272 cam and automatic tranny = high stall converter...PART 2

[cfmustang]

The original post was getting a bit long in the tooth, so I thought I would start a new one. To read the old post, see http://fordsix.com/forum/viewtopic.php?t=13653.

Anyway, sorry about the long delay but I finally got my hands on my dad's old tuneup tools.

For starters, I pulled the vacuum line from the base of the carb and plugged a vacuum gauge on there. Now, the engine was not completely warm and the idle was swinging pretty radically (surging, actually), but the vacuum was reading between 8 - 13 (8 on the low end of the swing, 13 on the higher end).

Now, when I pulled the vacuum line I didn't seem to notice that much difference in the way it was running. However, it would not start with the line removed.

I also pulled the #1 plug and it wasn't as bad as I thought. I expected it to be really sooty, but it didn't look to bad to me. I'll try and get some pictures up in the next day or two.

Still having a hard time getting the RPMs for you guys to give you more info. My interior tach is shot. I did find a old Craftsman Dwell, Volts & RPM gauge mixed in with his tools, but I wasn't sure where to hook this up to. It has two leads. A wide green alligator clip and a narrow black aligator clip.

Anyone know where I hook this up to?

 

[cfmustang]

Anyone? Buehler? Buehler? Bueler?

 

[Anonymous]

It has two leads. A wide green alligator clip and a narrow black aligator clip. Anyone know where I hook this up to?

Green to Neg. Coil
Black to ground

Did you ever pickup another distributor?

 

[cfmustang]

Thanks, will try that tomorrow morning.

No, I haven't bought it yet. I want to get the carb set right first. Also, it seems to me that the mechanical advance would help for acceleration and not idle. That is where my main problem appears to be.

 

[cfmustang]

Okay, spent yesterday afternoon under the hood. It took me longer than it probably should because I'm so green with the basic maintenance...

Started out by driving it across the street to get some gas and it kept stalling on me. That and the gas gauge stopped working over the last week or two. Got it home and pushed the vacuum line in further and the stalling seemed to stop (couldn't get it to even idle in the driveway before this).

With the analyzer, the at temperature idle was around 1100 rpm with 11-12 Hg vacuum. No matter what I tried, the idle still oscillates a bit. With the vacuum fixed (?) I was able to lower the idle to around 800, but it was still pretty rough. Played with the timing by ear, since I haven't figured out how to use the timing light yet (next weekend) and ended up advancing it a tad and it ran smoother. Unfortunately, I had to up the idle again so that I could put it in gear without stalling.

Tried putting in the Pertronix and nothing. Seemed pretty simple, but with it in (left the old coil on first to see if I could get the Ignitor II running first) the car would just crank. Fiddled with it a while to no avail. Ended up putting the points back in and it fired right up. To check, I checked the voltage from the coil and am reading about 11 volts. I have heard that you need 12v, but it should at least try and start, shouldn't it?

Oh, and during all that fiddleing the gas gauge started working again...must be a loose wire.

So, here are my questions:

1) How should I check for a vacuum leak. My idle is still swinging up a down a bit and I am wondering if it is a vacuum leak. Should I just check the line from the base of the carb to the dizzy or is there anywhere else?

2) Is the idle at 1000-1100 to high? It seems that is where I need to keep it to keep it from stalling in gear. Is there a way to set that idle independent of the idle in park?

3) Is 11Hg of vacuum too low? I am running a 272 cam, so I am expecting a lower vacuum but is it too low?

4) Any clue about the Ignitor? I know you should have 12v from the coil, but 11v isn't bad is it? Also, my electric choke is wired from my coil, could that be causing the 1v drop? Would 1v prevent the thing from working at all? How do I tell if there is no spark?

Thanks!
Chris

 

[Anonymous]

To check spark, remove a spark plug. Attach the plug wire, and hold the plug near the block (close but not touching). Have someone crank the motor. Watch the plug. You should see it arc to the block, or across the electrode. This is best done in low light conditions, which is easy under the hood. Makes the spark easier to see.

