Ok, I'm still trying to get the timing setup correctly and am still having issues. Wen't to the local speed shop and bought a 8" balancer with the timing mark in the 2:30 position and the timing tab to match so I would now that is correct. I recently put in a MSD pro billet dist., coil and MSD digital box. My goal was to have around 18* to 20* initial timing and use the black bushing and springs in the dist. to give me 18* mech. advance with 36* to 38* all in by around 2800-3000 rpm. I got TDC and the balancer and timing tab match up but when the car is running good with no hesitation it shows 40* to 42* initial and around 60* total. When I back the timing off to put it around 18* to 20* it still runs but is kinda rough and as soon as I try to give it any gas, it cuts out. I'm running a Mighty Demon 750 and recently switched from a 31 accelerator squirter to a 35 because I was having hesitation issues at WOT and it solved that problem so I tried to move the timing back so it would read right on the tab but it cuts out when set by the timing tab. The car runs pretty good but feels like I'm getting some pinging above 3000 rpm and when I try to back the timing off it doesn't run right. I'm trying to figure out what would cause this if the balancer / tab are right and TDC is right. I talked to the local speed shop and the only thing he could suggest is that the idle circut in the carb is messed up which is causing me to have to advance so much to get it to run right. They said to get rid of the Demon and buy a Holley HP carb but I'm trying to do a "process of elimination" before I drop $500 on a new carb since I already spent around $600 on the Demon a couple years back.

 

The bolt-on aftermarket timing tab I had a few years back was 4 degrees off.

 

The one I got has an adjustable tab so when I got TDC I put the pointer to line up with the balancer. Going by the tab and balancer I'm about 20* off. Any ideas on a bad idle circut causing me to have to advance so much?

 

Did you determine TDC with a piston stop?

Generally speaking, the timing tab is a reference spot so you can easily tell how much and which direction you moved the timing from the last spot while finding what the engine likes. The actual number is irrelevant if the engine is happy.

 

Thought there would be some more info on this matter. So in other words there isn't a reason to use a timing tab or set timing by it if it is just to reference a number you had before. If thats the case, shouldn't everyone just power time their engines. My thing is if the engine should be around 36* to 40* and your running 60* to 80* then something should be wrong. Performance small block chevy shouldn't require that much timing and can cause detonation.

 

Any other ideas?

 

Mine does same thing. I have a 292/292 dur 508 int 510 ex lift hyd cam proformer rpm air gap, performer rpm heads, re curved hei, 3200 rpm stall, th350 trans, holley 750 dbl pumper ect and I was having a hesatation issue also. At first after carb rebuild I noticed the thing was running way rich due to running standard 65 pv, dropped down to a 35 pv then timed it in with vac dissconnected to 8 deg then went to 10 read some on it and went to 14 int and had slight hesatition ended up timing it at almost 20 running at about 40 static timing cured problem. I know I have correct balancer and timing mark but maybe its off quite a bit. Didnt check when re bearinged and installed new crank and heads cause she worked great before I took her apart. I was told by some exp engine builders and tuners that every motor is differant and part combos differant that timing is differant for each app. I was ready to chuck carb and get something else but playing with timing cured it all. Starter doesnt drag at all and car dont run over 180 so I am not gonna complain. Hard to tell what timing is exactly at due to running stock balancer with out timing tape. I rambled but all I am trying to say is play with the timing some and I would bet problem goes away if you havent already solved.

 

start by correcting the timing tab location by using a piston stop to find true TDC. They are always off at least a bit. sometimes a lot.

Buy or make a piston stop

Big duration cams need a bit of specific setup.

What cam is in this motor?

Some demon carbs have QC issues. ( internal cross leaks or incorrect internal orrifice drill size or simple junk in the carb) get the timing sorted out first.

What cam?

A quick simple diagnostic check to see if the carb idle circuit is too lean is to temp block the idle air bleeds with your fingers while its running at idle.

Idle improvement or vacuum change indicates its lean at idle.

Fix all the intake manifold and carb base vacuum leaks, first.

either a home brewed narrow band ($50) or a wide band AFR gauge ($200) is a big help in dialing in the carb.