Anyone using Autolite 308's????

[48 New Yorker]

I've got a 48 New Yorker 8  that runs quite well.  Currently running the spec'd Autolite 295's gapped at .025, but they become sooty after a few thousand mi.  The engine has moderate blow by for which I've installed a PVC system (based on the factory reto-fit plans).  Other stats:  timing: 4 degrees adv., valves I.008/E.010, dwell 29 degrees.

 

I'm thinking that the recirculated vapor might richen up the mixture causing the sooty plugs.  (the carb Stromberg AAVS-2 has been recently rebuilt and has correct original jetting).

 

To fix the soot problem, I was thinking of going to the hottest plug available, the 308 (2 steps hotter than 295)....does anyone have any long time experience using them?   I tried 306's not much better than the 295's.  Also, the 306/308's are resistor plugs, not spec'd for the 48, and the gap is  spec'd @ .035".....vs .025" for the 295's

 

To recap: Anyone have experience with 308's in a Chrysler 8/ 6 or Dodge/Plym 6? .....what gap do you use?

Thanks all.

 

FYI my old Motor's manual lists the correct plugs as follows:

46-48 Chrysler 6/8 = AL (Autolite) A5

49-50 Chrysler 6/8 = Al (Autolite) AR8

 

 

 

 

 

 

 

 

[chrysler1941]

Been using 295 .025 for over 10 years with no issues.

Sooty is usually rich mixture. Also too many cold start. Oil deposit is another story.

Try advancing your timing with a vacuum gauge to get better burn.

[greg g]

Might not be the plugs.  If they are uniform in appearance and it's soot not oil it suggests your engine is running rich.  Do you see Grey or black smoke from the tail pipe at start up? Is there a smell of gasoline at the tail pipe?  If so you may have some conditions that you might wish to check.  First and easiest is unobstructed air flow into carb.  Air cleaners clean and functioning properly, and choke butterfly opening completely? Second is your heat riser operating properly?and third, is the stepup jet in the carb operating as it should.  Not 100 % sure about the eight cylinder carbs, but others have a step up or power circuit that enriches fuel air ratio when accelerating or climbing hills.  This provides for a richer mix after the initial squirt of the accelerator pump.  These are internal and depend on a vacuum signal through the carb to modulate its position relative to intake manifold vacuum.  If it sticks open it will provide an over rich mixture all the time.

 

Your sooty plugs are a symptom of a problem not the problem in itself.

[48 New Yorker]

Thanks for your replies:

Chrysler1941: 

It's timely you should mention "timing w/a vacuum gauge.  I just tried that a while ago without getting definitive results.  My vac is nice and steady @ about 18-19"....problem is, when I dialed in more advance it never got to a point where it dropped off.....signaling me that there was too much advance...in fact I ran out of "room" to advance (the advance unit hit the block preventing it's further movement).  At that point, I "guesstimated" that I had dialed in about 10 to 12 degrees of advance....far too much...so I reset with my timing light to 4.  Most of what I've read here say no more than 3 to 5 degrees max... The cold start issue may be part of the problem as well as my driving habits .....mostly slow around town driving.....not much highway.....fyi...no oil on the plugs....just soot.

 

GregG:  No black smoke, but sooty tail pipe and strong burnt gas smell (bicyclists hate me)..... I've modified my air cleaner to take a standard Fram paper element (see pics)....and I think the flow is ok....maybe I should try w/o it for a while.  Heat riser is free and moves easily....clunks when I open/close throttle quickly.  

 

You're point about the carb circuits is a good call....but one I've avoided because I don't really know how I could diagnose and fix it.....re-jetting????....so I've kind of avoided thinking about it.  I've had the Stromberg apart several times for cleaning and rebuilding (have another as a backup) and I feel that I've cleaned out the passages as well as possible.....using a very fine wire, soaking and compressed air. 

 

I've replaced the Sisson with a manual choke, so I'm confident it's not hanging up. Also, added some heat shielding to prevent "hot soaks" b/c of alcohol/gas issues.

 

One other thing....up until recently I have a 3 year old 6v battery that was getting tired...now replaced.  Perhaps I wasn't getting a strong spark....New battery makes it start a lot quicker....much less cranking....FYI I have copper core wires and new points/condenser too. 

[Sniper]

The idle mixture screw essentially sets the baseline for the air/fuel mixture at all speeds.  If that's rich everything else will be.  You can use your vacuum gauge to tune that.

 

http://www.yourolddad.com/tune-up

[48 New Yorker]

Yup, did that with vac gauge and confirmed with a  tach ....found the highest smoothest idle after backing out the idle speed screw to drop the idle..... then adjust the mixture...then reset idle to 500ish....

 

Re: spark plugs, I guess no one uses 308's.  An additional FYI, I replaced the coil with a new one thinking the old one may have had an intermittent problem....the new one is (correctly) not internally ballasted....

Edited August 18, 2021 by 48 New Yorker
more info

[wagoneer]

@48 New Yorker Sounds like a beautiful vehicle you have; The description alone is pure poetry. One day I am going to get a straight 8 for myself. That's a rare engine with beautiful engineering in and around it.

 

I'm running NGK BR6S plugs in my 48 Windsor 6, and in my recent testing, are really solid and bright sparks compared to Champions and Autolite spark plugs. I run them at .035 gap. As far as I can tell, the only reason Autolite A5s (resister less .025) were recommended was due to the technology not being prevalent yet. In 50, all of the DPCDs moved to resister plugs (.035).

Edited August 18, 2021 by wagoneer

[greg g]

You shouldn't need to mess with jets other than to assure they are open and flowing at the right time.  The attached illustration is typical of what I am referring to.  It probably isn't exactly like your carb but was typical for the Era.  The metering rod goes into the jet.  Reacting to the spring which wants to open it upward position, and the vacuum signal which wants to pull it down and close it.  So the default position is open with the spring or springs holding it there when there is no vacuum.  Starting the engine and idle creat high vacuum inthe intake manifold. This vacuum passes up into the carb via a slot inthe carb to manifold gasket and a hole in the bottom of the carb base.  When vacuum is present the jet or jets in a two barrel are held closed against the spring. When vacuum lessens as in accelerating or climbing a grade, the spring will over come vacuum opening the jet. High vacuum being reestablished by resuming cruise, the valve is then pulled closed by the signal overpowering the spring.  So no vacuum from a plugged pathway, or an incorrect gasket installation leaves the valves enriching the mix when not necessary.   So assure the metering rods are opening and closing and the vacuum path is established and clear and that source of app rich mix is not the fault.  Generally these assemblies are located in the float bowl on the other side from the acc pump.  The top of the carb will need to come off to access them.

 

https://www.google.com/search?q=carter+carburetor+power+valve+circuit+diagram&client=tablet-android-samsung-nf-rev1&ei=Y2gcYaObI5PRtAbYkKuQDA&oq=carter+carburetor+power+valve+circuit+diagram&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAMyBQgAEM0COgQIABBHUNioIVjuyCFg9tghaABwAXgAgAGtAYgBmgiSAQMwLjeYAQCgAQHIAQjAAQE&sclient=mobile-gws-wiz-serp#imgdii=-kyrskFksbSgLM&imgrc=BW8In5eOLqG13M

[chrysler1941]

13 hours ago, wagoneer said:

As far as I can tell, the only reason Autolite A5s (resister less .025) were recommended was due to the technology not being prevalent yet. In 50, all of the DPCDs moved to resister plugs (.035).

What technology are you referring too ?

[48 New Yorker]

Wagoneer:

Thank you for the complement. 

"Ol Geezr" was originally  delivered to Carter's Garage in Centrailia WA (this from the id plate info that I sent to Chrysler Historical).   Strange part is.....the firewall ID plate reads DeSoto, but has all the correct info for the car.  I think it was owned by a woman who did not drive much, currently has about 34k miles, and is rust free (other than surface rust.  Unfortunately, I don't think it was garaged as the chrome is shot and it's been repainted twice from it's original Heather Green (see door jams).... I refer to it's present color as medium Bile. 

 

My guess is that it sat for years, and as a result, the oil control rings either got "lazy" or are carboned up, hence the blow-by, doesn't use an inordinate amount of oil tho'.  I've had the head off, but didn't remove any pistons.  One shows some pitting that I think occured as a result of a leaking head gasket many years ago; and a couple of cylinder walls have some slight pitting as well, again maybe water intrusion.

 

I recently got the seats done and treated myself to the Highlander option (original was dark green)....see pics. Next projects are the door panels and headliner......and finally paint, and back to original Heather Green.....hopefully in the next year or so.

