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Dizzy Issues With 260Auto. Dizzy Is Electronic From 280


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#1 Mickl

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Posted 25 February 2017 - 11:09 AM

I am not so mechanical so have to get the car looked at down at the garage, and I live in a small town so access to dynos and specialist mechanics is difficult.
The auto 260 has been rough to keep going under idle when cold and occasionally backfiring when put under load. Mechanic had a quick look recently and thought the vac advance was shot and that the vacuum from the twin carbs was not working that well either. He suggested I investigate a fully mechanical dizzy from a speed shop to overcome any vac issues. The initial setting is 15 degrees of advance, don't know what the total is.
Looking for advice on:
1. Will it be possible to replace the vac unit to overcome the issue and where do you find the right one to buy
2. Would it be best to spend some $ to get a new dizzy and if so what is recommended?
3. Could the water temp switch or relay be the issue?
4. Something else???
Cheers, Mickl

#2 PB260Z

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Posted 25 February 2017 - 04:11 PM

Hi,

 

Very hard to diagnose this type of problem with having the car in front of me.

 

Having said that, if your mechanic says there is a lack of vacuum from the twin SU's I would be looking at them first.

Is the piston sticking / seized in one of them ?

 

Cheers

 

PB


Edited by PB260Z, 25 February 2017 - 04:58 PM.


#3 Cozza

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Posted 26 February 2017 - 06:54 AM

As PB has suggested, it is difficult to diagnose from a distance but if a new vac unit is what you need, they are hard to find in serviceable condition.
I remember ZEDS4EVER on this forum had one of his reconditioned.
Maybe flick him a pm for who did it and how much.

Mick

#4 nizm0zed

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Posted 26 February 2017 - 10:20 AM

I used to have a similar problem with the old Gemini's i used to play with, the vacuum advance inside the dizzy would stick causing crappy performance.
There is a round plate with ball bearings in it that the points plate sits on, the vac advance pulls and rotates it.
The bearings would gunk up with 30+ years of crap. Not overly complicated to pull it apart and clean it all up, but defintely not a job id suggest a novice to attempt.
It may be a similar situation with the zed distributor? (I dont know, didnt keep the original dizzy long enough to know)
You need some sort of spark advance or the engine will run like garbage.
A fixed dizzy will need an electronic system to adjust the advance, that could easily cost a few hundred $$$ just for the unit, then it needs to be installed and tuned.
https://www.msdperfo...iver/parts/6201
this may have issues with interfacing with your stock tacho. You'd also need to modify your distributor internally and lock the advance plate down permanantly.

Definelty check out the vacuum of the engine, a vacuum gauge can be bought pretty cheaply of ebay
http://www.autospeed...gnostics&A=2393
Have a read through this, Its a good explanation in basic terms of how and why, and how to read a vacuum gauge.
This will help to work out if the vacuum advance isnt working because its damaged, or because there is low vacuum, or a leak somewhere.
You can check for vacuum leaks by squirting soapy water around the engine, on hose fittings, gaskets, throttle shafts ect while the engine is idling.
If the idle increases slightly there is a leak at the point you sprayed as the soapy water is pulled into the leak temporarily blocking it.
You can do the same with a stick of incense (or a nice cigar) and watch the smoke, it'll get sucked towards the leak, however you'd need to disable the fan to do this and work in a very still environment.


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#5 Mickl

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Posted 04 March 2017 - 09:42 PM

Thanks everyone, I will follow up and post what I find out cheers, mick

#6 Mickl

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Posted 25 March 2017 - 05:10 PM

I have discovered today that SU carbies do not have any vacuum pipe on them. Not sure where the tube onto the vac unit on the dizzy comes from as the car is at the repair shop atm. A friend has advised me that the manifold can be removed and drilled for a pipe barb then connect it to the dizzy vac unit. Also, there is a thick spacer(?) almost one cm thick between the carbie and the manifold and alternatively it can be drilled for the barb instead of the manifold. The vac unit itself has been found to be split so I will also have to get a new one or get it repaired.
So......can anyone confirm the above and which path would you take?
Thanks, Mick

#7 Gareth. J.

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Posted 25 March 2017 - 06:54 PM

The factory SU carbs will have a vacuum pipe off the rear of the front carb, google is your friend. The one cm spacers are factory phenolic spacers

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Edited by Gareth. J., 25 March 2017 - 06:55 PM.


