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1970 Bronco Wheeler

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pocketlock

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Might be. I can’t remember where the correct one is on the stock carburetor. Someone here will know.
If that’s the correct one, then it shouldn’t change at idle.
Might mean your throttle blades are open too far.
I will have to check. It’s frustrating because I can’t even check my vacuum with the advance hooked up so I’m not sure if I’m getting good reading or not. It does feel like the port that is supposed to be for the ported vacuum was moving more than it should have at idle so I’ll need to look into that tomorrow. I clamped the hose to the vacuum advance, had great idle, opened the hose and it immediately backfired and died so it seems to be an issue with the vacuum advance on the carb. I read about tuning down the sensitivity on the distributor so I may try that tomorrow as well. It’s been a frustrating process for sure.
 

DirtDonk

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It can also be an issue with the distributor mechanism.
But you can’t really diagnose this thoroughly without a timing light. You really need a timing light’s expert opinion on this.
 
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pocketlock

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It can also be an issue with the distributor mechanism.
But you can’t really diagnose this thoroughly without a timing light. You really need a timing light’s expert opinion on this.
I have a timing light on it, I noticed that at idle with no vacuum advance connected, I am at my 12-13 BTDC. The few times I could connect my vacuum advance and it didn’t die right away. It was at 35-45 BTDC. Honestly I couldn’t read the marks, just judging the distance of my 0 and 10 BTDC marks. If I disconnect it, it will idle fine.
 

DirtDonk

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Remember that in different iterations, these very same engines were designed to run on 5 quarts. Perhaps even less…
Like was said, I’ve never seen a Windsor pan that held 7 quarts. But the larger capacity pans, such as the 6 quart bronco and 4wd pickup pans were designed with the extra capacity for engines that might see severe duty.
Not severe as in racing, but severe as in working hard, pulling heavy loads, sitting on hilly terrain for extended periods, etc.
Mustangs and other cars with 5 quart capacity pans were, I’m sure, raced extensively even without the custom race pans with higher capacities.
Another good Engine Masters watch is their story on free horsepower through oil or something like that.
They kept reducing the capacity in the pans, even the big race pans, and gained power at maximum RPMs with less oil.
Granted that doesn’t necessarily equate to our use and our need for power and that last 3 hp at the top end. But it does indicate that you can rev your engine to 6000 RPM and not starve it for oil.
Even if it’s only got 5 quarts total in it.
 

DirtDonk

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So whether or not your vacuum advance is working properly, you are definitely getting full vacuum when you connect the hose.
At idle there is supposed to be zero vacuum, so you need to check and readjust your carburetor.

Do you know what your idle speed is? You may have to lower the throttle blades with the speed screw, and then re-compensate with the idle mixture screws.
Sometimes that’s not enough when there is something actually wrong. But sometimes you can just tweak it a little bit and get it to cooperate.
 
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pocketlock

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So whether or not your vacuum advance is working properly, you are definitely getting full vacuum when you connect the hose.
At idle there is supposed to be zero vacuum, so you need to check and readjust your carburetor.

Do you know what your idle speed is? You may have to lower the throttle blades with the speed screw, and then re-compensate with the idle mixture screws.
Sometimes that’s not enough when there is something actually wrong. But sometimes you can just tweak it a little bit and get it to cooperate.
Idle speed holds steady around 650, I have adjusted that with the throttle screw. I was trying to set the vacuum advance so I could start tuning the idle mixture screws when I ran into this issue. At the moment I just have my idle mixture screws screwed out 2-1/2 turns.
 
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pocketlock

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So whether or not your vacuum advance is working properly, you are definitely getting full vacuum when you connect the hose.
At idle there is supposed to be zero vacuum, so you need to check and readjust your carburetor.

Do you know what your idle speed is? You may have to lower the throttle blades with the speed screw, and then re-compensate with the idle mixture screws.
Sometimes that’s not enough when there is something actually wrong. But sometimes you can just tweak it a little bit and get it to cooperate.
I believe I was getting 15 hg vacuum from the port under the choke that is supposed to be ported. (This is off memory so may not be 100% correct.) So maybe this aftermarket carb is routed different than a standard MC2100, I will have to check if theres another port that is ported vacuum. I am almost at the point of canabalizing this aftermaket carb to rebuild the other rebuilt carb that was on the truck. (This is what I get for trying to save money and time by buying a rebuilt carb for $100 vs just buying a $60 rebuild kit.)
 

DirtDonk

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Usually, but of course not always (🙄) the port that is higher up is the one that is ported.
 
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pocketlock

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Usually, but of course not always (🙄) the port that is higher up is the one that is ported.
Thank you for clicking that connection in my head, I guess you can't trust everything you read on the internet. I guess I will cap everything off again tomorrow, get it idling right without vacuum advance and check every port for ported vacuum. So I am looking for something that has 0-very low vacuum at idle, but increases vacuum with throttle. That's correct?
 

raleigh_bronco

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Hi Pocketlock. I just read the thread for the first time and wanted to express my condolence. Me and a few other guys on here met Ed in Uwharrie over 16 yrs ago at the MEB event and really enjoyed wheeling with him. Ed would lend his expertise and very capable repair & troubleshooting skills at the drop of a hat. Very sorry to hear of his passing.
 
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pocketlock

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Hi Pocketlock. I just read the thread for the first time and wanted to express my condolence. Me and a few other guys on here met Ed in Uwharrie over 16 yrs ago at the MEB event and really enjoyed wheeling with him. Ed would lend his expertise and very capable repair & troubleshooting skills at the drop of a hat. Very sorry to hear of his passing.
Absolutely he would! He showed me the ropes back when all I had was an old Daihatsu Rocky, and helped teach me all the way through building my wrangler before he passed. He wouldn't hesitate to help someone out no matter how it impacted his day, he was a great guy!
 

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. . . check every port for ported vacuum. So I am looking for something that has 0-very low vacuum at idle, but increases vacuum with throttle. That's correct?
Yes

Does your distributor have fittings for 1 or 2 vacuum lines?
The second line would be for vacuum retard.
 
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pocketlock

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Apparently I had the damn plugs wired wrong. I think I wired it clockwise instead of counterclockwise? I’m honestly not even 100% sure but I went to double check it and nothing was in the right place idk how it was running as smooth as it was before. Runs like hell now. Vacuum advance hooked up and working as well.
 
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pocketlock

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Great! Good find. What firing order are you using?
1-5-4-2-6-3-7-8. It’s stamped on the intake manifold and being at my wits end I decided to go through and double check it. I’m pretty sure I had done it clockwise when I had put them on originally and so I was going around and nothing was lining up where it should have been even had I gone that way. Went online and saw I should be doing it counterclockwise so I checked that way and it was still wrong. I have no idea how I wired it or how it ran. But now it’s wired 1-5-4-2-6-3-7-8 counter clockwise and screams. Both from the engine and the belt haha. The vacuum is still reading 10-15 so I need to adjust it a bit I think, but I also think that’s because atmospheric pressure is 14.7 so that’s technically 0 I guess? I’m not sure, it’s just a harbor freight vacuum gauge so it may be busted as well.
 

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sprdv1

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Absolutely he would! He showed me the ropes back when all I had was an old Daihatsu Rocky, and helped teach me all the way through building my wrangler before he passed. He wouldn't hesitate to help someone out no matter how it impacted his day, he was a great guy!

memories you won't soon forget remember the good times
 

sprdv1

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Apparently I had the damn plugs wired wrong. I think I wired it clockwise instead of counterclockwise? I’m honestly not even 100% sure but I went to double check it and nothing was in the right place idk how it was running as smooth as it was before. Runs like hell now. Vacuum advance hooked up and working as well.

happens to the best of us right :)
 

DirtDonk

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Sounds like you got it nailed then.
But you can’t always go by the intake manifold alone, if the cam has been changed.
The camshaft dictates firing order. So if there was a cam change at some point and the stock intake is still used, the normal firing order might no longer apply.
 
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pocketlock

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Tinkering with the idle now. I am getting 20 inches of vacuum off the manifold vacuum port at idle. Seems to be idling great. Once warmed up, I have the ported vacuum at 0. I am idling a hair under where I think I want to be at around 450-500 RPM. If I tighten the idle screw up anymore (it's back almost all the way off) I can increase it to 600-650 RPM but ported vacuum jumps up to 20 inches immediately. I was thinking about getting my RPM correct by bumping timing up a hair, but didn't know if there was something I was missing or if this seems normal? I added 2 videos of the manifold vacuum reading I took earlier today.
 

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