Hot Rods Awful gas smell - help me troubleshoot

So advance more? Like I had it to begin with I have always been one to use a vacuum gauge. Never lied to me. I got my skills tuning old **** like stove bolts with a brake suction bleed / vacuum gauge. I guess I resort back to that. I’ll be doing a fuel pressure regulator this week, 5 psi to start. Also checking those piston rod springs.


The exhaust is the tiniest bit white for the first 10 minutes, too. That could be a tired motor.

What a hemorrhoid :-/


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Fuel regulator in - sweet install. Filter totally hidden, regular on the firewall. Still smells. Wondering if exhaust is tumbling under the car and up through the trunk and in....


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Ok I’m back. Reluctant to post 3 times in a row. I think it means I lost you guys. My next project is to extend my tail pipes from 2” before the end of the bumper to like 3” past. I took off my turndowns and noticed that they are totally black, so is the inside of the pipes. Rich?


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Pipes don't "color" the way they used to with leaded gas either. Sounds like it. It's tricky. I think a grey or slight brown tint is more what you want to see these days. What do the plugs look like?

 

Bad photo, but somewhat tan. That WASNT pulled roadside after shutting the car off at 5ph. It was idle


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Looks like some deposits of some kind. I'm not too good at reading plugs. Yeah they look pretty rich though, too. Modern unleaded fuels don't normally leave much color on the plugs.

 

Somewhere I have one of those Edelbrock kits, with all the Jets and metering rods. I think I heard it said somewhere in a video made by them to start by going to sizes down… I’ll need to track down the kit and have at it. I would be afraid to go to lean, though as I might not know until I smoke my motor. I have considered using spark plug anti Fowlers To install oxygen sensors from a modern General Motors car, and plug-in a multi meter to read the air fuel mix and various speeds, but we’re talking a good amount of money, and all to do something the old guys were able to do without a computer


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If you want to do that like the old timers, have to learn how to read plugs, and it's a lot tougher now with modern gasoline, I don't believe those spark plug chart posters with pictures of all the different colored fouled plug deposits apply to much of anything anymore.

 

For starters, are the tips of the metering rods straight or might they have gotten bent? Do the power pistons move freely thru their complete range of travel without binding or sticking? This is how they need to be installed to work properly.

 

Your smell can ONLY come from unburned fuel. At idle screw your idle adjustment screws in a quarter turn each till you hear a miss. Once you hear a mess back that screw back out of half a turn and then do the same thing only turning them in an eighth of a turn until you hear it Miss. Then back them both out a quarter turn. One of the best things you can do for yourself is to buy a wide band
Oxygen sensor kit weld The bum in one of your tailpipes and then you don't have to guess about anything relative to you carburetor performance. Nearly everybody including Edelbrock sells their carbs to run rich to avoid any liability for burning exhaust valves. After I did mine I had to back off two sizes on both sets of jets to get it right. It's a bit of work but well worth it.

 

Thanks guys!

Rods are good, and idle
Mix is good. I think it’s the cruising mix BUT the smell Being on me is a different problem - it’s exhaust getting in. I extended my tail pipes well beyond the bumper and manipulated my vintage turndowns so they are not noticeably different than before. The change is night and day. My bride and I have done 100 miles since and literally have 0 smell on our close. A shirt that had been in the back seat for 200 miles barely smells. I bet if I seal the package tray and back if the rear seat with 10mil and upholstering it will be a done deal. Fire wall and a floor down the road. The turndowns and pipes were black, so it is rich. 98% of the time it’s at 60mph so it’s a matter of jets and rods



As for the O2 sensor, I had an idea the other day. I am going to run a set length (to keep resistance the same) if wire to the 02 sensor on my healthy running old school Lexus and measure its voltage under various conditions. I will then use the same 02 sensors and a bung in each down pipe. I am guessing about 0.5 volts is where the Lexus will run at 14.7:1 so I’ll look for the same in my Chevy. DONT STONE ME FOR SAYING LEXUS. Is a 2002 -
A safe car for $3,000 I couldn’t p***.


That said, this has been helpful. I will report back. The latter part of this won’t be done for a good while, but I will jet down in the mean time and loot at plugs and turn downs.


Does anyone have some kind of information on what jet/rod is in a sock Edelbrock 1406 and how that compares to the ones in that edelbrock jet/rod kit? I was gonna see if I can find my kit it’s packed somewhere


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14.7 to 1 by weight is "stoich" or stoichiometric and theoretically perfect, but is rarely seen in real life. Your lexus is probably EFI and will probably run around 18-1 AFR cruising down level highway. Can't begin to do that with a carbureted engine. Since the 1940s at least jetting for economical cruise in a carbureted engine is about 16-1. Power acceleration on the other hand, 14.7 AFR is way, way too lean. Usually around 12.5 to 1 AFR for safe power. You want a wideband O2 sensor for what you're trying to do.

 

This is what I used to lean up my 1406. I went all the way to the lower left part of the chart to get it right. I might have used option 11. Don't remember for sure. Digital oxygen gauge loves it !


https://goo.gl/images/eMSr3T

And

https://goo.gl/images/M8Anpo

 

Don't forget the power piston springs as well. How much vacuum does it take to keep the metering rods down out of the enrichment range? How much vacuum does the engine make at a steady 60mph on a level stretch of road?

 

I run a 250 inline six with dual W-1 carters, stock exhaust manifold, O2 sensor in the down pipe. At 65 mph on level ground, mine runs around 16.5 - 17.0 AF, at 35 mph it stays in the 15.0 range. Full throttle it drops to 14.0 or so, this is a stock engine, maybe 125 hp, 3300 lb truck with 3.08 gear ratio. The engine runs 2750 rpm @ 70mph. Fuel mileage went from 14.5 to 21 after installing gauge and tuning correctly. I have run it in the 17.5 to 18 A/F range, it didn't seem to help the mileage so I back it back down to the high 16's. I also tried lowing full throttle to 12.5 - 13.0 range, didn't make much difference. You just have to try different setting and see what the engine needs or wants. Most of what you read about A/F ratio's are from the racing side of tuning, very little is written about everyday cars with low compression and low HP.

Any 02 sensor and ****og meter with a slow dial will work, digital will be changing so fast you can't read it. Mine is constantly moving, you basically just take an average reading, even the slightest throttle change is seen. 1/16 turn of just one idle screw can change the A/F by 3/4 point or more at idle.

https://www.speedhut.com/gauge/GL258-AFWB-09/7/Standalone-Air-Fuel-Wideband-O2-gauge-8-5-18

 

ThanKs all!! I’ll have to look at vacuum at speed. Also, the LSU4.9 from Bosch looks promising but many wires? The one on my Lexus is 2 wires. I also see “kits” on eBay with a guage and a sensor for $160 but I have 2 downpipes... also want to be able to do it with a multimeter to save money. Wonder if there is a “slow” readout multimeter setting


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This is what I used, and it's excellent... you only need one sensor/bung ...
https://www.amazon.com/AEM-30-4110-UEGO-Ratio-Gauge/dp/B00N3VGPYS