How hard would it be....?

[AK-Z]

How hard would it be to convert a vacuum actuator on the dizzy to a boost actuator? Or convert the vacuum actuator to retard timing? This being on a NA l28 being converted to a turbo, with the intention to have less electronics.

[2126]

If you are talking about the vaccum advance pot on the distributor, I don't think so. Inside the distributor, a linkage arm is connected between the vacuum pot and the timing advance plate assembly. I cannot see how you could use this as a boost actuator. Or, are you suggesting that you take the vacuum pot off the distributor completely and use it?

[Guest ZFury]

Unhooking it would be the easiest thing to do.

 

But here is my 2cents. Seeing that the larger the vacuum the more the timming gets retarded. Here is what you can do. Hook up the vacuum hose to infront of your turbo intake. The air rushing into the turbo intake will create vacuum, the more the TB or carb is open, the more vacuum it will create. Thus the timming retarding will increase the more you open the throttle. More boost will = more vacuum. You will want to place the hose fitting furthest away from the air filter, and as close as you can to the turbo. Finding out your typical intake manifold/carb vacuum at idle going to the distributor will help you guage things. Then find out your vacuum that is created in front of the turbo. My guess is that the vacuum in the intake of an N/a will be more than the turbo vacuum, but you should still get the distributor to retard some with the vacuum created from the intake of the turbo.

[mario_82_ZXT]

I'd take a look at the Euro 280zxt Dizzy's.

 

If I recall they did just that. You might be able to copy the mechanism or something....

Mario

[olie05]

But here is my 2cents. Seeing that the larger the vacuum the more the timming gets retarded. Here is what you can do. Hook up the vacuum hose to infront of your turbo intake. The air rushing into the turbo intake will create vacuum, the more the TB or carb is open, the more vacuum it will create. Thus the timming retarding will increase the more you open the throttle. More boost will = more vacuum. You will want to place the hose fitting furthest away from the air filter, and as close as you can to the turbo. Finding out your typical intake manifold/carb vacuum at idle going to the distributor will help you guage things. Then find out your vacuum that is created in front of the turbo. My guess is that the vacuum in the intake of an N/a will be more than the turbo vacuum, but you should still get the distributor to retard some with the vacuum created from the intake of the turbo.

 

no... On a N/A l28 dizzy, the vacuum "advance" actuator "advances" timing. It does nothing to retard the timing. If you were to run a vacuum hose to the inlet of the turbo, when you got on the throttle and drew some vacuum, it would be advancing the ignition timing.

 

yes, "more boost will = more vacuum" but in this case, More vacuum = advanced timing.

 

I would do as the first line of ZFury's post says and disconnect the vacuum advance all together.

 

You could also run the msd 6btm which will retard timing one degree per lb. of boost.

 

or do as Mario said

 

btw... AK-Z, aren't you going to do a KA swap?

[Guest ZFury]

One easy way to tell. Take off the hose. Plug the hole in the manifold. Start the car, let the car idle. Then suck on the hose with your mouth or use a vacuum pump. The car idle/timing should slow down. If it does, then it is how I explained. If not. If it speeds up, I was wrong. If it speeds up, you could just leave it on how it is with your car boosted. It will retard with positive pressure then. You will just reach your max retardation within' a few PSI. But it will still retard.

[AK-Z]

Uh, you guys are making it more complicated than it may seem. Yes I've thought about vacuum retard.

 

Goal: retard timing under load (vacuum or boost, depending on how its plumbed and what optin is used)

 

Possible solutions:

 

1. dismantle vacuum actuator and some how reverse internal components to convert to a boost actuator. The load adjustment plate has some play to move counter clockwise (retard)

 

2. Some how make a plate that move the mount location of the actuator arm to the other side of the dizzy to retard under vacuum.

 

3. Find a boost actuator that will fit.

 

How did the SSS/cartech system deal with this? Don't need any one to explain pumbing to me since that seems obvious. Any other options?

[510six]

Why not just use an MSD boost timing master.I ran one for years on my car with a 82 NA dist with the vacuum advance disabled.I think I even have the dist sitting around somplace one of the cool things about the MSD units is that the little black trigger box can be removed. and the MSD can function as the trigger.

 

http://store.summitracing.com/partdetail.asp?part=MSD-8762

 

http://pg.photos.yahoo.com/ph/sss510six/detail?.dir=15c7&.dnm=5971.jpg&.src=ph

[Bernardd]

As soon as you go into boost the vacuum advance isn't doing anything. You could adjust the mechanical advance to whatever you want to be your max advance. You'd have to determine what your max mechical advance is, then change the stops to bring it down. I'm not positive on what it is but I believe it's around 36deg's at 4000 rpm.

[AK-Z]

As soon as you go into boost the vacuum advance isn't doing anything. You could adjust the mechanical advance to whatever you want to be your max advance. You'd have to determine what your max mechical advance is, then change the stops to bring it down. I'm not positive on what it is but I believe it's around 36deg's at 4000 rpm.

 

you obviously didn't read my last post. GOAL is ot retard timing, not advance. For turbo application.

 

And you didn't read zfury's post either. vacuum retard can be achived by routingthe plumbing to the intake side of the turbo. Getting the dizzy to retard timing some how is the problem.

[Bernardd]

i read it and completely understand it. i've over estimated your knowledge. sorry about that.

