Chevy 350 questions...agan. help me!

[ERIC87442]

ok, well i took it out tonight and set the total timing, from what i seemed to have done with the vacuum advance dissonected and the port for it plugged for good mesure i set the total timing to 33, i let it back down put it in gear adjusted the idle to 650 in gear and my timings at 10 degrees. and the vacuum is at 14inches, seems to me like its running much better, ill have to see how it goes when i go to start it cold tomorrow, and as far as not using the vacuum advance, last time i forgot it off it ran like crap horribly so i dont know if i wanna go the whole no vacuum advance route, its not a hard core highperformance engine and i only take it to the track like 2 or 3 times a year other words its my street car and i drive it for fun so i dont think ill blow it up anytime soon.

 

[MD13ailey]

i thought the timing was a little retarded and i would stick with the vacuum advance its makes the motor more efficient at cruze speeds. i have a vaccum advance on my engine and it works great but I'm running 36 degrees of timing because recurved my distributor for performance reasons. hope it all works out for ya

 

[blk74nova]

Eric,I think you are really close with total timing. I have read that vortec heads dont like much more than 32. The rate of advance may need to come in faster. Lots of companies make a spring curve kit. There are 2 springs under the rotor, very easy to change. Trial and error is the best thing here as every motor is a little different. Try to get your advance to come in as quick as the motor likes with no "pinging".

All my cars run vacuum advance connected to full manifold vacuum. It helps the motor when it needs it. At idle, part throttle and cruisng speeds, the motor will like the extra advance and should give a little more mpg.

 

[ERIC87442]

ok, well ive left it at 33 so far, when its warming up from a cold start it still runs kinda funky, and pops untill it warms up a bit, when i put the distributer in i put different springs on it, and i dont remember what ones... i lost the ones that came with it somehow so i dont know what i used, its not doing to bad though. combined highway and city driving im getting about 15 mpg.

 

[olds307 and 403]

Make sure your carb is tuned and the choke set properly. My TBI equipped truck was popping back through the throttle body when cold, increased the timing, problem gone.

 

[ERIC87442]

its not popping through the carb, its almost like its poping out the exhaust, i got the choke on the leanest setting, and ill set the choke, start it up, runs ok for about 5 to 10 seconds then the idle drops a little bit and it starts sounding and runing almost like its not firing on all cylnders, then as it warms up about 30 sec to a min later it starts running normal again, and no matter how high i set the fast idle it still does it. i ordered a spring kit for my dist. tonight. i have an accel dist. it came with springs that i lost,im pretty sure i got the med. springs in it, im gonna put the light ones in when i get the kit. and maybe try droping my timing down to 32

 

[custom442]

fix your distributor, plug off the vac. hose when setting timing, check your plugs and wires, fuel filter, other vac. connections or egr. make sure the popping isn't an exhaust leak. Check your floats, fuel pressure, etc etc

What model holley is this?

question - was this working correctly before you switched out the alternator?

Also, is this a one wire or three wire alt? Have you tested it out at napa or somewhere?

 

[ERIC87442]

the carb is a brand new holley 600cfm 4150 or 4160 was the model i cant remember, i put a new fuel filter on with the carb, its all new exhaust, i dont think its an exhaust leak because you can feel the car shake as its doing it like its miss firing. its got new plugs (i had the wrong plugs before and it did it much much worse i had plugs for the stock 74 chevy heads not the vortec heads) and wires are new, and the cap came with the dist. i plugged the port for the dist. and disconnected the vacuum advance and timed it to 33, the distributer is a year old, the alt is a 3 wire brand new alt. bought it last week, and theres no egr, and no it was doing the same thing before i put the new alt. on. my thinking is i may have a intake leak, it looks like its leaking coolant slightly in the front of the intake. i ran a propane torch around the intake and nothing happend and i tryed the whole intake cleaner around the intake too and nothing happened. also my idle (i think) is high out of gear, in gear its at 650-700, out of gear its about 1000-1150 rpms it kinda bounces around a bit

 

[406cutlass]

This sounds almost like a problem that I had with my 406 Chevy, take off your valve covers and check to see if any of your rockers are loose. If any are loose you may have whipped a cam lobe. When my engine was doing this it was coming back through the carburetor(it was an exhaust lobe, yours might be an intake), I bought a new performer rpm intake and a new edelbrock 750 thinking it was slight detonation and it wasn’t getting enough fuel. I put on the new parts started it and it sounded like a train was coming through my shop. I changed it to a comp cam extreme energy cam, did the correct brake in and it ran great. We couldn’t figure why my engine with 2000 miles on it whipped a cam lobe until I did some research synthetic engine oil didn't provide enough lubrication and it was just grinding away.
It just sounded eerily similar to my issue, if it isn’t then it’s a timing issue.

 

[turbo78]

does this car have a vacuum modulator on the transmission? check it if it does, thats a dead vacuum leak if its off. also could try checking the position of the idle air screws on the sides of the carb, they should be about 1.5 turns out from bottom, you might just be alittle lean, that can cause a little surge when driving at low or partial throttle. 🙂