well... this is kind of got me wondering.

I installed a 350HO in my car about a month ago and it had been running fine idled great, but some of the top end power was missing. yesterday when i was trying to get my heater controls to work, i realized that i had the vaccum advance for the distributer on the wrong vaccum port i had it on the EGR port, rather than the timed port. so when i changed it over, the car ran really rough (because now the timing is off) so i adjusted it by hand, advancing it till it ran smooth. i took it for a drive, and the power was finally there (amazing what happens when things are hooked up the way they are supposed to) but then, my weak starter couldn't turn the motor over. so i went back today, plugged the vaccum line, and checked the timing with a light, and it was off the tab by a mile. i probably had it at about 26ish degrees or more.

well at 10 degrees the idle is once again choppy, but that is what GM reccomends for the motor.

so should i advance it back to where i had it, at like 24 degrees? it ran smooth w/o detonation on 91 octane, and just buy a stronger starter?

anyone have any suggestions?

 

i'd back up, connect the vacuum to the correct ports and reset the timing to factory spec, or close to it, following the factory procedure ,not just moving the distributor and see what that does for you

 

well thats what i did. when i first installed the motor, i had the vaccum hoses connected to the wrong ports, so i connected them to the RIGHT ports,

then today, i re-set the timing using a timing light to the factory spec.

but now it idles choppy. if i advance the timing, it idles great, seems to be more powerful, and doesn't sound like its detonating, but the starter has a hard time starting it.

right now i have it advanced enough to idle smooth, but still start. so i guess i kind of solved the problem.

 

If you're still using the electrtonic distrtibutor and EST system, you'll need to bypass the EST to set the base timing.

There would be a four-wire flat connector at the distributor that should be disconnected before adjusting the base timing.

 

nope, its a non-cc distributer.

 

Then you'll need to disconneect and cap the vacuum advance, lower the RPM to the DRIVE curb idle spec or below to limit any centrifugal advance, then adjust the timing.

I've encountered engines that don't run well without a lot of advance (other than the old Pontiac blocks, which LOVED advance) and often the cause is incorrect cam/valve timing. Was the cam degreed when it was installed?

 

i would sure hope so.... its a brand new crate motor from GM.

what do you consider DRIVE curb idle spec?

i dropped it down to about 600?

i like the idle around 700-750.

and i did plug the vaccum advance line to the distributer when i set the timing. I think the motor just likes the advance. i double checked the timing mark on the balencer, and its within a degree.

either way, its running good right now, i gave it some more advance, just enough to run smooth, but still so the starter will turn it. when i finally break down and buy a gear reduction piece, i suppose i will advance it a little more, because it wants it.

 

How is your 350ho running? Mine is doing the same thing...wanting a ton of advance. What did you finally end up with?