Tired with my engine...

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Vinnie

Project manager "Project AmsterFoose"
7173 Mustang Supporter Member
Joined
Nov 7, 2013
Messages
1,589
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274
Location
Amsterdam, The Netherlands
My Car
1973 Mustang Grande 351C 2V, built on the very last production day (July 6, 1973) for Grande's.
Hi,

I'm getting tired with my engine now... After 4 years my engine (351C-2v) still doesn't start well, always takes 2-3-4 or more tries. Today I went for a drive and I had a feeling the engine wasn't running great. But it had enough power so I took it out anyway. Drives OK until I pull up from the lights with an Audi next to me and I thought I'd give him a bit of a run (all within reason). Then my car starts holding back, dropping power intermittent until I let go off the gas. This happened again later. Also I noticed that I had fireworks in my exhaust when letting go off the gas at high speeds. Sounds nice but it's not normal. In my idle mixture I smell petrol, eventhough the garage I went to 6 weeks ago adjusted the carb to make it less rich.

At the last traffic light I thought my engine would die on me but it didn't thankfully. It kept running but somehow it didn't sound like it normally does.

Back at my garage I measured the temperature of the manifols at each cylinder. The driver's side was about 125C (260F) and the pass. side was about 190C (370F). The temp. of the coolant hose (top one) was about 70C (160F).

So far I have:

- Refurbished Edelbrock 1406

- 1" carb spacer

- New plug wires (cheap ones - 7mm)

- New fuel pump

- New starter

- New distributor cap

- New air filter

The fuel filter is nice and full so fuel is being pumped right up (that's why I bought the new pump coz first it wasn't).

I'd really like to get my engine running well and reliable.

What options do I have to fix this guys? I never checked timing and don't have the equipment to but I believe you can get low priced timing lights?

I have no idea if anybody ever cleaned the engine or anything. Maybe I should take it apart myself... Wouldn't mind but probaly takes me a century coz I have no equipment for that...

Any ideas would be appreciated.

Thanks,

Vincent.

 
It sounds like you have a 160° thermostat, which is too low. You should have at least a 180° thermostat and engine operating temperature. Your engine cannot operate efficiently at 160°. I run a 192° thermostat.

Yes, your engine definitely needs to be timed, but you didn't say if you have points or aftermarket ignition. If you have points they have to be properly gapped before you time it. Setting the gap by dwell angle is the preferred method. You also didn't say anything about having replaced or checked your spark plugs. I suspect your plugs are fowled on the driver's side, possibly as a result of the low operating temperature.

 
Thanks for your thoughts guys.

Before I reply to your comments: A friend told me to check on the valve (distance?) because if they don't close well it can explain bad/incomplete combustion which in turn explains the temperature, the power loss and the afterburning in my exhaust? Could this be the case?

Don:

It's a Stant 90C (195F) thermostat. I did drill a tiny hole in it though (some say it's OK, some say it's not) but I don't see how that creates the difference in temperature between 2 complete sides of the engine.

I run points which I have never touched. The plugs I will have to check.

Mike:

I have no idea what's inside the carb. At this point I'm assuming (yeah yeah) that it's refurbished to original specs.

Twins:

I have an Edelbrock performer intake to allow the 4 barrel carb.

Thanks,

Vincent.

 
Check with your favorite auto store. I bet they have timing lights, dwell meters, etc. that they will rent (or even loan) to you to help you diagnose your engine. Start with the basics - find out how things are set now, and where they should be according to spec. Replace anything that looks burned or worn (points and cap come to mind if you haven't touched them in awhile). Once you know you have good spark, you can move on to tuning the carburetor.

 
Check with your favorite auto store. I bet they have timing lights, dwell meters, etc. that they will rent (or even loan) to you to help you diagnose your engine. Start with the basics - find out how things are set now, and where they should be according to spec. Replace anything that looks burned or worn (points and cap come to mind if you haven't touched them in awhile). Once you know you have good spark, you can move on to tuning the carburetor.
Well, the very next thing on my to-do list was to actually replace the points with a Pertronix ignotor II as I heard many good things about it.

Still, that doesn't explain the difference in temperature to me. I will get the timing light, they are not incredibly expensive I think, just didn't fit in this month's budget...

And I just took another look at the intake and noticed that air is being split in two, that's called dual plenum? Does each plenum correspond to one row of cylinders? If so I can see how the carb could indeed be influencing this...

 
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cking all the above with the ign sys is needed.. also u really need to pull the carb and ck for dirt, plugging,

when i got my stang i didn't notice it did not have a fuel filter and ran like crap. when i pulled the carb i found i was running off the secondaries for the pri's were

plugged... what a difference a rebuild kit does.. and it's an edelbrock 1406 too.

