I was out cruising home from visiting my parents. Our interstates are 80mph, but I usually like to keep it at 70 for the gas mileage, although it'll do 80 - 85 just fine!

Decided to floor it and see what it had in it.


This is with a 3.00 final drive and 32" BFG A/T KO2 tires. Not too shabby!

 

That looked like fun. Sounded good too.

 

AB, have you corrected the speedometer for the taller tires?

 

I haven't, but that's because, according to my GPS, it was even closer to accurate with my new 32" tires than it was with the 31" tires. I'd done my best to get the speedometer with the 31s as close to accurate as possible, but it was still a tad off. (ie. it'd say 73 when I was going 70).
When I put the 32s on, it was almost spot on.

 

Don't you just love it when a plan comes together?

 

Hehe, it definitely was a nice bonus. I needed an "Easy" button.

 

I finally got around to installing my new metering block in my carb. I set it up with 67 jets to begin. That was what I had in the Summit carb, on the secondary side, and they seemed just about right. The imperceptible opening is impressive, but I know when they are open b/c I can hear/and feel that certain ... moan the engine makes.

I am doubly pleased with the Holley for performance and b/c with it I make it through the hot summer w/o vapor lock/hard starts which the Summit carb and the Quadrajets suffered from.

I wish I had hooked up my AFR gauge with the two QJ's that I had running perfectly.

 

Don't you just love that rich, throaty sound when the secondaries open? It makes me giddy. It's basically the same sound, but it drops an octave.
If there's no perceptible change in feel, that means you have them opening at just the right time.
I remember my dad always telling me he loved when the secondaries would kick in because he'd feel that surge of power. Now that I'm older and think back, I know he probably just had them set wrong.

I do like that with the Holleys, how they have the largest of the fuel bowls. It helps with vapor lock (which sucks).

I wish I'd had my O2 sensor earlier as well. I struggled with that Holley 390 for about 2 years and could never get it right. Plus, it just sucked gas (my best was around 12 - 13mpg on the interstate). I'd really be curious what the numbers were saying.

 

When we designed the first Mustang 5.0 GTs our executive insisted that he wanted the secondaries to come in early enough so that the customer could hear and feel it. The boss is the boss - he got his request. The carb guys measured venturii signal off the primaries only, which, with a little secondary pulldown tinkering, accomplished the task. Many customers said they love that.

 

That actually makes sense, it's an exciting feeling. People equate secondaries with power, so I imagine they'd be disappointed if they didn't feel it.

 

So, I've been having a weird issue lately. When I start it up in the morning, it is just pig rich. Like, sputtering at 200 RPMs, 10 - 12 vacuum blowing black exhaust, 10:1 AFR rich. It basically stays this way all the way to work, which is about a 20 minute drive.
Stalls at all the stoplights, sputters to get moving, and is still even a 10:1 AFR rich while I'm going 75 on the interstate. It's acting like the powervalve is fully blown, even though I just replaced it.

However, unlike a blown power valve, it goes back to normal. There are some mornings where it drives just great. 12:1 AFR idle, 15:1 cruise, 12 - 13:1 power circuit. It's like nothing is wrong. It almost never does it in the evening on the way home. The only noticeable difference is 25 degree mornings and 35 - 40 degree evenings.

I took it apart, cleaned it, inspected it, and couldn't find anything wrong with it.

I also took off the site plugs while it was running poorly and there was no extra fuel (was wondering if maybe the floats were sinking). I also looked down the throat of the carb and saw no extra fuel entering the air stream.

I'm stumped as to what's going on, or what could be causing it.

Any ideas?

Otherwise, it's just been a great carburetor.

 

Remind us Justin, do you have preheat to the air cleaner?

 

I don't. However, I never have had it with a 4bbl and have never had this issue. Plus, this only started a few weeks ago and I went through about 2 months of 10 - 15 degree weather with it firing up with a snap of the key and driving like a champ.

I'm wondering if it's temp related, but you'd think after 25 minutes of driving and the engine fully warmed up, it'd cure the issue.

 

It appears that the wire feeding the choke heater is close to the front exhaust manifold. Could it be shorting and affecting the choke?

 

Hrm... I don't think so. The choke seems to be functioning correctly. I've checked it a couple times. The wire is a bit further away than it looks in the pic.