5 BTDC vs 5 ATDC

paul w · Post by **paul w** » Thu Sep 02, 2010 12:41 pm

Apologies if this is a really, really thick question, but the manual for the timing on my auto N12, says 5 degrees BTDC. That's what I've been using.

Anyway, I checked the timing and such yesterday, just moseying around the engine, and found that the mechanic who last worked on it put it 5 degree AFTER TDC, i.e. the first mark clockwise on the pulley (anti-clockwise has five marks: 0 . 10 . 20. I was using the second mark on this.)

I'm presuming it's for more power....but why change it?

sgs · Post by **sgs** » Thu Sep 02, 2010 4:09 pm

dude that will make ur car gutless and backfire, five degree before TDC not after

Damo · Post by **Damo** » Thu Sep 02, 2010 4:41 pm

sgs wrote: five degree before TDC not after

Sorry, is that so! According to which manual?

Damo

paul w · Post by **paul w** » Thu Sep 02, 2010 4:50 pm

"dude that will make ur car gutless and backfire, five degree before TDC not after"

The car is running like a dream.
But...fuel consumption is up from 7-7-5km/l to 8.5km/l.

Post by **tassuperkart** » Thu Sep 02, 2010 6:46 pm

because your engine is running with a 10 degree retard.
Itll run smooth allright but youll be well down on performance.

However, atmo e15's dot take kindly to much advance and low octane ULP.
"rattle rattle rattle tinkle tinkle!

l8r
E

sgs · Post by **sgs** » Thu Sep 02, 2010 6:58 pm

when the heel on my points worn off due to lack of oil, it dropped back to exactly TDC, car was guttless and backfired when i buttoned off the trottle. i would hate imagine what five degrees after TDC would be like

Damo · Post by **Damo** » Thu Sep 02, 2010 10:29 pm

sgs wrote:when the heel on my points worn off due to lack of oil, it dropped back to exactly TDC, car was guttless and backfired when i buttoned off the trottle. i would hate imagine what five degrees after TDC would be like

If you have a look at the emissions placard under the bonnet, it will show you ignition timing it should run. Any E15 carby engine sold in this country runs a setup timing of from 5-7deg ATDC! This does move a long way back into BTDC with the vac line hooked back up after tune up checks, but factory timing is ATDC.

Damo

sgs · Post by **sgs** » Fri Sep 03, 2010 9:43 am

my car is New Zealand new

will be trying out the so called factory settings out. will get back to you guys with how that goes!

paul w · Post by **paul w** » Fri Sep 03, 2010 2:16 pm

Damo

Interesting point. I just checked my Gregorys (Australian) manual, and it says 5deg BTDC, but my official Nissan Australia manual workshop says 5deg ATDC.

Okay, back to basics for me; the marks on the auto N12 are, anti-clockwise; (mark) 10, (mark) 20. In other words, four marks indicating 5, 10, 15, 20. Clockwise, just on mark that corresponds to 5deg.

So, let me get this right; the single mark clockwise is 5deg BTDC, and the rest are ATDC?

If that is so, I made a mistake in my opening post; the timing set by the mechanics is actually the 5deg single mark going clockwise.

I've been timing it at the 5deg mark in the anti-clockwise.

sgs · Post by **sgs** » Fri Sep 03, 2010 3:45 pm

Damo,
i'v change my timing to 5deg ATDC, car is running mint. It now makes more down bottom end

nothing strange happening, has alot lot better exhaust note also. i have a feeling im gonna save heaps of gas!

well we learn something new everyday! Thanks Damo

btw, are nissan E series engines unique in this way because everybody i talked to about it looked at me kinda side ways

Denied · Post by **Denied** » Sat Apr 05, 2014 6:29 pm

holy thread revival Batman.

Figured I'd bump this since I just ran across this 'fun' today. Manual for N/A version does state timing @ 5° ATDC when dizzy vac line disconnected

It is 5° BTDC when vac line is connected. Which is the mark to the left of the 0° timing mark (counter clockwise when looking in from the drivers side wheel well)

After driving around with what amounted to 10° of retard, I now know how important timing is... absolutely no power, hesitates whenever you press the accelerator. Returned the timing to 5° BTDC and she's much more responsive and back to her usual self.