Ignition advance specs?

[danzo]

Even after Weberration, my car continues to predetonate likes nobody's bidness. Even with the idle timing set at 5* it will ping, and at ~12* it's a total cacophony. Awhile ago I swapped in another dizzy but I can't remember what car it came out of. I'm thinking it's advancing too much since my car doesn't have any vaccuum leaks.

Does anybody know what the fully advanced timing should be for a T4wd? They are usually around 35*, but I can't find the spec anywhere. Of course our timing marks don't go that high, but a timing light w/advance dial will tell you. I don't know what my dizzy is advancing to, as I will buy such a timing light later tonight. Thanks in advance.

[dlb]

danzo, i'm still in the same boat as you though it sounds like your case of pinging is way more severe than mine. with the cooler weather my ping is rarely there, with the phenolic spacer in it's better, and with cooler air coming in there is no pinging at all. i'm still waiting for my scoop to show up though and i've become obsessive about this so i will remain doubtful until i actually get the scoop on and test it out. i had also thought about the advance in the dizzy being off and my lack of EGR contributing to hot temps in the head (since the exhaust gases exert a cooling effect in the head) but i don't think it is the dizzy in my case, as the pinging started quite suddenly when my friend and i first disconnected all the emissions stuff and put the weber on way back when. i'm working through it step by step though--if i still hear ping after the scoop is on i will try hooking my EGR back up (much to petros' dismay, i'm sure!), and failing that, i'll look at ignition advance.

incidentally, is your EGR hooked up? could it be plugged up with carbon deposits?

[Petros]

If you are using it for competition, I would totally disable the vac advance (does nothing when at full throttle). David has the right idea with a cool air intake, in fact for competition I would consider running an intake duct from the grill area directly into the carb, and use one of those conical type K&N filters in front of the rad support wall (eliminating the warm air riser and pull all the intake air from in front of the radiator). Put in the coolest T-stat you can find for it, or for compaction, just take the t-stat out. You might wire the exhaust flapper valve into the closed position so it does not allow hot gases up against the intake manifold (if you want to go all out, you might find a way to detach the intake manifold from the exhaust all together, will require fabbing parts). The plastic carb isolator is also an excellent idea. You want the engine to run as cool as possible, and the intake air to be as cool as possible. Route the fuel lines in the engine compartment away from heat sources, and wrap all the fuel lines with foil or other insulators.

There might be something else wrong getting all that ping, verify your distributor is working properly, verify (if possible) you are not running too lean a mixture. I have 11.25:1 compression ratio and I do not get any ping unless I lug it badly (I use premium pump fuel and run 10 deg advace). Try running premium fuel (or premium plus octane booster), change the spark plugs to a cooler range. You want to run the coolest spark plugs without fouling (too cool gets you black carbon deposits). You also might want to double check your TDC mark (through the spark plug hole) just to make sure the key or front pulley is not buggered up. Also, get new cap and wires, they might be arching under load.

Even on a hot day you should not be getting that much ping with stock compression ratio. Carbon built-up on the pistons perhaps. Something is not right, you need to get it running properly to find out if you need to take all the other actions.

[danzo]

All good advice Petros 'n' DLB, but this damn car is supposed to not ping without all those mods. It's just a daily driver with an occassional autox, I just want the good driveability it should have. I have overridden the intake heater flap and plugged the EGR vac lines but left the large EGR-to-exhaust line intact. Would this cause higher combustion temps? Right now my PVC is going to the brake booster vac line until I can fab up the patented Splatter(tm) mod.

The carb uses a K&N type filter on top as per stock. I don't think the phenolic spacer will do any good: today at ~80* ambient temp and with the car fully warmed up, the carb body temp was 85*, the aluminum spacer was 95*, and the intake manifold was 125*. I'm using the stock sheet metal heat shield.

