Chryco's Tech Shop => Engine & Go Fast Goodies => Topic started by: CudaJon on January 06, 2019 - 11:55:18 AM

Title: Engine startup question
Post by: CudaJon on January 06, 2019 - 11:55:18 AM
So a little background before a pop the question(s), have a 73 340 Cuda. I just finished changing all the ignition components with new spark plugs plus cleaned the bulkhead modules, check ground connections. I did all this due to a non-spark condition. Within a couple of weeks will be changing out the plug wires. The problem cleared itself up after I moved the engine harness wires around therefore focusing on cleaning the bulkhead.

What I have been doing now is making sure it's starting up by going out to the garage like maybe every other day and starting up the engine, I'm in the Northeast so it get cold which is good if it's temperature relative. The issue I see now however is after the initial start and running it for about 5 - 10 minutes if I wait for x amount of minutes afterwards whether 10 minutes or 30 minutes, it takes awhile for the engine to caught and start. Sometimes it just starts with no issue, sometimes it takes about 4 to 5 seconds of cranking. I'm just looking for reasons why it takes so long SOMETIMES and other times its fine. Thank you for reading!!!  Hope I explained it clearly, let me if it's confusing.
Title: Re: Engine startup question
Post by: 70chall440 on January 06, 2019 - 04:35:47 PM
Sounds like a fuel problem to me rather than a spark problem. Usually (not always); spark either works or it doesnt (this is very general); however fuel delivery can cause the issues you describe. Do you have a fuel filter on it? If so, when was the last time you changed it? If you can't remember then its time. Also, there is a "sock" in the tank on the bottom of the fuel feel line; if the car has sat for a long time they tend to get clogged with crap. Its possible that the fuel pump is a little weak as well. Lastly, the carb maybe having some issues, specifically the needle and seat in the float bowl (either not shutting off and essentially flooding the engine or set too low/stuck too low and thereby not providing the amount of fuel your engine needs to start initially.
Title: Re: Engine startup question
Post by: CudaJon on January 06, 2019 - 06:16:36 PM
Hello Mr. 70chall440 - your the man!

So the fuel filter is new from last summer - very good one which the name escapes me. The fuel sender is new also last summer and I do remember something like a sock can't recall from memory. That was a lot of fun. So what's weird here and I'll keep on trying this out is that the initial start meaning after the car has been sitting for 24 hours or more would always start  (I would like to think I cleaned the harness connections and getting spark now)  What I would do is pump the accelerator petal once and then start, the car will start in high idle and then I would kick it low. This scenario has worked for me since I corrected the spark issue but after letting it warm up for what ever time I would turn it off and wait at different duration of time then I would go out and start the car again. Sometimes it would crank right over other times the engine cranks for about 3 to 4 seconds before it would caught and starts clean. So far it always starts sometimes it starts but goes quiet for a second then I pump the accelerator and I get it going its like the timing is off in my mind.  No rhythm or reason.

Your comment on carb is interesting, this is an unknown that is I have not touched the carb since I purchased the car two years ago. It's an Edelbrock but don't know how to identify it yet nor do I understand it.... yet. Not knowing anything about the anything on the carb what exactly can I adjust/clean/whatever to prove that this is the problem or not.  Thanks as always.
Title: Re: Engine startup question
Post by: jimynick on January 06, 2019 - 10:38:47 PM
When you go to start it again, before cranking it, take off the air cleaner and look inside the carb for 2 things. 1- the choke should be closed once you pump the gas and there should be visible gas squirting out the accelerator nozzle when you do that. If there's no fuel or if the choke isn't closing, it'll be hard to start. The carb shouldn't lose it's charge within a day or two unless the engine heat is high and boiling it dry prematurely, or a Mike mentioned, it wasn't getting enough gas in the first place. Every carbureted car that I've owned had it's own starting likes/dislikes and it's only by trial and error that you'll find what she likes. Some like nothing, some like 3-4 pumps of the throttle. You'll have to experiment a wee bit. Good luck  :cheers:
Title: Re: Engine startup question
Post by: 70chall440 on January 07, 2019 - 12:57:03 PM
Jimy is 100% spot on; every carbureted vehicle Iv'e ever had required some type of "procedure" to get them started consistently. Most times (when things are relatively new and in good condition) it is minor such as one or two pumps or one pump and then as it starts a little pump. Other times it may take more pumping and "feathering" when its starting. I once had a 67 Satellite with a 383 4 spd (still miss it) that required about 10 pumps of the pedal to get it to start (yes there were carb issues).

As Jimy says, you need to pull the air cleaner when cold and see where the choke plate is at, then manually open the throttle and see if the choke plate closes and if it squirts fuel. The squirt should be pretty significant and not just a dribble.

