I have a 75 f 250 360/390? and I am having some issues with it running rich. not too sure where at. I checked the vacuum at idle (600rpms) and I am getting about 10in, but if I rev it up to about 1200 then it jumps up to around 20in. I also have an issue that is simmilear to a post that I saw by steelone on 9-23 06 dealing with 1405 and a rebuilt 400 where it will bog at idle if you give it gas, have to rev it up then stomp on it and it still bogs at wot. (can't figgure out how to put a link to it here) I have as far as I know, an all stock engine. not sure if it is a 360 or a 390 though, there is a tag on the intake that says it is a 390 out of a 69 though, not sure if it was a car or truck. any help would be great. I am kinda limited on funds att so I can't experiment with rods and jets. Also I don't have a very vast knowledge on carbs either, I know a few things but not enough to tune it. but any direction that I can get for when I get some money would be great.
another thing. the pcv valve is going into a plate under the carb and not into the port on the font of the carb. also was wondering if he dvance was plugged into the right port. it is currently pluged into the port on the left side of the carb, right next to the idle screw... also about how many turns should the screws be at from bottomed out to give me a good base to start tuning at.

 

1st:
I'll make this thread you mentioned available.

https://www.ford-trucks.com/forums/5...questions.html

2nd:
Here's the Edelbrock page for the 1405

http://www.edelbrock.com/automotive/carb_square.html


Link to Edelbrock carb support page and Online manuals

http://www.edelbrock.com/automotive_...ess_main.shtml

The 1405 is a 600 CFM carb

Everything you need to know is in this manual.

http://www.edelbrock.com/automotive_...ers_manual.pdf

Please post the info from the engine ID tag.

 

The tag is on the intake and being that it is a 30 year old truck with a iron 4v I will assume that the previous owner swapped in a entire engine there are 2 lines, the first reading 390 69 11 then a ford emblem, the second line reading 8 L K 378 S
something that I forgot to mention in the first post, the idle isn't a very clean one, it has a lope in it up intill 1000 to 1100 rpm

 

Make sure you read pages 7-10 , 12,23 on this link.

https://www.ford-trucks.com/lc/lc.ph...ers_manual.pdf

 

390
390 cu "
69
Model year of engine - 1969

11
Change-up Level ,engine design has had 10 changes made...to this point

then a ford emblem, the second line reading

8 L K 378 S

8 [b] Year of Production - 1968
L Month of Production - November
K Engine plant code - ?

378
No Listing in Ford books...However if it is a 1 instead of a 7 . Engine 318 is a 390 4v
Code S

S - Engine Letter code ...This relates to above engine info - 390 4v

 

well thanks for that.. been wonderin how that breaks up

 

Do you know what metering rods and jets and springs are in the carb now? Metering rods and springs pop right out. I have a Carter AFB on my 460 and Edelbrock are the same. Your 10Hg of vacuum seems really low. My tired old 460 pulls about 18.5 off the manifold vacuum port at 650 rpm. Mine was rich too but I got it dialed in enought to pass California smog. Metering rods and jets are pretty cheap. Set both screws about 1.5 turns out and start there. Why do you think you are running rich? You can find ported and manifold ports on the carb with the vacuum guage. Tha advance should be connected where there is no vacuum at idle. It is the one on the passengers side of the carb next to the idle screw. Remember, the screws only adjust the idle mixture. Once your pulling some vacuum through the carb the rods lift up and it's all rods and jets. The PVC is probably fine where it is if it's below the carb.

 

Do you know what metering rods and jets and springs are in the carb now?

no I don't. Will have to pull it apart tommorow to find out. are there gaskets there that I need to replace once I open it up for the rods?

Why do you think you are running rich?
From the smell

Tha advance should be connected where there is no vacuum at idle. It is the one on the passengers side of the carb next to the idle screw
that is where I have it hooked up an there is vacuum at idle, do I need to move it or did you post wrong? or is my carb broke.

The truck had a carter afb on it when I bought it, but I swapped the 1405 that I had on my 350. when the afb was on the truck, it would diesel very badly and it was very hard to control the idle. and it would overheat real bad. when I swaped the afb to the 350 the traits followed it, and most of them left the 250, but it will still diesel when it is hot. also I have a hard time starting the truck back up after it has ben sitting for a few min when it is hot.
Still overheats a little but I think that is the waterpump pulley is too big so the fan isn't spinning fast enough when it is at idle. Also I can't touch the timing much at all, if I go any further than where I am at now either way then the truck will have all sorts of problems. ( backfiring when I get into the secondarys, and bogging down very badly when I get into the secondarys)

 

You don't need gaskets to check the metering rods. If you split the carb and remove the airhorn to get to the jets, you'll need a gasket. Check the Edelbrock manual posted earlier. It is good. What kind of vacuum are you getting on the passengers side vacuum port? Does it increase with rpm on the vacuum guage? Your overheating is unrelated to the carb in my opinion. Check for vacuum leaks aroond your intake. If you are rich it will not make the engine run hot. Lean would make it run hot. It's hard for me to tell rich conditions by smell. Does it make black smoke? You got some several problems working together. Hot starting is a different deal altogether. Carter AFB and Edelbrocks are the same thing. What shape are these carbs in? Is the dizzy advanced at idle because of the vacuum port you are connected to? What is your fuel pressure like and how's the filter?

 

When I got the truck the advance wasn't hooked up to anything, I kinda guessed with where to hook it up at. I will hook the vacuum guage up to that port to see what kind of vacuum that I am getting in the morning. I don't have my timing light here to see what the timing is set at right now... when I did it I set it at 10*BTDC and then drove it and changed it accordingly from there depending on what it would do as I drove it. Where it is now is anyone's guess as far as static timing is concerned. I do know that it is turned almost as far as I can turn it counterclockwise and I have never removed the dizzy to miss match the drive gear at the cam. I think that it is a little too far so something has to be wrong with the advance. I was looking at a rebuilt unit from napa for around 55 dollars thinking that the advance circut on the dizzy was bad but if it is something simplear(sp?) then that will be a good thing for the wallet. What is a good way to check for leaks... I have heard everything from carb cleaner to propane to whatever. There is no black smoke that I can tell. the exaust dumps below the bed so it is a little hard to tell, but I have never noticed any while I am sitting in the drive way. When the 140 was on the 350 it worked pretty good, just had a little bog in it that i can remember. will have to check the fuel pressure tommorow. what is a good way to check that without getting the vacuum guage full of gas? I was thinking putting a t in the fuel line but it is my brothers guage and it ain't a cheap one so I don't want to mess it up... the fuel filter is brand new. just replaced it the other day. but there is a chance that the one that I replaced it with could have ben letting some stuff through, it was just a fuel/water seperator. as for the hot, it only does it at idle, when you get moving it cools down, leading me to believe the fan isn't going fast enough to move enough air to cool the engine. Thanks for the help and sorry to be writing books here

 

Sounds like the throttle plates are open pretty far at an idle and that is why you have vacuum. The advance hooks to the passengerside front port on the carb.
What is the duration of the cam @ .050?
There isn't any fuel dripping down from the boosters in the barrels when it is idling is there? If so, the floats could be too high or too much fuel pressure or a small piece if debris in a needle and seat.

 

Your vacuum guage should be able to test fuel pressure. Look up on the manufacturers site for instructions on the correct method. Your dizzy may be a little off by a PO dropping it in incorrectly. You really need to get the timing squared away and the vacuum advance working properly to get the carb adjusted. Is the linkage of the carb binding? The throttle plates should be closed at idle. Read that Edelbrock book carefully. It really describes the theory of operation and adjustment procedures for the 1405 and it works almost exactly the same for the AFB. There are also many things that can be checked on the carb that are described in the manual. You say both carbs are doing similar things with bogging or backfiring? Sounds like timing.

 

Ok, I have mostly established that I need a new timing chain... the advance seems to be working fine. I am getting about 3HG at idle(600RPM) and it climbs steady from there as I rev the engine. I have about 20 to 23HG of manifold vacuum from 1000 to 4000 RPMs. I don't really want to take it any higher than that. Not sure about the fuel pressure though. am going to be checking that later. I will have access to a timing light tommorow to find out what the static timing is. I hope that the dampener is right though.... are there any good ways to test that? I know to put #1 cylinder at tdc and see where the mark is, but what is a ood way to find out where tdc is? I don't really know the cam profile. not sure what the engine came out of. anyone know a way to find out without pulling the cam out? as for the bogging. while I was getting the truck warm to find out the vauum and the other stuff I went for a drive. I didn't have much of a problem at all with it bogging from idle in 2nd gear (np435) out of the secondarys. it just took it a min to wind up at the lower rpm. then I tried the secondarys in 3rd gear from about 1500 rpm and did ok. I tried to stomp on it and it would jerk like the rear was torquing on me then the tires barked and was off, that was just one time from 2nd at about 1000 rpm start in a turn. I think that it might be doing a little better. need to find out what the timing is though. still haveing a problem with it dieseling though when you turn it off. I played with the idle screws, ran them both in all the way( they were out a good bit) then backed them both out 2 full turns. seems to be doing good. would start in the drive without touching the gas after you turned it off and let it sit for a few min. the further that you back them out, does it go leaner or richer? thanks for the help so far guys...
Travis

I forgot.. I looked at the throttle plates at idle and they don't seem to be open at all, didn't see any fuel from the boosters driping at idle either.
When I was parked I tried flooring it all the way and didn't get any bogging or hessitation. the engine just takes a sec to get moving then it revs sky high at about 1500 rpm like it has a car cam

 

I looked at the tag, it is a very clear 7... curious... miss-stamp?

 

Something else that I thought of was that when the 1405 was on the 350 I had no problems with dieseling at all or really no other problems. all of the problems followed the carter that was on the 250. I reaing through some of the other posts I am thinking that my dieseling probems could be caused by a loose/warn timing chain. I seem to remember that when I checked the timing on the truck there was a lot of variance in the position of the timing mark. can't remember for sure.