Ignition/Timing/Carb Question

[zack_280]

Ok,

The mechanical advance is not working on my distributor. I see no advance at 3500RPMs. None. I just finished rebuilding my engine. Before I knew about this problem I set the timing to 10 degrees BTDC with no vacuum and then drove it for maybe 50 miles. It didn't seem to be running right. So I checked the timing and found out that the mech advance isn't working.

Well, I decided that I should probably do a compression test and make sure that everything is ok, just to be sure. When I removed the spark plugs I found that they were very sooty. When I installed them I had them gapped at 0.050" (suggested by MSD). I'm thinking I may reduce that to 0.040". In addition to the sooty spark plugs the exhaust tip has some soot built up on it. The exhaust also has a little color to it (as it should with all that soot in there). Well, my compression was ok. All cylinders are between 180 and 190 PSI.

Here's a little history...I have an MSD ignition and coil with a points type distributor

-I checked the float level and it seems ok

-I synced the carbs and checked the mixture setting. (The mixture seems like a bit of a mystery to me, but I turned them a half turn in and the idle seemed to get a little rougher and then I turned them a half turn out and the idle seemed to get rougher, so I left it at 2.5 turns, which seemed like a safe setting.

Why do I have so much soot built up on the spark plugs and tail pipe? Is this from the timing/distributor or could this be from a rich mixture from the carbs?

I obviously need to get a new distributor and I think I'm going to get a Unilite. Is there anything wrong with advancing the timing to some magic number (between 25 and 35 degrees) and driving it as is?

Thanks in advance.

Zack

[jfairladyz]

I obviously need to get a new distributor and I think I'm going to get a Unilite. Is there anything wrong with advancing the timing to some magic number (between 25 and 35 degrees) and driving it as is?

Thanks in advance.

Zack

Try this for setting max. timing advance: Advance it til the engine starts to act up at idle (it'll start missing). Then back it off til the missing stops. Now rev it up slowly through the rev range. If you have pinging then back off the timing a little til you can get through the entire rev range without pinging. That will give you the maximum advance that you can run off your particular grade of gasoline.

But setting the initial timing too high to compensate for a lack of mechanical advance will cause issues. If you set it that far advanced (25-35 degrees) while the engine is turning slowly (idle) then the spark is going to disipate before there is compression. Thats why initial advance is so low and then rises with engine speed.

[jmortensen]

I'd sooner go for a 280ZX distributor than a Unilite. You'll probably have to rebuild the 280ZX distributor, but that's easy enough to do: http://www.jrdemers.com/280ZX/distributor/distributor.html

[beandip]

I agree with jmortensen on the dist. As to the question on the mixture I think it is too rich at 2 1/2 turns out . It is OK for starters but you will need to adjust from here. You need to sort out he ignition first . I am running a '79ZX ignition and really like it. You also need the ZX coil and eliminate the resister. All the non turbo dist will work from '79 to '83 , but you need the 12 80 module that attaches to the side of it. There is allot of information on this and adjusting the mixtures here . do a search and you will find it all . Gary:p

[a7dz]

I agree with both jmortensen and beandip on this one as well. I will be running a 79 ZX dizzy in mine as well. Bought it rebuilt last month or so.

[Arne]

It's unanimous so far, I also have the ZX ignition on my car, works very well.

[Mat M]

I will throw in my 2 cents...

I have an 82ZX dizzy and alternator (thanks for the adaptor, Arne) and haven't had any problems. The toughest thing was getting the wiring correct, especially when the PO had a serious bout with POD when he installed an aftermarket electronic ignition (thanks again to Arne and jmortensen et. al.).

[zack_280]

Thanks for the information. I am thinking that I will keep the MSD ignition (for now) and just get a ZX distributor.

Anyone got one for sale? Any thoughts on buying a Beck Arnley from Autozone?

Zack

[dspillman]

Hi Zack,

I recently picjed up a rebuilt zxdizzy from Advance Auto for $114...even came with ignition module attached. $20 core. This can be hooked directly up to stock coil ready to go...keep a spare module thou, I've had problems with module failure...Sporadic failure....frustrating to track down...... MSD/Crane both work well.

david

just get a ZX distributor.

Anyone got one for sale? Any thoughts on buying a Beck Arnley from Autozone?

Zack

[zack_280]

Thanks to everyone for the information. Hopefully after getting the new dizzy, I'll be able to get the mixture setting correct.

[Arne]

Still sounds like your carbs are too rich, though. Lack of advance won't cause sooty plugs.

[jfairladyz]

Hi Zack,

I recently picjed up a rebuilt zxdizzy from Advance Auto for $114...even came with ignition module attached. $20 core. This can be hooked directly up to stock coil ready to go...keep a spare module thou, I've had problems with module failure...Sporadic failure....frustrating to track down...... MSD/Crane both work well.

david

I'll second the module failure. When I had my ZX that was probably the hardest problem to track down because it was so sporadic. I carried a spare module in the glovebox because I replaced my bad one with a good junkyard unit.