Originally Posted by 83chevytruck
thanx for the input , found a bad vacuum line this afternoon and also took the starter apart and found it burnt severely inside, the field was shot replaced it, adjusted timing a bit more and its doing alot better. found out that i cannot set the timing by the timing tab, DUH, i should have known better to much cam so its well off the mark i have to guess here but close to 14 degrees or so. still has a gas raddle with a load so i am gonna keep adjusting till i get it right.
That cam (.495" lift) isn't really that mild in a street driven 350 SBC. I'd expect it to have at least 230º duration @ 0.050".
You'd like there to be at least 16º BTDC at idle speed, more would likely be OK. For the total timing you need about 36º-38º BTDC total, all in by about 2500 RPM. You will need a set of springs to change how soon the advance comes in. Advance weight and spring kits are sold but use just the springs.
You may need to modify the distributor to limit the total advance so as to not exceed the desired 36º-38º total timing. You want about 10º-12º of vacuum
advance. Connect the vacuum advance to a manifold vacuum source. This will help keep the idle RPM up, w/o opening the primary throttle blades any more than they need to be. If they're opened too far, the idle will go pig-rich and you'll lose control using the idle mixture screws.
If needed, there are adjustable vacuum cans like the ACCEL #31035
If you find the vacuum advance adds too much advance (more than 10º- 12º) but is OK otherwise, you will need to physically limit the vac can's travel w/a vacuum advance limiter: [/B] Crane #99619-1
; #99619-1 INSTRUCTIONS
If you're unsure, or just want to check the accuracy of the tab/mark for TDC, DETERMINE TDC
will help you to see for yourself.
You can use MAKE A TIMING TAPE
for instructions on making a temporary timing tape to use to check/set the timing if you don't have a dial back timing light. Before removing the tape, permanently mark the damper w/the total advance position and any other positions you want.