Nothing Special's '71 Bronco

[Gary Lewis]

Looking at the 48 jets under a microscope, the output end looks pretty square, with just a simple chamfer on the input end. So I should be able to get it pretty close. And my intent is to just get it pretty close, then to order a range of "real' jets around wherever I end up. (And we'll see how many years it takes me to actually do that if "pretty close" is "good enough" )

I was just keying on Bob's statement.

[Nothing Special]

Looking at the 48 jets under a microscope, the output end looks pretty square, with just a simple chamfer on the input end. So I should be able to get it pretty close. And my intent is to just get it pretty close, then to order a range of "real' jets around wherever I end up. (And we'll see how many years it takes me to actually do that if "pretty close" is "good enough" )

I was just keying on Bob's statement.

Yeah, I think Gary and I are pretty different in this area. But I think we both do a pretty good job of appreciating the differences!

[Gary Lewis]

Yeah, I think Gary and I are pretty different in this area. But I think we both do a pretty good job of appreciating the differences!

Yup. And yet I have a t-case shift lever that.....

[Nothing Special]

Yeah, I think Gary and I are pretty different in this area. But I think we both do a pretty good job of appreciating the differences!

And on another note... Success!!!

I stuck in my custom-made 52 jets and took it for another test drive. It's still pretty cold here (high today was about 35 and it's snowing again) and the temp gauge still didn't get to where it normally runs. But there was no misfire in steady-state cruise!

It's not perfect. There's a brief flat spot when I accelerate from cruise. So maybe I need to move the accelerator pump linkage (it's in the farthest-out hole which gives the least squirt for the throttle movement). Or maybe the power valve does need to open sooner. And it does stumble a bit when dropping down to idle, sometimes even dying. But it's running better than it's run in over a year, so right now I'm happy!

[Gary Lewis]

And on another note... Success!!!

I stuck in my custom-made 52 jets and took it for another test drive. It's still pretty cold here (high today was about 35 and it's snowing again) and the temp gauge still didn't get to where it normally runs. But there was no misfire in steady-state cruise!

It's not perfect. There's a brief flat spot when I accelerate from cruise. So maybe I need to move the accelerator pump linkage (it's in the farthest-out hole which gives the least squirt for the throttle movement). Or maybe the power valve does need to open sooner. And it does stumble a bit when dropping down to idle, sometimes even dying. But it's running better than it's run in over a year, so right now I'm happy!

Yippee!

On the flat spot, if it truly is what I'd call a flat spot I think you are still too lean. The accelerator pump covers up a quick transition, but to me a flat spot is when you are just easing into it and nothing happens until the PV opens. If that's the case I'd say you are still too lean. Either that or the PV needs to open sooner.

And, by the way, that is exactly the situation my '72 F250 w/a 390 and a 2100 had. At cruise nothing happened until the PV opened. I changed to bigger jets and that solved the problem.

[Nothing Special]

.... On the flat spot, if it truly is what I'd call a flat spot ....

If I slowly roll into the throttle it sort of feels like it loses power briefly, then starts to pick up, slowly at first, then it builds pretty quickly. So I'm pretty sure it's going lean. Wether jets, accel pump or power valve is the best way to address it? That I don't know.

I should also point out that "everyone" says I should be running at ;east 4.56 gears, if not 4.88s, with a 302, 33" tires and an overdrive trans. And this is in 5th gear. If I drop a gear or two it lights right up.

Still, I'm pretty confident that it's going lean, and sometime I'll do something about it. Maybe soon, maybe not.

[Gary Lewis]

.... On the flat spot, if it truly is what I'd call a flat spot ....

If I slowly roll into the throttle it sort of feels like it loses power briefly, then starts to pick up, slowly at first, then it builds pretty quickly. So I'm pretty sure it's going lean. Wether jets, accel pump or power valve is the best way to address it? That I don't know.

I should also point out that "everyone" says I should be running at ;east 4.56 gears, if not 4.88s, with a 302, 33" tires and an overdrive trans. And this is in 5th gear. If I drop a gear or two it lights right up.

Still, I'm pretty confident that it's going lean, and sometime I'll do something about it. Maybe soon, maybe not.

I don't think it is the accelerator pump, but that's an easy try so I'd do it were I you.

Then I'd drill another set of jets to 54 and try them.

Last would be the PV.

But that's just me. See what others say.

[Nothing Special]

I don't think it is the accelerator pump, but that's an easy try so I'd do it were I you.

Then I'd drill another set of jets to 54 and try them.

Last would be the PV.

But that's just me. See what others say.

I can probably live with it the way it is now. But there does seem to be some room for improvement, so I'll keep poking at it a bit more.

To that end I drilled out my new 49 jets to .055". A little bigger than the .054" that Gary recommended (and that I'd've preferred. But I made my 52 jets using a #55 drill bit (0.052" OD). The next larger drill is #54 at 0.055". So that's what I now have.

I stuck the 55s in tonight but didn't feel like going for a drive, so I'll try it out another day.

I did have another question come up. On a Bronco forum I'm on someone said that a hesitation on tip-in could happen if the weight above the check ball is missing. I do not have a weight above the check ball, but I really don't have room for one either. There's only about 0.190" between the top of the ball and the bottom of the screw.

I don't know how big the weight is supposed to be. But since I got this carb I've bought two rebuild kits. Both came with a metal cylinder that looks like it COULD be the check ball weight. But it's .25" OD and .68" long. Both of those dimensions are significantly too big to let it fit.

So am I missing something? Or did some Autolite 2100 carbs not have the weight?

[Bruce moose4x4]

I can probably live with it the way it is now. But there does seem to be some room for improvement, so I'll keep poking at it a bit more.

To that end I drilled out my new 49 jets to .055". A little bigger than the .054" that Gary recommended (and that I'd've preferred. But I made my 52 jets using a #55 drill bit (0.052" OD). The next larger drill is #54 at 0.055". So that's what I now have.

I stuck the 55s in tonight but didn't feel like going for a drive, so I'll try it out another day.

I did have another question come up. On a Bronco forum I'm on someone said that a hesitation on tip-in could happen if the weight above the check ball is missing. I do not have a weight above the check ball, but I really don't have room for one either. There's only about 0.190" between the top of the ball and the bottom of the screw.

I don't know how big the weight is supposed to be. But since I got this carb I've bought two rebuild kits. Both came with a metal cylinder that looks like it COULD be the check ball weight. But it's .25" OD and .68" long. Both of those dimensions are significantly too big to let it fit.

So am I missing something? Or did some Autolite 2100 carbs not have the weight?

Pull your screw out and look at it most are hollow to let the check weight go up into it.

[Nothing Special]

Pull your screw out and look at it most are hollow to let the check weight go up into it.

It is hollow. I assumed that was to let gas get through it. Does the weight go in it too?