I have a 84 460 and I wanted to know what are the signs of needing to rebuild the old 4 barrel. I get about 4-6 miles to the gallon. Also don't know what this problem is but while im driving on the freeway at about 75 mph I hear a hissing sound that I think comes from the engine. Some guy in another forum said if i just recently changed the air filter, the sound is the air going through the filter into the carb. The hissing sound only comes on when I'm cruising, not when I punch it or let off. thanks in advance

 

the hissing sound might be comming from one of the vaccum lines on the carb.

 

4-6 MPH with a stock 460 carburetor truck is not good. Yes, I would suspect a serious vacuum leak. Stock 460's were never known for their great fuel economy but you should be able to double what you are getting now.

At idle or no load, is when you have the greatest amount of engine vacuum and that is when you would be more apt to hear a large vacuum leak. I would check the power brake vacuum booster first, then start checking all the vacuum lines. If everything checks out good, I would suspect a carb to intake leak, or intake to head gasket leak. Vacuum leaks are best found in the driveway at idle.

A few words of caution here. A vacuum leak in any engine will spell disaster if left unattended. A vacuum leak causes a lean fuel condition meaning that the combustion ratio is way off, causing unnecessary excessive heat. The higher combustion temperature will eventually deteriorate valves and significantly reduce engine life along with engine performance. If the leak gets worse, the engine will fail completely. I don't know how strictly enforced your local state inspections are, but a lean fuel condition will not pass emission tests. A lean condition will also reduce and eventually destroy the efficiency of the catalytic converter.

 

Yeah I just passed the smog test a couple of months ago. But a while back i shifted into D2 and I heard a popping sound from the exhaust. Also two months ago when I was backing up, I guess the fuel cut to the carb, I think my teacher said it was running lean and he took a hammer and tapped the secondaries?(not sure but i know they were hoses going to the top rear of the carb). Also I cleaned the carb with GUMOUT. I sprayed into the two small pipes on top of the carb( -> I-/-I <- ). Please help me out. The gas milage is rediculous but i want to keep the truck.

 

When you shifted to D2 the popping sound was detonation.
The secondaries should open only at 50% or better throttle position.
Seems to me that you may have more than one problem.
The most serious problem is a vacuum leak. You need to find the leak first.
The lesser problem may be an out of tune carburetor that a rebuild kit may help.

 

One of the problems I ran into on my 86 460 was leakage past the secondary metering body. The other problems you can get on a Holley (at least it should be in 84) is the power valve and the accelerator pump delivery tube. The power valve will leak either from age or a backfire and the pump delivery tube has O rings that can leak. Does your truck have the dual or single air pump system? I am not familiar with CA emissions setups. The other issue would be if you have a catalytic conveter, it could be partially plugged up, this will give a hissing noise through the exhaust that gets louder the faster you go. This will also kill your gas milege. My 86 gets about 10 mpg empty and 6.5 to 7 towing a 10000 lb 5th wheel.

 

I don't know if my carb is a single or dual air pump system. How can I tell. I don't have a cat in my exhaust and it's stock. I am thinking about buying a Holley rebuid "trick" kit. Has anyone ever used one before.When I was checking out my carb today I found these numbers on a tag E3TE9510SC, does anyone know what this means. Here are some other numbers I found on the carb 4E18, and 6R5696B. Are any of these carb model or list number. I have around 68,750 on the stock original engine. Also what is the orange bar that connects to the carb and goes down to the trans? Thanks a lot for all the info everybody.

 

The carburetor you have is a Ford Motorcraft made by Holley. You would be better off with an OEM rebuild kit from your local auto supply store. There should be an aluminum looking tag hanging from a corner bolt on the carburetor, take that to the auto parts store for ordering the correct rebuild kit. Be sure to replace the tag when you are done. The orange bar (OEM COLOR IS YELLOW but probably looks orange now) is the kick down lever for passing gear.

I am not absolutely certain about federal laws, but I thought by 1984 all gasoline trucks under one ton had to have a catalytic converter. I am thinking that law went into effect in late 1982 or early 1983 for all states.

 

How can I tell if I have mechanical secondaries or vacuum secondaries. Also if I have manual or electric choke?

 

You have the original type carb, then you have vacuum secondaries and a electric choke. I would pull the carb off and take it to someone to rebuild.

 

Ok, in the rest of the US, the weight break was over 1/2 ton until 1979, then it jumped to over 8500 GVW. My 86 is over 8500 GVW and has two air pumps, but no cat. The numbers you list,the E3TE9510SC, is the Motorcraft number, the Holley number should be on the front of the air horn and e omething like list R-XXXX or list R-XXXXX where the Xs are numbers either 4 or 5 digits. The two air pumps are feeding different areas on the exhaust, one feeds the ports,the other he manifolds.

 

I found the number, says 6 R-5696B. So if I get some headers, I have to get the headers with air injection(L&L). Can I run headers without air injection and still pass smog if I do have stock air injection. I think I have two smog air pumps.

 

That is a casting number. I don't think you can even think about passing CA smog without everything working though.

 

The only numbers I found today were E3TE SC and A 4E18 was underneath it on a tag on the carb. I will look for other numbers on it if I have to tomorrow morning. Do I have to buy a Motorcraft rebuild kit or can I buy a Holley rebuild kit.

 

You need to go to the parts store and buy a kit made for your truck. Take the carb numbers with you. They may have a kit for it made by Holley, or it may be made by someone else.

The carb says "Holley" on it, but it has special features made for the emissions controls and other stuff on your engine. It's a specific carb made by Holley for Ford.

If you didn't have smog checks, I would have recommended you get a new universal Holley or Edelbrock, and bolt in on and go. But it probably would not pass the emissions tests.