SOLVED: Still running poorly, still having vacuum issues

[cfmustang]

I suppose that is possible. When I first rebuilt the engine 11 years ago, we shaved the head .060 to bump up the compression ratio. When the engine was rebuilt again last year, I have no idea if the machine shop decked the block or shaved the head to true it up. I did not request either to be done, but it may have been done as SOP.

I am assuming that doing either just to true up the surfaces would not be enough to raise the compression too high, but in combination with the original head work is it possible? Also, I did not supply the head gasket so I will have to assume they went through normal channels and got the thicker more readily available gasket.

I am running regular old 87 octane right now.

Will the compression test I am going to run validate that the compression ratio of the engine is high enough to require premium?

I won't have time to test the timing mark tonight, but plan on doing it on Saturday.

 

[MustangSix]

Insufficient timing at idle could easily overload the three row radiator. Retarded timing shoots the temperatures way up.
Doug

I dunno, Doug. I just don't think that retarded timing alone could cause an overheat at idle. Under a load, for sure, but retarded timing causing that at idle....I'm skeptical. I think I could pull the timing all the way to the point that it would barely run but it would never overheat just sitting there. I really think there's something else going on.

I wouldn't blame it on the age of the flexfan either. I doubt the material would "go limp" on you.

Put some premium in it. Even a stock 200 is likely to have issues with regular. If your CR is above 9.0:1 you may need better fuel, but again, that is largely load dependent and might have no effect on idle quality.

Any chance of getting a video with a sound clip to see this thing running? A picture (movie) is worth a thousand words.

 

[cfmustang]

A soundclip is no problem. However, I don't have any sort of video camera at all for video. Honestly, I don't know of anyone off hand that I can borrow one off of either.

What you want the clips of? The rough running when first started cold? When it has smoothed off some at temperature? When it is overheating?

 

[Soldmy66]

While I can’t comment for others, I found the Charo reference both appropriate and tasteful. It is always comforting to rely on sitcom points of references in cases like this.

JK

I’m sure it is frustrating, keep up the good fight.

 

[MustangSix]

Any of the above conditions would be helpful. Without some sort of audio/visual reference, I'm no more helpful than a blind man.

900 rpm is probably where the idle should be, given the cam. And it may take way more advance to light it off than normal. 20-25 degrees initial might not be out of line.

Keep tinkering......you'll get it.

 

[Anonymous]

Cris, don't give up bro! I've been following your troubles from the beginning.

I agree with Jack, and the others about your cooling issue. You shouldn't be overheating. I think once we figure out what's causing the excessive heat, we can then concentrate on tuning that Weber.

By-the-way, what is your definition of over heating? Curious. What's the coolant temp.?

 

[cfmustang]

Okay, here are the results of the compression test:

1 - 130
2 - 135
3 - 145
4 - 135
5 - 135
6 - 150

Also, the #3 and #4 plugs are pretty fouled.

While I was there, I threw on the Tach, Dwell, Volt meter:

Once warmed up at idle:

RPM - 900
Dwell - 37 (Chiltons says ti should be 39)
Volts - 6.5 (measured off of the positive post of the coil)

Ported vacuum off of the Weber : flutuating between 5 and 7 Hg

Coolent temp : I have no idea how to check this... The temp gauge was going almost to but not pegging. B.T.W. Tonight, I ran it for a half an hour without it overheating (stayed in about the center), however, it was 70 degrees outside tonight and in the high 70's low 80's yesterday.

 

[Lazy JW]

I see nothing alarming in those compression numbers.

I agree that late timing alone shouldn't cause overheating at idle, but combined with too much fuel it might. Definitely put some premium fuel in it until you get it running right,

A big cam with lots of overlap often needs more ignition timing at idle, 20 degrees or more is not unusual. But that usually means too much at top end also, this is why you need to map the advance curve.

