don't know what the heck is going on here on this carb motor
when running on 87 octane fuel I have to retard the timing so much that it doesn't run right. you know dies when comming to a stop runs rough no power even less in the upper rpm range.
if I advance the timing a tad it runs better BUT it starts to ping mainly in the 1500-2400rpm range


put 91 octane in there and I can advance the timing a little more and it seems to run better but again seems to ping a little to get it to run best though less ping then before


it only seems to do it at partial throttle or if I have it just on border line ping it does it during throttle transitions but once I hold steady throttle it's fine


one thing I noticed funny though is the ground arm on the spark plug is covered in a white (not tan or brown or anything but white) powder like stuff while the outside ring is a black ash like stuff

shouldn't the ground ring be a little more tan not this white color?

 

How much advance are you getting there? Id say the engine probably has too much timing in that area but its ok most other places. Maybe even little lean. It may not have enough pump shot as well. I had the three rocks in a coffee can detonation when I didnt have enough accel. enrich.

 

If it's a ThermoQuad, you can jet it differently for more fuel in the transition. If it's a Rochester, you can raise the float level slightly to provide the same thing. If it's a Holley, you can suffer.

Using EGR? What's the coolant temperature? Are you running at altitude? Tried colder plugs? Compression ratio?

 

coolent temp is just into operating range, compression is 8:1 thinking of trying colder plugs and altitude is around 2000-3000 feet here

pinging usually isn't that bad mostly during transition periods on the throttle or when switching from primary to just getting into the secondary.
also seems to get worse after doing some heavy load like freeway driving and such which I know can lead to need a colder plug


anyway to read the plug to find out if the heat range is a little too hot?

 

How many miles on what motor? The wankle or a sbc in a 3rd gen. 305's are notorious for ping esp. if high miles and alot of carbon build up. EGR passage plugged?
Threw EGR away?

 

which plug are you using now?

How much static, total, and vacuum advance (never used a vac. adv. dist. so forgive if the terminology is wrong) do you have?

Definatly a good idea to find that out before you go chasing other problems that may not exsist. Might just be too much timing in certain spots. Also detonation can dump a good deal of heat into the motor, which will only lead to more detonation, so its not surprising that it gets worse after prolonged high speed operation.

 

static advance I'm not sure how much I have
supposed to run on 87 octane and I have it on 91 with a bit more dvance nor do I know the rest of the timing numbers since I don't have a timing light

as far as timing too far
on 87 octane timed as just a tad retarded from pinging it would just run like crap
no power stalls at everylight and so on

egr passage might be pluged and I wouldn't even know how to fix that one other then to replace

might have to borrow the friends timing light to see what the timing says


I think lean mixture might of been a little bit of it. raised the fuel float a little and the pinging went away as did it when I started running cheveron rather then the crappy maverick gas.
but since then I'm now getting flooding and so forth issues

stop the car and you can hear fuel just flow into the carb. adjusting the float by the needle seat screws does nothing so off to take the top of the carb off and see if I can fix that

 

So far, you've established that a change of fuel has helped, so that may have been an issue.

You've also enriched the mixture to compensate, and apparently the detonation stopped. What kind of carburetor?

Evidently, your EGR is no longer present. Is there any means of installing another, or is the manifold not equipped to accept one?

3,000 feet shouldn't present that much of a challenge. You can't blame it all on bad altitude.

 

the egr should still be there but I havent' checked
the carb is a keilhin or something like that.

as far as enriching the mixture don't really think I did t hat think the carb did it on it's own. lovely thing just wants to flood now.

 

Carbon build-up gets my vote too. Have you tried Seafoam and/or GM top cylinder engine cleaner? That plus dribbling some water into the engine via one of the vacuum hoses to the intake might help. You might try these before you chase a possible phantom timing problem that's really excess compression from carbon build up in the cylinders.

 

That sounds like a really good idea. Eveything else is just guesswork if you dont know what the timing is.

 

thing I'm curious though with the timing on the car

it was made to run 87 octane
since I have upped my timing and started using premium how much would that really help?

 

Assuming its a timing issue, getting the dist. set up to deliver the right ammount of timing in most areas will help the most. Youll be able to go back to running 87 and itll make more power and run better.

 

even if I get everything running right would better performance be achieved using premium and then taking the timing and advancing it from stock with the higher octane fuel?

I understand with if the car was designed for regular and your keeping the stock timing using regular is prolly going to make things better
but what about with advanced timing still better to just keep it stock and use regular?

 

I doubt the premuim would have much effect with a motor like that, certainly not enough to offset the cost IMO.

 

so far more then offset the cost

gas mileage went from 32-33mpg up to high 38mpg along with finally getting a little mroe pep out of it vs the regular was having a hard time getting on freeways at the correct speed