Using the dial advance timing light with idle timing at 8*, it advanced to 42* at around 2500-3000 (couldn't see the tach). If I really revved it high I could get another 2*. So is 42 degrees of advance too much? BTW I drove the car tonight under these settings at about 65* outside temp and it still pings badly, but only under light load. As soon as I apply more than ~20% throttle the ping goes away immediately.

When I talked to the Weber tech help line guy last week he recommemded a slightly larger primary idle jet. So I went from a .60 to a .70 but there's really no change. Otherwise he seemed to think my jets are OK (140 mains, 170/160 air, .70/.50 idle).

Plugging the large exhaust EGR port will be my next move, but I will be away from the car until prolly Friday. Maybe a scoop is in my future, even if for nothing other than chica collecting.

[dlb]

ha! chica collecting, i like it.

i agree with you that the car should run fine without mods, as it was designed to. were you having ping before you disabled the EGR? as for the phenolic spacer, although i haven't checked i imagine that it will definitely impact the heat of the carb body since it is designed (partially) to keep the carb body from heating up through induction. once i get my scoop on and the spacer back in i will check temps and let you know what i find.

[ARCHINSTL]

Well, I dunno if this is any help, but...STL is warmer than BC but not as warm as TX in the Summer.
Goldie has a Weber with a somewhat shortened Redline filter, the EGR is disconnected, all emission stuff is removed, the vapor canister is still there (but vented to the atmosphere), the phenolic spacer is there, the ignition is advanced to 10°(verified using the advance's dial feature), and a Toy OE 180° t-stat.
I run regular 87 fuel and have used inexpensive OGK G-Power plugs ($10/set) for years.
IF she is pinging - it must be extremely subtle - and I ain't hard of hearing, despite senesence.
Now, even with the OE carb and all emissions and stock 5° advance - I never noticed any pinging - ever. No pinging with either setup, or in any weather. Of course, I rarely drive in bumper-to-bumper traffic any more, if that is relative.
After the mods, based on some others' experiences, I expected something and kept listening - but got nothing... The last time I heard pinging was many years ago on some of my Morrises with the BMC A-series engines; this promptly ceased with the use of premium fuel.

The only differences I've noticed with the mods is that it idles somewhat faster in cold weather than in warm (even when warmed up). Also, the water temp is noticeably cooler in Summer than in Winter (I've remarked on that before with no real answers).
Tom M.

[splatterdog]

Carbon buildup in the combustion chamber?

[ARCHINSTL]

Carbon buildup in the combustion chamber?

That was common with the BMC A engines - even with the low power/compression of the Morris/Austin applications (compared to the Spridget versions). This occurred regularly, even after valve jobs; the usual fix was to run premium - and I always told myself it ran smoother and had more pep...
I think it was common on the B-series engine as well ('A' and 'B' MGs and bigger BMC cars), but dunno for sure.
Tom M.

P.S. Always loved the Brit expression for pinging: "If your motor is pinking..." Where else but the Sceptered Isle?

[shogun]

have you tried gaping your plugs to 0.030" and check your valve lash, i had that once and i had to tight exhaust valve lash

[danzo]

were you having ping before you disabled the EGR?

Can't remember, I believe so, but I do know it was pinging long before I slapped in the Weber about 2 months ago. Nonetheless I will remove it completely and cap off the EGR exhaust manny port to be sure this is not a possible culprit.

Carbon buildup in the combustion chamber?

I have Seafoamed 'er twice in the last 2 years so I don't think carbon is a problem.

check your valve lash,

I thought about that too. When the engine idles the vaccuum gauge needle fluctuates wildly then steadies as rpm's rise. But the vac never gets above about 20" even when I lift throttle on the highway. I haven't checked the valve lash recently so this is on my list definitely. BTW Shogun it's going to be really interesting to see how much power you get out of your motor. Many eyes are on your build.

Any input on the various mixture gauges available ? They use the O2 sensor. I was going to get one to help tune the carb but don't know if they are accurate enough to help.

ha! chica collecting,

Can't believe a Cannuck (sp?) got that. Did you live down south for awhile?

