V8kilr

on paul yaw's page here

he first says "Most 12A's will make best power with total timing of 24 degrees before top dead center leading, and 16 degrees before top dead center trailing"


but then later tells you to take off your pulley and make marks after top dead center

and "Now that you have marks on the pulley, rev the engine above 4,000 rpm, and set the timing at the appropriate spot. I mentioned 24, and 16 which of course is not marked on the pulley. It is easy to eyeball this and arrive at any number you wish. If you are concerned about accuracy, you can add as many marks as you want to the pulley, but I have found that marks every five degrees are sufficient"

which he is reffering to the marks after tdc that he had you draw on????????

SilverRocket

A lot of inexperienced people that try this with lightly-modded setups end up experiencing detonation and breaking sparkplugs, which as you probably know can very easily lead to a blown engine. And trust me, from someone who screwed with timing for months, it hardly gives you any more power on a near-stock setup! It just feels different, it revs quicker and you don't feel your secondaries coming on as much. If you insist on trying this, be sure you know what you're doing!

That's just my 2 cents, but dude be careful.

REVHED

If that's what the article says then it must be a typo. The marks you make on the pulley are BEFORE top dead centre. ie, 24*L and 16* T or there abouts.

Silverocket, you may remember that I also broke some plugs with these timing settings but I just had my new Weber tuned and the mechanic also uses approximately the same settings as Yaw. He said that as long as YOUR MIXTURES ARE CORRECT these timing settings will not cause any problems. BTW, this guy has about 15 years experience building and tuning rotary engines for all applications.

moremazda

iTrader: (4)

I have had my 12a set by Paul Yaw's timing recomendation for more than 30,000 miles and I have had no detonation, no broken spark plugs, and still have excelent compresion with 175k on the ticker. If you want to run these settings follow Paul's instruction to the "T". AND GET A TIMING LIGHT. Not a cheap one!!! Having a crapy light at these settings could get you into trouble.

IMO, the timing could not be set any better. The is just my oppinion.

V8kilr

so you guys are telling me that the first part is true?
i should retard my timming 24 degrees?

how the hell do you detonate off a retard?????

REVHED

If you set your timing to 24* and 16* BEFORE top dead centre as the article states you are advancing the timing, not retarding it.

Sterling

This sort of thing (Pauls advice) should not be dealt out loosely like venerial desease awareness pamphlets! These are serious settings for timing...the knife's edge for pushing your engine to it's limit in order to achieve the best results. I think it's people that never did enough research in the first place that have had the worst problems.
If you set your timing as per Paul Yaws suggestions, you had better have a perfectly tuned carburetor; the ability to keep it tuned perfectly; and a good understanding of just what's going on with your timing inside the engine. If not, then you can end up with blistered plugs, or worse.

And while ****** around with carbs, it's best to put the timing back down a bit till you get the bugs worked out.

I've run Yaws settings for over a year with no problems. Hot plugs in the car right now even, and I drive her hard, too.
BUT- I know my carb very well, and I NEVER-EVER let it run lean!

V8kilr

ok,well just to double check,
to advance you do go toward the right of the pulley correct?
looking at the engine from the front.

V8kilr

damn thats confusing,
so before is clockwise
after is counterclockwise???
wow how hard is that to remember.

peejay

When you're on the distributor side of the engine, looking down on the pulley, advance is towards you. (for when you are marking the dizzy)

crankit

I read an article elsewhere that said stock 12a works best with just a little bit advance and to advance both the lead and trail the same amount. also when you look at the dist. and you rotate it clockwise it will advance your timing. Got mine at 3degrees advanced. I also noticed trying the Yaw settings that you didn't feel the 4 barrel kick in to well past 4500 rpm but now it comes in around 3500rpm lots better

SilverRocket

Good point... I guess I'll change what I said before:

If you have a totally stock carb, stock fuel pump (bad I know, it will change...) with headers, gutted emmissions and other little mods, from my experience I wouldn't recommend going this advanced. Sorry boys, I should have qualified what I said a lot better. Just didn't want to see anyone wind up very unhappy.

V8kilr

yes but to advance is to go before tdc correct?
and to retard is to go after???
thats just confusing when you look at it like that,
i always knew advancing was toward me when by the dizzy,
but didnt know that i was going btdc i though it was called atdc

SilverRocket

Correct.

BTW I suggest reading the technical articles on Paul Yaw's website, they provide a very good explanation and pictures of all this stuff. I actually printed them all out and put them in my RX-7 binder

BTW thanks REVHED and Sterling for setting me straight... I'm thinking I am likely running on the lean side with my current set up. I was planning on re-jetting my carb (already have the jets) and installing a better fuel pump/FPR/FPG this year and now my mind is definitely made up.

V8kilr

yeah i read most of his articles,
i was looking for a certain one "cant remeber which"
but stumbled across that one about the timming,
was thinking of marking my pulley and didnt know the best way to do it,
now i do

i try to suck up as much rotary info as possible,
and get other peoples opinions before preaching the word,

so what would you all agree is a nice advance for a stock 12 and stock 13b

this will be info for the seven sport club site,
im adding an ignition section in there and would like to put in a small section on timming,i already have the stock timming charts.

SilverRocket

I should give this a try sometime

I think what we've all learned from this is that the right setting depends on many variables... most importantly how certain you are that you're running proper fuel mixtures. If you have a stock motor,minor mods and aren't sure about your a/f levels, I'd say the order of the day is caution. I reiterate that you aren't going to make very much power from this on a minor-modded stock port motor (ie. you aren't going to be blowing the doors off people with the same mods and stock timing) so it's hardly worth risking engine damage by breaking plugs like I did last summer. It could easily have been rebuild time for me because I was messing with stuff I didn't know enough about. Just my 2 cents.

BTW I'm now running 1 degree advanced all-round as RB recommends, and haven't had any more problems.

mar3

iTrader: (8)

OK...now is that at 800 RPM or 4000 RPM and are your vacuum canisters connected or disconnected when you set that timing? Inquiring minds would like to know...

V8kilr

i think i got my timming setup for 14 degree advance on leading and 6 or so on trailing.
would have to double check,i set the timming last year and havent played with it since,
i advanced pretty high,took it for a test drive and no problems,
from there i think i retarded 5-10 degrees just to be safe.
now that i have my msd boxes i dont worry bout it to much
since the units are supposed to spark 30-50% longer then stock.

SilverRocket

Another thing I noticed about the Yaw settings is that emissions seemed to get a bit worse (due to the 8 degree split I guess), my car stank even worse than usual. Losing the vacuum advance also contributes to this.

I've eliminated vacuum advance on my car, and that's set at idle. It's just an extra degree of advance over the stock setting. Nice and conservative

At what rpm and set how? That sounds like a pretty weird setting to me.

Just so you know, my problems didn't show up for 2 months after I started running the Yaw settings. I think it depends a lot on conditions, what you're doing with your car, etc.


Just so you all know, I also drive my car quite hard pretty much all the time, this probably contributes to the experience I had.

V8kilr

i set my timming @ 3,000 rpm,
its been set for aprox 7 months

SilverRocket

Interesting... you sure it was advanced all the way by then? Total advance is around 4k.

Since stock total advance is approx 20 degrees, I'd say you're running a pretty conservative setting. You might want to try going back to stock settings and see if you pick up any power, just an idea for you. By stock settings I mean 0 leading 20ATDC trailing at idle, and approx 20BTDC leading and 0 trailing at 4000 rpm, both with vac advance disconnected.

Whatever works for you though, we all seem to have our preferences in this area

V8kilr

well i have a rebuilt slightly modded carb
open air element with a ram air type setup,
full rb exhaust to muff
muff is a straight through design
i run msd 6a' ignition boxes with blaster 2 coils
and msd wires

so im afraid to advance to much

im going to readjust it now that i have some new toys on there,
thats why i looked into the article
thanks for all your help

V8kilr

whats the vac advance do when disconnected?

nipplebandit45

if its disconnected, it shouldt do anything, right?

Mike

V8kilr

how do you effectively disconnet it?
i like the sounds of a locked ignition system