 

For anyone who remembers my prior posts, I had complained about heavy steering and opined about getting electric power steering.....which is impossible as I've learned, because I have chosen to retain the 6v pos ground electrical (you need 12v neg for electric).... I've keep the 6v pos, but upgraded to a 6v alternator....(a very good and $$$ reasonable upgrade).  The car came with L78x15..... a Freighliner steers easier.

 

The solution to the steering was to buy a set of Cocker "Bias Ply Look" radials (wide whitewalls).  Even though the recommended size for a '48 is 8.20x15, I chose to go with the 47's size of 7.60x15 because they were narrower.  Radials tend to grip better making them harder to steer, but this is offset by the fact they are quite narrow.  It still steers heavy when parking, but is manageable - I'm happy. 

 

2 issues with the Cockers tho' ....two tires were defective - sidewall blisters, (exchanged free) and they are very hard to have mounted because they come tightly wrapped.....the bead would not expand enough to catch the rim.....had to leave them in the sun with bricks in them to spread the bead....what a pain.

 

[48 New Yorker]

Greg G:

Thanks for the good info... I'm now an expert at popping the top of the carb off to check stuff (float level...etc). I'll check out what you've suggested.....

Narrowly avoided a real headache......during my rebuild of the AAVS2.....I decided to use my compressor to blow out a bleeder (looks like a long needle).....damn thing shot out of my hand when I hit the air... finally found it .....about 4 hours later....stuck in my bench grinder.....don't know where I'd locate another .......at least I found it. 

[wagoneer]

@chrysler1941 Resister spark plugs

 

standard equipment starting in 1950. There is a great MTSC covering the whole topic, and the transition from A5/A8 to AR5/AR8 covering topics like  how to choose which is right for the customer .

 

https://www.mymopar.com/downloads/mtsc/036.pdf

 

 

@48 New Yorker   Have you checked your vacuum advance is working properly? I have two, and neither is any good. I'm looking at retrofitting a more modern (late 60s) to my old one to get a reliable vacuum advance.

 

 

What a beautifully done interior; I was just thinking to have my own highlander redone, and the springs fixed in my seats. Where did you order material from? SMS? I got a sample from them but it looked too heavy to me . I see you didn’t get the carpet done yet.

 

I was also thinking the same about bias ply tires. I too have radials, and I wanted simpler steering.

 

How is your braking and steering now compared to with radials? 

my odometer reads 14300 and an inspection sticker from 1998 says it had 11300. I’ve put 900 on it myself in the last year!  “Elise” (all my cars and trucks are called Elise) has been mostly a parade car, and somebody did a nice restoration some unknown years ago (likely 20 or so). 
 

unclear how accurate the odometer is but the car doesn’t feel or sound like 114000; it’s just too good of a shape and still feels pretty original.
 

I too get blow by from the rings but I hope to do an in place piston ring job .

 

 

Edited August 18, 2021 by wagoneer

[chrysler1941]

22 hours ago, wagoneer said:

standard equipment starting in 1950. There is a great MTSC covering the whole topic, and the transition from A5/A8 to AR5/AR8 covering topics like  how to choose which is right for the customer .

Resistor plug became standard for all makes due to more FM radio stations popping up around the world.

Resistor plugs do nothing good for our engines. On the contrary, concentrated spark is more suited for high compression engines.

Hence the name, resistor. resists spark and i.a. weaker. That's why gap increased.

[48 New Yorker]

Wagoneer:

To answer your questions in order:

 

I think we are parallel in our repairs.  I had the vac advance rebuilt by Terrell Machine DeLeon, TX years ago and it's still doing ok.

 

I did get my material from SMS....I was warned that it might take a while to get, but they filled the order in about 2-3 weeks....I'm very happy with the quality....but not cheap.... I think it also comes in a blue/green combo,  there is an even more rare, a Navajo pattern (see photo), but I don't know if they carry that.

 

The steering w/the Cocker radials is still somewhat heavy during parking, but better....once under way moderate effort.....don't expect Chrysler's (later) full" time steering" --- I have a DeSoto with that....and can park it with 1 finger. 

 

The radials cornering grip exceeds the capabilities of the suspension....it will really heal over before sliding.  There is a highway gradual sweeper turn near me which I drive often....over time, I gradually took it faster to see what the limits were.....can't recall the speed, but when Geezr started to drift, it was very gradual, tail slightly out and controllable....the kind of thing ya do only once....just to see.... 