 
Hey Vincent. The very first thing you need to do is confirm the dwell angle of your points. If this is off then any other adjustments will be pointless. (Yes, that's a joke). ;)

If you have plans to replace the points with the Pertronix you should do that before messing with anything else. Then set the timing. THEN you can start to mess with the carb.

If you get a timing light you can also use it to test spark of each cyl. You simply move it to each wire and watch for how steady the light flashes. If you get a more expensive light that includes an RPM reading you can compare the RPM reading between cyls.

Worn points does a couple of things. It will retard your timing and reduces the time the coil has to send the spark. The retarded timing will impact idle and performance. The reduced spark time can impact higher RPM performance. It's also possible the contacts on the points are burned or pitted which can impact performance as well.

 
I wouldn't worry about the temperatures until you get the cause of your poor engine performance sorted out, then recheck them. Your thermostat may not be working correctly, you may have to pull it later to test it.

Jeff is correct about the likely cause of the temperature differential.

 
I have an Edelbrock performer intake to allow the 4 barrel carb.
Do you have factory Ram Air, or just the TuTone hood paint? The TuTone paint on the hood was an indicator from the factory that the car came with Ram Air. People often add the TuTone hood paint to their cars (oftern without actually having factory Ram Air) when they repaint because they like the way it looks - which is cool, but not always accurate. That's why I ask.

If you have factory Ram Air, you will not be able to use the 1" spacer under the carb. The factory Ram Air air cleaner seals to the underside of the intake plenum that's fastened to the hood - adding the spacer will cause issues when trying to close the hood. Everything else you've listed will fit just fine... just not the 1" spacer.

If you don't have the factory Ram Air set-up, then disregard - but be mindful of how close the top of your air cleaner is to the underside of the hood. If the air cleaner post is a little too tall, and you add the spacer, you could put a dent in your hood when you close it.

If the starter is spinning the engine with little or no difficulty, I'd hold off on replacing that. There's also probably nothing wrong with the fuel pump, either.

Getting the 'Fire' part of the FFA equation (Fuel, Fire, Air) needed to keep the engine running is what you need to focus on. I think you're on the right track. Get the ignition issues figured out (the Pertronix and setting the proper timing should take care of that), then the rest is a matter of "tune-up type periodic maintenance." I think you'll be pleased once you get those things taken care of.

Good luck and keep us posted!

 
Hey Vincent. The very first thing you need to do is confirm the dwell angle of your points. If this is off then any other adjustments will be pointless. (Yes, that's a joke). ;)
And a good one, too...::thumb::
lol

 
right then. I'll get the pertronix and figure out how to check the timing. I need one with rpm reading coz I have no other way of reading the rpm... any tips on how to check timing are appreciated too, never done that. I'll also try reading up.

about the thermostat; I tested it in hot water before I put it in and it worked fine.

the hood is just pretty, I have no ram air.

but what about the plenum thing? Does one half of the carb fuel one side of the engine?

 
right then. I'll get the pertronix and figure out how to check the timing. I need one with rpm reading coz I have no other way of reading the rpm... any tips on how to check timing are appreciated too, never done that. I'll also try reading up.

about the thermostat; I tested it in hot water before I put it in and it worked fine.

the hood is just pretty, I have no ram air.

but what about the plenum thing? Does one half of the carb fuel one side of the engine?
Carb does not work like that. Your cab works "front to back" so to speak. Primaries and Secondaries. Most of the time the primaries are delivering the fuel, the secondaries come open under harder throttle, on the 1406 this is achieved by vacuum.

 
Some intakes have a divided plenum, while others are open. It is indeed possible if you have a divided plenum to have one side of the primary circuit affected by dirt causing one bank to be lean or fuel starved or rich.

Some intakes don't do a good job of distributing fuel evenly.

All that being said-your symptoms sound electrical in nature to me.

 
but what about the plenum thing? Does one half of the carb fuel one side of the engine?
Generally there are two types of intake manifolds. Single and Dual plane. (Yes, there are others but most fall into one of these two categories).

What you are describing is a 'dual plane' intake. And yes, each side or plenum provides air/fuel to half of the cylinders. But most dual planes don't split this up between one side of the engine or the other. Generally they split it between the outside and middle. So one side of the plenum routes to the two passenger outside cyls and the middle two on the driver side. The other plenum feeds the two outside drivers and the middle passengers.

There are a couple of reasons why they do this. First, they are trying to keep the length of each individual cyl plenum as consistent as possible. Second they are trying to make the length be longer since longer lengths help with low/mid range power. Third it works best with the intake stroke of the engine (which mimics the firing order). No two cylinders on the same plenum are next to each other in intake stroke order.

 
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