Not really a performance question but a general Q

P

Positively Ralf

Well-known member
Have my bare stock 200 six in my 74 Maverick and I have a question about something I am experiencing with the engine. I somewhat have had this problem ever since having the car and that problem is that after riding for a while, when I come up to a red light the engine spurts and shakes. Then when I am ready to go, when I hit on the gas the engine struggles for around 3 seconds before it goes off normally. This happens all the time and I noticed after getting a temp gauge installed, that it only ever happens when the engine is hotter than normal.

Now a firend of mines who used to own a few 200 Mavericks and 250 other cars, told me today that he thinks that it may be the thermostat preventing the engine from breathing at a normal rate and that there is more hot air in it than there should be.

Wanted to know if there may be other ideas as to what the problem with my car is.
 
Im sorry but I am not understanding how air in the cooling system could make the thermostat cause the engine to stumble.

Seems more likely to me that you are having a carb or fuel problem.
 
8) it sounds like you have a minor heat soak issue in the carb. what is happening is that the fuel pump at idle doesnt flow enough fuel to help keep the bowl cool, and thus the fuel in the bowl boils. when you step on the throttle you have a lean mixture and the engine stumbles. when the fuel pump catches up the engine runs normally. using a heat shield will help prevent that problem.
 
I would buy, beg, borrow, or steal one of those IR temp guns and use it to confirm the temps. If your gauge has numbers on it you can confirm the numbers, if it does not you can get an idea of what the temps are where. It does sound like a heat soak issue. Make sure air flow under the hood is all as it should be. Shroud, fan clutch, and anything else that would effect air flow. Its also likely that you have ethanol in your fuel and that makes it just that much easier to boil it. If you have the option to get fuel without ethanol that may help.
 
What carb is on there? Check it for loose screws causing a vacuum leak.
Have you ever cleaned it or run some fuel additive?
 
The air cleaner snorkle has a thermostat in it that dirrect hot air off of the exhaust manifold to the carb when the engine is cold. As the engine warm up this thermost closes off the air from the exhaust manifold and dirrect normal air to the carb. Yours may be broken. Unless your in a realy cold climate you could wire it to get normal air all the time. The effect of havig it open all the time to the exhaust manifold is that you get hot air with a lower Oxigen content making your mixture richer that normal and heating up the carb, giving you less horsepower and causing you to stuble at idle because the plugs are loading up, check the plugs for color. As you drive away the plugs clean up and start to fire normaly and the increased airflow causes the air temp to drop.
 
Ok guys I took it to a friend of mines that works at AAMCO. He told me that the problem is the tranny and that it is a C3 tranny. I could have sworn it was a C4 on my car but he confirmed it with me and others at his shop told me as well, it is a C3. He told me that the parts for this thing would run double for what a normal trans should be but he is going to check around with his guys to find the parts for me since he has a connection after restoring his 71 Skylark.

Now my question, what do you guys think I should do? Shoul dI stick with the C3 or go with the C4? I don;t know much about Transmissions so any input would help.
 
If it really is a C3 then it's not worth spending any money on.
Heck you could probably find a C4 for a couple hundred bucks, perhaps even with a motor or a car still attached. I'd scrounge my local scene, scrapyards, craiglist, ebay.

I think your friend is way off base telling you everything for that C3 will cost twice as much as other stuff. A vacuum modulator (which is about the only tranny thing that I think could be related) shouldn't be any more than $10-20.
 
Sounds like you are getting very poor advice.

First someone says your thermostat is bad and causing air problems which simply could not do what you describe, then someone's trying to take you for a transmission job.

First things first. Have you tuned the thing up? Checked plugs, wires, cap, fuel filter? Cleaned the carb and checked for vacuum leaks? Checked the vacuum hoses?

Start with a good shop that knows what they are doing. This isn't rocket science, but you can spend a whole lot of time and money following advice of people who don't know their stuff.
 
Heated air does not have less oxygen content, per se, it is just thinner meaning that the air is less dense as it is heated.

The hot air stove on the manifold should keep the a/f mixture at around 100 degrees or so. It keeps it from puddling up on the intake runner and causing lean backfire.