 

Re: breaking.....Coker's grip very well for stopping, but I haven't done any (intentional) panic stops....for fear it would pull to one side or the other...very tricky to adjust, even with the Ammco Brake tool.

 

My speedo with these tires (7.60R-15) still reads about 7-9 mph fast.

 

I tried everything short of pulling the engine to free up the piston rings to minimize the blow by...and it has worked to some extent....still got some, but manageable ......ATF + Acetone cocktail.... sitting in the cylinders over a couple of days...re- apply as it will drain into the sump....then drain .....don't run it with that brew in the crank case....fresh oil and filter....takes time....maybe an occasional Berryman's B12 chaser in the gas once in a while......

[Andydodge]

48Newyorker.........absolutely love the new seat upholstery.........45 yrs ago I had a 1948 Windsor....these are very rare in Oz as we only got Plymouth/Dodge & Desoto cars all based on the Plymouth chassis with different grilles, badges etc however there apparently were some 24 Windsors imported in one order for State or Federal use.....the one I had had the Highlander upholstery, same as yours tho' not as good.......lol.........at the time , mid 1970's I had no idea exactly what it was........my only knowledge of 1946-48 Chryslers came from reading the USA sourced Rod Action magazine in which the editor Tex Smith had a 1948 Chrysler which he called "Walter P Chrysler" and hotrodded it with I think a small block mopar V8...........I'm a hotrodder so it was o/k by me..still is & still am..........I ended up selling the Chrysler after a couple of years as I lost storage space for it, it was rust free, in fairly good condition, everything worked including the clock and drove like the Titanic......lol...............yours brings back good memories................regards from Oz.........andyd      

[wagoneer]

@48 New Yorker 

 

for your original question, I think based on your description, you need hotter plugs to burn off the soot. I refer you to following excerpts from MTSC linked above:

 

 

Regarding the highlander, it seems to me the sms fabric is a bit more woolly texture than original. I can see that is how yours looks. It looks nice; I’m curious if that is how it was originally?

 

@chrysler1941 True that radio interference is a motivator but according to MTSC there are other advantages that is described as like an oil filter - keeping good spark in and leaving bad interference out, and they compensated for extra resistance by increasing voltage for the ignition coil.

 

 

 

 

@48 New Yorker

[chrysler1941]

@wagoneer

 

Personally I don't listen to FM stations so no need for resistor plugs. Booklet fails to mention spark width. Resistor plug spark is more concentrated (narrow band) and is perfect for the later rounded combustion chamber of the OHV models where plug is pointed towards intake valve flow unlike side valves where it was placed somewhere where there was room. 

Anyway my engine has complete ridiculous combustion chamber design and intake and exhaust flow is obstructed so many times, that a fat and wide spark is needed to burn it. Even so most side valve engines have a poor burn and most gas escape unburned. Not efficient burn is the word I'm looking for.

No to mention coil needs to work harder to compensate for extra spark.

 

Anyway we all have choices so each to his own 

 

 

[Sniper]

Noise reduction was for AM stations, FM by it's nature isn't really susceptible to spark static.

 

As for the rest of the reasoning, not, not even close.  Intake and exhaust port design has zero to do with light off the air fuel charge, which is the plug's only function.  Spark plug design has zero to with how it burns once it's lit off.     

 

The only reason non-resistor plug were originally specified is that was all there were.  Then the resistor types came out and they were sort of fragile.  The sole possible redeeming value of a non-resistor plug is as a crutch for a poor performing ignition circuit that is so weak in output that a resistor plug can materially affect the ignition of the air fuel mixture.

[chrysler1941]

9 hours ago, Sniper said:

Noise reduction was for AM stations, FM by it's nature isn't really susceptible to spark static.

 

As for the rest of the reasoning, not, not even close.  Intake and exhaust port design has zero to do with light off the air fuel charge, which is the plug's only function.  Spark plug design has zero to with how it burns once it's lit off.     

 

The only reason non-resistor plug were originally specified is that was all there were.  Then the resistor types came out and they were sort of fragile.  The sole possible redeeming value of a non-resistor plug is as a crutch for a poor performing ignition circuit that is so weak in output that a resistor plug can materially affect the ignition of the air fuel mixture.

