a lot of info here

http://forums.corvetteforum.com/c4-g...-adjusted.html

 

Thanks for the link, really great tutorial there.

I've been searching for a lamp all week, unfortunately they are pretty hard to find where I live, or people ask $150+ for one. I'll try getting a used one off ebay or something.

In other news, went for a test drive today, (since I had re-timed it "by ear" last weekend), oddly enough the car runs more smoothly (no more explosions in the converter), but I now have a lot of difficulty doing cold starts: the first two tries, the car often stalls.
I haven't concluded on anything, I'm waiting to do a proper timing job with the lamp...

 

http://www.summitracing.com/search/P...r=timing+light

 

In the other hand yesterday I found a timing light down here. for $22 dollars. also I found a set of spark plug wire.$18 dollars so so I just need the special distributor wrench. I think I will be bending a 9/16. to do the job.

 

the engine starts, then stalls? or the engine "kicks back" or hesitates while trying to start?

if the former, that is more than timing issue -since it runs ok. if the latter, it is too far advanced.

your setting by guess has been done many times. if it is too advanced, the ecm will retard it anyway. if too retarded on base timing, it is simply lost in the equation. of course, you have to eventually use the light to know where you are.

didn't follow this thread but explosion in exhaust can be plug wires crossed. or retarded timing.

as for the "special wrench" the 9/16 bolt holding the dist clamp can be accessed with a 6" 9/16 wrench.

 

@stoydido: it actually does both. First time it cranks a lot longer before the engine actually starts, and even then it starts weakly (400 rpm...) and then stalls. Second time it cranks faster, car starts but immediately stalls. Third time I gave it a little gas and it went smoothly.

Went for a ride and tried accelerating a bit harder once warmed up - it's still far from perfect, I maybe get 50% power and still a "70s muscle car with no muffler" sound

@calderone: thanks for the link but they charge $50 for S&H Fortunately I just found someone selling one for $40 in France, I'll have it shipped this week. Can't wait to get it right !

 

sounds like timing is retarded, possibly running rich also.
if you are in the mood to get it running, try to advance it, turn counterclockwise until the engine races slightly, perhaps .100-.200"

you won't hurt the engine, and the ecm will retard timng if it detects a knock under power

*** if you have to open throttle a bit to start it, open WOT, in case the engine is rich for some reason. that is "clear food". if it starts ok, you may have a rich condition. normally you don't touch throttle. if you have not checked TPS you may want to.

 

to set the timing you can also take the #1 spark plug out and stuff the hole with paper, bucking the engine till the paper pops out. this will indicate your at tdc. take the distributor out and set the rotor to dis cap terminal #1. Mark were the rotor lines up on the cap at #1 on the dis base. Put the dis back in the engine making sure the rotor lines up at the mark on the dis base. your timing should be set. You can fine tune when starting the engine and adjusting by slowly turning the distributor till the idle is smooth.

 

not debating marc, but if he follows that he will wind up with #1 in the #8 hole, because the rotor turns CW by 30* when dist gear and cam gear mesh. THEREFORE, rotor has to be turned CCW before dist seats into cam gear -in direction of #2.
if you fail to do that you can rotate the base, as you say, but your harness wires will be out of position.

if dist is installed and wires are positioned correctly, no need to remove it, just time it.

 

stoy, i was speaking from a perspective of starting from scratch with setting the timing, with the rotor moving clockwise to the #1 terminal.

 

I had seen the procedure for the technique you mention, they talk about it in the SM in case you accidently crank the engine while distributor is off.
In my case I believe I put the rotor & cap correctly, just in doing so moved it a couple inches therefore creating my problem.

@stoydido: if the problem persists after getting the light and doing it right, will check the TPS !

 

Ok guys, received the timing light today, yay !
Only problem: I can't get the car not to stall once I removed the brown wire. Should I take it for a ride, get it warmed up, and then do it ?

 

engine should be warm anyway, to idle at low rpm normally. ecm is likely advancing timing because rpm is high, 1000 or more.

if warm and it stalls, rotate dist base 10* or so, CCW, to advance timing. each degree is about .015" measured at the BASE, not the cap, if dist is stock. paint or scratch a baseline mark on dist hsng and manifold, whatever, so you know where you are.

joe

 

Thanks Joe

So I went ahead and did the test with the engine warm, and managed to make it not stall with the brown wire off. It was at +4° retarded, so I set it to 6° advanced, and the car now has a bit more power but a lot of small explosions in the converter when cruising at 20 mph. I thought that happened when the timing was retarded ?!
It's still not running perfect, any ideas ?

Thanks !!

 

If you set base timing per the book, the explosions may not be timing related -4* retarded would affect performance, not sure it would cause explosions, since ecm and dist model adjust timing constantly. on my 91, 2* retard caused hard start, but it ran "fine."

IF is the key word. if engine was idling hot, trans in drive if auto, at lowest rpm, most likely it is accurate. but if ign module was advancing timing, you can actually set it back, thinking the marks you see are your doing, rather than the module.

also, I think that we can set timing retarded -if module is also advancing- but not set it too advanced. comprende? IOW (in other words) if it shows 6* advanced it is not likely more than that, but can be less.

just read part of the thread, and it is possible that many things are out of spec. be SURE spark wires are not crossed -have to trace each one from plug to cap and not rely on marks, whatever. can be some simple thing that is overlooked. not sure if the module or pickup coil can contribute, someone will know.

also, GM stresses ElectroMagnetic Interference caused by plug wires too close to ecm wiring behind dist. that's why they say to route #1 and #2 in front of cap. it's easy to route them so as to avoid ign wiring. a clue is if you notice tach fluttering with no change in actual engine speed.

chk wires and let us know.

 

Thanks for the precise answer

I went ahead and checked the wires...they're all over the place, crossing and whatnot (mecanic put them back like that...) I'll try putting them a little better tomorrow.
Also, when I did the setting of the timing, I remained in neutral, not in gear; should I redo it in D this time ?

(on a side note, got some angry comments from a neighbor who told me the car was too noisy and preventing his kid from sleeping...if I can't do tests on the car on a saturday at 4 pm when can I ? :smash )

 

fsm says D, I guess to hold low rpms. be sure wheels are chocked, etc. I noticed that when rpm gets to 1100 or so, dist module adds timing advance. rpms is the key.

I don't think timing is your issue, as I think I said. if it was starting ok, timing is close, definately should not cause exploding cats. that sounds like one cylinder exhauting a chage without burning.

1-8-4-3-6-5-7-2. you did plug in the ecm bypass tan wire?

5, 7 often get crossed. all are "high potentials."

joe

 

Alright, here is a pic of the engine as is (I know, it's a real warzone...)



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On the other side, wires are perfect, no crossing, nice & clean. I guess I'll have to work on this side...

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the engine bay is not too bad -seen a LOT worse, on Callaways!

the left bank drvs side wires need to be verified, appears that 1, 3 are correct, never sure until you trace them. I would mark the individual wires on dist end with small paint dots, whatever.

 

Traced them all, they seem okay. Rerouted them so that they wouldn't cross anymore.

I redid the timing in D this time, and it was the same, 6° before, moved it to 8-10°, same thing. The car runs ok, idles in neutral at 800 rpm, but I keep getting a lot of explosions when I accelarate hard and then cruise, or just do some low speed cruising, plus it smells massively like petrol when I put it in the garage.

I'm really getting out of ideas here !