I know this question has probably been asked plenty of times and I apologize for repeating it but...I am new to the 4.9 six and the Carter YFA 1 bbl. I bought this 1980 F-100 w/auto, NO A/C, NO power brakes and only has P/S. All the parts appear to be in place on the motor but are original, so old. It ran fairly well for a couple of days. It had been sitting for a year or two indoors (PO said he only put 600 miles on it in three years) and I have now pulled the carb off to do a rebuild (due to a gasket leak), the PO had disconnected the smog air pump and several of the vacuum lines have been plugged with screws. I want to clean up the engine and am NOT concerned about emissions as the vehicle is registered "Historic", no N.J. state inspection required.

FINALLY, to the main point...Which vacuum lines, imission valves and other valves (EGR,etc.) do I REALLY need to make the 4.9 run correctly? Most of the rubber and plastic vacuum lines are dry/brittle and will be replaced IF NECESSARY ONLY. I want to "streamline" this motor as much as possible and make it run smoothly. I do NOT want to "beef it up" with modifications.

I purchased a Chilton shop manual but am confused by all the emissions related abbreviations. I need some "straight talk" help figuring this out. I would appreciate any type of "must have" list you guys could provide for me.

Thanks, Ken.

 

You should only need pcv. You will need to replace all the vaccuum and plugs though to prevent vacuum leaks which will cause rough idle, hesitation etc.

 

1) PCV valve (positive crankase ventalation) should stay. It helps burn off the "toxic" gases in your engine to keep the "toxic gases" from corroding internal parts.

2) Vaccume advance line to the distributor, from the carb.

3) Air cleaner heat riser valve (helps warm the engine on cold start ups and keeps the air flowing into the carb at a set tempurature to prevent iced up carbs on really cold days.) This is optional of course but if you live in a cold climate it does help things out.

4) Keep the choke heat riser tubes intact. Prevents iced up carbs and allows for proper choke function. The vaccume for this is inside the carb anyway, behind the choke plate and gets vaccume from the air horn itself etc, though make sure that the tubes don't have holes in them or is open to outside dirt. Can cause the carb to foul up etc...

That should be all the vaccume controlled devices that you need really. IMO.

Hope this helps.

 

about the carb heat riser can I just replace it with a piece of tube wrapped around the exhaust manifold? I put the efi manifolds on so I dont have the tubes anymore, dont mean to highjack the thread but its an 80 engine also
thanks

 

You should be able to do that yes. or stick the end of the tube into a unused bolt hole. etc... It will still leave a way for dirt to get into the carb via the tubes however. Maybe a vacuume filter of some kind can be put in it's place? So it can suck in the heat it needs without the dirt....

 

Anyone have Pics or Diagrams of the Carb Heat Riser setup ??

 

I've been helping a person on the 1980 - 1986 truck forum with this very thing.

http://img.photobucket.com/albums/v1...rog/truck5.jpg

https://www.ford-trucks.com/user_gal...oid=96620&.jpg

The top photo shows a carter Yf Carb Non Feedback. You can see the top of the exaust manifold and the port where the line attaches, and a simulated line going to the brass fitting on the carb. And another simulated line going from the bottom of the exaust manifold to the nipple on the passenger side of the carb.

The second photo shows a Carter YFA Feedback carb, thats slightly different, but you can see the lines attached. the all metal tube goes from the brass fitting to the port on the exaust manifold pictured in the first photo. And the red rubber and metal tubed line goes to the bottom fitting on the exaust manifold. The bottom hole. Larger than the top one should be directly below the top one.

Hope this helps.

 

Hi im in the process of trying to figure out why my 83 f100 is stalling under load and needing to figure out if i have my vacuum lines in the wrong place ive replaced icm cleaned carb it will idle smooth in park and in gear but will stall out when at full throttle any help will be appreciated wires are new cap is new rotor button new new ignition coil new might be some issues with choke

 

Sounds like a vac leak. I knocked off the hose from the carbon canister and mine did the same thing. On the passenger side core support there is a vacuum routing tag. I would follow those lines for your version. My layout and your layout could be completely different.

 

Remember, an engine will idle pretty smoothly with the initial base ignition timing way off on either side of spec, either retarded or excessively advanced, but it won't run right when under load out on the road. It is also common for crankshaft balancer rings to slip, and along with it, the timing marks.

In this case using a timing light to set ignition timing will result in large errors. It is important to verify that when the #1 piston is at TDC on the compression stroke that the TDC "0" mark on the balancer is also accurately indicated. Everything related to ignition or valve timing is based on TDC. The easiest way to do this check is to use an inexpensive tool called a piston stop.

Recommend checking this when getting a "new" old truck engine in unknown condition. Anything over maybe 15 or 20 years or so is a likely candidate for this defect. 1980 definitely qualifies. I'm not gonna say this is for certain the problem, but start from the beginning and eliminate it from the list of possibilities. An engine will also sometimes idle reasonably well with a couple plug wires crossed and out of firing order. Check that they were installed correctly.