How much Spark Advance

[pressonregardless]

After I changed my timing belt and all was safe in the world, plus my idle was much smoother, I set my static timing to 0' TDC as is states on the engine plaque. Not having the power I was looking for, I advanced the timing to 10' BTDC and of course it idles faster and had to be adjusted as well as starts fine and does seem to have more power with no pre-ignition. My question is how much advance can/should the 1756 engine have at the basic setting. I am running NGK plugs and 87 reg unleaded fuel?
My last tank running around the country side with the wife and not driving like I stole it gave almost 23 mpg?

Looking for advise, thanks, Charlie

[mdrburchette]

It may vary slightly but it should be around 36 degrees total unless you've got the electronic ignition setup. Then it drops significantly.

[pressonregardless]

Thanks Denise, again. I take it the 36' total means at some RPM above idle when the flyweights advance the distributor, right? I have no vacuum advance on a '74. I am trying to determine what the max "safe" static timing might be on a 1756. So I guess you just bump it up another 2' or so and listen for light knock. Do you know what RPM the max advance come in on?

Thanks, Charlie

[mdrburchette]

I'd say around 3200 rpm. Guys, feel free to jump in and correct me. I'm basing this on a 1608 with mechanical advance but it shouldn't be much different

[pope]

Hey Charlie,
Did you know that Fiat recommends 92 or higher octane in these Spiders? With the way gas was, seemed crazy to go there, with gas under $2 a gallon, its nice to get a full tank every once in a while for a peppy surprise.

[pressonregardless]

Well, I know in California our Fuel has a "added value cost" as we are lucky we are allowed to drive private autos, that said, I'll have to step up the static timing and take advantage of all that octane! Has anyone heard one of these engines (1756cc) ping? I've dumped the clutch pretty heavy and never yet hear a knock. Just wondering? Thanks, Charlie

[racydave]

I would think that you would want 36 btdc at around 3 to 3200. You can find some diff springs and play with it, the fuel milage and butt dyno tell all! I adapted some chevysprings before going total electronic. If the static is more than 10, it might not wanna start when warm. Mine hasnt spark knocked yet...and I run 87 octane. But Ive never checked the milage either...

[So Cal Mark]

I've got several running at 15 btdc initial timing and they start just fine

[mdrburchette]

Yep, my 71 is set higher to give a little more advance with the electronic dist and it hasn't affected the starting. I also don't have any pinging. As for gas, all my babies get 93 octane.

[pressonregardless]

Thanks guys! I can't wait to get my 1978 Craftsman timing light out this weekend By the way, I finally found a Dwell meter at Harbor Freight and had my Points almost perfect, .017" and 54' dwell (book says 55' dwell) does any one else know were to find a dwell meter these days? Just wondering. Charlie

[racydave]

I think Sears has dwell meters, mines dusty, musta got it in the 80's.

[majicwrench]

Just my two cents, but I would leave well enough alone before it DOES ping. Pinging is dang hard on an engine. Ten degrees is ( I believe ) what most of the old Spiders set the timing to, and that would be a good place to leave it. In theory, the more timing you can put into the engine, the more power and mileage TILL IT PINGS. Pinging ruins power, mileage and engines.
If you want to set the total advance to 36deg,, measure the curcumfrance (sp?) of the crank pully and divide by ten. That measurement will get you 36degrees. For the sake of this post let/s say the circumfrance was 21". Divide by ten = 2.1". Now find the TDC mark on the crank pulley, and measure 2.1" from that mark in a clockwise direction, and make another mark, say with a dab of white paint. Now start engine, look with timing light, your original mark should be at 10deg. Rev engine, you will see original mark begin to move up (conterclockwise) and your new mark will start to move up as well. At some point your advance will quit advancing, likely tween 2500 and 3000, adn at that time your new mark should, in a perfect world, line up with the "0" mark on the belt cover. Most engines, fiat and otherwise, will take about 36deg total advance. Still, better safe that sorry, leaving it backed off a bit is good insurance.
Of course all this is easier with a timing light with an advance feature.
Jeesh I got long winded...
Keith

[TulsaSpider]

On the octane question/issue... is it not true that you should use the lowest octane level possible without detonation? Octane only prevents detonation right? Denise you run 93, but aren't your motors pretty modified?
On the advance issue. Mine is a stock points/carbed 1800. When I was trying to tune my advance by ear I could never get mine to ping, and yes I did try. Are these things hard to ping? I set it to where I thought it ran the best. When I got a hold of a timing light it was pretty far advanced. recently I have gotten it running much better doing a complete tune up. With all these threads about timing lights lately I have the bug now! none of the parts stores around here have them in their loaner program though. I'll see what I can find out there. It is running the best it has ever ran so far, but I'd like better, of course!

[pope]

On the octane question/issue... is it not true that you should use the lowest octane level possible without detonation? Octane only prevents detonation right?

You should use what the manufacture says. Lower octane gas ignites quicker than high octane gas. This can lead to your gas igniting before your engine is ready for it, which means that it can change the timing of your engine. This means it is not optimal for your engine in theory. Fiat tells you what is optimal for your car and anything else might need a slight timing adjustment, which is what most have done already by timing it with 87 octane.

It would be kinda cool if someone timed their engine to 87 and went for a week and checked milage and performance. Then switched to 92 or 93 and retimed their engine with another week of checked milage and performance. Would like to know the difference.

[mdrburchette]

My owner's manual says to run 91 octane and the Fiat service manual says to run premium fuel. It may be different for the later model cars. I've only run 87 octane in my 71 once when North Carolina ran out of gas a couple months ago and I didn't notice a difference in the way it ran.