1984 Chevy 350 still being a headache to get running right

[Pro Carry 2]

Years ago i had one acting very similar. found out i had about 10 gallons of water in the tank. it would suck up the water and run like crap but sounded good at idle

 

[grandall1972]

Years ago i had one acting very similar. found out i had about 10 gallons of water in the tank. it would suck up the water and run like crap but sounded good at idle

Tank is 1.5 months old as with the rest of the fuel system.

 

[Shads]

Is this a daily driver? If not, what do you normally drive? Those trucks weren't known for being power houses. Also, What tire size and gear ratio is it?

 

[jeep78]

Is this a daily driver? If not, what do you normally drive? Those trucks weren't known for being power houses. Also, What tire size and gear ratio is it?

Sorry, they are quite fast with a v8. I have had one for more than 30 years.

 

[jeep78]

Try advancing the timing. Your harmonic balancer may have slipped, and they always slip so as the timing retards.

Mine did that and low power and low vacuum resulted.

Advance using a vacuum gauge.

 

[harrycalahan]

Will look for vacuum leaks but at 15 vs 18-21 which would be ideal I wouldn’t think I would have so little power.

Fuel system is new from the Tank to the carb.

Vacuum is one indicator of the health of the engine. The more vacuum, the better your air pump is. 15” of vacuum for a stock grind cam is an indication of a bad tune, open vacuum source or mechanical failure such as a blown gasket, bad rings etc.

Hook up a vacuum gauge to a direct intake port. Plug off all other sources including the vac advance on the distributor (diaphragm can be blown and leak) and brake booster. Take a vacuum reading. If its still at 15”, and you’re certain your ignition timing is correct, then you have a bad tune (throw out the edelbrock) or a bad intake gasket etc.

 

[jeep78]

My 350 has over 250,000 miles and shows 21 inches of vacuum at idle, eldebrock square bore 600 cfm carb.

 

[41mag]

Is the choke adjusted on the carb properly ? Pulloff working? I would go to an older emission test station and pay them to take a 5 gas off the tail pipe. Then you can see if its rich/lean and also watch values as you quickly eliminate poss causes.

Other than that....take it to someone who can diagnose it correctly.

 

[Rambler]

I know you say all the parts are new, new means new, not good. I have seen way too many new parts be worse than the ones that were replaced. Always check the function, don't be fooled by a bad part just because it is new.

 

[grandall1972]

Try advancing the timing. Your harmonic balancer may have slipped, and they always slip so as the timing retards.

Mine did that and low power and low vacuum resulted.

Advance using a vacuum gauge.

We tried it without driving and the timing window is pretty tight between running smoothly and roughly.

we took the harmonic balancer off when inspecting the timing chain. It was on correctly and put back on correctly.