Anyway thanks again for the responses. Like Ted Nugent says "if you can't lick 'em, lick 'em!"

[Petros]

sounds like something else is wrong with the car. Not the carb. The EGR when working properly will slightly reduce the tendancy to ping at full throttle (the exhaust gases mixed in to the intake reduces combustion temperatures). The effect if small and most cars when you remove them have no noticeable effect. And it would have no effect at light loads on the engine.

Going back to basics: Ping is preignition of the mixture causing shock waves in the chamber. It is very inefficient and destructive on internal parts (especially the head gasket). Ping is always worse under high loads on the engine. The things that can cause it are timing off, poor quality fuel (very old fuel), bad spark plugs or carbon build up that get hot and ignites mixture before the spark, a bad vacuum leak and/or very lean mixture for some other reason. Sometimes a bad cap or wires causes arching to the wrong plug and causes mixture to ignite in wrong cylinder.

if you get ping at low loads than the weber tech had the right idea to check the low speed jet was not too lean. but something else is causing it, I would suspect there is a vacuum leak somewhere. Do the carb cleaner spray check. It is possible it is a bad brake booster than acts like a vac leak, a bad distributor vac advance will act like a vac leak. Or if your EGR is leaking it will act like a vac leak. In addition to all intake gaskets, seals and connections, check all the components that could possibly cause a vac leak.

You need to find what is causing the fuel mixture to preignite. Good luck.

[dlb]

hmm, valve lash. never thought of that. since i had this problem both before AND after i swapped engines, i don't think it's the cause of my ping but ya never know. i'll remember it as i work through possible solutions.

canuck, one 'n'!...but i f-ing hate hockey. no, i hate the heat so i generally stay north but my wife fancies herself some sort of latin sensation so she's always dropping lingo like that. and ted nugent is the MAN.

good luck in your continued ping search!

[shogun]

if youre looking for a good reliable o2 sensor go to 14point7.com and email Alan, i use their stuff for tuning, very reliable and onboard datalogin

[tercel4wdrules]

One of my cars is exhibiting the same problem as danzo's car. When I had about 2 or 3 hoses plugged in wrong it ran ok, except there was a flat spot around 20% throttle. I double and triple checked all of the hoses and now it accelerates fine, but under light throttle cruising there's some surging going on. However, when I disable the EGR (I plugged the hose), the surging goes away, but I can hear ping under light load acceleration, even though I retarded the timing back to the stock 5* and of course it was worse with 10* base timing. I notice the ping as the car warms up. With the EGR enabled, there's some negligible ping. I swapped EGR valves to see if there was a difference, but I didn't really notice any. I did notice that the gasket was a little wet on the EGR when I removed it, perhaps there's a problem with the seal there and that might just be the cause of my woes. I thought I was the only one with this annoying problem... let us know what you find.

[danzo]

FIXED FIXED FIXED FIXED FIXED FIXED !!!!!!!!!!!!!!

While dozing at work yesterday morning, I started to think more about my half-assedly disabled EGR. So I printed the vaccuum line diagram and noticed that the top vac line on the EGR goes to the dizzy advancer. So during my lunch break I simply removed the vac cap and hooked that EGR port to the line going from the carb to the advance pot and SHAZAM! No more ping!! It's great when you fix a car using parts that are already under the hood.

I suppose the EGR valve is open or at least partially open under high intake vac conditions? Don't know if mine is operating properly or not, but that certainly was the cause of my predetonation. I didn't touch anything else. However, I must admit that when the coolant temp gets above half (I have a manual fan switch until I replace the busted stock switch) and I put a light load on the motor and it's warm outside then I can detect a very slight ping with the ignition timing at 8*. Maybe the EGR is leaking a little into the intake? Dunno but when I finally remove it the damn thing is going to have one awesome funeral pire.

Now where's that 40 of Schlitz.......