I am going to check my timing for my 350 swapped Z28. The book lists 305 CID timing. What is the standard timing for a 350 CID, I heard 8-10 degrees. Just checking before I start.

 

Setting initial base timing? Does this motor have the EST timing control stuff on it still like factory EFI cars do? Or is it carbed?

Carbed cars, depending on the cam setup and compression, you can have anywhere from 10-28 deg of initial timing at idle
Factory L98 TPI specs are 6 deg base timing but once you connect the EST wire, the chip will add timing so at idle you will see about 16-20 deg total.

So for carbed cars, I would set timing to 20-24 deg initial at idle, and setup the vacuum advance or mechanical advance to bring in 34-36 deg timing all in by 3200 rpm. that should work well enough.

 

IT'S carbed. and uses the stock cam.

 

I'm not so sure. I've never heard or read of initial timing beyond maybe 18 degrees, unless it was a race engine with the advance locked.
28 degrees with the vacuum advance, that seems about right.
Total timing should be about 36-38 degrees, without vacuum, all in by 3500, or something similar, with stock heads, cam, and compression.

 

IF its vacuum, just set intial to something low and allow for vacuum advance at idle to be in the 20-28 range depending on the motor. With stock cam it wont need alot of advance to run properly

 

I know you're far past me at the LSx stuff, but I'm competent with 350s.
And 350s with pre-'87 "smog" heads and 8:1-9:1 compression likes about 38 degrees of total centrifugal advance.
An efficient head like a modern RHS, AFR, Vortec or whatever, with 9:1-10:1 will do fine with more like 32 degrees total.
I wouldn't run less than 6 degrees initial, or more than 16.
But as with most things, ya gotta experiment a bit to find out what works best for you.

 

I'm not real good with LSx, getting familiar tho. I'm an EFI guy so carbs arent my thing. Just thinking of what EFI cars do with timing and trying to apply the same concepts to carb. i dont see why it would be different. If a carb is only seeing 16 deg advance at 1000 rpm, to me that would seem extremely lazy but like i said, i dont do carb setups

 

What would you guys set base timing on a 350 tpi with a 278 h comp cam. 1.6 rockers, edelbrock performer heads and edelbrock intake? 8-10ish or higher?

 

You would set the base timing such that at about 3500 RPM, with the vac adv line disconnected, the timing is 36° BTDC; like just about every other gasoline motor. To get it "perfect", it might need to be as little as 33° or as much as 38°; probably not, but maybe. 36° will probably be within a ° or 2 or "perfect".

Since about EVERY distributor is different, there's NO TELLING what the "correct" base timing might be with your particular unit. Once you get the "real" timing (high RPM) set right, check what the base happens to retard back to at idle, so you can put it back in case somebody ever gets stupid and messes pointlessly with it as always seems to happen since people for some reason think that it changes and needs periodic adjustment or to be twiddled with when something else fails.

Then, if you want it to really run RIGHT, get a "curve kit" and tailor the curve to your engine's needs. WHich will probably be, somehing about like 20° of "static" or "base" advance, about 16° of centrifugal advance starting just off idle (1200 RPM maybe) and "all in" by about 2800 RPM giving your 36° of "total" timing, and about 12 - 15° of vac adv on top of that.

 

Over time, the timing does change. Because cheap timing chains never stop stretching.
Also, over time, engines will gradually change in what timing works best, as the wear accumulates, as well as carbon deposits.
But all of these are a simple matter of twisting the dizzy, not playing with curve kits.
Seafoaming an engine is beginning to get some attention here on TGO, but most of the world doesn't do it. a few of the really old mechanics did know how to de-carbon an engine by misting ATF into the engine while it was running. That was their seafoam.
Sofakingdom's curve would be close for a new 290 HP 350 crate engine. It has 8:1 with smog heads, and a cam with a late intake closing.

 

If you arent tuning via chip programmer, then 8-10 is a good place to start. When I didnt have chip tuning stuff, my TPI bolt on car ran best with 8 deg timing at base with EST disconnected. Once I got tuning software, I was able to custom taylor the curve for the motor and it ran really well.

With custom chips, it really doesnt matter what base is, just go with the lowest timing that the engine will run on for base timing and then reconnect EST and tune the timing tables for the motor. My 383 would start to stumble at idle pretty bad when initial went below 10 deg, so I locked it in at 10 deg and had the chip add 18 with EST connected for a total of 28 at idle. Most all of my cruise cells at that time were 35-36 deg with WOT being 34. That motor likely could have handled more cruise timing but I left it where it was since it felt ok to me. So thats 28 at 1000 rpm idle, and 35 by 1600 or so rpm, basically same til redline.