1970 Bronco Wheeler

[DirtDonk]

With the engine preferably off, remove the air cleaner, and while looking down the throat of the carburetor, rock the throttle linkage open a couple of times.
Each time you open it up you should see a pretty healthy squirt of fuel coming from two independent nozzles into each barrel.

Most carburetors have at least two or three different holes that you can move the rods to in the accelerator pump linkage outside the carb.
Usually moving it closer to a pivot point increases the amount of fuel squirted during each event.
Check yours out and if you’re not sure post a picture of your linkage.

 

[pocketlock]

With the engine preferably off, remove the air cleaner, and while looking down the throat of the carburetor, rock the throttle linkage open a couple of times.
Each time you open it up you should see a pretty healthy squirt of fuel coming from two independent nozzles into each barrel.

Most carburetors have at least two or three different holes that you can move the rods to in the accelerator pump linkage outside the carb.
Usually moving it closer to a pivot point increases the amount of fuel squirted during each event.
Check yours out and if you’re not sure post a picture of your linkage.

Ok, yes there’s a solid fuel stream that comes out when I push the throttle and it comes on pretty quickly. I’ll try to snap a picture of it tomorrow for which hole it is in.

 

[pocketlock]

31.5 mile trip on the bronco now that it’s legal! Lost a gas cap after I left it loose to vent the overfilled tank and forgot to tighten it before I got on the road. and had my clutch rod fall off the pedal because I forgot to put the pin in it. Always fun when the clutch pedal hits the floor at 50mph when you go to shift. Holds 55-57 mph pretty solidly steering wasn’t super sketch but wasn’t perfect either. About what you’d expect at 50+ years old. Getting some of the kinks worked out and getting used to the clutch and trans. Still some fine tuning on the carb but felt great to cruise around.
Back to the bogging issue I had, the aftermarket carb is shaped differently than the OEM MC2150 and when i used the extra gaskets around what I thought was the spacer, it caused a vacuum leak. Removed that and retuned the carb slightly and now it has a slight stumble on tip on but rips when you get on the throttle. 4th gear going up a pretty decent hill and it was perfectly fine climbing from 45-60mph. Still need some tuning on the carb I think, I may try to bump the accelerator pump up one more notch to see what that does. (It is on the middle of 3 holes for adjustment). Looking forward to taking it out for a cruise with the wife tomorrow. Trying to gain some confidence in it after it's sat for so long.

 

[pocketlock]

Cruising around another 20 or so miles in the bronco today still working out the kinks in the idle/tip in. After the cruise it was idling kinda wonky so while it was warm I went snooping and noticed all of the spark plugs on the passenger side had backed out to where they were just barely loose. Snugged them down and decided to turn the carb all the way in from the 4.5 turns out it was and start over. The video attached is about where I got to. 2-1/4 a 2-1/2 turns out on the idle air mixture screws, highest vacuum I could get that stayed fairly steady was about 21-23. Idle was around 830-860 though. Vacuum advance was engaged at idle. Haven’t taken it for a cruise on this setup yet so not sure how tip in will be but wanted to see how this sounded to everyone on here.

 

[DirtDonk]

Always good to do final carb adjustments when the engine is fully warm. Always good to have those spark plugs all the way tight too!
The 2 1/4 to 2 1/2 sounds much more normal than 4 1/2. And remember the number of turns is unimportant as it’s all about the end result.
And remember too that they don’t have to match side to side either.
Every carburetor and every engine are different, so you might find one screw at 2 1/4 and the other at 2 3/8 to get your best results. Just like setting the timing with points. It’s a dance.

So it’s normal, and all the written references are just that. Simply a starting point of reference.
And 21 inches a vacuum is outstanding!

 

[DirtDonk]

Oh, and turn the idle down to about 600 or so, and then re-adjust the idle mixture screws just like you did this time.
See if the ported vacuum fitting still has vacuum on it.
Even though 800-ish isn’t tremendously high, it’s still higher than it should be.

 

[DirtDonk]

I forget. Manual or automatic transmission?

 

[pocketlock]

I forget. Manual or automatic transmission?

Manual, NP435. I will definitely have to turn them out more if I want to lower the idle any and keep it smooth. But trying to find a happy medium. Ported vacuum is getting manifold vacuum at idle because of how high the idle screw is turned up. But I’m trying to get it back down just taking time. Going to take it for a spin tomorrow on this setup and then go from there to see where it needs to go.

 

[DirtDonk]

Why take it out for a drive when it’s adjusted wrong? Just turn the idle down and readjust the screws.
Sure, it’s not perfect because it’s not warmed up fully. But then when you get back from your drive you can tweak it if it’s needed.
But at least you don’t have to put up with the high idle and wonky vacuum in the meantime.

Since the vacuum advance is not working properly, are you leaving it disconnected for now?

 

[pocketlock]

Why take it out for a drive when it’s adjusted wrong? Just turn the idle down and readjust the screws.
Sure, it’s not perfect because it’s not warmed up fully. But then when you get back from your drive you can tweak it if it’s needed.
But at least you don’t have to put up with the high idle and wonky vacuum in the meantime.

Since the vacuum advance is not working properly, are you leaving it disconnected for now?

I’ve left it connected under the argument that it should only be affecting the idle because once I’m moving I should be on manifold vacuum once the throttle is opened. There’s plenty of people who run manifold vacuum on their advance so I wouldn’t think it would be an issue. I figured taking it for a drive now when everything seems the smoothest at idle would help to point out any issues at speed that may have been covered up by poor idle conditions.

 

[pocketlock]

But I could be wrong and that’s why I’m posting here in case I’m missing something. So I may try to turn the idle down to where it is back in posted at idle and go from there with my tuning

 

[DirtDonk]

No, it’s a fair enough argument.
But it is effecting your idle, which is a negative in any context.
And since the idle screws are literally only for adjusting idle quality, getting it set properly now is just a positive overall. It has no effect on how it runs overall when you’re driving it. Only at idle.
It’s correct that once you’re driving, you are basically running manifold vacuum into the vacuum advance.
But otherwise it’s just giving you trouble.

Now, if you’re going to tune it permanently to run on full manifold vacuum, then by all means do so.
But in that case just connect the hose to manifold vacuum right off the bat and work from there.
No sense in fighting it one way for doing it the other.

 

[pocketlock]

Got the idle down lower to the upper 600s. Vacuum is slightly lower but steady, around 16 inches but fairly smooth. Also got it to where the throttle is backed off until just before ported becomes manifold. Feels good, still have this flutter at lower rpm in gear, nothing like a bog, so not sure if it's just low rpm gearing issues, accel pump, maybe even just tire vibration since i have unbalanced tires? It isn't holding me back from driving it though so I think i'm going to stop while i'm ahead for now and just enjoy it and keep checking everything else out. Been working on my ultimate end goal/build while i've been getting everything sorted. Planning to keep the 1 inch body lift since I need it to clear the trans/cases. Would love to go LCG and full width 44/9. 37s and 2.5-3.5" lift with clearancing the body panels, adjusting fenderwells, etc. Long term goals for sure but trying to have a vision in mind. Basically using the Coco bronco as a vision board haha. Took the bronco through the ditch beside the house to check clearances on everything. The spring touches the bottom of the fuel pump just barely which should be fixed once I'm on lift springs and not a lift block and once bump stops are in. Other than that have some gear noise in double low that I need to investigate but it wasn't constant so I'm not too concerned just yet. All in all, happy to be able to start cruising around and looking forward to taking a wheeling trip for memorial day weekend!

 

[pocketlock]

Took the Bronco out to Uwharrie here in NC and had a good day and a half of wheeling. Bronco did everything I asked of it and preformed great for where it's at. Definitely need to invest in some bump stops. Only a few issues I ran into. One being my carter rotary vein fuel pump connectors kept falling off (granted after the leaf spring pushed into them but still). I'm wondering if I can solder the wire to the terminal and heat shrink over it to fix this. Second, the cotter pin that goes through the pin in the clutch pedal linkage sheared itself. Managed to loop it back through and zip tie it to the linkage to try and keep it in place. Held up the rest of the weekend. Lastly I think i've narrowed down the lo range noise to the front. I (accidentally) was riding around in front low and it sounds like someone threw a bag of marbles in the transfer case. But if i'm in 4 hi, rear hi or rear lo, the noise isn't there. Is there a bearing that I'm not thinking of or is this just teeth chatter in the dana 20? I'm at the point where I am wondering if it would be worth swapping to an np205 considering I have the np203 range box in already and that would make up for the slightly worse gearing. Just considering options and longevity. Got home and started to pull apart the body and mask everything off to start painting it teal. Plenty of plans in the works but just wanted a simple project, nothing show worthy but a color change, scuff and shoot job that I won't mind scratching up.

 

[1969]

Are you talking about doing a 205/203 doubler?

 

[pocketlock]

Are you talking about doing a 205/203 doubler?

considering it. Not pressed for it, but I do worry the dana 20 isn't long for this world If I wheel it on 37s.

 

[1969]

considering it. Not pressed for it, but I do worry the dana 20 isn't long for this world If I wheel it on 37s.

I’ve never wheeled a Dana 20 but from what I’ve read they can last depending on how you wheel.

As for the 205 I put one in my bronco and was going to do a 203 doubler with it but after measuring I wasn’t comfortable with a one foot rear driveline and like three foot front and the angles of the shafts.

 

[pocketlock]

I’ve never wheeled a Dana 20 but from what I’ve read they can last depending on how you wheel.

As for the 205 I put one in my bronco and was going to do a 203 doubler with it but after measuring I wasn’t comfortable with a one foot rear driveline and like three foot front and the angles of the shafts.

I'm currently running an NP435 so it's pretty short. I'm curious how much longer the np205 is than a dana 20 though.

 

[pocketlock]

I’ve never wheeled a Dana 20 but from what I’ve read they can last depending on how you wheel.

As for the 205 I put one in my bronco and was going to do a 203 doubler with it but after measuring I wasn’t comfortable with a one foot rear driveline and like three foot front and the angles of the shafts.

From what I can see, the np205 is 2-2.5" longer than the dana 20, so I think it wouldn't affect me that bad especially if I were to stretch the rear an inch or so with an adjustable perch. Options to consider for sure.

 

[Robertkrafts]

Connecting to the port directly beneath my choke on the carb which I thought was the vacuum advance fitting.