[AK-Z]

i read it and completely understand it. i've over estimated your knowledge. sorry about that.

Over estimated my knowledge? Don't you mean under estimated?

If you advance timing under boost, that will cause the spark event to happen too early in the stroke cycle causing the engine to knock. On NA motors it is advanced because it gives the air/fuel adequit time to burn. on turbo motors timing has to be retarded because since more air and fuel are being forced into the cylindars, that causes the air/fuel to be hotter than a NA motor, which make the burn to be much quicker. thats why when you put too much boost is tends to predetinate (knocking), which would mean you wouldneed more fuel to displace some of the air entering the cylindars.

 

Now, no has mentioned how they managed to SSS or cartech (carbed turbo) system to work in context to the dizzy.

[Bernardd]

Over estimated my knowledge? Don't you mean under estimated?

 

 

I never mentioned anything about advancing the timing in my previous post, hence the comment about your knowledge, which I still stand by. You should know how it works before you go about modifying it. I'm sorry if I pissed you off, I didn't mean to. BTW I have a buddy with a supercharged L28 running the stock distributor. He's at 7psi and hasn't had to retard the timing at all, just make sure the afr's are good.

[AK-Z]

Super charging is a little bit different than turbo charging since the with a SC the amount of boost is dictated by the amount of load (RPM) the engine is under. A SC system behaves more like a NA system, as in its more of a linear boost gain than, more of the on off (on boost, then shifting) of a turbo system. Fuel maps are more like a NA map also, than one for a turbo system. And honestly the 7 psi of boost isn't enough to have to retard timing. With a SC system you can just put in bigger injectors (with vac advance disabled) and put on a smaller pulley.

 

You are also forgetting spark dwell timing, which is mechanically dictated. If you advance the advance plate and adjust the dizzy housing to compinsate, it will shorten the amount of spark dwell, which is not good for idle.

 

I have 2 L28 engines and have one of the dizzies in front of me. So Bernardd how do think I should accomplish retarding timing.

[Mack]

I think what Bernardd is trying to say is that you CAN'T retard the timing using the stock dist. its a one way thing. it only advances and to my knowledge, no one has made it retard instead of advance.

 

with the old school carbd turbo set-ups, they didnt have to worry about ign retard because none of them ran more than about 7psi of boost, to the best of my knowledge.

 

also, there is no such thing as pre-detonation. its either detonation (which is livable to some degree) or pre-ignition, which will hole pistons and kill motors in VERY short order.

 

and about the SC vs TC thing, boost is boost. SC's heat up just as much as TC's. the only reason an SC map looks like an NA one is because there is no sudden onset of boost. If you had a turbo that spooled at idle, it would look like an NA map as well.

[spotfitz]

Making a small push rod with a fixed centered fulcrum, one end attached to the vacuum pot arm and the other end hooked up to the breaker plate assembly would reverse the direction of actuation. This would make it retard timing rather then advance it. Offsetting the fulcrum would increase or decrease the ratio of movement, depending on which direction you offset it. Depending on what degree you have the breaker plate when attaching to the push rod could limit the amount of retard. Confinements may be the problem though.

I would throw together a drawing, but I'm alot better at autocad then paint. LOL

[AK-Z]

I think what Bernardd is trying to say is that you CAN'T retard the timing using the stock dist. its a one way thing. it only advances and to my knowledge' date=' no one has made it retard instead of advance.

 

with the old school carbd turbo set-ups, they didnt have to worry about ign retard because none of them ran more than about 7psi of boost, to the best of my knowledge.

 

also, there is no such thing as pre-detonation. its either detonation (which is livable to some degree) or pre-ignition, which will hole pistons and kill motors in VERY short order.

 

and about the SC vs TC thing, boost is boost. SC's heat up just as much as TC's. the only reason an SC map looks like an NA one is because there is no sudden onset of boost. If you had a turbo that spooled at idle, it would look like an NA map as well.[/quote']

 

Sorry, you are right. I got the words mixed up. Pre detination happens when fuel leans out on boost.

 

Spotfitz, I though I asked that on one of my earlier posts, I guess when I type at 2 in the morning, it comes out differently than what I though lol. But looking at it closer there is a plate underneath with ball bearings what I assume to limit the amount of movement of the advance plate. I haven't taken it apart that far to figure out if thats possible yet.

 

Does any one have pics of a euro turbo dizzy setup? I remember seeing one a while back but I don't think I saved it anywhere.

[Bernardd]

As soon as you go into boost the vacuum advance isn't doing anything. You could adjust the mechanical advance to whatever you want to be your max advance. You'd have to determine what your max mechical advance is, then change the stops to bring it down. I'm not positive on what it is but I believe it's around 36deg's at 4000 rpm.

 

I should have said "limit" your mechanical advance to whatever you need it to be. These guys are doing what I meant to say.

http://forums.hybridz.org/showthread.php?t=114128

[Tony D]

To address the original topic question, why bother? Just get the Advance/Retard Can for the ZX dizzy from a European Spec L28ET.

 

They had a vacuum can that did EXACTLY that! They didn't need no stinkin' ECCS. They got no cat, a .82 A/R Turbine, no ECCS, no EGR, and 20 more HP than Stateside vehicles.

[rztmartini]

where could you get a Euro zxt dizzy? those might be hard to find yea?