PEAK PUTTERS

Ok, so after a little discussion in the chat box, and with Fozzie via text, my curiosity is killing me.

Let's hear some opinions on the best CARB for a 258!

I still think the 2G tuned up is good. The kid down the street just put a Weber on his and canned all the smog crap, and it acts like a whole new rig...

The yeller banana?

Carb discussions seem to be almost as bad as oil or tire discussions.

That being said, I stumbled upon what I believe to be a golden nugget of info lately, that relates to carbs:
-too high fuel pressure coming into the carb can have a huge detrimental effect on the way it runs, especially in an offroad vehicle.

Many stock mechanical fuel pumps for carbureted systems sit around 5-7 psi of fuel pressure. This works in a stock system that sees mostly street use, but can unseat the float easily if the carb is not sitting level. I used to read in the magazines years ago where they often recommended lowering the fuel level in the bowl by adjusting the float level, and even used this method myself, but it doesnt always cure the problem. The typical systems are poor idle, loading up at idle; especially off-level. Engine vibration will also make it worse, which is at its' worst at idle.

This could also be why so many different people have different opinions and experiences on the same carb/same engine combo.

The guy at Clifford Performance is the one who shared this nugget, and recommended that I purchase a regulator that bumps the incoming pressure to 2.5psi. If I remember right, the kit he sells is pretty spendy.

Now, I havent tried it yet, but I just picked up a small 12v fuel pump from Ebay that should do the trick, for around $20. If you have flooding issues with any carb, I would recommend the same.

Honestly, though, even though I can tune a carb, I am MORE than ready to ditch the whole thing in favor of a fuel injection system I can tune with my laptop or phone.

As to your question:
Opinion: though my Weber 32/36 has served me well, I find it tempermental and am about to find out if a 2G works better.

Roman wrote:The yeller banana?

No, the blueberry...

I have also wondered about jetting. Steve's carb came of a late '60's GM 350, so I'm pretty sure that some fiddling could help. Just haven't really looked into it...

I've had the stock BBD, a Motorcraft 2100, a Weber and a Rochester 2G on the jeep. I like the 2G the best. When it runs good, it runs great. It'll get upset if you bounce it on a steep hill climb, and the needle valve will stick if it sits for a while.

I can't honestly discredit the Weber, because I believe it needs to be rebuilt.

I'll give the regulator idea a shot! It my help with my 2G running a fat.[/u]

So Don, you have the 2G on now? Wow, ya, you were dumping some MAJOR fumes in camp!

After doing some web "research" I was surprised how many threads were about the Holley 350. Some had done Truck Avenger type mods, others were actually running Truck Avenger 470's with good results.

So in no particular order (for now) the list looks like this:

-Motorcraft 2100

-Weber 32/36

-Rochester 2G

-Holley 350

-Holley TA 470

Paul, I second the comment on fuel pressure... As a matter of fact, Toby, didn't you fight the same issue on your YJ 350?

Ya, I have the 2G on right now. To be honest, I've had it on for a few years and never noticed it being as fat as it was the couple times in camp last weekend. I've had it running in the shop and not gassed myself out. So, I don't think it's indicative of how that carb normally runs.

Anybody know what carb Curtis used to run on his 5?

Thought it was a 4 barrel on a Offy intake...

Roman wrote:Anybody know what carb Curtis used to run on his 5?

Thought it was a 4 barrel on a Offy intake...

Pretty sure it was a Holly 500.

Once you start talking about "new" carbs, you are in the price range of a 4.3TBI. It would pay for itself in fuel economy pretty quickly.

OldGreen wrote:

Roman wrote:Anybody know what carb Curtis used to run on his 5?

Thought it was a 4 barrel on a Offy intake...

Pretty sure it was a Holly 500.

Once you start talking about "new" carbs, you are in the price range of a 4.3TBI. It would pay for itself in fuel economy pretty quickly.

So, are you talking a TBI swap, or a 4.3 engine swap?

Just the tbi

OldGreen wrote:Just the tbi

Ah, gotcha. But SOME of us don't get along with wiring, or don't want too...

I know this thread is a little "old school" and not applicable to most of us. I found myself with a carb again, and am thinking about trying to keep it (or something similar) Also Steve (Fozzie) is wanting to tune his 2G a bit.

The reading I have been doing is also very relevant to the carb work I need to do on the Motor Home.

It is tough....if I were in that boat, I would get jets for the 2G from a 283, lower the float, andfet the fuel pressure down under 3psi. See if there is a spring loaded needle and seat for it too.

If you are feeling really adventurous, you could do an adjustable regulator with a return line and a gauge. Can't remember how the 2G is metered, but the metering stuff should also be from a 283. The intake on a 258 heats up quickly, but all amc motors pre 4.0 are cold blooded, so you just need to plan ahead when it is cold outside. Also, don't underestimate the importance if the idle circuit and the choke for cold weather and off-idle transitions.

I played with this stuff for a long time, it finally was dialed in at about the time I swapped motors.

I think I'm going to get a vacuum gauge heading this way. Will help in tuning, but I also read about using it to diagnose engine health... Now only if I could find that thread

Should be 20" or so at idle in Kennewick (under 1000' elevation). 10" or so at cruise.

Less would indicate a leak, timing fubar, or valvetrain/rings. Assuming stock cam....lol.

I would also recommend running seafoam every 6 or so months for all you carb guys, with the way our fuel is these days, the corn just gums them up and they need to stay clean to run properly. Just my .02

Jafo wrote:I would also recommend running seafoam every 6 or so months for all you carb guys, with the way our fuel is these days, the corn just gums them up and they need to stay clean to run properly. Just my .02

This is one of my other reasons for going electric on the pump. The last few years I have noticed that it takes FOREVER to get fuel back in the carb if the Jeep sat for even one month. That Ethanol seems to dry the carb up aweful quick!

Roman wrote:I think I'm going to get a vacuum gauge heading this way. Will help in tuning, but I also read about using it to diagnose engine health... Now only if I could find that thread

I have a vacuum gauge floating around here somewhere that I have never used. If I can find it, you are more than welcome to use it.

The Dual Jet on my truck seems to run about as good as any old carb out there. Curtis ran four barrel 500 Elderbrock that Al Yenny setup for off roading. I would not go that route. I have a vacuum gauge if you need it. I also have a 4.3 TBI Carb, Modified Computer, wiring harness, and Fuel pump that I will sell for $500. I'll throw the motor in for free.... Rumor is that its a good runner:)

Paul, let me know...
I almost ordered a cheap one, then looked around and found one for 2x the $$$ (still only $25) that came with a nice case and better fittings. Not sure how much I would actually use one, so it would be nice to take one for a test drive...