Ignition advance specs?

[danzo]

I should add a few items I noticed when my EGR vac ports were blocked - my car earned a record low mpg, around 23. It was getting about 29-30 with the stock carb. I know, apples to oranges, but still noteworthy. Also when I hooked the lower EGR vac port to the manny vac source the car ran terribly so I immediately recapped it.

Hopefully today my brother in law's brother (my brother squared in law?) can cut me a slick EGR plate with his fancy CNC machine. Of course pics would follow. Speaking of pics, I parked next to a Lamborghini yesterday but didn't have the camera handy, rats. Had the automotive ying and yang in one shot.

[ARCHINSTL]

Speaking of pics, I parked next to a Lamborghini yesterday but didn't have the camera handy, rats. Had the automotive ying and yang in one shot.

If the Lambo driver came out before you - ya think he didn't examine the side of his car for a T4WD marking its territory?
You shudda left a note: "I've got six gears forward, too!"
Tom M.

[danzo]

"I've got six gears forward, too!"

Good one Tom, I didn't think of that! It could have also said "My $400 car gets me to the nudie bar just like your $200k car will". But alas I was in a hurry. I'm sure the owner was in the restaurant monitoring his car for door dings, which is one of the main reasons why it sucks to have a car worth that much. Too much to worry about.

[Petros]

And in some circles, the Tercel4wd appears to be just a good a chick magnet as the Lambo too! Do you think?

When I was in collage is so. California beach cities I had a friend who I helped rebuild his MGB, which he later sold and bought a Fiat sports car (which I also helped him rebuild). One day driving in his Fiat we saw a sports car dealer on PCH in Manhattan Beach CA that had a nice little lotus elan convertible we wanted to drive. So we stopped and started looking over the Lotus (I helped another friend sort one out, they always have electrical issues being all fiberglass bodies, so I was familiar with the Lotus elan as well). The salesman let us drive off in it without him since it only had two seats. My than girl friend (now my wife of 26 years) only lived two blocks away so I thought it would be fun to drive over there to show her the Lotus.

Both my girlfriend and her sister, two sunshine blonds wearing little tight shorts and tank tops that expose their slim mid drifts (normal summer wear in the beach cities) loved the car and wanted to go for a ride. So they climbed into the area behind the seats (this was before manditory seat belt laws) and we drove it around the block, top down and blond hair streaming in our wake. I thought we should hurry back to the dealership before they start to worry. So with the two young women in the back be turned the corner and back into the sales lot.

It was very funny to see the look on the salesman's face when we pulled back onto the lot, two tanned scantily clad young blonds climb out of the back of the Lotus and than head strait for the Fiat giggling. I handed the bewildered looking salesman the keys to the Lotus saying "it works great!", and we drove off with the girls in the Fiat.

I still get a chuckle out of it every time I think about it. I always wondered if the salesman took the Lotus home for a "test drive" that night.

[dlb]

excellent story, peter, i love it. you dog, you!

[danzo]

DLB might want to hear this. I thought I should post a recent update to my car's former pinging problem. I know, I know I've claimed victory in the past but I think it's gone for good. After replacing the front main seal (lost 2 quarts in a week) and water pump (still had the original Aisin) I put in a slightly smaller 135 primary main jet to complement the 140 secondary. Still pinged even with the timing set at 0* and 95F outside temp.

So I remembered someone mentioning we could run these cars without the vac advance unit at all. I pulled to the side of the road and yanked/capped the ported vac port on the Weber, thus completely disconnecting the vac advance. This gave me the slightest ping under light load. So when I got home I checked the timing, it was now 16* and would advance about 10* if I revved it above 3000rpm or so. So I simply set it to 10* and now it doesn't ping at all, even when fully warmed on a very hot day. The car is running better than ever and it doesn't leak oil to boot! Next up is fixing the a/c.

BTW initial mpg results look very favorable as per gas gauge. When I run a whole tank through it I'll be sure to email the figures to takza.

