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Hello fellas,
I have an '84 GS with 56k on the original 12A. It has had the current problem since I bought it, and I haven't been able to sort it out yet. I used to be very, very good with carb'd V8's, but it's been about 15 years and this little guy is a little different and, well,... I'm rusty.
When I bought it all the stock emissions and engine management parts were on and seemed to function properly. Stock air pump and exhaust, rat's nest, etc.. 90 psi compression on both chambers in even pulses. But the previous owner had just installed new NGK plugs and wires, and the throttle and choke cables were all out of adjustment on carb. I think he was trying to fix the same problem I've been dealing with.
Recent engine mods -
*Rat's nest removed
*Intake switched to RB manifold and Holley (Thanks again sen2two)
*Mallory 70 series 6psi pump and new filter (cut-off valve removed from fuel line)
*New RB complete exhaust (header to tips)
THE PROBLEM --
Car runs very rough, motor jerking, and wants to stall if rpm's are under 2000. This problem has not changed with the intake change, and I'm sure it's not a vacuum leak. The Distributor securing bolt was dead center of it's adjusting range and looked like it has never been adjusted from the factory, BUT the timing light ( L1 plug wire, vacuum disconnected and capped) showed the pointer half way between the two marks. I had to turn the Dist clockwise as far as it could go to get the pointer dead-on the white mark (yellow?), and L2 timing shows dead-on the red mark (note this is at 2000 rpm). It improved, but is still rough and won't idle below 2000. All the plug wires are going to the proper spots on the Dist cap, and the Coils I believe (if the forward coil is the Leading one).
I am tired and frustrated and going to bed. But when I go back to it tomorrow, where to start? I am not sure how to check the coils / ignitors / etc.. I don't think I ever had a bad coil on any of my Distributor equipped piston engines. I'll search the forum(s) better tomorrow, but just thought I'd ask. I know many of you have already dealt with something like this.
I would suggest you check the distributor installation. Pull the distributor, set engine to tdc, confirm that you’re really at tdc with the flywheel trick to make sure you’re at tdc and don’t go by the front pulley. You can search flywheel to set timing and the post should come up. After setting tdc on engine, make sure you align the distributor, the dimple on the shaft to the one on the case and make sure you’re on leading 1 at the rotor. Install it on the engine and test again. Hope this helps. Report back with any new findings.
Thank you kutukutu1, I was just looking up how to set TDC. Tomorrow I'll do the exhaust-side cover plate inspection. I was also just looking at jeff20b's wire in the plug holes method. I understand the instructions for both procedures. On the Dist drive gear, is it either correct or 180 off, or can it be off any # of teeth? Guess I'll find out tomorrow. The plan-
*Pull insp plate and line flywheel "divot" up.
*Look at pulley marks and see if they're close. If yes, move to Dist.. If not, double check TDC with wire-in-plug hole method, and remove/remount pulley correctly (if needed).
*Once sure of TDC and pulley mark orientation, check Dist orientation. Remove and reinstall if necessary to get marks lined up and Dist Rotor pointed at L1.
I think I have it. I'll report back. Also I should probably start a build thread, as I've been replacing and upgrading.
Another question on the topic-
When people write about specific timing #'s (0/10, 3/13, etc) how do you know the exact # you're setting? When I had V8's there was a tab with #'s on the timing cover and the white mark on the ballancer, or else I would put a marked cover over the ballancer and a pointer on the timing cover. Either way I knew exactly where I was - 28, 32, 34 BTDC @ 4000rpm. On the 12A's it's just yellow or red mark. How the heck can you adjust it with accuracy?
Another question on the topic-
When people write about specific timing #'s (0/10, 3/13, etc) how do you know the exact # you're setting? When I had V8's there was a tab with #'s on the timing cover and the white mark on the ballancer, or else I would put a marked cover over the ballancer and a pointer on the timing cover. Either way I knew exactly where I was - 28, 32, 34 BTDC @ 4000rpm. On the 12A's it's just yellow or red mark. How the heck can you adjust it with accuracy?
You use a flexible measure and wrap the pulley and make marks where you need them. Some folks take masking tape and measure off the marks.
I agree with the dizzy being installed wrong. It can be off by 90 degrees and will not affect the leading ignition (ask me how I know) but it will have an immediately poor impact on trailing.
@kutukutu1 and @t_g_farrell, thank you both for the help and tips. I went out today hoping to find an obvious problem, but I'm still stumped. Here's what I did so far (please see pics of these findings) -
*Removed exhaust-side inspection plate and rotated the E Shaft until the "flat spot" was pretty centered in the window (flat area extends past window about an inch on each side).
*This put the leading timing mark (pulley) right on the pointer.
*Pulled plugs and used wire to verify. Front rotor is indeed flat against plug holes (wire goes in 2 inches on both holes) and rear has an apex between plugs (wire goes in at an angle about 4-5 inches on each)
*Marked the Dist Cap and advance pots for L1 location before pulling cap.
*Pulled cap and found rotor pointing at L1 location. WTF? I expected it to be way off, but no, everything looks correct.
*Pulled rotor and tin shield to inspect the metal "rotor"/throwing star underneath.
So, I don't see anything wrong yet, except for the fully-clockwise orientation of the Distributor. But despite that, everything else is lining up. Should I proceed with pulling it, and re-install with the lock bolt centered and everything else the same? I had asked previously, can I move it one gear tooth at a time? I wanted to report this info before pulling the distributor out. Please tell me if I'm on the right path - I'm going to pick my boy up from school and will get back to this after dinner. Thanks guys. Hard to photograph but the window and the flat are pretty well centered. This puts the timing mark where it should be. Marked where the L1 rotor "should be"... And it is! Everything good so far, I think. I think all is good inside. But this is how I need to set the Distributor to get it. Pull it and reset?
If you have everything lined up correctly, that dizzy adjuster bolt should be almost in the middle of the adjustment range normally. So you may be off a tooth on that dizzy install.
Well, I went back and quickly turned/re-centered the distributor a few degrees to where it was when I got it (I did not remove it yet). This positioned the rotor so it points exactly to L1 terminal / plug wire, sooooo..... everything seems to be fine. Front Rotor is TDC as indicated by flywheel, pulley and distributor rotor, and everything lines up perfectly for proper ignition. This is how it's always been -- I haven't changed anything at any point regarding the ignition, other than turning the distributor a few degrees to smooth it out. But it won't run right.
I don't think the Dist is in wrong at all. If I did pull it, I would be looking to put it back in exactly as it is now.
So what's next? The plugs are now black from trying to get it running and not letting the choke open fully (because it would stall), so I will clean them up before re-installing, but they were great looking up until yesterday so I don't think that was the issue. The new fuel pump is delivering fuel as it should, and the stocker was too. I have been all through the new carb and it is clean and delivering fuel as it should. I do believe it's the ignition, but I don't believe it's a mechanical issue. There's a gremlin in the electricals somewhere.
Before I put the plugs back I'll cut the fuel and have my boy crank it so I can check for spark. Then I think I need to check the coils, ignitors, etc. Fun fun. Any thought or suggestions are greatly appreciated.
".............. and the Coils I believe (if the forward coil is the Leading one)"
I am not 100% sure on this, and the 1984 cars may be different, but I think the front coil is hooked up to Trailing. This is how my 1982 is and I don't think the previous owner switched it from factory.
This may be why you needed to clock the dizzy so far when you had a timing gun on it?? It is out by the L/T split?
Not certain this is your problem, but double check that the coils go to right L and T on dist cap AND they have the correct igniter wires. Front coil is T and rear coil is L.... assuming your coil power wires are still as factory. It is really the power wires that are critical instead.. not which one is mount ahead...
Front Coil (Trailing): Yellow Green (YG colour code)
Rear Coil (Leading): Yellow Black Blue! (YL colour code)
Thank you @tommyeflight89 , I will check the
Front Coil (Trailing): Yellow Green (YG colour code)
Rear Coil (Leading): Yellow Black (YL colour code)
after dinner. I DO know that the factory wiring harness up to the coils is original and unmolested, but the cables from coils-to-distributor were replaced with the plug wires, and the forward-most coil is wired to the L post on distributor. I sure hope it's this simple! I will report back, Thanks.
