Frankenstein318

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sheppard10

sheppard10

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Eielson Alaska
Ok So I am in need of some help again. I have been working on this car what seems like forever and I have not gotten very far. A little background on the car, 1974 Plymouth duster originally a slant 6 car, still has the 904 transmission and 7 ¼ rear… that is what I know. The engine is where things get exciting. When I bought the car in 2004 it had a 318 two barrel on it. And it ran great. Just got tired quick and was in need of a rebuild. I went out and bought a refurbished 318 from a friend of the family. I did not think to get the build specifics from the guy. I figured it would be a plug and play…lessons learned I guess. So here is what I KNOW (this list will be short) I know the engine is stamped 4006730-318-11as far as I can tell this is a 318 block used from 1976-1984. The heads are stamped 3769973 1975and as far as I can tell that means they are 318 heads that were used from 1975-1983 but with the date stamp of 1975, I am going to go with 1975. The intake is stamped 4173915 2 and this is a little harder to narrow down I get conflicting information on it being for a either a 318 or a 360….date stamped 2-13-81? The distributor is stamped 411150 and I can find 0 information on it. I am running an Edelbrock 1406 650 CFM carb (brand new outta the box).

Ok so now that I have told you what I am working with, can anyone tell me if this combo is compatible with my car? Or even if this engine combo will ever come together and work? I have been fighting the timing on this car like no other. Right now I have set the base timing at 12 BTDS and it runs good, no ping, no back fire, (BTW the engine has less than 300 miles on it)..but the car acts differently every day. I have gone through the carb 4-5 times thinking that was an issue, but I think I have it narrowed down pretty sweet. The car pulls great vacuum (right now at idle it pulls 23 HG of vacuum from the manifold side not the ported side because that is where the vacuum advance gets connected…learned that on this website). I guess the question I am asking is this… am I chasing my tail on this car or will this set up work. I have heard all sorts of “if it where mine….” Most involve me tearing the motor back out of the car or spending a bunch more money to replace heads or intake or take the cam out…… hopefully my mad typing makes sense to someone out there. Maybe this is more or a rant than anything else. Oh and I can and will supply pictures of anything if it will help clear the mud.. thanks
 
So what is the issue that is causing concern? (aside from "the car acts different every day")
Sounds like it should work fine.
 
Sure it's compatible. It's sounds to me like you need some tuning to get it where you want it.
 
Awesome! First off thanks for taking the time to read my long post. I guess my main question was if this combo of parts would work together. Some of the issues I have had are. Overheating, black soot shooting out of the tail pipe…but only one, hard starting when cold, engine cranks but won’t start. The idle seems to adjust itself from time to time. I have the idle set at 840ish. But none of the issues seem to repeat themselves so I can track them down. Of course, I am always adjusting something…. Guess I should leave it alone for a bit and see what I come up with. …. Oh and most recently, I was playing around with a temperature light and I found that I was about 100 degrees colder on one exhaust port. The number one exhaust lobe on the manifold was running around 293 while the others were in the high 400 to low 500. This again led me back to timing! Pulled the plug and it is clean. Most of the other issues I have had I have cleared up. My main concern is I did not want to keep running the car if I was way off in regards to timing.
 
Kind of a big delta in temp there-have you run a thorough compression check yet? Also if you're getting soot, that's rich...is it all the time, or just when you get on it? Are any plugs reading rich?

Overtemping could be any number of reasons...ignition timing too far retarded, blockage in the rad, stuck t-stat, collapsed lower rad hose...
 
Shooting soot once sounds as a blocked exhaust system?
Hard to start, is that after sitting a few days?
Have you done a check of the choke function?
 
The intermittent problem could be plug wires or distributor cap.

Have you noticed it happening after an overnight temperature/humidity change that might form condensation?
 
Do you have exhaust manifolds???? If so, the "heat riser flap" which is in the passenger exhaust manifold could be stuck shut. I have had this happen. This will cause a lot of variations and inconsistent running/temps and other things that seem weird. See if it actuates. Make sure the shaft in the center turns. I've had this be stuck on a 318 once and a 383 once.
 
318willrun said:
Do you have exhaust manifolds???? If so, the "heat riser flap" which is in the passenger exhaust manifold could be stuck shut. I have had this happen. This will cause a lot of variations and inconsistent running/temps and other things that seem weird. See if it actuates. Make sure the shaft in the center turns. I've had this be stuck on a 318 once and a 383 once.
Click to expand...