We all have different opinions. We can agree to disagree

[48 New Yorker]

FrankenSpark experiment:

I'm going to run the following spark plug set up in my New Yorker (323.5ci) for a while to see what the different ranges yield....why not?  After a few hundred miles, I'll pull them and compare.

 

The Autolite 306's are (resistor) one step hotter than the 295's (no resistor) and the NGK B4's (no resistor) are approximately 2 steps hotter (equal to the Autolite 308's (resistor).  I've heard NGK's are superior to what I've been using (Autolite), so I'm going to give them a try.  

 

I've checked everything else, ign, carb, timing etc.  I think the PCV setup I've installed has fundamentally changed the mixture in a way that can not be easily "leaned out" without re-jetting the carb.... recall this engine had moderate blowby.

 

That's something I'd rather not do....yet. Where would I find an assortment of jets?....which one to use? .....lots of trail and error.   The "plug trail" may give an answer more quickly with less expense.  I'll keep you posted....

 

Btw, the PCV valve I've used is  marked 2257 and I believe it to be a Fram FV333, which is sized for a 318ci Chrysler/Plymouth/Dodge engine....approximately close in size to 323.5 in ci.

 

 

"IT'S ALIVE...."....(and remember.....there's always Egge for replacement pistons)

 

[wagoneer]

@48 New Yorker

 

The plans for PCV call for replacing the carburetor idle orifice tube and replace with number 862322 (available from ams nos) but that is the P17 L6, and not your L8 and stromberg carbs. 

 

There was discussion here awhile back (can't find link at the moment) about the PCV robbing vacuum  as well as causing the carb to incorrectly idle due to the blow by going back into the base. Someone here may remember better the nuances.

 

 

 

 

[Sniper]

You do have to retune for a PCV, it is essentially a controlled vacuum leak.  But the OP's issue is not running too lean, which is typically what a PCV would do.  However, that assumes a properly functioning engine.  With lots of blow by, who knows.  Simple test might be to cap off the PCV and see how it runs.

[48 New Yorker]

Wagoneer:

Finding an idle orifice tube in a different size may be a "toughie".... I just found a Stromberg manual on line (below) and it lists the carb as only being used until '47  (although my '48 came with an AAVS-2 from the factory...probably a leftover  or special order). 

 

If so, this is a bit before Chrysler was doing PCV retro fits which is why there may be not tech info on it.  If I can't resolve this on my own, I might try giving Mike's Carburetor a call for some advice...(where I purchased the rebuild kit).  I'm attaching a link to the Stromberg manual should other's need it -- the pdf is too large to attach here.  The individual AAVS-2 chart page is attached below

 

https://www.carburetor-parts.com/assets/manuals/stromberg-seriesaa-manual.pdf

 

[greg g]

`Is name w a s Mr. NORMAL, MR ABNORMAL. 

 

I have been running Ac45r since the rebuild going on 15 years and 50k miles.  They are infact the same plugs installed at the time.  I have pulled them 3 or 4 times to check the gap and see how they are holding up.  I set my gap at .032.  They still look like everything is as it should be combustion wise.  No deposits, nice gray tan color, no visible pitting or erosion of the ground electrode.  I carry a set of the equivalent autolites pre gapped in the event a fault may come up.  Starts well runs great.  No radio so static isn't an issue.  My spark plug wire are from Tractor Supply.  Copper core universal trim as needed set.  Not sure they carry them anymore.   They are holding up well, no light show after dark, no problems in or after driving or sitting in the rain.

[wagoneer]

@48 New Yorker

 

To fix your original original issue for this thread, it sounds like the simplest fix is to just run hotter plugs. Go for the 306s, or the NGKs (I tried to get the B6S without resistor but couldn't find them, so I've been happily running NGK BR6S plugs). Your experiment is interesting, and I am excited to see the results. Should only take a few hundred miles, maybe?

 

 

Leave the rest  regarding PCV and Blow-by for stage 2 of your testing. I've wrapped myself around the axle enough times over thinking solutions, when I realize the paid mechanics tend to iterate step by step, always finishing the simplest fix first, and when that doesn't work, charge you for the next logical step... ?

 

Simple fixes before tearing that beautiful engine down.

 

On 8/17/2021 at 1:49 PM, 48 New Yorker said:

To fix the soot problem, I was thinking of going to the hottest plug available