Pinging and popping?

[ShelbyZ-TII]

Ok, so I got the new Action + intake and a freshly rebuilt Thermoquad (model 6138) on my stock 318.

I put in new Accel plug wires, Champion RN14YC plugs, cap, and rotor. I set the timing in it at 10* BTDC with the vac advance disconnected and was having problems with it popping and pinging under light loads and wide open.

I swapped the TQ for another known good TQ that was running very well on a 360. Same deal.

I had my brother take a look at it and he threw the timing light aside, loosened up the distributor, and retarded the timing _a lot_. It sounded better running under part throttle and cruise (no popping), but, when it's floored, it just pops and spits. 3/4 throttle seems to run pretty good.

I've tried running it with the vac advance disconnected and it doesn't change anything. The jets and metering rods are the ones for a stock 340, with the secondaries bumped up one size.

At this point, I'm assuming that the heat range on the plugs is way too high causing ping and popping, but, I'm just guessing here. I'd pull the plugs, but the car is currently 200 miles away.

Anyone have any thoughts or suggestions on this?

[DEMON SIZZLER]

Definately check the plugs and if black carbon is built up on the plugs, clean all and recheck the gap. The heat range would not likely cause the popping.

Next, crank the engine and note that the choke pull-off(on the passenger side rear corner of the base plate)plunger has pulled inward and then push down on one of the 2ndary air door dimples
to make sure the pull-off is holding vacuum(air cleaner has to be removed). If you can push down on the air door and the plunger moves out with little resistance, the pull-off is bad. Also note that the air door should have about .080" to .150" of slack when you push on an air door dimple at idle. Look at both metering rods to be sure both are still attached to the metering rod tree and that the metering rod piston moves freely up and down. I would drive the car without the air cleaner and se if the popping goes away and if it does, then returns with the air cleaner back on, the air cleaner is too restrictive.

[ShelbyZ-TII]

Hmm...I suppose I should have stated this earlier, the rebuilt carb does not have the choke pull-off. It also does not have the linkages for the choke or the choke door (not sure if this is what it's called, it's the door on the top of the air horn over the primaries).

The other carb I tried was originally off of either a 73 or 74 440 and had not been changed. That one did have the choke pull-off and ran very well on the 360 I pulled it off of.

I had checked the metering rods and the metering rod piston, it all seemed to be in good working order.

For reference, I am running an Edelbrock Pro-Flo 1000 series, the triangular one with the reusable foam filter.

Thanks for the input and I'll try your suggestions when I get a chance.

[rumblefish360]

Sounds like a lean condition. Look for leaks. The carb sounds like it should be jetted rich since it comes off a 340 and then jetted up. Even so with the open air cleaner.
Also, the distib could use a cleaning for a smooth operation.
Findout were the advance stops advancing on the car. USe light, get brother. With the vaccum hooked up, you should not be morethan 52* total. Vaccum disconnected, 32* will do max.
He may have retarded the timing more.

[DEMON SIZZLER]

I read your last post above; the air cleaner should be fine for the carb. You said the choke pull-off is missing so that explains the popping and lack of performance from the 2ndaries!

[ShelbyZ-TII]

The lean condition was suggested by my dad, which is why I jetted the secondaries up. This is the first carbureted car I've had in 10 years and it's the very first that has had a four-barrel, so I'm really relying on other people's advice here

I'll go ahead and pull the distributor back out and clean it up, I would assume that carb cleaner will work well once I get the electronics out of it. I'll have to see if I can dig up another timing light to check the total advance.

So I should try to dig up another choke pull-off then. Does the linkage need to be hooked up, or can I just run it with the pull-off plumbed in?

Thanks.

[DEMON SIZZLER]

You do have to run the choke pull-off and associated linkage as it's all crucial to the function of the 2ndaries. Without these parts, you would also loose automatic choke function too. The pull-off and linkage is what 'times' or 'delays' the 2ndary air door opening rate.

[rumblefish360]

Leave the distrib alone. Lets see what the carb work brings. If it works after you have all the carb parts on the carb, then just re-time the engine and leave it.
Work on 1 part at a time. Were doing a carb first here.

[ShelbyZ-TII]

Alrighty, I'll see if I can dig up the pull-off and all associated linkages...I should be able to find at least one full setup laying around.

I'll leave the distributor work for later.

[ShelbyZ-TII]

I hate to drag this back up, but is the choke butterfly(?) necessary? I may not be able to dig one of those up and if I can, I don't really want to mess with it unless completely necessary...

Thanks.

[MoparMarcIdaho]

didnt help any,you must have other problems.do you run points or electronic?Does it backfire out the carb or the exhaust?

[ShelbyZ-TII]

Well, since it's been a couple of weeks since I've driven it and I'm planning on heading back down this weekend. I don't believe that the carb change helped.

It runs electronic ignition, swapped out the stock box for a chrome box, no change. It doesn't seem to be backfiring, it sounds like it's just not firing. It ran ok on the two barrel that I swapped out (it didn't run well, it just didn't have this issue).

[MoparMarcIdaho]

from there?used to be my favorite station.We need to define your drivability complaint better.Pinging or detonation is caused by either too lean mixture or heat or overadvanced timing.Just slapping a 4 barrel on doesnt always work either.Its cammed for the 2 barrel and has restrictive exhaust too mabeye,I just dont know what to say at this point.