Why can't mechanics repair older vehicles?

Question

we have a 1986 ford F-150 truck with a 4 barrel Holley carb. we've been trying to get this in running shape for 2 years and 3 different mechanics said they had fixed it but we get it home and it floods out or backfires and spews gas upward. got to be the carb, right? can no one fix anything without a computer?

Answer 1

It doesn't seem so long ago that if a vehicle had a computer no mechanic wanted to get involved, he'd rather stick to what he new, like carburetors, coils, condensers and points ignition systems.

I suspect in your case you have a sticking valve or malfunctioning valve lifter or even a broken valve spring, checking the valve timing gear/ chain for slackness or wear and also movement on the key ways could be useful as a long shot

Answer 2

one sounds like the timing may be off for the backfire and 2 the floats are not adjusted correctly,there is a sight s***w on the float bowl,it sould have a flat head s***w remove this s***w and will see the gas level in the float bowl on top of the bowl is a nut and a flat head s***w together loosen the nut and turn the s***w until the gas level is just below the hole in the side of the float bowl.depends on where the gas is in the bowl if you turn the top s***w in or out to adjust the fuel level,after you have this replace the s***w in the side of the float bowl and tighten the nut and make sure not to move the s***w,has too stay where you adjusted it too.so hold the s***w in position and tighten the lock nut down and the gas should stop coming out of the top float tube...

Answer 3

The average lifespan for a mechanic before they burn out and change professions is 10-12 years.

Your truck is 22 years old and uses technology at least a decade older than that and was never that great to begin with (there is a reason nobody uses that junk anymore).

How many people do you think are still around that have ever worked on such a thing?  

Answer 4

Backfiring through the carb indicates its a timing issue. Backfiring thru the exhaust means to much fuel is going into the exhaust, therefore detonating in the hot exhaust pipe. You also may wanna check the valve train.

Answer 5

It is true that modern technicians have to rely on computers a lot.  But a mechanic of any experience should be able to help you.  86 is not that old.

Answer 6

your problem sounds like timing to me. i fix any thing, my specialty is the older ones .  

Answer 7

Most working mechanics these days have never seen a carb. They've been gone from cars for >20 years. our best bet is to pull the carb and take it to a specialist shop. most big cities have a few around or you can ship the carb to one of the shops that advertise on the web.

You might well be ahead to simply replace the carb. Holley and Edelbrock  both make great replacement carbs which would work just fine on your truck.

Given the symptoms you describethoughh, I'd suggest the problem may not be with the carb. Backfires suggest the timing seems to be off drastically on your truck. Perhaps your timing chain has slipped due to vehicle age and wear? It is alsopossiblel that one of the floats is stuck or that one (both) are set to the wrong float height.

Astrobuf

Answer 8

It has always required some real intelligence to fix carburetors.  Back when everything was carbureted, there were many people who thought they could fix one.  About 10% of those people were correct.  So really, nothing has changed.

Carbs are pretty simple, but you still have to think about what's wrong.