[dlb]

the saga continues. i've been working through this as well. i found a small vacuum leak at my splatterdog PCV mod--i had cracked the old EGR casting by overtightening the barb fitting so i made another and used JB weld in the threads and was careful not to use my superhuman strength on it. i also found the vacuum hose was swollen and a little loose on the vac advance port from the oil that had been leaking from the dizzy before i replaced the o-ring. i trimmed the fat there and it then fit snugly. went for a drive, still pinging. disconnected the aft PCV port from the valve cover just to rule it out, still pinging. only other vacuum hose leak possibility is in the PCV valve which was a little lose in its retainer, don't know if that makes a difference but i replaced it and made sure it fit snugly. i've sprayed carb cleaner everywhere and the PCV leak was the only leak i found so if the ping is still there, i'll reset the fuel mixture one more time and try some different vac advance stuff.

something interesting that i will look at today: at the bottom of page 218 or IG-5 of the manual, it looks like there are actually two vac advance ports on the vac can. then on page 227, or IG-14, in the manual it clearly shows in 3 different pics that the vac advance port is one of the upper ones. i wonder if there are two ports that do the same thing to advance the timing under different conditions or if the manual is mistaken--petros has mentioned how horribly wrong these things can be. anyway, i'm going to play with my spare dizzy today and familiarize myself with it.

danzo, let me know how your MPG shapes up w/o vac advance and if the ping stays away. that would be a rad thing. i work around mine but would seriously love it gone.

[4wdchico]

The vac adv assy has two diaphragms in two canisters on US cars. Pretty sure that Canada cars have the same vac adv units. I call the canister that is the farthest out from the dizzy the outer canister and the closer one the inner canister. Tho outer canister has only one vac nipple on it and it is hooked into the same vac circuit as the EGR valve. If the inner canister has two vac nips on it, one should have a brass restriction just inside it's end. This restricted port is only used on the US Federal cars that were equipped with the high alt comp system (HAC in FSM speak). The other, unrestricted, nip on the inner canister should be connected to the gas filter on the intake manifold on a Canada M/T car.

I know that you have a Weber on Ron so the above is mainly for your better understanding of the ignition advance vac system.

[4wdchico]

dlb:

If I had the option of doing without an EGR valve I would probably use the EGR valve mounting position on the intake manifold to mount a nozzle for a water injection system. It is about as close to ideal a place for a water nozzle as one could imagine on the strange 3ac intake manifold. If you ran half methanol in the water injection system you would have a power boost. Even without adding methanol to the mix your combustion chambers would be so clean after a while that your small amount of ping would most likely go away. You would have to add the methanol in the winter to prevent freezing.

Is your car pinging at full throttle?

[4wdchico]

The EGR when working properly will slightly reduce the tendancy to ping at full throttle (the exhaust gases mixed in to the intake reduces combustion temperatures).

Sorry Petros, but I have to disagree with this. EGR systems are designed to not function at full throttle. On cars with vac emission systems this is very simple as there is no engine vac at WOT to actuate the EGR valve. On cars with electronically actuated EGR's (very common on GM products) the ECU is programmed to not open the EGR at full throttle.

For anyone who wants a better understanding of EGR function please see my post at the bottom of this page:

http://www.tercel4wd.com/forums/viewtop ... 8&start=15

[dlb]

The vac adv assy has two diaphragms in two canisters on US cars. Pretty sure that Canada cars have the same vac adv units. I call the canister that is the farthest out from the dizzy the outer canister and the closer one the inner canister. Tho outer canister has only one vac nipple on it and it is hooked into the same vac circuit as the EGR valve. If the inner canister has two vac nips on it, one should have a brass restriction just inside it's end. This restricted port is only used on the US Federal cars that were equipped with the high alt comp system (HAC in FSM speak). The other, unrestricted, nip on the inner canister should be connected to the gas filter on the intake manifold on a Canada M/T car.

thanks for the vac can info, 4WDC. i'm definitely interested in this. one more question on that topic, how do the inner and outer canisters jobs differ? do they both advance the timing, but under different conditions?

If I had the option of doing without an EGR valve I would probably use the EGR valve mounting position on the intake manifold to mount a nozzle for a water injection system. It is about as close to ideal a place for a water nozzle as one could imagine on the strange 3ac intake manifold. If you ran half methanol in the water injection system you would have a power boost. Even without adding methanol to the mix your combustion chambers would be so clean after a while that your small amount of ping would most likely go away. You would have to add the methanol in the winter to prevent freezing.

