1972 351C runs crap

[Odmark]

Hello Stanglover, thank you for your input!

I actually found the problem, quite embarrasing. But in my defence i was in an hurry while assembling the carb after setting the floats.

Look at my metering rods:

Please dont laugh too much :angel:

Getting new ones tomorrow!

 

[basstrix]

Oops!

 

[rcadd1ct]

Well you did say you wanted to learn.

Good catch.

I would replace the fuel, too. Anything over three months is questionable even with fuel stabilizer.

 

[Stanglover]

To quote basstrix............. Oooops indeed!!

I would never laugh at someone else's "slip-ups"......... I make enough of my own.

 

[Odmark]

Yes i will get rid of the fuel and put new in it

New metering rods are installed! Did not have time to put the carb back on the car today though, maybe later tonight. But i will test fire it tomorrow.

 

[Odmark]

So i fired it up and it runs better, but still not good...

Tried to set the timing again, and it seems to run best and smoothest at about 10 ATDC :huh::huh: So something is definatly wrong here.

Double checked the tdc and no1 piston was in top as wel as the rotor pointing to number 1 cylinder.

Double checked firing order, ok.

Did a small very careful test drive and it runs strong when the rpms are up a bit.

Still before the new needles the car was so rough at idle it wasnt even driveable.

Also there now is no fuel visible in the fuel filter :huh:

And also, when i plug in the cars tachometer to the distributor the car dies :huh: but a aftermarket works perfect...

Getting tired of all this

 

[midlife]

Aftermarket tachs and Ford tachs use completely different wiring systems and are not interchangeable. The Ford system is in-line with the signal going to the + side of the coil; aftermarket tachs use the negative side of the coil as the sensor signal.

 

[Stanglover]

So i fired it up and it runs better, but still not good...

Tried to set the timing again, and it seems to run best and smoothest at about 10 ATDC :huh::huh: So something is definatly wrong here.

Double checked the tdc and no1 piston was in top as wel as the rotor pointing to number 1 cylinder.

Double checked firing order, ok.

Did a small very careful test drive and it runs strong when the rpms are up a bit.

Still before the new needles the car was so rough at idle it wasnt even driveable.

Also there now is no fuel visible in the fuel filter :huh:

And also, when i plug in the cars tachometer to the distributor the car dies :huh: but a aftermarket works perfect...

Getting tired of all this

If it were a horse, I'd shoot it!!

I too am going through much frustration trying to get my engine to run as it should. I feel your pain! Seems that you have other sh*t going on besides timing and carb issues. I'll be sooo happy for you to learn that you have it all corrected and finally enjoying your ride.

Good luck

Geoff.

 

[Odmark]

Midlife: oh okay, that explains that. Is there some fix for this?

Stanglover:

Yes this really is a pain in the ass...

Sorry to hear you are also having trouble, hope it works out for you too mate! Keep on trying ::thumb::

And still the exhaust coming from one pipe is cold, that is a sign of that side not running, right? Is it a sign of it not sparking? Since exhaust gases are still coming out of the pipe it has to get fuel right?

And also still no difference when turning the idle mixture screws. Except now it almost stalls when i screw them all the way in.

 

[basstrix]

WIth the PCV disconnected and the vent on opposite valve cover and dipstick tube plugged, remove the oil fill cap (on valve cover) and put something over the hole so you can see if it pulls a vacuum(the palm of your hand, a sheet of paper, plastic film...something). If it does pull vacuum, you have a significant leak on the lower side of intake ports. If it does build up a vacuum, don't let the vacuum build up. An alternate way is to squirt a little bit of whatever it was you used to detect vacuum leaks before...This is somewhat of a 1-way test...if you don't get a rise in RPM, it doesn't necessarily mean there's not a leak but if you do get a rise, it's a very good sign of a leak (at the intake manifold to head interface).

 

[Stanglover]

Midlife: oh okay, that explains that. Is there some fix for this?

Stanglover:

Yes this really is a pain in the ass...

Sorry to hear you are also having trouble, hope it works out for you too mate! Keep on trying ::thumb::

And still the exhaust coming from one pipe is cold, that is a sign of that side not running, right? Is it a sign of it not sparking? Since exhaust gases are still coming out of the pipe it has to get fuel right?

And also still no difference when turning the idle mixture screws. Except now it almost stalls when i screw them all the way in.

I definitely am NO expert, trying to find my own way as best I can and with the help of others here. Getting closer though.

I remarked before about cool exhaust on one side before. In my case it WAS a dead plug. Plugs can seem fine out of the engine, but fail under pressure. If you have any doubt I would put in new correctly gapped plugs. I use Autolite 24 or 25. I will never use Champion, never had good luck with those.

May I suggest going back to the beginning. I chucked all the old stuff, plugs, wires, cap, rotor, new points if you're running old school. Then rethink the carb. I had a Holley 670 on my car when I bought it that I could not get to run right. It turned out that it had a bad primary metering block from new. I could take the right side idle screw out and it made no difference. I could also screw it in far deeper than the one on the left side. The left side worked fine though. I just replaced the carb with another new 670. I would now go to a Quick Fuel as it is a better carb. The fact that yours stall out when the idle screws are turned in all the way suggest they are working.

Then there is the distributor issue. I have a Cardone reman original, but it has way too much mechanical advance to run anything more than 6* initial timing. I'm going to rebuild it by welding the limit pin slot and resizing it to suit. Going to be some work, but with the help of many others on this forum, I'm confident I'll get-it-done!! A DuraSpark also seems to be a good alternative and something I may consider going to later IF I don't get where I want to be.

Edit: basstrix has a good point.

 

[Odmark]

First of all, i need to correct myself. The fuel filter was in fact completely filled, no idea how i tricked myself into believing it was empty :huh:

Pulled the carb again and double checked metering rods, jets, floats etc.

Tossed the electric choke in the trash (not really, just disabled it)

Triple-checked tdc timing.

Basstrix: I will try that! You mean spray directly into the engine?

If i have a leak at the lower part of the intake, wouldnt that mean that gasoline is getting mixed with the oil?

Stanglover:

The plugs are new, they are champion though... The distributor complete with everything (rotor, cap, wires, coil) also brand new.

The carb i was going to swap out for a holley, but maybe i should get a quick fuel instead.

Thanks for all the tips

Tomorrow i will start troubleshooting again. And doing something i already should have been doing. Checking the spark...

 

[basstrix]

Just stick with plugging everything except the oil fill port and check for a vacuum. I don't want to be the cause of something bad happening to your engine, so forget about squirting a little fuel in there.

With regard to your comment about exhaust on one side being cold, you can loosen the plug wires from the plugs on that side and using either well insulated pliers or heavy rubber gloves you can pull the wire away from each plug and note the RPM change. It's a makeshift cylinder balance test. Cylinders with little to no drop in RPM are suspect for bad plug, bad wire, no compression, vacuum leak, etc.

 

[Odmark]

I mean if it already has a vacuum leak there wouldnt it suck fuel from the intake manifold down in the engine? I should be able to smell it on the oil?

I will check those things tomorrow hopefully not a compression problem since everything internally is brand new...

 

[basstrix]

I mean if it already has a vacuum leak there wouldnt it suck fuel from the intake manifold down in the engine? I should be able to smell it on the oil?

I will check those things tomorrow hopefully not a compression problem since everything internally is brand new...

To clarify, when I refer to the "inside" of your engine, I mean anywhere engine oil normally comes in contact with (excluding the oil galleys).

When the engine is running with the throttle plates closed or only partially open, the pressure inside the intake will be lower than the ambient pressure. With the PCV removed, the pressure inside the engine should be pretty close to ambient pressure...the difference due to blow-by past the rings (your rings haven't seated fully, so there may be substantial blow-by) or blow-by past the exhaust valves (not likely).

If there is a manifold leak and it's to the inside of engine and a significant enough leak, it will pull a vacuum on the engine, itself.

The scenario you're asking about (the engine sucking fuel from the intake and into the engine) would require that the pressure in the manifold is greater than the pressure inside the engine...you don't have a supercharger or a turbocharger, so this is not possible in your case.

In the same sense that you were spraying fuel to check for a vacuum leak on the outside of the engine, my initial suggestion was a way to get fuel to a possible vacuum leak on the inside of the engine by means of providing fuel vapors to the leaking intake port.

 

[Odmark]

I mean if it already has a vacuum leak there wouldnt it suck fuel from the intake manifold down in the engine? I should be able to smell it on the oil?

I will check those things tomorrow hopefully not a compression problem since everything internally is brand new...

To clarify, when I refer to the "inside" of your engine, I mean anywhere engine oil normally comes in contact with (excluding the oil galleys).

When the engine is running with the throttle plates closed or only partially open, the pressure inside the intake will be lower than the ambient pressure. With the PCV removed, the pressure inside the engine should be pretty close to ambient pressure...the difference due to blow-by past the rings (your rings haven't seated fully, so there may be substantial blow-by) or blow-by past the exhaust valves (not likely).

If there is a manifold leak and it's to the inside of engine and a significant enough leak, it will pull a vacuum on the engine, itself.

The scenario you're asking about (the engine sucking fuel from the intake and into the engine) would require that the pressure in the manifold is greater than the pressure inside the engine...you don't have a supercharger or a turbocharger, so this is not possible in your case.

