Timing Advance

[vercingetorix]

Hello,

I just installed a 280ZX distributor with an E12-80 module in my '71 and was wondering what the best timing advance is for it. I have it set about 17 DTDC and it seems OK, But I know nothing of this unit.

Thanks ,

H Houghton

PS

Still cant get the tach to work.

[cj71z]

I've been dealing with this for awhile as well and what I finally decided to do is disconnect my vac advance because at cruising speeds it would over advance. I had mine set at 8 degrees with the vacuum connected and it was still detonating. Now with it disconnected I run about 15 degrees since my dist mechanically advances 17 degrees. This now gives me a total of 31 degrees advance. Other threads here describe the different mech. advance rates avance rates available on these distributors. You can find out yours by checking the stamp on the shaft where the centrifugal weights are connected. Take this figure and double it and you'll have the total mech. advance for your distributor. There are ways to recurve the distributor for more initial advance, but still retaining vacuum so the gas mileage doesn't suffer. Rebello can do this for 70$(I think), check their website. One way to figure out your total advance is to get an adjustable timing light and shoot the timing with your car at 3000k. If you google timing mark calculator, the first hit is a website where you can enter figures to determine the placement of a mark at a specific degree. Find the place for 32 degrees, mark it. Crank your car to 3k, shoot the timing and adjust your dist until the mark lines up with the pointer on the timing cover.

[jmortensen]

15-20 degrees should be right in there. Need a dyno to pinpoint it any farther than that I'd expect.

[Victor Laury]

If you have a dial-back timing light, you can determine your dizzy advance without lifting the breaker plate.

Disco the vacuum line.

set the idle for 2,500

check the timing - adjust to 34 BTDC

set the idle to 700

check the timing

Let's say you find it to be 12 BTDC

34-12 = 22

22/2 = 11 - you have an 11 dizzy advance - lift the breaker plate and you should see the "11" stamped into the advance weight guide.

My opinion is that the 9.5 and ideally the 7.5 dizzys are the better perfomance models. I call the the 11's "Smog Dizzys". Just 2 cts, I could be wrong.

your total advance should never be higher than 35 on astock engine, using high test gas, unless you want to start melting pistons. Racing cams with lots of overlap can run higher.

[vercingetorix]

Thank you gentlemen,

I will check it on the highway and perhaps play with it some more. Took it to town today and could not believe how much better it accelerates. Also it has never started so easily, one crank and away it went.

Best,

H Houghton

[jmortensen]

your total advance should never be higher than 35 on astock engine, using high test gas, unless you want to start melting pistons. Racing cams with lots of overlap can run higher.

Generally best power on the L series running a distributor is had around 35 degrees advance. If you run that much and it pings, add octane and keep the increased power. If it doesn't ping, don't worry about increasing the octane. It has not been my experience that running 35 degrees of advance causes any damage whatsoever as long as the car doesn't ping. I cannot think of any good reason why more advance would melt a piston without preignition or detonation as a factor. I'd love to hear one though Victor...

[kully 560]

I am new to this forum but have had my 260z since 1979.I need some help on tach hook up ,I just installed a 1979 280zx dissy 12/80 module .I removed the ballast resister and do not know how to hook up the tach.what color wires do I use and where do they go.I have been reading this post and saw some discussing on the 280 dissy and thought maybe I could get some help thanks kully

[Victor Laury]

Generally best power on the L series running a distributor is had around 35 degrees advance. If you run that much and it pings, add octane and keep the increased power. If it doesn't ping, don't worry about increasing the octane. It has not been my experience that running 35 degrees of advance causes any damage whatsoever as long as the car doesn't ping. I cannot think of any good reason why more advance would melt a piston without preignition or detonation as a factor. I'd love to hear one though Victor...

Jim, Didn't say not to run 35 degrees, I do on the roadster and the Z. But I don't recommend to anyone that they arbitrarly set to 35. Their head may have been shaved or their mixture may be a bit too lean, and hell yes you can melt a piston. I have one in my trophy case. You might not even hear the pinging, but, at speed, pushing against the aerodynamic barrier, you could be detonating like mad and not even know it. I'n my case, it was 5th at 5,500 126MPH (roadster) - and suddenly my windshield was full of oil

[jmortensen]

I've never heard of any of my friends' Zs or 510s having any issues at all at 35 degrees. I used to run 87 octane at that advance in my L28. No ping, no damage. I think advising people that they should stay away from that much timing unless they have a big camshaft is overly cautious. That's my opinion anyway.

PS-It's Jon, not Jim.

[Arne]

As for the tach part of the question, I had little or no problem getting the tach to work in my '71 with the ZX/E12-80 combo. I'll have to take another look at the wiring on mine when I get home, but I don't recall doing do anything special. Jumped the two wires from the ballast resistor together, and connected the other to the coil. I think that was it.

[Carl Beck]

I've never heard of any of my friends' Zs or 510s having any issues at all at 35 degrees. I used to run 87 octane at that advance in my L28. No ping, no damage. I think advising people that they should stay away from that much timing unless they have a big camshaft is overly cautious. That's my opinion anyway.

PS-It's Jon, not Jim.

Hi Jon (everyone)

Keith Thomas said that when they put the L24's on the dyno - they found that they lost HP with timing advanced much past 32/33 degrees total. They'll take 35/36 but it wasn't the best HP producer...

Lets all keep in mind that it isn't just total advance that you want to control - it's the total timing curve over the RPM range... which in many cases means you start with the timing curve dialed into the distributor...

FWIW,

Carl B.

[jmortensen]

Carl, it totally depends on the engine. Examples:

I have seen an N/A Lseries motor lose 16 HP on a dyno simply by retarding the timing 6 degrees from 37 to 31 degrees, so don't think you can go high on compression and then eliminate pinging by retarding timing and not expect to lose HP.

I've also been to the dyno and LOST 18 hp by running VP11 fuel, vs. 93-octane pump. I got 8hp back by advancing the timing from the 34deg (lowest advance that didn't hurt hp on 93-pump) up to 39deg with the VP11, but still didn't make as much as I did at 34deg on 93 pump. Go figure...

Mid 30s (I suggested 15-20 degrees for the ZX distributor which is 32-37 degrees total with the 17 degree advance model) generally speaking IS where L series make the most power, unless you're running distributorless igntion. Check this out:

Big surprise was these motors like a slow and steady

advance all the way from idle to redline. We had

fooled around for years trying to get the right amount

of kick back dialed into the distributors.

The first motor, a very high compression L18 autocross

special, makes 207 hp through about 43mm venturis, big

valves, about 14:1. It was best at 18' initial/18'

more at 3000/ 6' more at 8000.