1984 Chevy 350 still being a headache to get running right

[grandall1972]

I’m still having issues getting power out of the 350 in my 1984 Chevy Pickup. I went through most of the previous ideas and now looking for more.

Truck
1. 1984 Chevy k10 long bed
- 4 speed manual
- 350 of unknown year
- HEI ignition

Tried so far
- Fuel system is brand new from the tank to the carb.
1. New plugs 2x, wires, cap, rotor, and coil
2. Timing set 12 degrees at idle, 36 degrees at 2500rpm
3. 150 psi across all 8 cylinders
4. 6.5-9 psi fuel pressure
5. 15 inHg vacuum at idle
6. Checked timing chain and cam mark, both right and no slack in timing chain.
7. Stock style cam shaft.
8. Checked plug wires. All are correct firing order
9. Changed carb, new carb was worse, put old carb on.
10. Advanced and retarded timing, very narrow area for the engine to sound right.
11. Dual exhaust are flowing well
12. Required and adjusted electric choke.
13. No valve noise or clacking

Symptoms
1. Starts and idles great.
2. Revs while parked well
3. L and 1st run ok and feel decent, not too strong
4. Once in 2nd or 3rd it just doesn’t have any power to pull at all.
- 3rd slowly accelerates, but in 4th will not pull at all. Maxes out 45mph.
5. Every once in a while I feel like there could be a miss when reving, but it’s smooth.

Questions
1. What do I need to check next?
2. Anyone near Dalton a guru on the 350?
- I’m about at the end of my abilities
3. I want it fixed and getting to the next steps of cleaning and building the truck. The part I enjoy more. Any help would be great.

Thanks for all the help so far as well.

 

[Alaskan]

Carberator? @Lionheart has one for that engine

 

[D_Max]

If by chance it has Cat converters on the exhaust , make sure there not stopped up

 

[Bass Akwards]

Carb jets?

 

[Rambler]

Your vacuum is too low at idle, should be 18 to21 inches. I would look for a vacuum leak or restricted exhaust system. This truck should have the bead type catalytic converters, they are bad for stopping up and causing problems.

 

[MRM]

The one I sold was at least 21. I think it was a tad too advanced. IIRC it was around 23.

 

[whiskerz]

Too much fuel pressure for a carb. What kind of carb? Have you checked the throttle linkage for full throttle? Vacuum is low. What intake ? Why no engine picture ? We don't need a picture of the outside. Stuck EGR valve ? Vacuum leak sounds like an option. You need to help us. What is the actual camshaft ? Stock type is vague? Could it be a boat cam ? Is the cam worn out ? You say you checked the cam is the cam sprocket adjustable ? crack sprocket ? Look at the linked article. someone could have improperly installed and adjustable timing chain set. https://www.racingjunk.com/news/degreeing-a-camshaft-for-small-block-chevy/

 

[davans]

Might need to drop the exhaust to eliminate that.
The motor is pretty much stock right? Not radical as far as HP and cam shaft?

There is a shop in Chamblee.
J&L Auto Service.
Good folks that specialize in older cars. This would be right in their wheelhouse.

 

[whiskerz]

Is the timing pointer correct for the engine? Are you sure it is a 350 ? You set the base timing with vacuum advance unplugged from the distributor?

 

[jeep78]

3 to 4 psi is all you should have on fuel pressure.

21" is what you should have on manifold vacuum with the engine warm.

Take the cat converter off temporarily to check for obstruction.