In the same sense that you were spraying fuel to check for a vacuum leak on the outside of the engine, my initial suggestion was a way to get fuel to a possible vacuum leak on the inside of the engine by means of providing fuel vapors to the leaking intake port.

Oh okay, i understand!

On behalf of the rings, i run moly rings and i was told the rings are pretty much seated when the camshaft is broken in?

I will get back to you when i tried some stuff.

 

[Odmark]

Okay, now i tried some things.

First of all, since the stuff i did 2 days ago (deleting choke etc) it runs a liiittle bit better. Also now i could set the timing to 16 btdc :huh::huh:

Did as you said and plugged everything but it absoluteley did not pull vacuum.

Started pulling cables with the engine running, no.5 made no difference what so ever.

6,7 and 8 resulted in an major increase in rpm.

Checked spark everywhere and it was ok, although maybe a bit weak, hard to say in direct sunlight since i had to crank the engine and check for spark from the drivers door.

Pulled the plugs on the cold side and they look like this:

5:

All wet and grimey

6:

7:

8:

 

[Stanglover]

Stanglover:

The plugs are new, they are champion though... The distributor complete with everything (rotor, cap, wires, coil) also brand new.

The carb i was going to swap out for a holley, but maybe i should get a quick fuel instead.

Thanks for all the tips

Tomorrow i will start troubleshooting again. And doing something i already should have been doing. Checking the spark...

As for your choice of carb, it depends on what you can get where you live, unless you are going to mail-order. There is nothing really wrong with the Holley, but the Quick Fuel is more tunable. I believe it was designed by former Holley engineers who took it a step further. For me, I have a 670 Street Avenger. This is a square bore carb for my 71 4V intake. I think the 72 is a spread bore unless you have an aftermarket intake. I think you can get an adaptor plate. Many go with way too big carbs, a 670 is all you need for a 351. If I remember, the QF is 650cfm.

 

[Stanglover]

Okay, now i tried some things.

First of all, since the stuff i did 2 days ago (deleting choke etc) it runs a liiittle bit better. Also now i could set the timing to 16 btdc :huh::huh:

Did as you said and plugged everything but it absoluteley did not pull vacuum.

Started pulling cables with the engine running, no.5 made no difference what so ever.

6,7 and 8 resulted in an major increase in rpm.

Checked spark everywhere and it was ok, although maybe a bit weak, hard to say in direct sunlight since i had to crank the engine and check for spark from the drivers door.

Pulled the plugs on the cold side and they look like this:

5:

All wet and grimey

6:

7:

8:

Hmmm! I'm not qualified to answer this, but from what little I know, you may have a big problem on #5 cylinder as it looks to be oil fouled as you know. #'s 6 & 7 look to be right on, 8 looks rich. I'm sure more experienced members will have a better idea and can offer help. Have you done a cylinder compression check? Again, from what I understand, I'm afraid you might have a ring issue on 5. BUT, it could also be those Champion plugs. I won't even run them in my lawn mower!!

For me with my engine troubles, I was afraid that as the engine was broken in on a stand by the builder who didn't realize it was only firing on 7 ( dead plug) and from subsequent running, that the #4 cylinder had suffered a 'wash down' and screwed up the new rings. I too will need to do a comp test to find out, but so far, I think I dodged that bullet.

I really hope I'm wrong on this one in your case. Very worrying and getting expensive no doubt.

Good luck,

Geoff.

 

[Odmark]

Hmmm! I'm not qualified to answer this, but from what little I know, you may have a big problem on #5 cylinder as it looks to be oil fouled as you know. #'s 6 & 7 look to be right on, 8 looks rich. I'm sure more experienced members will have a better idea and can offer help. Have you done a cylinder compression check? Again, from what I understand, I'm afraid you might have a ring issue on 5. BUT, it could also be those Champion plugs. I won't even run them in my lawn mower!!

For me with my engine troubles, I was afraid that as the engine was broken in on a stand by the builder who didn't realize it was only firing on 7 ( dead plug) and from subsequent running, that the #4 cylinder had suffered a 'wash down' and screwed up the new rings. I too will need to do a comp test to find out, but so far, I think I dodged that bullet.

I really hope I'm wrong on this one in your case. Very worrying and getting expensive no doubt.

Good luck,

Geoff.

Thank you for the answer Geoff, yes it seems 5 is a bit oily, it reeks of gasoline though so most of it is probably fuel.

I was hoping compression issues was out of the question but seems like i have to check now anyway.

I too only have had troubles with champion plugs in the past, but they were the only ones in stock when i bought the rest of the parts so i got them...

Really hope there is an easy fix to this, cant afford to throw any more money at this thing right now...