#8 zeds4ever

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Posted 26 March 2017 - 04:53 PM

Hi Mick , glad you recvd the info on Vacm unit . Mate is it a 280 ZX ? or do you still have the 260Z points system in use. Check with the mechanic if he removed the vacuum unit from the dissy to see that it leaked , it's best to remove it & place a tube on the tube into the unit & suck on the end of said tube , if the diaphragm is stuffed you will be able to draw air thru it but if no air is forthcoming the unit should be OK from my experience with them .

It would also be advisable to remove the top internals of the dissy & check the oscillating plate that is immediately under the fixed mounting plate , as NismoZ states this part is usually a problem being that it is only made of a type of plastic material & over a period of years of heat & cold becomes very brittle & eventually breaks apart so a new vacuum is of no use then !! .For the amount of money you will spend on getting your old dissy fixed I would highly recommend that you invest in a reconditioned 280ZX dissy you will get far better all round performance with less problems .

Your water temp switch & relay? have no connection to your dissy so they have no bearing with your issue . Send a PM to Gavin as he may be able to direct you to someone in The states to get a recndnt 280ZX unit for you .

 

                                                                       Regards : Alan .

 


Edited by zeds4ever, 26 March 2017 - 04:58 PM.


#9 Groundhog

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Posted 26 March 2017 - 08:22 PM

Alan helped me with parts for my 280 dizzy rebuild.

It is worth checking as I found my rotational plate stuffed. The ball bearings fall out of the little plastic spider.

There should be three ball bearings in this keeper.

IMG_1152_zps5szd5ivz.jpg

 

This is what I did to repair it. Made a spider out of sheet aluminium and placed three new ball bearings in.

IMG_1157_zps5twyfpth.jpg

 

And lastly, I got a new vacuum advance from this guy.He remanufactures the diapraghms and has most on the shelf.
http://www.dualfuel.net.au/



#10 zeds4ever

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Posted 26 March 2017 - 08:38 PM

That's exactly what I made up for my dissy when I re built it & it works great might also point out that the ball bearings from the rear axle of a push bike are ideal for the spacer bearings .

By the way how much did your replacement V/advance cost .

 

                                Regards : Alan . 



#11 Groundhog

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Posted 26 March 2017 - 08:55 PM

Don't want to derail Mickl's thread.
If anyone wants more info on the dizzy rebuild drop me a PM or jump on a thread for rebuilding dizzys.
From memory it was $75 less a discount if you were a ZCar Club member. ASK FOR THE DISCOUNT.
He can rebuild, replate any vac advance and mine was on the shelf as there are a couple of variations.
Another service he offers is replating rebuilding bright work on carbs including the diapraghms.
I remember that the tang on the back of the vac advance has to be long enough to reach the vac advance rotating plate and it has to be in the right orientation (i.e. flat) .
There are a couple of variations depending on dizzy type.

IMG_1156_zpsmpiqzkq8.jpg

 



#12 Mickl

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Posted 27 March 2017 - 09:16 AM

Thanks everyone for the detailed input on my problem.
I just contacted the mechanic and he confirmed that the vac unit diaphragm was split so it needed refurbishment to get it going and the place in Caboolture sounded very suitable. The rest of the distributor seemed OK. However, there was no "ported" vacuum on the Su carbs, only the manifold vac. and the manifold vac does not perform properly between isle and revving. I got the Su carbs long ago from a guy in Wollongong before I swapped the old mechanical points distributor over for the electronic 280zx distributor so maybe they don't complement each other? Do the original hitachi carbs have this "ported" vac off take which my su's don't have?
The mechanic says I either need to find a way to get the SU carb "ported" and then the vac unit repaired, or
Get a mechanical distributor and forget the vacuum, which could be expensive, or
Get different carbs, which sounds expensive too.
As I mentioned earlier, I am no mechanic and I am having some difficulty with the concepts and communicating exactly what the mechanic is explaining. Getting the car to start easily, smooth warm up and running properly under load is what I am hoping for.
Next move??

#13 Groundhog

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Posted 27 March 2017 - 09:20 AM

You can get your vacuum port takeoff from the cross manifold tube that takes the throttle linkage shaft.
PM me your email and I'll send you a photo of a spare one I have. I'll see if I have an old vac advance diagpragm also.
GH


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#14 Mickl

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Posted 30 March 2017 - 08:52 AM

Thanks again everyone for helping out. Suggestions centre around the distributor not operating properly as well as the diaphragm being split so I have asked the mechanic to send the lot up to Dualfuel at Mooloolaba to get checked out thoroughly.
If there are still problems after that, it might be a trip to John Collins in Newcastle for a spin on the dyno.
Regards Mick




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