As to adjustments; there are whole books written on this subject but it isn't all that bad. There are essentially 3 issues to deal with on a carb;

1 - mechanical set up: this refers to the actual set up of the carb to include jets (or metering rods), float level, choke plate adjustment, initial air bleed screw setting. this could be referred to as "initial set up" and most people just buy a carb and bolt it on and call it good.

2. Initial or idle tuning of the carb: this refers to tuning or adjusting the carb for your specific application/engine. This activity involves adjusting the idle speed, idle air screws, high idle (aka choke) speed, choke adjustment (if needed). This is essentially tuning the carb for your application at idle.

3. Performance tuning of the carb: this refers to determine and applying adjustments to enhance driving performance of the carb. This is where the real magic comes in with regards to a carb and guys/people who are into this spend a considerable amount of time working on it. This is mainly due to the fact that a carb is basically a linear device in that it does not adjust itself for changing conditions so you have to find a "happy medium" between starting, idle and driving. As an example, you can tune the carb to wok awesome when starting and idling, however it may have a dead spot or lull under acceleration and/or fall flat at WOT. Consequently, a carb might not start or idle great, but run like a scalded dog under acceleration. Racers spend LOTS of time dialing this in. This is but one of the many reasons EFI has become so popular; because they have multiple personalities; they can be set (or they set themselves) to start and idle great but change under acceleration and WOT to provide the optimum performance. They also adapt for changing altitudes/elevations, temperatures, etc. whereas a carb does not. So if you tune it now at 30 deg F, this summer when its 80 degs it most likely will operate differently. Not saying it will be a problem per se, just something to understand.

I am not suggesting that you should convert to EFI (although you should if you intend on keeping and driving the car) but I am telling you that you need to understand your vehicle and how it works as well as how to do what is necessary to keep it running as you want it to. As much as I like EFI I will say that carbs have been used for many years and have seen many millions of miles, so as cool as EFI is, it isn't mandatory. Just keep in mind that living with a carb is an exercise in compromise; you have to find the middle ground that you can live with; for most that is starting, idling and general light throttle (normal driving).

Hope this is helpful
Title: Re: Engine startup question
Post by: CudaJon on January 07, 2019 - 08:23:35 PM
OK well thank you very much gentlemen. The temp in the garage today was high 20's low 30's and got home from work tonight and with the air filter/assembly off I witnessed that after I press down on the accelerator petal once the choke plate on the primary barrels goes from showing a little space - cocked just a little to fully closed - I'm learning about all this and that's pretty neat to witness. The better part was the car started after a couple of cranks.  Now from your comments, I didn't spent too much time in the garage tonight but I did manually move the throttle while it was running and although I didn't witness the squirt of the fuel the engine accelerated beautifully. I did witness this squirting before trying to distinguish if gas or spark from my previous adventure but will make sure I have a visual tomorrow.

Still learning the carb and also identifying my Edelbrock but I what to get you's guys opinion on something else maybe totally barking up the tree but I was wondering if since the fuel line has a 'overfill limiting value'  could this be an issue if it's sort of a check value that is a ball in it that gets stuck. It seems 'so far' the initial start always starts but after that it's a crap shoot as to how long it's going to crank could the ball be getting stuck cutting of the supply??? I'm just thinking out loud and had a brain fart while reading the service manual. BTW the previous owner(s) did not have the charcoal canister re-installed, I have the PVC and breather and that's it. As always thank very much for comments and interest. Thank God for this forum.
Title: Re: Engine startup question
Post by: jimynick on January 07, 2019 - 08:38:52 PM
"the fuel line has a 'overfill limiting value'" -huh? The carb has a very simple fuel regulating device called a "needle and seat" wherein the gas goes into the float bowl and as it fills same, the rising fuel level raises the float and in doing so, presses upward on a neoprene cone shaped part- the needle- and shoves it into the cone shaped base- the seat- thereby shutting off the gas flow into the carb. As the engine consumes gas, the level drops as the gas goes into the engine and the needle comes down off the seat allowing more gas to come into the float bowl of the carb to keep the fuel level in the calculated spot it should be to provide sufficient fuel to operate the engine while preventing unchecked ingress that would overflow in said carb and piddle out into the engine making it run overly rich and rather ****tily if I may say so. It's really not that complicated regarding it's basic function, but, as Mike says, if you want perfection- carbwise- you may have to work some for it. As he also said, these things have been around over a 100 years and the old ones will still work. Read up a bit and check the threads for the subject and away you'll go!  :cheers:
Title: Re: Engine startup question
Post by: 70chall440 on January 07, 2019 - 09:23:20 PM
Perhaps a simple example of how a float bowl works is go and pull the cover off your toilet, flush it and watch what happens in the tank; your carb float bowl operates exactly the same way.

