TheSamba.com :: View topic - Running rich on cylinder 3 & 4 and lean on 1 & 2

Thu Jun 09, 2022 8:07 pm

got a stock 36hp 1955 semaphore 113 with birth certificate (built April 23, 1955) over the weekend and already trying to sort out the first noticeable issue. pictures to follow soon.

the issue,

cyl 3 and 4 have dark soot on their spark plugs, where as 1 and 2 are dry and clean. engine idles and drives fine, just lots of gas smell coming out of exhaust, i.e., un-burned fuel.
also, unplugging the spark plug wires from 3 or 4 doesn't make much difference to the idle, 2 is similar but a bit better, and 1 makes a lot of difference so seems to be the only one pulling its weight.
i do hear some clacking from the valves so they will need adjusting as soon as i get around to it, but nothing terrible...

running BR6HS NGK/R plugs with gaps at .026",
VJU 4 BR 8 distributor with points/condenser, Meinhart Kabel spark plug wire set,
28 PCI carburetor with a disconnected choke cable (the choke housing/wire has not been pulled through the fan shroud to the carb, and goes who knows where from the dash to under the trunk floor (i need to trace it and attach to the carb). car starts fine cold without the choke.

what could it be, among a million things? :) thank you

Thu Jun 09, 2022 8:12 pm

A million and one things!

Valve adjustment stone cold.

Compression check after warmed up.

Run it and do a spark test.

Betting you got a cracked head and compression is leaving those 2 holes, or those 2 holes are worn out, or just weak spark.

Seen it a few thousand times! Time for you to prove what it is, on this engine!

Thu Jun 09, 2022 8:20 pm

VW_Jimbo wrote:
Betting you got a cracked head and compression is leaving those 2 holes, or those 2 holes are worn out, or just weak spark.

Seen it a few thousand times! Time for you to prove what it is, on this engine!

thank you for your Russian roulette reply. here's hoping that it doesn't land on the live "cracked head" round.

Sat Jun 11, 2022 11:06 pm

Before any other adjustment, the valve clearance must be correct.
It could be a leaking inlet gasket, try start gas around the inlet of the heads to see if it raise the rpms.
A way to check the state of the engine, is to test top speed.
Factory cruising speed is 68mph = top speed. Mine do a little more.
I use NGK BP5HS for better spark than B(R)5/6HS. 6 for hot areas, 5 for rich running engines/colder climates. P for prolongued electrode ignites 1-3% more fuel mix every time.
Valve noise isnt a good diagnostic, as too tight valves gives less noise. Uneven valve clearance could be one reason for different response on pulling out plug cables.
If it spitter fuel, I suspect leaking float valve or to high float height level in the carburetor.

Sun Jun 12, 2022 8:45 pm

yes, valve adjustment is next. i read that the gap should be at .004", others say .006". here is my source,

https://www.classicvwbugs.com/wp-content/uploads/2014/05/36hp_articles.pdf

what's best on a 36hp? thanks

Sun Jun 12, 2022 11:08 pm

.004 was when leaded gas was readily available. When non leaded fuel became more common place the clearance was increased to .006

That’s what I have come to understand. I think there is a VW bulletin out about it as well.

As a young kid I helped Dad adjust the valves to .004 Heck, my first time adjusting a valve I adjusted it to .004. Time marched on And some where in the late 80s, when I was at an independent VW repair shop, I was taught .006 This was backed up with the bulletin.

Mon Jun 13, 2022 10:34 pm

adaysnight wrote: yes, valve adjustment is next. i read that the gap should be at .004", others say .006". here is my source,

https://www.classicvwbugs.com/wp-content/uploads/2014/05/36hp_articles.pdf

what's best on a 36hp? thanks
I adjust my 36 hp valves to .004" although I check and adjust the valves and change the oil every 1500 miles. If I was only going to adjust them every 6000 miles I would set them at .006"

Tue Jun 14, 2022 5:46 am

My 2 cents worth, Re valve adjustment: bigger is better on an air cooled engine, no harm can come to your engine by adding that 0.002" and it may just extend the life of the valves.

Also:

I have a friend with a full WW big build kit on his 36er. I must say that is the fastest 36er I have ever driven, WOW! Anyways, he has the same problem: 1 and 3 are correct and 2 and 4 are way too rich and it is def not the valves or leaking gaskets.

Don

Tue Jun 14, 2022 4:32 pm

just did the valves adjustment at .006, 3 and 4 were too tight, 1 and 2 too loose. but first torqued down the heads (7 ft.lbs., then 27 ft.lbs., alternating from inside nuts to outside) and the rocker arms (14 ft.lbs). also connected the spring-acting rods inside the heater boxes (heard them and the flappers/vents jangle on bumps in the road on drives before and had no idea what it was, now all is quiet there).

now i hear and smell a noticeable difference - a slight improvement on the disconnected cylinders affecting the idle and less gas smell from exhaust. i likely need to drive it a bit more to get the full effect, this was just during the 1st start after the whole procedure. will also check compression after more runs.

thank you all for your help!

and here are some pics. original color was tan but was repainted jungle green inside and out. numbers match, all fenders, doors, hood and trunk are original. all window glass has the original large "SEKURIT" script except the driver's door glass only, vent has the original glass as well. prior owner drilled holes in front fenders to add turn signals. i could weld them up but will just add the peanut signals instead, it will be safer in traffic. he also cut the rear apron for dual exhaust, perhaps to install a 1600. shame, but that's how it is. i will most likely weld them up. this car was imported into the US with the M package as is evidenced by the birth certificate and specs on the car. the original owner appears to be a well known pilot who served in WW2, Korea and Vietnam, and then was a teacher in Long Beach, Ca, a guy by the name of Taylor H. Wagner. his laminated newspaper picture and commemorative dog tags were with the car docs and three sets of egg tail lights the previous owner wanted to install.

Tue Jun 14, 2022 9:39 pm

See, that valve adjustment is the big basic adjustment. Do not forget that, as you go down the road. Every troubleshooting chart starts with a valve adjustment stone cold.

You should change the oil. Check the points .016, then set the timing idle mixture and speed.

Then check the tranny oil, adjust the brakes and if safe, go for a drive!

Nice car!

Oh, get some new oil in the air cleaner. But clean it out really well!

Tue Jun 14, 2022 11:14 pm

VW_Jimbo wrote: See, that valve adjustment is the big basic adjustment. Do not forget that, as you go down the road. Every troubleshooting chart starts with a valve adjustment stone cold.

You should change the oil. Check the points .016, then set the timing idle mixture and speed.

Then check the tranny oil, adjust the brakes and if safe, go for a drive!

Nice car!

Oh, get some new oil in the air cleaner. But clean it out really well!

thanks! all on the list as time permits... (good rhyme, eh? :))

thinking of using this gear oil. i'm aware of the GL4 vs. GL5 debate and i'm Ok with GL5. this oil is left over from my BMW E30 days and has been sitting in cool storage for some 10 years if not more, has it gone bad or still good?

Sat Jun 18, 2022 11:31 pm

adaysnight wrote: VW_Jimbo wrote: See, that valve adjustment is the big basic adjustment. Do not forget that, as you go down the road. Every troubleshooting chart starts with a valve adjustment stone cold.

You should change the oil. Check the points .016, then set the timing idle mixture and speed.

Then check the tranny oil, adjust the brakes and if safe, go for a drive!

Nice car!

Oh, get some new oil in the air cleaner. But clean it out really well!

thanks! all on the list as time permits... (good rhyme, eh? :))

thinking of using this gear oil. i'm aware of the GL4 vs. GL5 debate and i'm Ok with GL5. this oil is left over from my BMW E30 days and has been sitting in cool storage for some 10 years if not more, has it gone bad or still good?

Its probably still better than the oil 60years + ago if it still smell and look like it should. 🙂
Think its GL1 recommended in old manuals...