1981 bronco 4spd 302 no hwy power

[81bronconinja]

ok here we go I have a 1981 bronco 302 2brl 4spd it drove and ran fine , now all power seems gone when trying to get up to speed , it did start to shake and sounded like I busted some valves or piston blew up but she starts fine and still drives around town ,,,,,,,,, just no go past 45mph ... no cat on it just glasspacks , oil looks ok .. i'am lost please help if anyone ran across this problem before

 

[miesk5]

yo 81,

Welcome!

Does your Bronco have oversized tires or gearing?

For now;

look through Recarbco's Basic Troubleshooting;

http://www.recarbco.com/tech-help

Can you do or have a compression test done?

Check Timing advance

To check the timing, you hook the gun to it, and then slowly increase the throttle with your hand on the carb linkage. Off the top of my head, idle advance with a mostly stock small block should be 10-14 degrees, and full advance should be 34-37 degrees at maybe 2800-3000 rpm.

Tune-Up Specifications 1981

http://content.chiltonsonline.com/content/images/8576/images/85762c03.pdf

Intake Manifold Vacuum Test

Vacuum Gauge Readings, Interpretation

http://www.diesel-dave.com/vehic/manual/stj/stj30013.htm

Insufficient Power

•Malfunctioning hydraulic valve tappet.

•Damaged hydraulic valve tappet guide.

•Compression leakage at valve seat.

•Seized valve stem.

•Weak or broken valve spring.

•Damaged cylinder head gasket.

•Cracked or distorted cylinder head.

•Damaged, worn or sticking piston ring(s).

•Worn or damaged piston.

•Malfunctioning or damaged fuel system. check fuel pressure and filter

•Malfunctioning or damaged ignition system.

•Slipping transmission.

it a C6?

•Dragging brakes.

•Incorrect tire size.

•Damaged or plugged exhaust system.

 

[81bronconinja]

It has the 4spd with granny low and the tires are 235/85/16 irok nd's there is no motor noise now I can rev it to 6000rpms and all sounds good , runs fine at idle , I know it needs a clutch but it still grabs , unless the clutch came apart , harmonic balancer? Timing jumped ? Or intake leaking ? Cause my problems of no Hwy power and under hard load up hill can't get up to speed and sometimes theres a light pinging sound like bad gas or timing

 

[Buckthetruck]

Hello.  Did you discover the source of the problem?  I know that I'm late to the game here but that sounds like a fuel delivery issue; you may have a dirty fuel filter, partially clogged fuel line, or failing fuel pump.