Also, insulate yourself from the plug wire. I've had jolts from poorly shielded wires. Nothing to hurt you, but it's a bit of a surpise.

Random thought. I've never intalled a pertronix, so I'm speculating. Could it be that the magnetic pick-up is installed in such a way that the timing could be a mile off, and thus causing the no-start issue? If you have spark, but no start, timing would be the next place I would look.

--mikey

 

[cfmustang]

Thanks for the tip on the spark check. Going to have to enlist the help of the wife for that.

As for the timing on the Ignitor, I was wondering the same thing. According to the instructions and a few articles I read on the 'net, you shouldn't have to really adjust the timing at all once it is installed. It should be ready to go.

I am thinking about calling Pertronix and seeing if they will warranty it, but I'll wait to see if anyone with more experience with it can enlighten me first...

 

[cfmustang]

Still hoping for some answers to my other questions, but I am also wondering. Should I be reading the vacuum from the carb or from somewhere else?

Still wondering:

1) How do I check for a vacuum leak. I thought I read to use carb cleaner. Will that strip the paint off my freshly painted block? Is there somewhere else to check besides the base of the carb?

2) Is the at park idle of 1000-1100 too high? Through more reading here on the boards, it seems I should be putting the car in gear (with the brake on :roll: ) and setting the idle there.

3) Is 11" of vacuum too low? That was read from the ported vacuum from the carb.

I have always relied on my father for tuning the engine and he is does't remember how or really have the time anymore so I am trying to learn how to do this myself. Besides, it is about time I learned how to do this. Heck before this weekend, I have never removed/reinstalled a set of points before. It sounds pathetic, but I'm learning.

 

[cfmustang]

Doth I offend?

It appears I can't get an answer no matter what I try.

 

[66200i6]

Just noticed your post. I've been very busy.

One of your last questions was should I be measuring at the carb (carb body?). No.

I'm assuming you mean carb body. You should be measuring manifold vacuum (PVC connection). I was wondering why your vacuum readings were so low. If you were measuring vacuum at the manifold and getting only 10â€￾ that would explain your surging, you would be running very lean.

A simple way to check for vac leaks is to use some WD40 while the engine is running and spray around the base of the carb-adaptor and carb. The idle should increase once the fluid fills the offending void.

Good luck, Ric.

 

[cfmustang]

Thanks for the reply. I was starting to wonder where everyone went.

Yes, I assume that I am measuring from the carb body. The Weber 32/36 has a port under the electric choke and I have been reading from there.

There appears to be a vac line running from the center of the log to the PVC valve. There is a second port on the valve that has a nipple on it. Can I read from there?

Also, if the dizzy is running off of ported vacuum from the Weber, shouldn't that be where I measure?

 

[Anonymous]

You want to connect your vacuum gauge to the manifold itself. 11" of vacuum isnt to bad for a 272 cam....I'm pulling around 10" on mine.

Set your idle between 800-1000 rpm's....it'll drop to 600-700 when you put it in gear.

Forget getting it to idle smoothly with a 272 cam...it aint going to happen!

When you order a stall convertor, try to get one in the 2000-2200 range. I'm going to have one made for mine between the 2800-3000 range.

Later,

Doug

 

[Anonymous]

As for your Ignitor II question.. I haven't had any personal experience with the Ig II... but I've seen on here a few people have had trouble with them, they wound up returning it and getting a Ig I... and not having any problems after that...

I don't know how much load the electric choke puts on the ign circuit (your cause of the 1v drop) but I don't think it's a good idea to run it off of the ignition, it does seem to take some of the power away from it (I have seen cars hooked up that way, and I've even run mine that way for a little bit out of haste, but later hooked it up to something differently)

If you're using an original style alternator (Autolite, Motorcraft.. externally regulated) you can hook the elec choke to the Stator terminal on the back of the alternator (I believe it's the terminal with the black ring on the back of the alt, it says STA). The stator term only has power when the engine is running...

Or run the wire inside the car and hook it onto a fuse on the fuse block that has power when the key is 'on'

Also, if you're gonna be running a Pertronix you need to have the full 12v to the unit (red wire from the module) and keep the original + coil wire on the coil (not hooked to pertronix, I've seen them run w/ the pertronix red wire hooked onto the + coil wire on the coil, but it only seems to run like this with the stock coil... since most aftermarket coils have lower resistance it changes the amount of voltage available to the pertronix)

But if you're running points, the original wire going to the + coil shouldn't have the full 12v! It should be connected to the original resistance wire (pink in color)..

To hook up the pertronix to the full 12v, find the wire or terminal on the back of the ignition switch that the resistance wire goes to (I think the wire of the back of the switch is yellow, IIRC) that way it has power when the key is on AND when it is in the start position... if it's hooked to anything else, it won't have power in the Start position of your ign switch, and it won't run!

I would try hooking up your Ig II that way before giving up on it, if it still doesn't work then see if it you can send it back and get an Ig I


(I hope this wasn't too long winded and confusing, I was gonna post a few days back, but I tend to read more than I post, sorry! And I don't have quite as much time as I would like to, then again... don't we all?)

 

[cfmustang]

Thanks for all the Ingitor info. I am printing that up and saving it for the next week or two. Until then, I have decided to tweek the carb and timing a bit more.

So.

I hooked up the vacuum gauge to the manifold and got a pretty steady 11" again. I know this engine is going to idle rough, that is why I picked the grind I did a long time ago. When I set the idle to 1100 rpm in park, the thing drops to about 400-500 rpms in gear and eventually stalls. This time I set it the idle to about 600 while in reverse and the in park idle is at about 1200-1250 rpm. Now, it will sit in gear with the brake on and not stall.

Unfortunately, I got cocky and tried adjusting the timeing. First with a light, but there are no marks at all on my balancer! So, I tried by ear. Now, when I drive it it still is not that powerfull but there is a dead spot at partial throtle where I seem to lose power.

I think I need to set the carb back to Weber specs and start over. Also, I have read that the Power Valve is based on vacuum. What does it do? Could this be an issue? My engine was surging when coasting or braking up to a stop. How do you time with a light when there are no marks?

Help!

 

[Anonymous]

I'm not sure how the timing marks are on the 6's (sorry I haven't dived into my 250 yet.. lagging again!).. But from what I've seen and remember, doesn't the balancer just have notches instead of 'marks'? Are there numbers on the pointer? Or do you set it by the notches? (Someone else know off-hand?) I'll have to look in my book when I get home (maybe I shoulda done that before I posted! hehe)....

But I can tell you that it's somewhat of a rule of thumb when tuning to make sure your ignition system is set before you start fooling with carburetion (you could be covering up an ign prob by messing with the carb) If you're running the points, make sure the dwell is in spec, then set the timing.. I dunno what stock spec is, but I think most people say 10 BTDC is a good starting point.. then start messing with your carb ( assuming your plugs/wires/cap/rotor/coil and all that are good)

Like MG said, 11" of vac is probably all you're going to get w/ the 272 cam..

I'm not too familiar w/ Weber carbs, so I don't know how the power system functions on them...

I can tell you the idea of the power system (I say system because some carbs use a 'valve' while some use springs w/ metering rods)...

The power system kicks in at a set vacuum point to provide full enrichment under full thottle or close to full throttle conditions (depending on the load on the engine)... Say if your power system is set to kick in at 15", since most stock engines will idle with close to or around 20" of vac this may be okay... but if you have a larger cam (say like yours) and now it's idleing with 11", it's going to kick in.... If this happens it will usually run REALLY bad, and being blowing loads of black smoke out of the exhuast (overly rich-unburnt fuel) being that the carb is giving the engine way more fuel than it needs at idle.

If that is the case then you need to change the point it kicks in at, like I said I dunno how this is done on a Weber... with a Holley they say to divide your idle vacuum in half, and put that size power valve in...

Also, if it's surging when coming to a stop it MAY be your float level, I've heard the Webers can be pretty sensitive to fuel pressure also...

If you can't see any notches or marks on your balancer with the light, it may have spun (balancers are 2 pieces, outer ring & and inner ring with a piece of rubber inbetween... when the rubber gets old it cracks or it gets swelled by oil leaks it can allow the outer ring to slip.. thus your timing marks aren't where they're supposed to be anymore! It is fairly common... especially when we're talking about 30 year old + stuff)

Hope this helps, AND makes sense! I feel like I kinda ramble sometimes!

 

[66200i6]

With that cam you are going to have to idle higher than normal. With that kind of flow through the carb you may be trying to idle in the main circuit using the progressive two-barrel. Make sure the throttle plate is in the proper position to engage the idle circuit. If you are in the Main circuit and want to continue to use the progressive carb you might have to apply the method Audi uses to tune. In order to close the throttle plate to engage the idle circuit you need to drill a hole in the plate to allow part of the airflow to go through the plate. I would suggest however that if this is a problem that you go to a larger one-barrel carb and keep it simple.

As for the timing look for a notch on the aft edge of the pulley and look for a wedge on the face of the timing chain cover. There should be raised numbers aligned with timing marks on the face of the wedge, they should read 14 – 10 – 6 – 3 – TDC.

Take the plug out of the number one cylinder and watch for the rotor to approach the number one position on the distributor. Use a long screwdriver to give you an indicator when the number one cylinder reaches TDC (Top Dead Center). The notch in the pulley should align with the TDC described above.

Good luck, Ric.

 

[Anonymous]

I was having vacuum problems on my 250 six (1966 Mustang) after we swapped it out of a 1980 Granada. Turned out the PVC vacuum line was the problem.

The PVC valve was not working properly. So, I removewd it and Plugged the inlet tube at the Carb. It runs great now.

Also, I do this when I race my 72 mach I and it always provides more vacuum and consistent times at the Drag Strip.

 

[cfmustang]

Rick,

I hate to say it but you are speaking greek to me. I do remember reading about drilling the holes your talking about in my Weber manual. It said that can help in low vacuum situations. The problem is I was not sure where they are talking about to drill the holes. Does the carb have to be taken off (I would assume so) and does it need to be taken apart?

Do I need a different power valve (still not sure what it does, but I heard it is affected by vacuum)?

The whole thing that I can't figure is the first time we rebult the engine, we had none of these problems. All I had done was a shortblock rebuild (no change in cam, crank, but went from flat-top forged pistons to dished cast so compression should be lower) and some head work (bigger SI valves, new double springs, guides and hardend seats).

The cam, header, exhuaust and carb are the same! None of these issues existed last time. That is why I am confused...

Mach,
My PVC valve vacume runs to the log, not the carb. Also, I tried spraying carb cleaner around the PVC valve and carb and didn't seem to find any vacuum leaks, but I'll give that a try.

 

[66200i6]

You mentioned larger valves? At first thought you would think this change would increase flow. But doesn’t the large valve only help at the top end? At idle the only change would be lower velocities around the valves at the head. If I’m not mistaken the flow at the carb should be the same. At idle there shouldn’t have been any changes needed in tuning. Maybe someone else can comment to clear up what you should expect based on the changes you made at the last rebuild.

I guess the best thing to do is start at the beginning. Find those timing marks and make sure your settings are correct. Remember to disconnect your vacuum advance at the distributor and plug the vac line when checking the timing.

Go back to your Weber book and check for the correct measurement for the throttle plate to throat clearance. This will tell you if your throttle plate is in the idle or main circuit when idling.

Good luck and keep at it, Ric.

 

[cfmustang]

Thanks. This is all helping...

I do have the little saw tooth wedge with the marks, but aren't there supposed to be marks on the balancer themselves (or at least on a TDC)?

To mark that, people suggested moving the engine to TDC with the #1 plug removed. This may be a really stupid question, but how do I do that? When I try and turn the engine by hand with the fan (a Flexfan...ouch!) I can't move it. Is there some other way?