Before you do anything else,switch the leading/trailing coil wires on dist cap. Front coil always trailing. Can't imagine that car ran(or made power) at all,not just wouldn't idle below 2k rpm..
Usually spark plugs that have been fouled like that won't clean up well. A light glassbeading is best,but be damn sure you spray them out with carb cleaner and blast repeatedly with air. You do NOT want glass beads anywhere in the engine.
A LOT of people don't recommend you do this but for a car that's repeatedly flooding and fouling plugs while you're trying to work your way thru diagnosing running problems and getting the engine started, it gets expensive real fast replacing plugs.
Glass beading is better than a wire wheel and carb cleaner spray/air combo. It gets the plugs closest back to near new. I keep old plugs replaced for maintenance and clean and keep them for this purpose.Once whatever problem you're having is identified and sorted out and you're sure you're not going to foul another set,replace them. Rotary engines are very finicky about their plugs being fresh/clean.
How many RXs i've gotten running with just a plug change,i can't give a number but it's a lot. Many people will chime in here with this very sentiment. If you tend to put a lot of miles on your car far from home,a fresh/cleaned set of plugs should be in your tool kit.
Use the correct NGK plug,don't put anything else in the engine. It may start and run but won't run right.
Since you're using a non stock carb/intake you'll have to pull and check the plugs for color to determine proper jetting,but you say you're familiar with domestic carbs on V8s,reading plugs on a rotary no different.
As far as basic specs...use ported vacuum source for vacuum advance. On your Holley carb this is the nipple that comes off front metering block about 1/2 way up. Make sure the manifold vacuum nipple on the front of carb on throttle body is capped off so you don't have a vacuum leak there.
Set your ignition timing at idle speed to correspond to the front cover pin leading/trailing respectively.
1/2 turn out from lightly seated will be about right for initial idle mixture needles. Float level should be right at bottom threads on removed sight plug.Shoot for about 850 rpm idle speed warm. It will idle lower but leaving it adjusted to that speed will help alleviate some of the wonky return to idle flutter/stall when coming to a stop clutch pushed in and or low speed light throttle input on turns. These carbs were meant to be oriented front to back on an incline to work properly and installing them 90 degrees on a rotary causes them to do a lot of things you can't tune out. Some people say you can,i'm not one of them.
Set up properly they're hard to beat in a straight line,it's the turns that cause the hiccups. I used to autocross a Shelby Mustang and had trick floats/bowls/jet extensions that civilized the driveability of the Holley on hard cornering but it was never perfect.
I think all is good inside. But this is how I need to set the Distributor to get it. Pull it and reset?
That's your trailing pickup coil. If that's what you have your timing light hooked up to you will be setting your ignition like 15 degrees retard. Yeah that'll give you a crappy idle for sure.
I don't know where my last post went but that pickup you are pointing at is the trailing pickup. If you are using that to time your machine it will always be out of time.
Basically you want to time the machine with the little ninja star looking thing (I can't remember the name atm) and the leading pickup coil. As the picture sits you are about 190 degrees off.
The cap and rotor have very little bearing on ignition timing. The magnetic strip on the black piece of plastic is the pickup coil. Don't be mislead by the two metal circles after the magnetic strip (don't know exactly their purpose but they're irrelevant).
So I guess you can sum all this up by putting the engine at TDC... then stab your distributer with the "ninja star's" points as close to the LEADING pickup. Put the cap on the distributer. Fire the engine up. Use your timing light to make small corrections.
@Qingdao , THANK YOU. Big thanks to everyone who has added to this thread. Everyone has given me an important piece of the puzzle. Where I'm at right now (before going back to remove and fix Distributor) is -
tommyeflight89 and GSLSEforme - The coil cables were swapped. I put them right, and it runs smoother (still not smooth enough), but was running much too lean and hot. Header glowing hot and wouldn't idle without choke closed (I wired it 80% shut).
The floats are good (just rechecked) and I had both bowl's off when I got the used Holley to clean the needles and bowls. I checked the idle mix screws though and they were waayyy too far out, like 7 full turns! I put them to 1.5 turns out as Holley recommends for baseline, and I will fine tune when I get a vac guage. But, the choke/stall and overheating exhaust tells me it's too lean. I only did a partial cleanup on the carb, but I'm thinking of a full rebuild now in case there's gunk deeper in the carb (mtering block, etc).
