After swapping out the 60 jets, and replacing them with a set of 57 jets I let the engine warm up on high idle while washing the 300. It sat purring at a rather high 2400 rpm. I had jacked up the idle speed a bit a few days ago to keep the vacuum up, and the power valve closed while stopped in traffic.

After the wash job, or about ten minutes, I sauntered over to kick her down, but when passing the back of the car there was a bit of an intermittent skip coming from the right exhaust pipe or last three cylinders, and that side did not sound as crisp & staccato as the left pipe. I had never noticed this before.

After idling the engine down to about 1000 rpm, the skip persisted. (any lower rpm starts a lope, vacuum drops, and than the power valve starts to open close exacerbating the already rough idle) I used the timing light on number’s 4,5,& 6 plug wires to try to see if there was an electrical reason for this skip, got what looked to be a steady flash on all three, and was unable to detect any non firing plugs with this method.

Is there a back yard method to ascertain which cylinder is offending, or do I need to go to a shop and put it on an analyzer?

I’m still suspecting one of # 4’s valves maybe involved. This summer it made a lot of noise for about twenty miles and than self healed, and I wonder if it got burnt a bit, as it has about 10 psi less compression than the all the others.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Willing to bet you have it with the valves.

Re-lash and see if that fixes it.

If your going for a milder cam, it's a good time to pull the head and do some valve work!

CJ

_________________
Part of Tyrde-Browne Racing

You could check for differences in rpm drop when pulling off the spark plug wire, one cylinder at the time.

Olaf.

_________________
Aspenized

If you don't like getting "grabbed" by the current if you get grounded accidentally

I use a test light (the kind with a clamp on a wire and the awl point at the other end). You can put the clamp on a ground, then use the sharp end to "probe" the end of the spark plug boot where the electrode and plugwire meet...that will "short out" the plug causing either a skip (good cylinder) or no change at all (bad cylinder)...

When using this method you have to try and prod as few times as possible or probe through the same hole you just made otherwise you end up with "swiss cheese" plug wire boots, that can "scatter some current" in some occassions.

Good hunting,

-D.Idiot

Me quoting me:
I did not describe the skip as well as needed. It is more of a hunting, where engine makes several revolutions, and offending cylinder misses one firing and comes back on line for a bit than off again for one firing. There is no regular frequency, and miss can be several seconds apart, or two quick ones than smooth for a second or two longer at 2400 rpm.

Olafla, pulling a plug wire won’t help as it is too intermittent, tried that all ready.

I’m thinking CJ is on the right track, (insert really sad face of a cheep bastard here) today I’ll do another lash check, and compression test. A few of the rocker adjustment screws are getting too easy to turn, and perhaps are allowing the adjustment to change.

If needed, where can I get a few new rockers?

Bill

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Bill
I have some good used ones. Just shoot me a PM with your address.
Do you have a helper? I think it may be a fuel distribution problem. Does the problem go away at higher RPMs? (hence the helper).
Just a thought,
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Frank,

Thanks for the offer. I first need to take an inventory of possible needed replacements, and than I’ll shoot you a PM.

I can crank down the idle speed screw to get to 3500 or more rpm.

When the 60 jets were installed, coasting down from a higher rpm such as down a long grade I could hear some unburned fuel firing off in the exhaust system, that pop-pop- pop… Not real noticeable, but there in the background. This may be a result of running on the rich side, and having those holes in the throttle plates. I don’t recall hearing back-off popping with smaller jets.

Bill

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Bill,

Are both mixture screws set the same?
Left bank the same turns out as the right bank?

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ted:
[quote]Are both mixture screws set the same?
Left bank the same turns out as the right bank?[/quote]

They were at one time, but due to all this screwing around with the jets; “Did I turn one out two turns, and the other three and a half turns… In all the excitement, “I kind’ah lost track… and can’t say at the moment.â€￾

I have been using a vacuum gage to find best idle & highest vacuum reading while adjusting the mixture. Come to think of it, after Monday’s jet swap I did not readjust the idle mixture, something distracted me, I was off and running in another direction, and now it is Wednesday.

I must have emptied fifteen boxes of work shop stuff, sorted and put it away yesterday, still more to go; and no soldering irons. Once the iron is located I’ll seal up the throttle plate drill holes, reset secondary throttle plate gap, and see what that adjustment brings to the pudding.

Bill

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Ted,

Got a chance yesterday to check idle screw position, both were with in a few degrees of two full turns out. However, having checked this with the engine not running, I discovered that the screws are loose, but not leaking. I need to replace the packing or “needle sealâ€￾. I suspect that this problem is a result of adjusting a loping/rocking engine one too many times.

Bill

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Ted, I soldered up the 3/23â€￾ holes in the throttle plates. Vacuum readings are same as with holes. Idle screws had to be turned out to 2.5 turns with 57 jets from 2 turns with 60 jets. Idle quality is the same as before hole filling.

While the carburetor was on the bench, I recalibrated the primary & secondary throttle plate stops, accelerator pump free play, and initial choke pull off.

Frank, hunting is still slightly evident up to the high 2000 rpm range than goes away. I think it is just that cam not liking lower rpm.

The light governor spring won’t always pull weights back to rest at ‘in park’ to allow an idle of 1000 rpm after throttle up. Engine will run at 1200 rpm and have 12 degrees of advance,1100 rpm at 11 degrees advance. Once it settles back to + 10 degrees it idles at 1000 rpm.

When in gear, timing creep is not a problem, as it idles at 600 rpm, which is slow enough for those springs to retract the governor weights, bringing timing to pre set +10 degrees. However the vacuum needle is now fluttering more wildly post hole filling between 1-9 “Hg compared to 3-6â€￾ Hg with drilled throttle plates.

Also the valve lash got rechecked, cold, because it is just too messy, and too much rocking & rolling with that lope at 500 rpm. The back three had tightened up a few thousands which were the ones skipping. Currently lash is: 0.026 exhaust; and 0.025 intake.

I know that when the engine is running one can most likely tune that skip out with the lash adjustment, but I don’t like the oil that gets squirted all over the fender, wires, fire wall, windshield, and floor… I have spread out rags during previous adjustments, but it still makes a mess.

What dose all this fiddling around with timing & carburetor amount to over the last two and a half years? --- It has me convinced that I need a camshaft change to something more streetable; Doc’s RV 15 grind is looking real good to me at the moment.

Bill

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Bill,

I agree, there isn't a hole lot more you can do at this point.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Today the sun was out, as opposed to downpours last evening, so a jaunt to the lawn mower store was on the docket this morning. Except for the old story of kick-back at shut down due to a return of low vacuum at idle, making the power valve spit extra fuel, the carburetor is spot on. No flat spot along the full rpm range, comes off high rpm and will idle in gear without stalling, and effortlessly runs up to 5500 rpm (my arbitrary red line) wanting more.

One thing I can say for this cam, it loves the revs. Engine is smooth, no harmonics or vibrations all the way to 5500 rpm, can’t say this for the vibrating crap tires.

For you lawn mower lovers out there, I got a 23 Hp 50â€￾ zero turn Ariens, & upgraded to an Ariens Platinum 30, 342 cc B&S Slant Cylinder(about 11 hp) Snow Blower all at cost. The old wimpy 8 Hp 24â€￾ Toro blower is now headed to my son’s place… if he wants it.

[img]http://i294.photobucket.com/albums/mm87/wjajr/House/100_1331.jpg[/img]

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Bill,

Sounds like a good job tuning!
Just leave it in gear when you shut down.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG