Progress Thread The next "big" project for my Cobra

[IICrew]

It does not stop does it? It's like we are driving or attempting to drive old cars with limited parts availability. I may have to call Ford and see when my warranty expires. Wanna bet they tell me it's voided because of some ridiculous reason.

I had to replace my speedo cable. I don't remember the details now but I picked up a longer one to loop further towards the front and avoid the headers.

 

[LILCBRA]

It's a never ending battle. I think all project cars are. They're NEVER done, there's always SOMETHING else to do with them....

Speaking of something else - I went ahead and ordered a rivnut tool today now too. Not that I need it right now for anything, but it just seems to be a good investment for something later.

Amazon product ASIN B07T8YZY23
I don't know if it's still available or if I just happened to look at it all at the right time, but Amazon had a 15% off coupon for this one, so it was <$50 with Prime shipping.

 

[LILCBRA]

The dangers of having a job that you find yourself with a good amount of free time is that you have all sorts of opportunity to shop online.

So I'm on Summit's website and looking at changing things up under the hood. I'm looking at these valve covers from Speedmaster:

https://www.summitracing.com/parts/sdm-pce314-1113

They're listed at $75.99 on their site, but aren't available until May 22.

So I shop around a little more and find them on Speedmaster's site (speedmaster79.com). They list them as in stock, but they want $118.40?!?! WTF?!?!

I have a set of Edelbrock valve covers on it now, but some of the simulated cap screw heads have come out and have been lost. The only real work around that I can think of is to get some new screws, cut the heads off, then epoxy them in place. Or, if there's room, I could drill holes and attach them with backing nuts - but I think I just want to do away with them altogether. Unfortunately it'll cost me. But I'm in no hurry, they can wait....

 

[LILCBRA]

Going to merge my carb tuning thread and this one to simplify things, but I'm picking up from here:

Tried it again tonight. Took the same path, but this time it didn't even make it back to the stoplight. But now I'm not so sure it's electrical. I think I have a fuel delivery issue as it was backfiring through the carb and I had to pump the go pedal a few times and then hold it to the floor to restart it. I fiddled with some wires under the hood and lost my A/F guage too, then after a minute or 2 of trying to keep it running I lost power to the starter altogether. I'm seriously contemplating pulling the whole harness from the engine bay and going through it wire by wire. I guess that would serve a couple purposes: I'd be able to tie up and take care of any loose or exposed wires IF I come across them, and I'd be able to clean up the harness and give it some new loom tubes. The wiring under the hood is a complete mess right now and could use it anyway if, for no other reason, to make it look a lot better.....

I took the car out last night for about an hour or so and it ran pretty well for the most part, but I still have the carb cough. The AF guage seems to work now that I've replaced the O2 sensor, but toward the end of the drive it was staying at the low point of 10.0 (the lowest the gauge reads). I may have to fiddle with some stuff yet, but the carb cough.... I checked the accelerator pump and it's actuating immediately as the throttle is moved, but the primary discharge nozzles looked like they weren't supplying a stream. It looked more like it was dribbling for a second before it'd hit the booster. I'll have to read back through the other thread to confirm, but it seems like I had just swapped the nozzles before it started doing that before. If that was the case, I'll be looking into either swapping them back or possibly getting a few other sets to try out.

I was able to use my GoPro to shoot what I think might be good video of the whole drive. I'll see about getting them uploaded and check them out to see what I can see with the gauge and find out if it'll help with some of these issues.

Another thing I'm thinking of doing is removing the Thrush chambered mufflers in favor of a pair of Flowmaster Delta Flow 50s, but that'll be at a different time. I'd still like to quiet the car down more than it is now. I'm also contemplating trying to find a way to run tail pipes from the mufflers in their current location along the bottom of the rear of the quarter panel, much like a Fox body LX or 85-86 GT. That would also help with the volume in the car....

 

[LILCBRA]

Most people route dual exhaust so 2 pipes exit where the muffler is usually mounted. This one is more like I'm thinking, except I'd like to run polished stainless pipes back from where they terminated the pipe. I couldn't find any other II with anything like it....

Classy and Clean Street Machine: Restored 1977 Ford Mustang II Coupe

Debuted for 1974, Ford’s downsized, compact Pinto-based Mustang II weathered the worst years for the American automobile but kept the Mustang lineage going through the EPA and DOT-dominated 1970s. Mustang II also...

www.zero260.com

 

[LILCBRA]

Just swapped squirters. It had a 25 in the secondary side and of the 3 spares I have, only one is a different number. It's a 32, so I installed that. We'll see what kind of difference that makes.

Since I only have these 2 sizes of discharge nozzles laying around, I went ahead and ordered some 28s.

Amazon product ASIN B00029J5E6
I'm thinking I'll swap the primary side with one of those to see if it'll help the cough. That is, of course, after I pull the carb again and make sure there's nothing obstructing the passageways. If the 28s don't help, I'll give the 32 a try. I've also thought that since I'll be giving it a little more fuel sooner, that maybe I'll have to upgrade the primary accelerator pump to a 50cc diaphragm - but I'll cross that bridge if it comes to that.

I'm uploading the last ~5 minutes of the drive from the other day. The sound sucks since the car's too loud for the camera's microphone, so I'd say you'd probably want to mute it unless you like hearing pixelated engine noise. But you'll see at about the 1:30 mark that the car coughs and dies on me. If you turn the playback to 1080, you can see that the gauge reads <13 until it coughs and dies, then reads >16 until I get it restarted.

 

[extra_stout]

What carb do you have? A 4777 650 double pumper? The stock 30cc pump should deliver more than enough. What accelerator pump cam is installed on primary and secondary side? To identify the pump cam, the color is important and in which hole (nr1 or nr2) is the screw?

 

[extra_stout]

Is the "carb cough" only slighty above idle? If this is the case, than the idle screw setting could be an issue (bad idle transfer slots/ bad idle mixture).
If you have it down the road at a WOT pull in second or third gear, than it is the accelerator pump (or something acc circuit related).

 

[LILCBRA]

It is a 650 double pumper. And here are a couple pics showing the primary pump cam. It looks to be orange to me.

And, because I was out there and thought of it, here's the new hood struts in action! I really wish I would've done this years ago!




The cough IS off idle. Was thinking, too, that I'll probably go back through and re-confirm everything I had done previously, starting with timing and engine vacuum. The idle screws are now at about 1-1/2 turns again after messing with them before I finally figured out the other issues (float level and wiring). So I'll most likely be tackling the carb tune again, although I think that it might be a lot closer now than it was before.

 

[LILCBRA]

Just got done rechecking everything. Started out with only about 5 inches of vacuum, so I fiddled with the idle mixture screws a little and got up to around 7. Then I thought "wait a minute, I had more than that before!" So I grabbed the timing light and found that it was retarded again, but couldn't make out the marks. So I grabbed some paint and a small brush and marked the damper at 10-12-14-16 BTC so I had some kind of visual. I loosened the distributor and turned until I was around 12-14 BTC and my idle and vacuum shot up accordingly. I then adjusted the idle again, then checked timing again and readjusted. Now my idle vacuum is back around 15 inches, so I adjusted the idle mixture screws again and that's where it sits. It didn't seem to have the cough when I'd blip the throttle anymore, now I'll have to take it for a test drive again and see how everything looks.

As far as the discharge nozzle goes, I looked up my carburetor and see that the most recent revision comes with a 28 on the primary side, so I'll go ahead and swap that in after it arrives in a couple days. It might not make that much of a difference, but I guess we'll see....

 

[LILCBRA]

And just got home from an eventful ride. Ran out of gas! The gauge read 1/2 tank.... I guess I must've bumped it when I painted the needles.

Anyhow, it's running a lot better! No more coughing, and the A/F gauge is reading between 11 and 14 most all of the time. The vacuum gauge I installed also read around 15 inches at idle too. These pics were after I got it home thanks to a buddy of mine who brought me some gas....

(The A/F gauge was reading 13.0 in the pic. )

 

[extra_stout]

Don't trust the AFR reading at idle, idle mixture setting is done by vaccum (tuning for max vaccuum).
If you get again into that issue: check for square transfer slots (see picture below) on the primary side and adjust idle RPM with the opening of the secondary blade.
For that you need to unmount the carb from the engine, which is not so nice, but in the long run its worth the work. If the carb is off the engine, also look for the idle RPM screw at the secondarys, they are usually stuck. So try to unstuck them.
I redrilled mine and installed a bigger screw with hex-head and a counter-nut... on my carb/manifold the part of the carburetor reaches beyond the manifold. Hope you understand what I mean. If not, I can make pictures, when I start the season (which is hopefully this month).

 

[extra_stout]

 

[extra_stout]

And here is a chart of the different pump cams:

If yours is the orange one (you only can be sure by unmount and read the numbers on it), you could swicht to yellow or something like that.
My double pumper runs great with the blue one primary and pink on secondary side.
But I think your problem was ignition and transfer slots...
Good to hear that it runs again without that cough.

 

[LILCBRA]

Thanks for the chart! I've never seen it. I do remember that 20+ years ago, when I put this carb together from a bucket of parts, I just eyeballed the pump cam and went with the one that seemed to be the most moderate of the bunch. I don't recall now what I had at that time, but I don't have many of them (if any...) anymore. But it always seemed to run pretty well when I got it running at that time. That was, of course, before I swapped intake manifolds. It may have been running extremely rich back then, too, but I didn't REALLY notice it until I swapped for the new imitation Performer RPM which is what prompted me to go down this path. I can say that I'm happy that I did!

I shot more video yesterday, I'll see if I can't upload some of it later tonight or tomorrow to see what you can see as far as the gauges go. The pics above are basically just for informative purposes now. It's really too bad you can't see the gauges so well on the earlier video, I don't think my vacuum gauge read above maybe 7 inches at idle before yesterday.

 

[extra_stout]

Frankly speaking for acc pump tuning you can't take the AFR reading, because it is delayed...
Also everything idle related: it's better to check for vaccum and do a baseline transfer slot setting.
Holley manual also says: baseline is transfer slot.
From my experience: only transfer slot at the primary is important. Secondary can be closed beyond transfer slot, but you need to take care, that it touches still the idle rpm screw and it doesn't bind in the closed position.
With my explorer cam I have a very solid idle and so I like to have it as low as possible. In the winter time, when its cold idle is higher than in summer. When I close the primaries to reduce idle RPM I also have a humble... At the secondaries I can't close the blades more. I than increase mixture to rich, but than it's to rich.
But as I said, my engine is very different than yours especially when idling.

 

[LILCBRA]

Yeah, I think I may have typed up what I did the other day in a confusing way. I adjusted the idle mixture with a vacuum gauge. Then I found the timing was off, so I adjusted that, then the idle speed, then timing again, then the idle mixture with a vacuum gauge again. That's when I got the vacuum from ~5 inches to ~15. It runs really well now and I've not experienced any hesitation or any other issues. I'm using the A/F gauge more as a guide while I play with things like the discharge nozzles now. And. like I said, the latest version of this carb comes with the 28 discharge nozzle, so I'm going to try that now too. At first I thought that maybe that was the issue with the carb cough, that it was running lean for a split second and the nozzle wasn't performing as it should. Now that the engine is timed properly there are no real issues to speak of that I've noticed. So if the 28 nozzle gives me any kind of driveability problem I'll swap it back to the 25 and call it good. On the other hand, if it works well I'll most likely leave it in place. And, after either one of those scenarios, I'm going to say that I've completed tuning the carb as I'm happy with how it's running now. Maybe there will be another dyno day later this year too, that way we can see the comparison of before it was running well and now that it's tuned. I'm hoping for a slight bump in the numbers.

 

[LILCBRA]

Posted a video of part of the drive from the other day after getting the engine straightened out. I turned the sound off since it can't handle the volume of the car.

 

[extra_stout]

On around 2:50 the AFR goes up to 13.5 to 14.0, that's your idle mixture, which is fine.
Everywhere else its more 11.5 to 12.5 which is very rich for cruise. I would exchange main jets for smaller size. In my opinion in cruise AFR can also be around 14.
Only for acceleration it makes sense to be more rich like 13.
When temperatures go up in summer, air will have lower density and the AFR gets richer anyways.
What main jet size is installed?

 

[LILCBRA]

I thought I had the smallest jets that I have in my possession already installed in the primary. I had to look through the old thread to confirm:

Ok, I lied. I decided to take the jets down a little more.

The primaries are now down to 64 (the smallest jets I have) and the secondaries are down to 66. I'll take it for a drive later to see where everything stands and I'll try to set my phone up for a video so everyone can see what it ends up with.

Just got back from a short drive. I tried to record it with the gauges in view but it didn't really work. My mount fell after about a minute of driving.

But, all seems to be running well until I floor it and open the secondaries. I was only able to try that a couple times and the first seemed to read lean in the 16s. The second time it didn't drop quite so much and stayed in the 15s for a split second before returning to the 14s. Is appears the secondary jets need to go up, but the primaries seem to be in a happy spot. Cruising it remains in the mid to high 13s. Like I said, those are the smallest jets I have, so that's where it's going to stay.

A few posts later I noted that I went back up on the secondary side.

Ok, what am I up to.... Round 3 I think??

Looks like I took care of the coolant problem. Replaced the thermostat, which turned out to be a 160 high flow unit, and the radiator cap with a 180 high flow and a standard 15 pound cap. Rejetted the secondaries from 71 to 77 and went for a ride. Most importantly, the temperature never exceeded 180. And it's fairly warm today, 82 at the time I took it out. So that seems to be a win! When I had the opportunity to floor it and get into the secondaries for a bit, it would read lean then settle back into the 14s, so it looks like the jetting is at least pretty close but the squirter shot needs to be increased. I only have a handful of them in my box-o-parts, so I'll have to see what I have.....

I really doubt that the secondary side would have an effect on the AF ratio at cruise, but it IS possible that the throttle is opened just enough to engage the secondaries? Otherwise it looks like I'm out of options to make any more adjustments on the primary side at this time. But I agree, it does appear to be on the rich side of things so I've ordered another jet kit to take it down a little more. Waiting on Amazon, but it says it'll be delivered tomorrow.