gemery10 Posted December 31, 2005 Share Posted December 31, 2005 First of all, Hi to everyone out there making this a great site. I have solved many a small problem with your archives but this time I'm a bit confused. My car (86 L series) still pings under load with 98, 95, 91 and 89 octane gas in it. History is it has 325,000 k's on it but a rebuilt engine (full rebuild top and bottom) at 240,000. I've had the usual probs of lifter tick, dodgy carbs, blown heads etc. Car has new rad and runs perfect temp with a/c on but as the summer has topped 39 deg C plus high humidity I've noticed pinging with a/c on at about 3,000 rpm or lower on highway or on hills without a/c. Car runs better with higher octane but still pings, lower octane (89) it pings like crazy. Car revs out easily and doesn't ping when over 3500 rpm with second throat engaged. Mileage is good It has done this for the 120.000 k's I've had it but I didn't know thats what the noise was cause the headers were loose for a bit and the cat was rattly too. Another prob I had was popping on decel which was rectified by something to do with clamping the (I think) egr valve (mechanic said to do it but It was ages ago and I can't remember what I did in detail) Only mods to car are lukey exhaust, bigger tyres, bit bigger jets for more bottom end I have replaced ditsy rotor cap and button, new airfilter (old one v dirty) Car runs much stronger after those few things but still pings I am at sea level Australia north coast My thoughts are: new plugs/leads possibly colder plugs (plugs and leads are about 2 1/2 years old bosch brand) fuel filter (I know...) Timing retard (currently 8 degrees) Carbon build up (I don't think long enough but I have babied the engine a bit) I have a pretty strong mechanical idea with motorbikes but still hazy on more than one cylinder Sorry about the longish post I just wanted to put all the details in as I'm a little low on finance and don't want to do superfluous things Any ideas? Link to comment Share on other sites More sharing options...
Subarian Posted December 31, 2005 Share Posted December 31, 2005 From your post, it sounds like you've done a weber 32/36 conversion. In any case, it sounds like you may still be too lean on the primary, especially considering that it goes away above 3500 rpm. If you do have the weber, did you change the idle jet? That's the one that does most of the work on the lower end. Aside from that, it sounds like you've done all the right things. Link to comment Share on other sites More sharing options...
NorthWet Posted December 31, 2005 Share Posted December 31, 2005 I'd start with the plugs and wires (general bias here towards NGK plugs), probably not go colder than stock. What was done with the PCV system? The hoses from the cam covers can get pretty crudded-up and constricted, and if you start sucking any oil at all into the intake it can cause pinging (detonation). My guess on what you clamped off was the air suction valve hoses; these allow air to get sucked into the exhaust to help oxidize hydrocarbons. The reed valves tend to go back and allow exhaust flow into the intake. Link to comment Share on other sites More sharing options...
gemery10 Posted January 1, 2006 Author Share Posted January 1, 2006 Thanks for your replies. I have retarded the disty by about 2 1/2 mills (no gun at present) and thats changed the power and the pinging. It has a more linear power curve and can hold revs on hills a lot better. Lost a bit of the pronounced hit of the second barrel but overall better to drive. Its pretty hard to make it ping even at 2000rpm under load maybe a bit with a/c on (95 octane ). Why do plugs and leads matter? Is it just that you get a stronger spark. Your spot on about that read valve for the exhaust so what is the egr valve that needs cleaning? It didn't ping before the engine was rebuilt so I was wondering if slightly higher compression or a rebore would have thrown the stock jetting out a bit? I do just run the hitachi not a webber but found from my motorbike tuning history on single cylinders that the plugs were a bit lean and the engine seemed to suffer when trying to hold wot on hills so I changed the jetting to bit richer. I'm going to change the fuel filter when shops open again do you think there is anything wrong with running a bit retarded from stock as it seems to run more powerfull in some ways anyway? Thanks again for your help, mechanics around here don't seem to know whats going on. Link to comment Share on other sites More sharing options...
gemery10 Posted January 1, 2006 Author Share Posted January 1, 2006 Just one more thing, I took out a few plugs today after some decent hill work and the tips are too white for my liking. Motorbikes run richer in summer why do cars get leaner? Why cant I just change the main jets up a size or two? Link to comment Share on other sites More sharing options...
subiemech85 Posted January 1, 2006 Share Posted January 1, 2006 here's what you can do: replace sparkplugs with NGK BPR6EY-11 OR BPR6ES-11 v-power or regular replace plug wires with NGK or BOSCH remove EGR valve, remove ASV, and block off run vac. line from vac. advance unit to intake manifold port near head remove emissions canister, one line is left open, one line is blocked, and I forgot the rest you should be able to run 89 octane Link to comment Share on other sites More sharing options...
gemery10 Posted January 1, 2006 Author Share Posted January 1, 2006 Thanks for your reply, I am seriously thinking of going one colder on the plug as I checked again today after retarding disty and there is still a white tip. I am a lot happier with pinging prob though. Where is the EGR and ASV valve? There is plumbing all over the show I'm not sure whats what. here's what you can do:replace sparkplugs with NGK BPR6EY-11 OR BPR6ES-11 v-power or regular replace plug wires with NGK or BOSCH remove EGR valve, remove ASV, and block off run vac. line from vac. advance unit to intake manifold port near head remove emissions canister, one line is left open, one line is blocked, and I forgot the rest you should be able to run 89 octane Link to comment Share on other sites More sharing options...
BobBrumby Posted January 2, 2006 Share Posted January 2, 2006 egr = exhuast gas readmision, it puts exhuast into intake manifold and i dont think aussie soobs came with it, my brumby doesnot. it should be bolted in the middle on the back of the inlet manifold. Link to comment Share on other sites More sharing options...
NorthWet Posted January 2, 2006 Share Posted January 2, 2006 Thanks for your reply, I am seriously thinking of going one colder on the plug as I checked again today after retarding disty and there is still a white tip. I am a lot happier with pinging prob though. Where is the EGR and ASV valve? There is plumbing all over the show I'm not sure whats what. Are you getting detonation or pre-ignition? Colder plug won't help with detonation; better to play with mixture. Don't know what emissions controls your vehicle came with, but lean mixture could be caused by improperly disconnect emissions control on the carburetor. In the USA, EGR runs from a port on the head (engine-left-side headjust below cam cover and pointing out towards wheel) up behind engine and into the back of the intake manifold; steel tubing (perhaps 1cm OD) all of the way. ASV attaches to special cast iron fittings bolted to exhaust port(s) on one or both heads, with steel tubes of perhaps 2-3cm OD running up to aluminum valves with rubber hoses on the other side. Link to comment Share on other sites More sharing options...
gemery10 Posted January 7, 2006 Author Share Posted January 7, 2006 Ah, I see. Haven't seen either valve on my subaru so i think thats not the problem. I do have heaps of emission stuff though and some of it has been cut and blocked, I'll look into it. Thanks again for your help Link to comment Share on other sites More sharing options...
gemery10 Posted January 25, 2006 Author Share Posted January 25, 2006 Thanks for your help everyone. Prob turned out to be mostly the pcv valve being full of crap. Link to comment Share on other sites More sharing options...
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