 from?

Its 5 man!

Course the FSM gives a margin of error of +/- 1 deg.

Jarrett

J-Rat

iTrader: (2)

dangit..

J-Rat

iTrader: (2)

Okay bro, there is a sequence that the pulleys get installed. There should be some divots on the outer edge of one of your pullies. They may not be painted, but if they are, one is red, the other is yellow.

You might want to clean up your pullies with some carb cleaner or something. And if they are stock pullies, they will only install on the eshaft ONE way.

Jarrett

Ary'01xj

What do you mean a sequence that you install the pulleys?? I don't follow. The pulley is nice and clean, not worried about there being grease and grime covering up the marks. How can I tell mechanically if the motor is at "TDC"?? Thanks

Ary

J-Rat

iTrader: (2)

there are 3 pullies that go on that motor, one double pulley that goes on first, then a large single pulley, then a small single pulley, and finally a metal ring that sits inside the outer pulley.

If you dont have all the pullies, and the timing mark, then I havent a clue how you would find "TDC". It would probably involve looking into the plug holes or something, which would NOT be accurate. Remember, TDC is a misnomer. Seems like your making this a little harder then it has to be.

Good luck!


Jarrett

Ary'01xj

Ohhh, I see, only found one pulley so far, I'll have to look for the rest. Thanks

Ary

Ary'01xj

Ok, so I'm a MORON. I found the other two pulleys buried in my parts pile. There are indeed to indents on the double pulley, one reddish orange, and the other bright yellow. So do I stab at yellow? or do that math you were talking about?? Thanks

Edit, nevermind, I just went back and re-read the math you were talking about. I think I need to go to sleep 'cause it doesn't get any simpler than that. I will proceed to stab at TDC unless everyone starts saying I should do it at 5deg ATDC. Either way, it doesn't matter about measuring, the motor is out of the car, so measuring is very easy. Thanks again

Ary

xXn3v3Rsat!fi3dXx

I have the marks but my pulley has been removed. What is another way to check?

GregW

This thread is an absolute clusterfuck and should be deleted.

TDC is when the volume of the combustion chamber for Rotor 1 is at its smallest. On the pully there SHOULD be two marks, 5 and 20 deg

You have a yellow mark and a red mark, The leading yellow mark is 5degATDC, the Red trailing mark is 20 deg ATDC.

If you dont have any marks on your pully, man the eff up and either find a pully, hub combo that was a match made at the factory (mixing pullys and hubs may not always give accurate marks) or get a degree wheel from summit racing. Use the Keyway to set it up, Im pretty sure (do research) that when facing the front of the engine if the keyway is parallel with the bottom of the engine, ie facing 9 o-clock thats tdc for R1.

fc323

huh...the haynes manual says that when u align the front keyway with the the little crap on the cover,its at TDC

TonyD89

iTrader: (10)

This should help understand TDC. There's really two TDC's and BDC"S

GregW

Go find your haynes manual, grab on to it good and tight, proceed to trash can.

Throw it away, spit on it, call it a few names.

Now order the factory shop manual.

boostedHULK

iTrader: (1)

not sure why the concern with top dead center. to install the distributor, turn the motor over until the yellow mark lines up with the pin, put the rotor of your distributor at leading 1 and install it. and that should be in the haynes manual.

RotaryEvolution

iTrader: (30)

i'm not sure why they reference bottom dead center, that image is false for a true top dead center. the combustion side used for timing the engine is 180 degrees out from that image. their TDC is actually BDC, their BDC is irrelevant and the true TDC is not shown.
the intake ports throw that picture off, because everything positioned incorrectly, if the rotor position stayed the same and you flipped the housing and iron in that image it would be correct for TDC.

at any rate, since someone revived this thread searching for info this thread would be of more use.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/how-properly-time-your-engine-while-disassembled-980099/

TonyD89

iTrader: (10)

I don't know man. It seems correct looking at a rear 6-port iron with a housing on it. The key way is at 9 o'clock corresponding with the vertical line marked TDC.

Four stroke engines are at BDC for two cycles. Power and intake.

They're at TDC for two cycles. Exhaust and compression.

On a rotary, they just happen to be on opposite sides of the engine.

RotaryEvolution

iTrader: (30)

look at it again, the image would be looking at the engine from the front. intake and exhaust on the left and spark plugs and combustion chamber on the right wall. the picture shows TDC exactly against the opposite wall of the combustion pocket, which is basically bottom dead center on a rotary engine. yes it's a different stroke pattern from a 4 stroke piston engine but the engine fires each full rotation, so 180 degrees puts the rotor against the intake and exhaust wall where that picture indicates top dead center.

even the factory timing marks follow my ruling on the subject as shown in the linked thread.

i'm not sure who created that image but it's 100% inaccurate.

TonyD89

iTrader: (10)

I comes from either Pinapple's or Mazdatrix's site. They left out the TDC on the other side of the engine which is where the front rotor would actually be with the key at 9 o'clock. It's more for porting so I guess they only showed the TDC on that side of the engine.

HAILERS2

He was going to use a DISTRIBUTOR on his 13B.

His pulley has no marks.

Early RX, say a 1982, 12B engine that used a DISTRIBUTOR, had the distributor set at the Lead mark on the '82 pulley. That mark was.............TDC, not 5* like on a 13B CAS car.

So he could have read this article: http://rx7.pw.cx/guides_manuals/coll...ystifying.html where it shows at the very bottom of the article how to get the engine at TDC. Well a ballpark figure in reality.

Then once he found that he could have filled up his front rotor with thick oil. Then rocked the e-shaft pulley back and forth a small amount and observed the oil level in the rotor. As the rotor approches TDC the oil will rise up. As you go past TDC the oil level will drop. So you find the place where you turn the eshaft and the oil reaches its highest point and make a mark on the pulley. That is TDC for that engine.

The first gen FSM shows how to install a first gen (carb) distributor and gives the value of the yellow mark on the pulley (zero degrees or TDC). That's on a first gen distributor car.

Or he could buy a used first gen 12B front pulley and install it. The first mark will be TDC on that pulley.

Or bought a RacingBeat pulley that has the TDC mark on it.

Then again I don't really know if a 13B using a distributor should be installed at TDC or at 5* ATDC. I guess a Europa FSM would say one way or the other. I'm too lazy to look.

HAILERS2

Well actually the Training manual shows 13B that used the distributor had the LEAD timing set for TDC at 500 rpm. So he did sort of need to know where TDC was and not 5*atdc.

RotaryEvolution

iTrader: (30)

explained all that in the thread linked to.

well except the oil method, seems like overkill, messy and a waste of money.