I agree with the ethanol content issue. The problem that you are describing has really been common in the last 6 or 7 years with the coming of age of gasoline.
 
If I were you I'd take the tune up advice and get the carb checked for leaks BEFORE you spend money on replacement anything.

Unless there's a vacuum leak with the transmission I can't imagine what the transmission has to do with this problem.

listen to Eaglo on this.
 
tony1963 » Mon Aug 03, 2009 5:30 pm

"Heated air does not have less oxygen content, per se, it is just thinner meaning that the air is less dense as it is heated."


Less dense air means fewer molecules per unit volume. Since Oxygen is a percent of total molecules (20.8%) if the total goes down then Oxygen goes down.

Since you don’t know how rich he is running to start with or how old his plugs are you can’t say for certain that he is not having problems with his stove pipe heater. The stove pipe heater is not meant to be on when the car is warmed up. A simple check will settle the question, is the air coming from the exhaust manifold when the engine is stumbling or not. If it is fix it if not move on.

I agree with the earlier comment give this car a complete tune up and check it over for vacuum leaks and such.
 
Well guys, I had 2 more opinions and all came back the same. It's the tranny. And I believe it to because the car all of a sudden did not want to shift correctly at all. Got the carb checked and it's not that. Checked everything else and finally got underneath the car and yeah, the tranny is the problem. I'm going to go for a really nice rebuilt performance C4 that someone over at the maverick.to boards recommended me.

Tried Craigslist and really couldn't find much here in NY for a Maverick since it's all pretty much Mustangs and everyone else just wants to get rid of the shells of their MAvs and keep the tranny and motors. Thanks for all the replies.
 
8) ok, before you spend a lot of money to rebuild or replace your current transmission, replace the vacuum modulator valve first, as well as fix any leaks in the trans. better to spend a few dollars now, and find you have to spend $600 later, than to spend $600 now and wonder. if you decide to replace the trans, you can get one from a mustang ofr falcon as they are the same. in fact you can get a V8 C4 trans as the bellhousing is replaceable and use your bellhousing on the replacement trans.
 
rbohm":2becar4w said:
8) ok, before you spend a lot of money to rebuild or replace your current transmission, replace the vacuum modulator valve first, as well as fix any leaks in the trans. better to spend a few dollars now, and find you have to spend $600 later, than to spend $600 now and wonder. if you decide to replace the trans, you can get one from a mustang ofr falcon as they are the same. in fact you can get a V8 C4 trans as the bellhousing is replaceable and use your bellhousing on the replacement trans.
Click to expand...

Ditto. I'd move to a c4, much cheaper than fixing the c3 and you get an overdrive.
 
The suggestion that was made, incorrectly so, was that heated air contained less oxygen and therefore, ran richer. This argument is incorrect.

Heated air becomes less dense but it still has the same chemical content, proportionately. The same elements from the table of elements are still present. There is just less of it going down the carburetor throat, from a density perspective.

The car will not run rich on heated air, but will run with less horsepower. With less air, the cylinder volume is not as high as with cooler air. The volume of air coming through the carburetor draws the fuel in, as well. Less air, less fuel. You have balance.

If the aforementioned explanation were true, cold air would contain more oxygen and cause the vehicle to run lean.
 
tony1963":5l6i4g0m said:
......

Heated air becomes less dense but it still has the same chemical content, proportionately. The same elements from the table of elements are still present.....
Click to expand...
This is correct.


tony1963":5l6i4g0m said:
With less air, the cylinder volume is not as high as with cooler air. The volume of air coming through the carburetor draws the fuel in, as well......
Click to expand...

Ummmmm......... then why is it necessary to re-jet leaner at high altitudes? And why do drag racers put so much effort into checking barometric pressure, then re-jetting?

You are confusing "volume" with "mass". There is a difference. If you have a carbureted engine set up correctly at sea level, then drive from sea level to the top of Pikes Peak, it will most definitely be too rich.
Joe
 
I suggest we table this discussion for a later time. We are getting sidetracked from the main problem of why this engine displays the symtoms it does. OK?
 
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