Qingdao - I never pulled the Dist. because everything seemed to line up right. If I had, I guess I'd have found the marks (dimple and line??) on the shaft 180 out of sinc. The white tape/ arrow points to the L1 spark plug wire post, which had the plastic rotor arrow pointed right at it, so I stopped there and thought all was good. I didn't know about the ninja star/flat of shaft relation to L pickup, but I understand what you're saying and will fix it. kutukutu and T G Farrell told me to line up the marks on the shaft, but I didn't get that far. I'm learning a lot with this thread. I am going to go out again and pull the Dist, like I should have this morning, and hopefully this chainsaw can go cut some trees! And hopefully I won't need to tear down the carb again!
@Qingdao , something's wrong with your suggestion. Everyone says to put motor at TDC, pull Distributor and re-install with the Divot on gear lined up w/ Raised mark on shaft. Done. And that gives you the above picture, with the D.Rotor arrow pointing to L1 spark plug wire, just as I had. I was following what you were saying, but it doesn't work out. It's 180 different from the divot/mark method. I'd appreciate if anyone can confirm what I'm finding.
So, tomorrow I'll go to PepBoys and drop 40 bucks on a rebuild kit. Either it will fix it, or at least I can rule that out.
Reluctator or reluctor.... Something like that is the name for the ninja star guy.
Glowing headers are a result of ignition timing. Advance or retard I can't recall.
I don't do that divot thing. Makes an simple process obnoxious. All that matters is that the A/C signal from the J-109 ignitor goes through the pickup coil at the right time. That's all done up top. EDIT: you are going to have to take the distributer out to get it right though. I just pull the distributer up a hair and spin the rotor with my hand; place the distributer back down when the rotor is at the position you want it to be at.
The arrow depicted on the rotor will let you know if you are 180 out. Although, being a wasted spark ignition I don't even see how being 180 out makes an difference whatsoever.
I hear what you're saying about the dot/divot making it more complicated, but lining them up is what Everyone, on this and all rotary forums, says to do. You want me to turn it 180 from that. So naturally I'm worried. Engine not running without choke indicates too much air, either from not enough gas or from significant vacuum leak. *Note - this is my piston motor head speaking. Both symptoms may well be ignition based on a rotary, I am still learning. Maybe someone at the factory put the Dist drive gear on 180 wrong, or maybe a wayward mechanic did it, but both are doubtful.
Alright, tomorrow I'll turn the D rotor 180 around and pray it runs. Worst case scenario, I can blame you for the resulting V8 swap. Har har. Drive gear lined up equals ... what I had / have. Same thing, without plastic rotor.
Glowing exhaust is always retarded ignition timing and or a very lean condition.
Are you certain you have no vacuum leaks?
All unused vacuum ports plugged off on carb,particularly 3/8" port on bottom rear of throttle plate of carb?
Thinking you have both fuel and ignition problems. That carb should supply more than enough fuel on idle circuit alone to start and run engine. Having to nearly close choke to get it to run suggests engine is not pulling enough fuel thru idle circuit..
On right track to take carb off and apart to clean. Recommend soaking all pieces in carb cleaner solvent and being certain all passages in metering blocks,throttle plate and carb body are open by verifying with spraying carb cleaner thru each followed by blasting air thru. You will find any blockages this way.
Check the power valve diaphrtis not cracked/split/blown. Does carb have power valve blockiff plug?
When disassembling pay attention to orientation of metering block and throttle plate gaskets-it is possible to install them reversed which blocks off passages particularly the idle circuit.
I agree with Mike, your problem is more than likely the carb. Might want to go back to a hogged out nikki, matches the rotary carb requirements much better. Anyway, your dizzy looks good but I really do think its one tooth or so off for the adjustment you showed in the first few pictures. Line the divot to the index mark as you pictured and then put it in and make sure the leading pickup is close to lined up with a nub on the reluctor wheel. Kind of like Qingdoa said, use your common sense and your eyes to make sure its stabbed right.
12-16-18, 09:25 PM
