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Thread: 12A help
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jfaplanet
Redlining
Posts: 356
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posted February 04, 2004 08:54 AM |
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12A help
Ok, I know some of you guys race RX-7's and many have been dealing with rotaries for many years. I too have been playing with them for many years but now I have a problem I can't seem to isolate. My truck has a 12A in it for the time being,(Lack of 13B usable housings). But anyway here is the trouble. When it is cold it is verrrrry slow to start like crank on it for 1 to 2 minutes before it ever seems to fire. I have checked the timing, air-fuel mixture, cleaned plugs, new cap, wires, different dist, different igniters, even changed the timing 180 degrees. But still the same thing. Compression seems to be good but have not measured it. Once it is started and warmed up it fires after about 3 revolutions. Does anyone have any ideas that I have not tried. Please share if you do. Thanks for any help in advance, Charles
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74 REPU "Red"
74 REPU "Jethro" "TII"
74 RE-Courier vert
79 SA-SE(aka deathtrap)
79 SA-SE-FC (project
turbo)
http://home.bellsouth.net
/p/PWP-crgj
TN Forum:
http://tnrotary.10.forume
r.com/
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Jeff20B
Moderator
Posts: 661
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posted February 04, 2004 01:06 PM |
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Slow starter? Too much carbon around the apex seals? Weak ignition?
My Cosmo and my bro's GSL-SE used to take a long time and many cranks to start. After we changed our starters, they fired up much faster.
Try some power foam in your engine to get rid of carbon (or at least enough to make a difference). Or I guess MMO can work, although I've never tried to decarbonize and engine with it. I'd stay away from ATF because it's bad news, especially if youe engine has trouble starting in the first place. Sure they say it will bump up the compression and all that, but regular old Castrol 10W30 dribbled down the carb works 10 times better, and even burns off in a couple minutes in a healthy cloud of smoke.
We had a 12A that didn't like to start (probably from missing chrome; check for that if you don't know your engine's history) until pouring just a little oil down the carb. It would start every time with the oil until we changed the starter ('84 automatic FB).
Your 180º change in the distributor's shaft angle won't affect anything. The REPU has small gauge wires down near the coils. Check for voltage drop. I've seen as much a 1.01V drop from the alt to the ignitors and coils. I also recommend an upgrade to DLIDFIS on older rotary vehicles.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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Mazdarx605
Redlining
Posts: 314
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posted February 04, 2004 02:42 PM |
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Just a guess here but could it be a bad set of cables from the battery to the starter?I know my 1st gen had this problem years ago.May be the cheapest easiest fix ever.
Chris
74 green REPU
83 Rx-7 limited
92 Cummins
00 Protege ES "hers"
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brad
Rotorhead
Posts: 1672
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posted February 04, 2004 03:26 PM |
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i used 00 gauge to redo my positive battery cable. bought 11 feet of it memory serving. also replaced the wimpy 8 (10?) gauge wire from bat to alt to fuse box with 6 gauge cable. and ran 8 gauge from fuse box to ignition switch.
REAL nice power upgrade. no low voltage issues anymores.
00 is also prounounced double-aught or double-oh.
is the choke working on the carb? carb been rebuilt in the last ten years?
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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jfaplanet
Redlining
Posts: 356
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posted February 04, 2004 10:51 PM |
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Thanks Guys
Thanks for all the tips. It is a fairly fresh 12A (less that 5000 miles since new seals and everything mic'd, checked, and cleaned) with good chrome on housings. Carb was rebuilt less than a month ago and problems before and still after. I cleaned the plugs with brake fluid and carb cleaner today, after that it fired. I will be getting a new set of plugs and looking into the voltage drops. Also see about a new battery cable. It never has seemed to spin very fast. Even with a fresh new battery. I have another starter that I might try also. Again thanks for the help from everyone, Charles
____________
74 REPU "Red"
74 REPU "Jethro" "TII"
74 RE-Courier vert
79 SA-SE(aka deathtrap)
79 SA-SE-FC (project
turbo)
http://home.bellsouth.net
/p/PWP-crgj
TN Forum:
http://tnrotary.10.forume
r.com/
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Klaus43
Rotorhead
Posts: 1259
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posted February 05, 2004 10:42 AM |
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Brake fluid???!
I hope you meant 'brake cleaner'...! Other thoughts: Any possibility there's fuel leakage anywhere from tank thru carb.? Perhaps a 'small' vacuum leak on the intake that maybe goes away when warm? Carb. base/float bowl gaskets? What about the condition of your fuel pump? Return line? Vacuum buildup in the system?
Still, that long REPU battery cable, and/or old starter/voltage drop seems likely...
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rotarydave
Hauling
Posts: 108
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posted February 06, 2004 06:34 AM |
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just a small spot of knowledge for you, i have found that Power Foam also works great to start one that is really flooded or is low on compression, makes one hell of a smokey mess behind the truck but it works, it does seem to help on ones that i have found that have "stuck seals" doesn't always work but often enough.
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jfaplanet
Redlining
Posts: 356
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posted February 17, 2004 10:52 AM |
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Thanks
Thanks for all the help guys. It turns out it was the starter. It just wasn't spinning the engine fast enough. I knew it had good compression and the carb was good. Again thanks for all the ideas and to who ever said starter. THANK YOU.....
Charles
____________
74 REPU "Red"
74 REPU "Jethro" "TII"
74 RE-Courier vert
79 SA-SE(aka deathtrap)
79 SA-SE-FC (project
turbo)
http://home.bellsouth.net
/p/PWP-crgj
TN Forum:
http://tnrotary.10.forume
r.com/
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