Can you beg or borrow a known good carb to try? Even a stock one-barrel would sure make it easier to tune things up.
Joe

 

[Anonymous]

Chris, I think someone else has asked what your "over heating" is. Is it boiling over antifreeze? If not, you may just have a bad temperature sending unit. A lot of replacement units are not calibrated properly. You may need to hook up another temp gauge and verify the overheating or borrow a infra red thermometer and get some readings on your hoses. If you are spewing antifreeze, you might want to replace the cap. And make sure that the system has all of the air bled out of it.
Doug

 

[cfmustang]

By overheating, I mean that once it starts getting to the high end of the temp gauge, the car (in gear) starts running rougher and rougher till it stalls after about 5 seconds of running. The only time it boiled over was the first time I filled it up after putting the new radiator in, I filled it and sealed the cap. It started steaming so I shut it down and removed the cap to find it low (the themostat must have opened and sucked fliud into the engine leaving the radiator low). I topped it off again and sealed it up (the cap is new btw). How do you bleed air from the system?

Ignition timing at idle of 20 degrees? At 14 degrees it is pinging like mad under acceleration. At 20, I think I would melt my pistons. Also, I am at 12 degrees with the vacumm advance disconnected and it is pinging.

As for a carb, the only thing I have is the old stock carb I had from before the first rebuild 12 years ago. It has been sitting in a box all that time, so I am sure it is shot by now. Unfortuantly, I have no one else to borrow a carb or any other tools from and my funds are completely drained for a while (wife is losing her job). So I can't afford to buy a carb, infrared thermometer or really anything else for that matter.

I am starting to consider mothballing the whole thing till I can afford to pull that POS 272 cam. I think that is way too big for our engines.

 

[Anonymous]

Folks, I think it's time to step in and give this guy a hand.

If anyone has a single barrel carburetor he can experiment with, he needs it.

If someone can help him out with this, you need to! Especially if you have a spare one that will do nothing but collect dust on some basement shelf. I would even front the shipping to get it to him.

Anyone?

Moderators?

 

[Lazy JW]

...Ignition timing at idle of 20 degrees? At 14 degrees it is pinging like mad under acceleration. At 20, I think I would melt my pistons. Also, I am at 12 degrees with the vacumm advance disconnected and it is pinging....

Yes, it may require 20 degrees or even more at idle.

Your stock engine probably used about 10 degrees at idle, then as it sped up the mechanical advance would gradually increase until it reached about 35 degrees advanced at around 3000-3200 rpm. This amounts to about 25 degrees of advance.

Now, with your bigger cam, you may need a lot more initial advance, but when you set it up to 20 degrees it will have 45 degrees at higher speeds. This is definitely too much. Your distributor would need re-curved (limited ) to allow this to work.

HOWEVER, if you set the advance at 10 degrees like normal, and then RE-CONNECT the vacuum advance to MANIFOLD vacuum (not the normal 'ported') it MAY allow your combination to run pretty well. If your carb is correct also.

As soon as you connect the manifold vacuum, your idle should speed up dramatically. Just adjust it down, this will also result in an increase in manifold vacuum.

Give it a try, it won't cost much.
Joe

 

[66 Fastback]

It sounds like you may not have an overheating problem. The radiator will burp fluid on the first fillup, untill it establishes it normal level in the radiator. You may have a temp sender that is not matching the temp guage. Bleeding the air out of the system is easy on the Mustang. There really is not much of an issue with trapping air on it. Sometimes you can trap some air in the heater hoses, since they may be at a higher elevation than the top of the radiator. I sometimes put the car on some ramps, with the radiator cap removed, and run the engine and rev it a bit in that position to circualte the air out of the system. That should place the radiator fill point at the high point. Some cars have high point air bleeds to vent air out. As hoodlines have dropped over the years, the radiator has been placed lower than the engine in many cases.
Doug

 

[cfmustang]

Doug,

I am hoping you are correct. Unfortunatly, I did not have any time this weekend to do anything to the car except search a few autoparts stores for a Piston Stop to verify the timing mark on the damper. I found some on the internet, but could not find any in the stores.

Anyone know what size our plugs are by chance? 14mm? 18mm? Thisis what I am thinking of ordering:



In the meantime, I'll put the car on ramps and run the engine to temperature without the cap on and see if that helps.

 

[WhitePony]

OMG! Now THAT'S a URL!

 

[MustangSix]

Shortened that up, didn't it?

 

[cfmustang]

Sorry about that...I should have done that myself, but I was in a hurry.

Anyway, I found out what size the plug is, along with other info from the Champion website.