Is your car pinging at full throttle?

showing my true newb colours here but i've never even heard of a water injection system. i'm going to have to google it.

as for pinging at full throttle, no. it goes like this: cruising at highway speeds, all is well. hit a hill, keep throttle steady, engine starts pinging--this is not due to lugging the engine, the revs can be as high as 3000 and it will still ping ever so slightly. if i give it a bit more throttle, the ping usually decreases substantially or disappears. i currently have the outer canister connected to the gas filter so maybe i should switch it to the inner can, in conjunction with what you just said and what the FSM says. could my current set up be advancing the timing at the wrong time?

[4wdchico]

dlb,

The inner and outer vac canisters should each provide roughly the same amount of advance for the same amount of vac applied given the fact that they both move the same rod and spring. That is if they both have the same diameter: IIRC they look to have the same OD. The major difference is that they are provided with vac from different vac circuits. In the case of a stock Canadian M/T t4wd the inner canister is hooked to manifold vac at all times. The outer canister is connected into the EGR vac circuit which is connected to the EGR vac port on the carb: that is a ported vac source that does not have vac until the throttle is opened a bit above idle.

What I would try is to connect the inner vac canister to the gas filter like it was stock. Then I would see if you have a ported vac point on the Weber, the odds are very high that there is one. Connect the ported vac source right to the outer vac canister. No need to use the TVSV in this case as turning off the EGR vac circuit was to prevent tip in stumble caused by having an active EGR system on a cold motor, not an issue in your EGR valve-less case. You will have to retard the base timing a bit as having two working vac diaphragms will provide more vac advance at the always important steady state highway cruise condition. The advantage is that having both canisters active and providing more advance, the amount of vac advance will vary more with small changes of engine vac. After all, your car was designed to have both vac canisters supplied with vac when the engine is warm and motoring along with the upper edge of the throttle plate above the ported vac point on the carb.

Way back in the day when the vac advance system was first invented, well before my time, the system was called the economizer as having ignition timing vary in response to changes in engine load was a major improvement in efficiency and engine durability.

[dlb]

What I would try is to connect the inner vac canister to the gas filter like it was stock. Then I would see if you have a ported vac point on the Weber, the odds are very high that there is one. Connect the ported vac source right to the outer vac canister. No need to use the TVSV in this case as turning off the EGR vac circuit was to prevent tip in stumble caused by having an active EGR system on a cold motor, not an issue in your EGR valve-less case. You will have to retard the base timing a bit as having two working vac diaphragms will provide more vac advance at the always important steady state highway cruise condition. The advantage is that having both canisters active and providing more advance, the amount of vac advance will vary more with small changes of engine vac. After all, your car was designed to have both vac canisters supplied with vac when the engine is warm and motoring along with the upper edge of the throttle plate above the ported vac point on the carb.

ok, sounds good. the wife has ron for today so i'll check to see if it was still pinging with the PCV disconnected and if so i'll give it a shot. this is the way that tom has his set up, incidentally.

i read up on water injection, it sounds rad. i'm surprised no one on this forum has mentioned it that i can remember. one site that has step by step instructions on how to make one says that the water would need to be injected before the throttle body though. is this not a hard and fast point?

here's the site: http://www.turbomirage.com/water.html

the guy is a little over excited about water injection but the site appears legit.

[4wdchico]

Wow, a guy claiming that injecting water anywhere before the turbo is a good idea! It is well established that doing so will cause erosion of the compressor vanes (blades if you prefer) in the turbo by the water droplets.

Back in the '60's & '70's a lot of cars had simple low pressure systems that basically dribbled water droplets into the carb throat, the nozzle was often mounted in the lid of the air cleaner assy. A sub-optimal system for many reasons, but they did reduce ping and octane requirements.

My suggestion of mounting the nozzle where the EGR valve was mounted was predicated on having a modern system that includes a high pressure pump (100-200 psi, higher the better), a sophisticated, correctly sized, nozzle designed for water injection (proper spray pattern) and an adjustable control based on a Hobbs switch. The Hobbs switch will allow the tuner to adjust the point where the water spray comes on relative to engine vac. Or you can go big and spend for a programmable progressive water injection controller that will allow you lots of tuning options. A fancy controller will still sense engine vac, but it will often also sense RPM's, coolant temp and throttle position if the car is equipped with a throttle position sensor.

Google up water injection kit and see what the many vendors of high tech water injection have to offer.

[ARCHINSTL]

dlb -
http://www.tercel4wd.com/forums/viewtop ... ion#p32172 Some good following posts from Petros, Snax, and danzo.
Also do a Search using water+injection with takza's name - he did some experimentation with this some years ago.
Tom M.