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Oct 25, 2011 12:22:09 GMT
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Hi guys, my brother has got a 2.0 Twin choke Mazda 626 (1980's vintage) the engine has done 40k and runs sweet on tickover, the car however doesnt seem to run at its full potential. when you have the throttle wide open, it seems to go better if you back off a little bit, it also is a little jerky . the dizzy advance/retard diaphram is working new plugs and points, the timing is correct the carb has been cleaned (jets ok) the fuel filter has been changed, air filter ok also would this car be leaded or unleaded does anyone have ANY idea what it could be ??  |
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um, not sure would only say that with the low mileage perhaps it need a good old run to clear it out.
You could also just move the dizzy about a bit and see if it runs better, remembered pinto's would never run properly with the timing set to factory setting alway pinked.
Also upgade to a good electronic ignition(unless it's fitted), contacts and condesors these days are rubish quality.
As for unleaded or not, look it up on google, then again if it alloy head it should be ok.
Good luck
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how hard should the vacuum diaphram be to suck in? as i cannot do it by mouth?
i have taken the dizzy cap off and i can move the advance/retard mechanism but its quite stiff
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You should be able to work the vacuum advance by sucking on the pipe, so I think you may have found your problem.
Also, 80's japanese cars always work fine on unleaded.
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Oct 26, 2011 10:18:34 GMT
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Lovely car BTW!!!
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1974 Lancia Beta Saloon
1975 Mazda 929 Coupé
1986 Mazda 929 Wagon
1979 Mazda 929 Hardtop
1982 Fiat Argenta 2.0 iniezione elettronica
1977 Toyota Carina TA14
1989 Subaru 1800 Wagon
1982 Hyundai Pony 1200TL 2-dr
1985 Hyundai Pony 1200 GL
1986 Maserati 425 Biturbo
1992 Rover 214 SEi 5-dr
2000 Rover 45 V6 Club
1994 Peugeot 205 'Junior' Diesel
1988 Volvo 760 Turbodiesel Saloon
1992 Talbot Express Autosleeper Rambler
2003 Renault Laguna SPEARS OR REAPERS
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Oct 26, 2011 15:16:05 GMT
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thanks, its my brothers , its running 15" compomotive minilites now,
I always thought the diaphragm should be able to be done by sucking on the pipe, as it was on my Audi coupe
will give him a shout and see if we can strip down the dizzy to loosen it up a bit
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kv77
Part of things
Posts: 62
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Oct 26, 2011 18:35:38 GMT
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I have been running these engines for years, still do.. All mazda's from the early seventies and later are fine with unleaded.
I know from experience that a leaky vac advance doesn't really affect engine performance; it just gives you (even more) curse word fuel economy.
I too wasn't able to advance the dizzy by sucking on the vac tube; had to use a pump to test it
What colour are the plugs? Any smoke?
I'd be looking at the carb. The secondary butterfly is vac operated. Locate the daiphragm on the carb; it can be opened up to check it out .
See if the acceleration pump is squirting fuel down the carb when you open the throttle. How's the float level?
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Last Edit: Oct 26, 2011 18:40:41 GMT by kv77
<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
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ah you sound like just the guy i need!
the plugs are new, havent taken them out to have a look, my brother cleaned out the carb however i havent seen the float level recently so cannot comment, the secondary butterfly seems to open slightly when rev'd on a standstill so can only assume it works fine when driving,
where is the acceleration pump?
the carb is the one with the clear view glass on the side
thanks for the info
Jim
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Sounds like a Nikki carb, were all the fashion in the 80's but not sure they were any good.
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kv77
Part of things
Posts: 62
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Oct 27, 2011 15:36:54 GMT
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<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
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Oct 27, 2011 16:37:09 GMT
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thanks very much will show my brother now.!
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Oct 27, 2011 17:34:45 GMT
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If it's got a Nikki carb, has it got wires running into it? Maybe red/black?
They sometimes (depending on age) have a number of electrical solenoids which open and close various fuel galleys cast into the carb body, Solenoids usually come off with a 19mm spanner.
If it has any of these solenoids, it won't run right unless these are functioning correctly - they are "open" (not interfering with fueling) when live IRC...
*edit* just seen it has glass float chamber - so unlikely to have solenoids, sounds like the same type of Nikki you get on Datsun L-series lumps of a certain age? The vac secondaries are curse word on those. I adapted one to open manually which seemed to work better - it was taking a long time to open fully on vacum.
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Last Edit: Oct 27, 2011 17:42:38 GMT by wilko
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kv77
Part of things
Posts: 62
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Oct 27, 2011 21:20:57 GMT
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The mazda 626 rwd nikki has one solenoid, but if that's broken it won't idle. The solenoid shuts of the idle circuit.
Converting the secondaries to mech operation is a popular mod with the rotary engine guys, but i've never had any issues.
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<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
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Oct 29, 2011 14:57:44 GMT
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well the float level is fine and also the acceleration pump is working ,
do you have a "how-to" on the vac-secondarys to convert them to manually open?
thanks
Jim
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kv77
Part of things
Posts: 62
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No , I haven't. And honestly I wouldn't bother. Was the carb properly cleaned out or did he just spray a can of carb cleaner in there?
This works sometimes: rev up the engine and put a rag or someting over the carb inlet. All the curse word gets sucked out by the engine vacuum.
Have a spray of brake cleaner around the intake to see if there's any air leaks knocking of the mixture
A nice mod to do on these is to install an electronic distributor from a later FE engine model (early eighties 626, 929, E2000, B2000) . Plug and play
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<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
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ah right, thanks for the info KV77 i might get him to look into doing that in the long run
he told me he stripped down the car completely and cleaned out the jets etc but it was all clean
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