Resistor plug, 18mm, .460" reach, taper seat, 13/16" hex head, standard projected core nose, copper core design.

So, I'll order the 18mm tool and be able to verify the timing mark in a few days...

However, I have heard people mentioning having the dizzy recurved a few times. How do you get that done? I am assuming a shop has to do it, but how do you know what to tell them to do?

 

[cfmustang]

Ok. I picked up the TDC piston stop today at Summit (they were the only ones that stock the thing) and went to verify the TDC mark on my damper.

I don't have much time this week to work on the car, but I thought this would be a quick check.

One problem...How do I manually turn the engine?

I was able to do it before by removing the plugs and spinning the fan. However, since I replaced the readiator and fan spacer the fan spins the water pump but is not spinning the crank...

Ugh. Is there a tick I am missing? I can't be this stupid...

 

[Anonymous]

Chris,

The '68 Dizzy has two weights that are beneath the breaker plate (which holds the condensor and points). The weights are the heart of the centrifugal advance system. One of them is "active" in that it advances the dizzy's cam to whatever degree of advance the engine spec calls for at a certain RPM. THey can be rotated to allow one or the other to be "Active." They are marked with a number. That number is HALF of the total degrees advance the dizzy will advance in the centrifugal system. In other words, if the weight is marked 10, then the total advance will be 20 degrees. They should both be different giving you two options.

The springs that are attached to the plate control how fast the dizzy will advance, or at what RPM. TIghter the spring, higher RPM.

The centrifugal system will kick in at around 800-900 RPM give or take and as such only the VAC system controls advance during idle as well as intial timing.

Curving your dizzy is a process of chosing how much advance you want out of the dizzy's mechanical advance and at what RPM buy adjusting the springs and weights. The shop manual or a tune up chart gives you the facotry specs which are ususally conservative.

This is a very crude description and I am sure someone can articulate it better than I can. But, I hope it is a start.

Jay

 

[Anonymous]

Bingo MontegoMan -

Your troubles are like the ones I had when I rebuilt my engine.
I had the same situation... fouled plugs... running hot (not overheating per say - but hot) low vacume, poor idle (although it never stalled).
I checked timing, fuel mixture, advance... everything back and forth loosing my mind - but learning along the way.

my cure... I changed the springs in the distributor and got a slower pull on the advance and limited the all in by enough to stop the pinging. By just trying settings and driving the car it turned out mine runs best around 16 degrees initial.. my idle is 900 with a 272 cam. I pull about 12-13 inches of vacume steady at idle and once we re-jetted the carb and dropped the float level it ran nice. but the process of dropping the fuel level and tweaking the advance eliminated the temp problems and no more black plugs. (I still think it runs a little rich... I am working on getting it dyno tuned for best performance)


If I were you, I would verify the timing at TDC first. Then setup the carb Idle Speed, Fuel Mixture with the vacume advance line pulled and plugged.
My guess is there are issues with the timing on this engine... unless you have a bad or backwards installed head gasket? that is a possibility too.
Measure your vacume level and use a vacume gauge to verify your fuel mixture (connect directly to the intake manifold) make sure the PCV is clean and sealed and you have no leaks in the system.

If you get the idle worked out - Then map the timing curve with the vacume still plugged. Use a timing light and note in 500 rpm intervals what the advance is starting out at 14@900 do a measurement at 1500, 2000, 2500, 3000, 3500(if you can) a dial-back light will help out a lot letting you pull the marker back into view. Then do the same with the vacume advance hooked up... will tell you a lot about the engine.

mine never ran right with the vacume advance disconnected because it was not getting enough advance... then with it connected it was getting too much too quickly... problems both ways! The timing and fuel mixture are everything on these engines.

The short version for me, too much fuel meant cranking up the rpms to compensate which in turn messed up the initial timing. Got the mixture and idle speed right and what I thought was 16 initial turned out to be 10.
When that was finally set right at 16... I was all in by 2500 rpms and my limit was 3000... the car would buck and ping if you tried to push it over that. Once the dizzy was re-curved...

Not a problem anymore, and it runs at an even temp even when it is 90 degrees. (unless I sit in traffic for a long time with the AC running) then it gets warm. and I can push into 4500 rpms now with a smooth running engine

Sorry for the book, hope something helps...