It seems like we are talking about several things simultaneously; spark, fuel, and timing. While they all are symbiotic they must be diagnosed on their own merits. Your comment about it starts initially but its a crap shoot later provides some insight to your mind set. First let me say that the comments by Jimy and myself about each car having its own procedure to start remains very true, however it extends to warm starting as well. In my experience, many carbureted cars act very different from cold to warm/hot. Most of the cars I have dealt with require not pumping or throttle once they are warm to start (or very little). In your case, you need to do some experimentation to determine what you need. When it is warm, you might try giving it 1/2 a pedal to allow some vacuum from the turning over engine to draw some fuel in.

Since you are "learning" let me explain this issue (if you know this I apologize in advance); a engine is a big air pump and while turning over (the pistons going up and down) it creates vacuum. This vacuum pulls fuel and air down through'from the carb and draws it into the cylinders where it can be ignited by the spark plugs thus creating power (i.e. running). Therefore, the engine must be able to receive both air and fuel in this sequence to operate (the spark must be happening in the correct timing to facilitate all this as well). All that said, each of these systems must not only be operational and functioning correctly but also set up to work with one another. Arguably one of the most important aspects of this specific situation is timing. You can be a several degrees off timing and the engine will run but will start hard (assuming all of the other related components are doing their jobs correctly).

Now, having said this I am not advocating you start twisting the distributor to alter the timing, rather I am suggesting that you spend some time trying to figure out what you engine wants in order to run in each condition. Right now you have the weather fighting you; when that car sits a day in 20 degree weather it is actually harder to get started because the cylinders and heads are cold and are actually combating the spark however it does assist the fuel making it cold and therefore dense.

So, what I would recommend is that you go out to the vehicle when it is cold. Since you seem to have the cold start somewhat figured out, start it and let it warm up. Once warm, shut it off and let it sit a few minutes; try and restart it but only for a few seconds. If it starts turn it off and let it sit longer (say 10 minutes) and try it again. If it doesn't start immediately, stop and let it sit a few more minutes. Now, go in and depress the pedal half way and try to start it. If it starts then you are on the right path. If it doesnt, let it sit for a little while and go and try again but this time hold the pedal 3/4 down. Again if it starts you moving in the right direction, if not repeat this except give it one pump. I think you can see where this is going and the idea is to determine what your engine wants when it is warm. Understand this though; older carbureted cars typically do not start like modern EFI cars; they will turn over a little while before catching. Even when these cars are outfitted with EFI they still tend to turn over a few times before firing up. This is a result of engine design and inefficiency of the design; the air fuel has to travel a ways to get into the cylinder in sufficient levels to create an explosion large enough to run.

It very well could be that your engine is as good as it is going to get without vast sums of money and some significant aftermarket equipment (i.e. different or better ignition system, better intake, better carb or EFI, better exhaust, aluminum heads, etc.).
Title: Re: Engine startup question
Post by: CudaJon on January 09, 2019 - 11:22:54 AM
OK roger all that.  Understand the carb dynamics of the float. I think I confused the issue, I thought there was some type of check value in the fuel line from the gas tank or maybe from the return line for the vapor. Sorry about that. Thanks again will report back this weekend - getting busy with other stuff - can you imagine.
Title: Re: Engine startup question
Post by: Oldschool on January 10, 2019 - 09:55:06 AM
Some great information in this thread..... :2thumbs:
Title: Re: Engine startup question
Post by: CudaJon on January 12, 2019 - 05:16:26 PM
OK little update on the car situation:  Have been starting the car up a couple of times during the week and today she started with the temp of 16 in the garage. So with the comments/advise given,  I have been shutting the engine down and starting it.  And I have to confess with the petal about 1/4 to 1/2 way down she starts almost 100 percent with about a 3 second crank time and then starts. One time I missed it when I turned the key to run to quickly when I thought the engine sounded like it started but it didn't.  I probably should have waited a couple of minutes before I tried again but instead immediately try starting it and that was hard starting. Today I started it and this time took a ride with the heater blaring.  Got back and waited different amounts of time in between starting it with the petal at least 1/4 way down - NO ISSUES.

So this is my final response on this thread, thank you all for contributing, It's been a sweet ride and learned quite a lot. I'm going to open another thread with the subject timing on a 340 if I have questions. I'm curious on the timing but need to tool up for the event and get educated. I actually downloaded a MOPAR timing procedure for a 340 in a PDF document. Take care everyone!!  /Jon     
Title: Re: Engine startup question
Post by: 70chall440 on January 13, 2019 - 12:09:29 AM
Congratulations and welcome to the world of old cars. Each car has its own personality and operating requirements. You have come a long way from the beginning. Its an adventure and at times a treasure hunt  :bigsmile: Enjoy!
Title: Re: Engine startup question
Post by: jimynick on January 13, 2019 - 11:18:06 PM
Glad to hear you're getting a handle on your starting procedure. As for the timing, look here for prior threads and Chryco Psycho had probably the best ones.  :cheers: