Poor performance

[J20]

Anyone help me! my 82 j20 with a 360runs and idles rough, i have done a tune up, checked timing checked vacum checked all the necessary applications such as vacum leaks, compresion etc. etc. the problem i have is at take off its really slow to get the revs up andhard starting when warm. I am totaly flustered now and losing my patients on this
Thanks

[J20]

im dropping in a 460 anyway just need the engine running right to sell it

[carrotman]

Looks like you checked all the basics. I would check the EGR, PCV, and TAC next. For EGR, you could disconnect the vacuum source, but the EGR valve could be stuck open. Have to pull it to check it out. It MUST be closed at idle. Replace the PCV. The TAC is the vacuum motor flap on the end of the snorkel. Keeps the carb from icing up. Make sure the flap can move, closed at start, vacuum hoses are hooked up, and hot air hose is on the exhaust manifold. Flap should open up when motor is warm (does that happen in Calgary?). Vacuum gauge will tell you if the exhaust is clogged.

[J20]

vacum gauge shows everything is fine, checked egr and exaust flap all ok. the thing i didnt know was when i have it hooked to the vacum gauge and i rev it up my vacum drops to zero then back to regular the only thing that would make sense would be a jumped timing chain but then it would show on my timing check so i am lost as you can tell.

[carrotman]

The vacuum should drop near 0 then back up when reving the engine. That's a good sign. I had over 200K on my timing chain before I changed it. No power down low, but plenty of power at higher revs.

To check for chain stretch, take off the dizzy cap and turn the crank clockwise with a socket until the timing mark on the balancer is next to the degree marks. Have someone watch the rotor while you rotate the crank backwards. Stop when the rotor starts to move. If the crank moved more than 10 degrees the chain is stretched.

[J20]

so you had no bottom but good top when your chain was stretchted?? I will have to check that.
Thanks

[hippymill]

are you losing vac around the intake? had that problem, would run, but got real rough at idle as it warmed up, the would just die. leaking manifold. you can check this by spraying carb cleaner around the edges of the manifold. if the idle improves, you have a leak at the manifold.

[J20]

i checked that all ok

[J20]

thanks for the help guys but everything checks out ok. So i really am lost and now i really dont care so the 460 will be started sometime this week as i am running way behind anyway.