If it does, wire that puppy open!
 
Whoa! Timing will NOT make one cylinder run different than the rest! (Unless you have an inaccurate distributor - rare, and can only really be seen on "Raster" view on an ignition scope... unless you take other steps, which I won't go into, because it's SO unlikely.) That cold exhaust manifold runner is a big clue for you. It bears inspection. It's indicating a problem with that cylinder.

Someone suggested a compression check. Yes, do that. Another not-so-hard diagnostic is a "power balance" test. Do this by shorting each cylinder individually and watching/comparing RPM drop for each cylinder. They should all drop equally, or very nearly so. If you're cold cylinder drops significantly less or not at all, you have to figure out why.

First thing I'd probably check on the cold cylinder is the intake runner to it, looking for a vacuum leak. Open vacuum source holes or broken vacuum hoses. Even the intake manifold gasket can have a leak. If you find no other leaks, spray a little squirt of carb cleaner where the intake runner meets the cylinder head. If the RPM rises and/or the idle smooths out, voilá!

Another poster suggested dist. cap and/or wires causing intermittent misfires. Yes, highly possible. Do you know how to check for carbon tracks in the cap and through the rotor? Sometimes those are called by excessive voltage demands of high-resistance plug wires. Have an ohmmeter? Check the plug wires on the cylinders that fail the power balance test.

There are only about 393 other things it MIGHT be, but these diagnostics are the best place to start.

Keep posting with your findings. I'll subscribe to the thread and see if I might be able to offer further ideas.

JD
(former ASE-certified driveability tech, currently a piano technician! what a life)
 
Cooler temps at idle on one cylinder are somewhat meaningless unless one cylinder is consistenly missing; the mixture distribution will tend to change as RPM's go up. You need to run the engine at a constant speed at load to see the variations. And #1 and #2 will tned to be cooler any way, being closeest to the fresh intake air. To make you readings accurate with any infrared temp guage, a spot needs to be smoothed on each exhaust runner and a flat black high temp enamel applied to each spot.

The only thing of significance I would take form the idle exhaust runner temps is if the black soot is out of the side with the cool runner; perhaps that one cyclinder is getting excess gas or has weak spark, and is having the combustion temps significantly lowered.
 
No need to hit the panic button. I was going over what you had. Everything adds up except the cylinder heads, 3769973 . My book shows a 3769974 however. The number I came up with is for a 360 CID engine. The engine you describe in your car is the Diplomat cop car motor less the roller cam (we think). Besides the big ports, the head yields low compression. As a combo, it works.

As far as the running aspects are concerned, it would be easy to over carb and over cam. IMO, you've made a good carb choice.

Back in the day, We had a problem with a 427 Ford that wouldn't tune. We set valves hot, valves cold, checked the ignition system up one side and down the other. In frustration one of the guys shut the lights off to get us to go home and think this one through. When he did, we noticed a blue flame reflecting off the engine. We traced it back to a cracked distributor cap. It was just a little hairline crack that one a couple of us could tell with the naked eye and then only because we knew where to look.
 
Thank you all for the replies. Let me try to answer some of the questions you all have asked thus far.
The overheating has only happened once so I have been unable to reduplicate it since. Of course, I have made some changes to timing and carb fuel/air mixture since that day.

As far as shooting soot out. At first I just noticed some wet spots behind the cars exhaust when I fired it up for the first time in the morning. I never really saw it as a big deal as I never saw a black cloud nor did it struggle to start. However, a coworker noticed that a black cloud would jump from both exhaust tips when I started it after it sat for a while (i.e while I had been at work) plus it always smelled a little rich on start up. The last time it blew soot out of the car was kinda funny…. To me anyways. I had run the car into town first thing in the morning and when I returned I parked in the driveway instead of putting it in the garage like I always do. My wife came home and she parked right behind me. Mind you she has a white mini cooper. I figured I had better get my Duster in the garage so she could pull her car closer to the house and off the sidewalk. I got in fired her up (mind you she started up quick no throttle used) I pulled into the garage turned around and her white mini now had TWO huge black eyes! I have since held white paper in front of the exhaust and have gotten minimal soot on the paper. I am not sure what the cause was that day. Maybe it didn’t like the mini being so close. Anyways I am still waiting for that issue to rear its head again. Nevertheless, the soot did come from both sides not just the cold side. I have adjusted the carb again since then.

