1953 Mercury unusual plug condition

[Merc Cruzer]

Merc, my mistake. I'm stuck in the .94 mode of thinking, not the Teapot. Your .054 jet size does make sense now. I hate to have unanswered questions, but Tubman's suggestion might be the way to go. Still, with the high altitude, that in itself may account for less vacuum on the longer runs, dumping a higher volume of fuel in the near cylinders. I don't know what I'm talking about, just a stab in the dark.

ford38V8,

You are right as to the vacuum, I can only generate 12-13 on a good day, no matter what I due to tune for higher vacuum.

Tubman's suggestion, is a good one and at this point, I am thinking just a thorough cleaning and swapping out the jets for .052's and looking for a with a lower vacuum requirement (if there is such a thing, my current one is a 52). This is what happens when you start going for just a little more performance.

Thanks again,

Roy (Meerc Cruzer)

 

[Merc Cruzer]

Given you're talking about plugs, coloring, etc.. How are you actually checking them? You can't just drive it, hit some stops on the way back and pull the plugs in the garage - that will tell you nothing. You have to load test on the highway, push the clutch in and coast to a stop. Also, reading plug colors with today's fuel is difficult. I don't see "chocolate" colors anymore. So, I use an O2/AFR meter to actually tell me what is going on.

Just curious, when you say reading plug colors with today's fuel is difficult, why?

 

[Bored&Stroked]

Just curious, when you say reading plug colors with today's fuel is difficult, why?

Today's fuels are so over-refined, that I find it difficult to obtain the ole chocolate colors we used to rely on.

I tend to see the insulator looking much more white - which in the old days would tell me too lean. I've seen the same thing at the race-track . . . plugs tend to look "hot" when they are not.

I also pay a lot of attention to the plating on the electrode and the bottom of the plug. I tend to use NGK plugs only - as the insulator and plating tend to tell me a lot (especially with heavy load conditions).

This is one of the reasons I like an O2/AFR meter - so I actually know what is going on - versus guesssing. They are not that expensive - and are a great tuning tool.

 

[tubman]

Dale, I am having a hard time seeing how an O2/AFR meter would help to find the problem here. If you didn't have 2 of them, you would be reading the AFR of the entire engine. (With two, you would at least be able to read each bank.) How would you be able to narrow it down to an individual cylinder (or cylinders)? Don't get me wrong; I'm a fan of AFR meters and have on on my run stand, but I fail to see how it would help to track down what appears to me to be a fuel distribution or ignition problem.

 

[Merc Cruzer]

As it turns out, there is a smaller power valve, and I happen to have one:


Roy,

The brass power valve marked #52 has two .037" holes in the shank of it to increase the enrichment when undel a medium to heavy load. The one marked 28 has only one hole that is .028" and was used on the '56 Ford/Merc 292 and 312 Y Block 4 barrel teapot carb. '55 teapot four barrels used a #43 power valve which had one .043" hole.

Most power valves in other carbs only had one hole as small as .021" in some carbs.
If your feel you're too rich because of the high altitude, changing the main jets to a smaller size will make it leaner under light, medium and heavy load.

The Holley manual says two sizes smaller for 5,000 to 10,000 foot altitude.

Sal

 

[Ross F-1]

Dale, I am having a hard time seeing how an O2/AFR meter would help to find the problem here. If you didn't have 2 of them, you would be reading the AFR of the entire engine. (With two, you would at least be able to read each bank.) How would you be able to narrow it down to an individual cylinder (or cylinders)? Don't get me wrong; I'm a fan of AFR meters and have on on my run stand, but I fail to see how it would help to track down what appears to me to be a fuel distribution or ignition problem.

Given the way the intake manifold is made, reading an O2 sensor on one bank is really reading 2 cylinders from one side of the carb and 2 cylinders from the other. Putting 2 O2 sensors really doesn't buy much more information.

 

[Merc Cruzer]

I also switched the pump arm, to the least amount of gas (far left). It was set on the highest ( far right). Admittedly it is a minor adjustment, but I am trying to be systematic in the process. Now need to do a few test runs.

Next I will switch out the power jet to the .021.

If that is not enough, I will go with smaller main jets, either: .053's or .052's

 

[tubman]

Given the way the intake manifold is made, reading an O2 sensor on one bank is really reading 2 cylinders from one side of the carb and 2 cylinders from the other. Putting 2 O2 sensors really doesn't buy much more information.

All I'm saying is that two meters would narrow down the problem to one set of four cylinders rather than all eight if they had different readings. I don't think it would matter much to me whether the four cylinders were in the same bank or not.

My original question still stands.

 

[Merc Cruzer]

Sorry for taking so long, but being retired doesn't mean you have an empty schedule.

For now I am going to live with this. I probably could go down a jet size though. It is a little trickier at 8300 ft.

Thanks again, for all of your suggestions.

 

[tubman]

I know people who would die for a set of plugs that looked like that.

 

[petehoovie]

Sorry for taking so long, but being retired doesn't mean you have an empty schedule.

For now I am going to live with this. I probably could go down a jet size though. It is a little trickier at 8300 ft.

Thanks again, for all of your suggestions.

 

[Merc Cruzer]

I know people who would die for a set of plugs that looked like that.

Thanks, I am happy with my efforts so far. It makes her more fun to drive, now that I have resolved a few of smaller issues. She runs smoother now, than she ever has. Rather than mentally complaining about any minor hesitations of late reactions to acceleration, I now notice the condition of the road, I driving on. I think I will turn on the radio and enjoy a few songs from the 50's, the next time I take her out.

 

[Lawson Cox]

Merc, my mistake. I'm stuck in the .94 mode of thinking, not the Teapot. Your .054 jet size does make sense now. I hate to have unanswered questions, but Tubman's suggestion might be the way to go. Still, with the high altitude, that in itself may account for less vacuum on the longer runs, dumping a higher volume of fuel in the near cylinders. I don't know what I'm talking about, just a stab in the dark.

Alan: So your commens are merely a WAG (Wild *** Guess) then? Then again, with your knowledge and experience, I will elevate that to a SWAG. (Scientific, wild *** guess.)