Light throttle ping from stoplight on hot days

[Voeltagear]

You might consider laying out all 8 plugs to read them all. The center two cylinders always burn hotter then the ends. If your plugs show this you can consider running one range on the 4 corners and another on the inner 4 cylinders.

Cylinder 5 and 6 look the leanest. I cleaned up the metering rods also. Considering getting one size smaller on the big end. Going to hook up a wideband in the next couple weeks also.

 

[Voeltagear]

View attachment 50221

Ok to slightly hot? Might be it. So few miles on these plugs.

 

[Voeltagear]

View attachment 50221

Another one.

 

[Voeltagear]

I had a thought today about the EGR block off. I checked the gasket and it looks like it was leaking slightly. It was previously sealed with RTV. I cleaned up the plate and re-sealed it with RTV temporarily. I was able to set the timing to the factory 2 degrees BTDC and I have no more pinging. It also sounds cleaner when I snap the throttle on a downshift. I'll order a new gasket this week and see how much timing I can add without pinging. Then I can add vacuum advance and see how it responds.

 

[Voeltagear]

Today I decided to take a look at the accelerator pump output. I remembered that it seemed a little lazy after the rebuild. I chalked it up a tight fit between the boot and the bore at the time. So today, the passenger side was putting out a stream (barely hitting the back of the port) while the drivers side was dribbling. I took the idle air jets and accelerator pump orifice manifold out and cleaned up the holes. Now both sides have a strong stream that hits the backside of the ports. I'm still waiting for the new egr gasket. Once I get that in I'll try some more mechanical advance.

On Monday, prior to cleaning the accelerator pump holes, I had a little detonation in 95° weather (89 octane w/ethanol). That's after sealing the egr gasket and adding 4° mechanical advance, so not too bad considering. I tightened up the vacuum advance spring and it helped.

 

[Duke5A]

Today I decided to take a look at the accelerator pump output. I remembered that it seemed a little lazy after the rebuild. I chalked it up a tight fit between the boot and the bore at the time. So today, the passenger side was putting out a stream (barely hitting the back of the port) while the drivers side was dribbling. I took the idle air jets and accelerator pump orifice manifold out and cleaned up the holes. Now both sides have a strong stream that hits the backside of the ports. I'm still waiting for the new egr gasket. Once I get that in I'll try some more mechanical advance.

On Monday, prior to cleaning the accelerator pump holes, I had a little detonation in 95° weather (89 octane w/ethanol). That's after sealing the egr gasket and adding 4° mechanical advance, so not too bad considering. I tightened up the vacuum advance spring and it helped.

Have you tried spraying ether around the vacuum seals and seeing if the idle picks up?

 

[Voeltagear]

Have you tried spraying ether around the vacuum seals and seeing if the idle picks up?

I used propane. Didn't find anything.

 

[Duke5A]

Next thing you need to verify is the timing marks are correct using a bump stop. The balancer may have slipped. These numbers just don't make any sense.

 

[Voeltagear]

Next thing you need to verify is the timing marks are correct using a bump stop. The balancer may have slipped. These numbers just don't make any sense.

I agree with you. I looked for my stop today but didn't find it. It does seem to be lean though. I'll be swapping on a 4 barrel intake and carb in the next couple of weeks but before I do I'm going to get bungs welded in for the dual wideband.

 

[Voeltagear]

I was able to confirm the carb number is correct for 1976 318 manual transmission. #6071s. Metering rods are also correct. #75-2155. I can't find a listing for the distributor #656672 other than dodge 318. Does anyone have a book that has distributor part numbers? And if so the mechanical advance specs? I'm getting about 22° mechanical advance at 3400 rpm.

 

[Oldiron440]

You might consider laying out all 8 plugs to read them all. The center two cylinders always burn hotter then the ends. If your plugs show this you can consider running one range on the 4 corners and another on the inner 4 cylinders.

I like this idea, I was thinking about heat range of pugs being off.

 

[Voeltagear]

I like this idea, I was thinking about heat range of pugs being off.

I did look at all 8 plugs. Cylinder 5 and 6 were the leanest. I'm running Champion RN14YC per vehicle specs.

 

[Voeltagear]

I stepped up to Amoco Ultimate on Thursday. After a 25 min beat run on the interstate I noticed a significant difference in idle quality. It idled slower and smelled rich. When I got home I checked the idle mixture screws and had to turn them in to get back to max vacuum at idle. I now have no detonation and even added 2 more degrees of initial timing. It's now 4 degrees BTDC. Not even a hint of detonation. So either the ethanol mixture was boiling or the additional detergents help clean something out. I had run 93 octane with ethanol and Kwik Trip recreational 91 octane previously and still had detonation issues.

 

[Voeltagear]

Have you tried spraying ether around the vacuum seals and seeing if the idle picks up?

Also, if there is a significant vacuum leak, slowly choking it by hand will cause the idle to pick up momentarily. It doesn't.

 

[Voeltagear]

Upped the timing to 6° BTDC. Still no detonation. It's like a different engine. Lol. I'm shocked honestly. The changes I made are installing the new EGR gasket and going to BP ultimate 91 octane without ethanol. It never ran without detonation since last May when I purchased it. Even with Kwik Trip non-ethonol 91 octane. Is BP fuel really that much better? The gas station is directly across the road from a boat launch and I heard about it from buddies at work with power boats.

 

[Voeltagear]

Just had a thought, someone mentioned collapsed fuel line? Could the ethanol have caused one of the rubber fuel lines to swell internally? Maybe I guess. I'll be replacing them as insurance for sure.

 

[Aspen500]

It's possible. Worse though, ethanol accelerates deterioration which can cause a fuel leak. Regardless, it's not a bad idea to replace potentially 40+ year old hoses anyway.

Unless it says ethanol free, whether it's 87, 89 or 91 octane, gas may contain "up to 10%" ethanol. Might have none, might have 10%. Last time testing was done around here, ethanol blended fuel had anywhere from 0% to 6%. Suppose all depends on the station and where they get their fuel.

 

[Camtron]

My buddy works in the lab for Shell out in, California. I had asked him about this years ago. It all comes down to region and supplier. In the Midwest, BP and Citgo/Costco refineries dominate and generally have the best quality and supply their own gas stations. However if your local gas station is supplied by like, Oswego (supplied fuel for our tanker/fuel truck and ground equipment at the airport) or a similar small refinery/distributor, you’re likely getting garbage blended B grade fuel.

 

[Aspen500]

I suppose gas is regional because it almost has to be. Different climates, etc. Some places have stations with E85 everywhere. Here in the metro area there about 73 gas stations, and only 8 carry E85 (all are Kwik-Trip). Of course in winter none have it. Alcohol is hard to ignite on a cold start when it's 1 degree, lol. Actually I guess it doesn't work well below 40 from what I've heard.

 

[AMC Diplomat]

I use ethanol free 91 or higher octane (depends which station I go to). Cold starts are great. Hot starts on hot days? I hold down the starter and pray. Either the fuel is leaking down or it's simply evaporating out of the carb.

Getting gas from places that sell boat gas or sell 100 octane for the fancy cars is definitely the way to go. Someone working there will know where the gas came from and what kind of oxygenates are in that gas.