The hard start.. I think I got that figured out I am certain it was an air fuel mixture that was causing my issue. I have not had the issue in a few days.

Yes I am running exhaust manifolds and I have not checked the function as of yet. I will test it and get back to you.

rub2stix.. When I first found out that I was running cold first thing I did was pull the plug. The plug was clean (less than 20 miles on new plugs) I rechecked the gap and it was spot on. I then put the plug in but left the wire off started the car and it ran like real rough. As soon as I plug the plug wire in it smoothed right out. I am sure that cylinder is firing. But while doing all the checks I ran into another problem. I have a harmonic balancer wobble now. I am certain it is new. As I have spent a lot of time looking at the timing marks to not notice it before. But when I took the power steering belt off due to a leak… well it was really noticeable. So now I am onto that.

nm9stheham thanks for the insight. I will look into your advice as soon as I fix the above-mentioned problem. Thanks for the vote of confidence!!

2darts. I found one website that showed my casting number
Cylinder head casting number 3769973 1975[FONT=&quot]
3769973[/FONT]
[FONT=&quot]318[/FONT]​
[FONT=&quot]1975-83[/FONT]​
[FONT=&quot]1.78[/FONT]​
[FONT=&quot]1.50[/FONT]​
http://www.mymopar.com/headcastnumb.htm
Also as far as chasing the blue spark. I will test again, but I have had the car in a dark garage, fired her up, and found no spark loss. My dad taught this trick to me years ago.

Again Long winded on my part but I wanted to make sure that I replied to everyone. I will make sure to update when I get the harmonic balancer sorted out…..now how to tell the wife I need to spend more money……
 
sheppard10 said:
The last time it blew soot out of the car was kinda funny…. To me anyways. I had run the car into town first thing in the morning and when I returned I parked in the driveway instead of putting it in the garage like I always do. My wife came home and she parked right behind me. Mind you she has a white mini cooper. I figured I had better get my Duster in the garage so she could pull her car closer to the house and off the sidewalk. I got in fired her up (mind you she started up quick no throttle used) I pulled into the garage turned around and her white mini now had TWO huge black eyes! I have since held white paper in front of the exhaust and have gotten minimal soot on the paper. I am not sure what the cause was that day. Maybe it didn’t like the mini being so close.

2darts. I found one website that showed my casting number
Cylinder head casting number 3769973 1975[FONT=&quot]
3769973[/FONT]
[FONT=&quot]318[/FONT]​
[FONT=&quot]1975-83[/FONT]​
[FONT=&quot]1.78[/FONT]​
[FONT=&quot]1.50[/FONT]​
……
Click to expand...

LoL on the soot story.

Found the casting, as you have noted, in my cross-reference book. (Blame the old age combination on senility and poor eyesight on my error). Whatever. It is still a big chambered head, with low compression using a stock piston.

Good luck
 
A couple of thoughts:

Check your float level, and make sure you aren't siphoning gas after you shut the car off; this could be a possible cause of black smoke at start up (gas puddled on floor of intake) and hard start (flooded). Check throttle shaft for movement in any direction other than simple rotation (worn out carb base)
 
hey read you heat issue , the hot running side , which side is it ? if its the pass side and you have stock exhaust manifolds on it . well it could be the damper flap part way closed . they stick all the time and sometime the return spring breaks as well . and black exhaust restarts could be leak down of the carb do to the heat crossover in the intake cooking the fuel out of the carb , heat gasses fuel rises to the top hit the airclear lid and drops down into the intake manifold and yes floods it with heated fuel which sits there until you crank it or drains down into the cylinders and by the rings then poluts the oil with fuel , bad for everything that is . here in calif we got crap fuel , it is a big issue , we in'd up blocking that crossover , but calif is alot warmer then your state . so for cold weather cars . we found that ford ( sorry for cussing ) used a water block under the carb works good enough for the colder starts . just has the heater hose routed thru it . if your running a small based two bbl you will be doing some big mods to it or even making your own . all of them i've seen are holley based bolt pattern , and a two bbl holley is larger then a carter or a stronberg ,or any other carbs used by chrysler . i'll just say a la with just one two bbl , not the six pack set up . hope i have helped . pm
 
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