miataman86
miataman86 New Reader
12/16/11 9:22 a.m.

I'm looking to advance the timing on my 91 NA when I change out the timing belt here in the near future. I've read that the ignition timing can be advanced from 10 degrees BTDC to 14 degrees BTDC without any adverse effects. I've read that some HP can be gained through advancing the timing. I've read that 4 to 6 to sometimes 7 or 8 hp can be gained from advancing the timing. What is the good figure of hp that would be gained from advancing the timing? I am also aware that my MPGs would go down, but really, I'm not that concerned with it that much. Also, I've read about the possibility of having to go to a higher octane rating of petrol. I just wanna get as much info as I can before I decide for sure about advancing the timing. I am also aware that it brings the powerband from 5500 to redline closer to 4000 or something to that figure.

Keith
Keith SuperDork
12/16/11 9:36 a.m.

It doesn't really matter what the exact horsepower gain is - it's cheap and easy and you'll do it whether it's 3 or 6 hp! It's a 5 minute job, if you don't like it then just set it back.

If it does affect your mileage, I suspect that's primarily because you'll be driving harder due to the massive power increase It is possible that you'll need to run higher octane.

miataman86
miataman86 New Reader
12/16/11 9:52 a.m.

Cool. Whats the easiest way to advance the timing? I know there is a little nut or something or like that on the right side of the engine, just behind the valve cover. Its a posistioning sensor for the timing, right?

drmike
drmike Reader
12/16/11 9:52 a.m.

My 94 just won't tolerate more than 11 degrees of advance. Then again it's a tired engine.

miataman86
miataman86 New Reader
12/16/11 9:53 a.m.

Ive got 136k on the engine btw

Keith
Keith SuperDork
12/16/11 10:12 a.m.

Based on your recent questions, I think you might find this book handy. It'll tell you how to adjust the timing.

miataman86
miataman86 New Reader
12/16/11 10:25 a.m.

Thanks Keith! Just put in the order for it! I'm sure it will be a great help to future projects! much appreciated!

iceracer
iceracer SuperDork
12/16/11 5:28 p.m.

4 degrees extra advance is not a lot. But then .

kazoospec
kazoospec Reader
12/16/11 8:08 p.m.
Keith wrote: Based on your recent questions, I think you might find this book handy. It'll tell you how to adjust the timing.

If that book can teach me how to get the oil filter out without spilling oil from the filter on my lower control arm, I'll take three.

miataman86
miataman86 New Reader
12/16/11 8:09 p.m.

Running past 14 degrees BTDC can increase the likelyhood of bad things happening. 14 is the most comon advancement in the timing.

EvanB
EvanB UltimaDork
12/16/11 10:00 p.m.
kazoospec wrote:
Keith wrote: Based on your recent questions, I think you might find this book handy. It'll tell you how to adjust the timing.

If that book can teach me how to get the oil filter out without spilling oil from the filter on my lower control arm, I'll take three.

That's just rust protection.

mistanfo
mistanfo SuperDork
12/17/11 1:50 p.m.

In reply to miataman86:

I've had a number of Miatas, some didnt like more than 12 degrees of advance, one loved 18! Most have been fine with 14, running premium in hot weather or when flogged upon. And generally, there was a slight increase in fuel economy.

miataman86
miataman86 New Reader
12/19/11 5:00 p.m.

Its gonna suck running premiuim in hot weather or when getting heavy on her, but more hp is the trade off. MPGs increasing, even slightly is better than nothing. I'll find out soon enough what she likes in the degrees of advancement part.

EvanB
EvanB SuperDork
12/19/11 5:03 p.m.

With my 1.6 I run 16 degrees with 93 octane always and it is pretty happy.

miataman86
miataman86 New Reader
12/19/11 5:08 p.m.

I'm gonna be looking for 14 degrees, but I'll be able to tell what she likes once I advance the timing

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