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"Pretty black plugs", that's definitely a sign your engine is using more fuel than it should (which is good since you can reduce it).
I don't think changing your timing by 8° is going to fix that entirely. 14° advance isn't that much, and 6° is OLD factory spec. You'd even be just fine with bumping it to something like 10°.
You might want to look into carb related stuff. Maybe you have a leaking/bad accelerator pump?
Yeah the initial timing # is just a part of the whole package deal. The important thing here is that the mechanical advance moves smoothly up and down throughout the RPM range to spec, and, that the vacuum advance on top of that is also working correctly. If they had found the timing was way off, that would be promising, but they didn't. One thing to always check on a "new" engine is that TDC is accurately marked on the damper with a piston stop. It is very common for old damper rings to slip and often overlooked. This makes the timing marks innaccurate.
Did they check any of this? Test drive? If anything, the mileage may be a bit worse by simply retarding the initial 4°, slow or late timing will not improve matters. Black plugs indicate a carburetion problem. Excessive fuel will tend to contaminate crankcase oil and wash out rings if severe. Make sure too the ignition is at 100%
I'm still thinking something besides the dirty air filter is making it run rich giving black plugs. Backing off the initial timing is not going to enhance fuel mileage. There's something else going on.
Ya could be carb.. not sure. Honestly I'm not smart enough on carb stuff. I know it was a reman about 3yrs ago however.
I did rebuild a 2150 and it's ready to go, I just don't have the Offy yet. Maybe I can find a single bbl carter and rebuild it so I can just swap for now.
Unless there is a non-repairable defect in the carburetor that is installed now, I can't see how it would help anything very much. Carbs will bolt up and run, but they need to be setup and tuned to run well. You're going to have to either pay someone $$$ to do this stuff - with no guarantees, or, learn how to do it yourself.
What do you guys think about these chineeesium's to use for a bit. https://goo.gl/JCfkuH
Originally Posted by Tedster9
Unless there is a non-repairable defect in the carburetor that is installed now, I can't see how it would help anything very much. Carbs will bolt up and run, but they need to be setup and tuned to run well. You're going to have to either pay someone $$$ to do this stuff - with no guarantees, or, learn how to do it yourself.
That carb is not that hard to rebuild and a kit is like $20 - $30. I would get a rebuild kit and take it apart for a good cleaning.
I rebuilt mine about a month ago and some one was in it before me and had things all messed up. They lost screws and used wood & sheet metal screws to put it back together what a mess.
They used a petcock to plug off the choke hot air intake so I had to fix that.
That reminds me, your sig has a 300 six with EFI exh manifolds and stock 1v carb.
How did you hook up the choke hot air as the manifolds do not have away to run the tubing?
If you did not hook it up then the choke may not be opening all the way and why it is running rich and the bad MPG.
I am also running EFI manifolds with the stock 1v carb and my fix for the hot air tube was to get copper tubing and make a few loops around the manifold to pick up the heat and back up to the carb just like stock.
Here you can see the copper tubing running to the carb like stock. The white on the back side is insulation on the hot side of the tubing.
The loops around the manifold. You can see the white insulation and the hose & clamp is for the stock intake heater.
I have a plate that bolts to the bottom of the stock intake and I run coolant thru it then to the heater. It heats the intake like the stock exh manifold did.
If you don't have that, that could also be a cause of it rich and you will need one for the aftermarket intake.
Dave ----
ps: I don't know what MPG I get as I am still rebuilding my truck, 81 F100 flare side 4x2, 300 six, T18 (granny first) and 2/75 rear gear. EFI exh manifolds, stock pipes & muffler and no pollution equipment.
I hope to get over 15 MPG that my DD does now.
Good call on the choke. That's definitely something to test if it's opening all the way!
Let the engine fully warm up and then take your valve cover off. Your choke should be straight up and down. If it's not, something's wrong.
You don't need a hot air choke if you have an electric choke. It helps, but is not needed.
When I first converted my engine to EFI manifolds, I still had the 1bbl carb. I just removed the hot air choke tube and only used the electric 7v post on the alternator.
With an SROD transmission and 235 75R15 tires, I got 19 - 22mpg on the interstate back then.
Yah I would rebuild it, it's just a time thing as in, my daily driver that I need everyday. Maybe a weekend I can.
I run an electric choke. AB, did you mean to say take the air cleaner off?
Not sure I'm happy with the valve cover breather I put on.. she pukes oil out of that (the front one, as the rear is PCV of course).
I'll check the choke as I just warmed her up after putting on the right stat just now.
Hahaha, yes. AIR CLEANER.
I have no idea where my head was at...
Your valve cover breather should not be kickout out oil. That's not going to change with a different breather.
That's a new engine isn't it? That's a sign of compression leaking past your rings and excessively pressurizing your crank case (eg. blow-by).
Unless, your PCV valve isn't working and properly venting.
Good call on the choke. That's definitely something to test if it's opening all the way!
Let the engine fully warm up and then take your air filter valve cover off. Your choke should be straight up and down. If it's not, something's wrong.
You don't need a hot air choke if you have an electric choke. It helps, but is not needed.
When I first converted my engine to EFI manifolds, I still had the 1bbl carb. I just removed the hot air choke tube and only used the electric 7v post on the alternator.
With an SROD transmission and 235 75R15 tires, I got 19 - 22mpg on the interstate back then.
I fixed it for you as he does not need to pull the valve cover to check the choke lol.
When I first did my change to EFI and only test running in the garage it was open but I also don't know if the choke was adjusted right, still don't as I don't have it on the street. I only run it to get it in / out of the garage to make room to work on other parts of the truck. I would still keep an eye on it till you know it works as it should with out the hot air.
I will be using about the same size tire on mine and some have said I should get upper teens to low 20's. I just don't have the SROD in the truck, got one from the parts truck, as I plan on using this truck as a backup to pull my car trailer and like the granny gear. I would like to get either a Gear Vender or Advance Adaptors Range Splitter OD unit.
Thinking more of the AA range splitter as you can split all the gears at any speed. The GV unit you have to be over 30 mph before you can use OD.
Also you can use an electric solenoid to shift the range splitter, 2 speed rear axle switch on shifter handle, so you don't have 2 shift levers to move.
I first have to get the truck on the road.
sorry to run OT
Dave ----
Hahaha, yes. AIR CLEANER.
I have no idea where my head was at...
Your valve cover breather should not be kickout out oil. That's not going to change with a different breather.
That's a new engine isn't it? That's a sign of compression leaking past your rings and excessively pressurizing your crank case (eg. blow-by).
Unless, your PCV valve isn't working and properly venting.
On that front breather it should have a hose to it going up to the air filter housing where it gets fresh air from.
Here you can see the hose going to the air filter, the PCV is just behind the housing in the rear of the valve cover.
This motor is newer than my truck from what I have found out some may have that hose going into the oil fill cap.
Dave ----
Crap, you're right. My PCV system isn't sucking.
Removed pcv, put my finger over it's hole, nothing. Removed pcv and put my finger over that hose, not sucking air at all...
I'll check the whole hose itself, but if it's clear.. then what should I do. that would be a carb thing.
Chock is straight up. So that parts good.
10-17-2018, 09:41 PM
