Please help:  I have a Chevy SB 350 in my 1984 3/4 ton Silverado, it runs fine, I just recently done the bolt on goodies trip, headers, (flowtech) Roller Rockers (Harlin Sharp), intake (performer EPS) HEI Dist (proform) 600cfm carb (Edelbrock) 8.5 MSD wires. gas 97 octaine.  Here's my problem, when I pulled the dist. to clean and overhual it, I done the standard, found TDC and the 8" harmonic balancer mark was dead on the o on the after market timing tab (Mr Gasket) plus the dist rotor was pointing just after no# 1 cyl.  Not moving anything re-inserted the dist, fired up the eng. it runs fine but have know idea where the timing is set because with the timing light on no#1 wire I cannot even see the mark on the balancer, so at this point I have just set the timing by ear, but that worrys me because I have no idea what advance I am running.  Further info Im using the timed vacuum outlet on the carb so there is no vacuum at idle, and the mecanical weights are stock with mid springs idle -1500 rpm

P.S. Everything else in the eng is stock

Thanks

Don't you just love accessory designers that block out the timing marks with their stuff. You can do the "by ear" tuning and hit it pretty close. The old rule of advance it till it pings under hard acceleration and then back it off just till it just doesn't ping will get you there. Don't worry about the vacuum advance, if it's hooked up and operating, the above proceedure will include those effects.

You can also relocate #1 at TDC, sounds like you know how to do this, then move the crank to the proper static lead position. Put the timing light on #1's plug wire. Slightly loosen the distributor retention bolt. Turn the ignition switch to the run position. Move the distributor in the advance direction untill the timing light fires, there's #1 with the proper static timing lead. Tighten the retention bolt and turn off the ignition switch. 

Bogie

Thank you old Bogie, for your input.  I'm going to do just what you said.  In the future I am going to install a new timing set from CraneCams, also replace the balancer and slip on one of those degree covers over the balancer, that way when all done I will be sure of the sprocket alignment and I would be resonably sure I will be able to time with a light and be accurate.  Your right, trying to flash with a light down between all that stuff in the way leaves a lot to be desired. Again thank you 

Badcrank

I had problems setting the timeing on my Camaro(350) I could see my mark but I was coming up with some pretty off the wall numbers to get the timing  to where it was running right. The indicator only goes to14 I think and it still wouldn't run right I decided to put new heads and cam and found out the balancer had spun in the rubber so the mark was way off where it was supposed to be No wonder everybody thouhgt I was crazy when I told them where the timing was set.  

what do you mean by ping do you mean like a back fire out of the carb or what?

The sound you hear when the engine detonates, this tells you the advance is too much, backing the advance off till the detonation (ping) stops places the advance at its most  efficient point for power development.

Bogie 

I sure can understand a slippage in the harmonic balancer rubber, but my question is if I find TDC and the timing mark on the HB is dead on the timing tab o mark, would that still mean the balancer sliped and will only show up when the engine is running.  I just cannot beleave on my 350  that when I set it to 14^ adv it runs very poorly, but I take it to 25^ adv and it runs great.  is 25^ to much? and bear in mind this is a stock 350 except for the roller rockers, 600 cfm Edelbrock, flowtec headers, MSD 50k coil plus module.  Also one other thing that I am foggy on and that is when I am on TDC I notice that the rotor is between no#1 dist post and no# 8 and since the dist turns clockwise It seams to me that this is firing after TDC on no#1 cylinder and by turning the dist further counterclockwise which is where it runs best I would think I am almost in line with no#8 dist post.  What gives?

Thanks everyone for help

Badcrank

Crank:

I think you have two separate issues:

1) Regarding the timing.  I presume the 14* and 25* are the "initial" settings at idle.  If so, I wouldn't get too hung up on that.  What's more important is the "total" timing when the distributor has fully advanced.  Usually, you want all of the advance in by ~3,000rpm.  In a sbc, you want to keep total timing at 36-38*.  If you've located TDC of #1 and the pointer is at 0* on the balancer, then it has not slipped.

Try adjusting your timing to not exceed a total of 36-38* at 3,000rpm and see how it runs.

2) Regarding the rotor being between the #1 and #8 post at TDC.  Again, don't get too hung up on this.  Remember, at TDC the plug has already fired.  Therefore, the rotor would be past the #1 post.

Edit:  Ensure you're using an accurate timing light.  More than once, I've seen guys pull their hair out on things like this only to find they've been using a bad light.

Thank you JCharlieM,   your responce was most informitive.

Yes the 14* and 25* was at idle.  This sbc 350 that I have is in a 3/4 chevy truck 1984, and there is no tac.  I will now go out and buy a small tac. so that I can run it up to 3000 and do just what you said.

And as far as that timing light, I relate to what you said, at the time I bought the one I have I was looking at the $60 dollar job and thought for no more than I will use it I figured the $25 dollar job would do just fine, as the old saying goes you get what you pay for.  I think the $25 dollar job is working ok but will purchase a very high quality one and proceed from there.

Right now as far as I can tell, since it is so hard to see the HB mark under the water pump I beleve I am about at least 20* BTDC and there is no pinging under load, and its running fairly decent.  But I'm a perfection freek and want it dead on.

Will let you know more after I get new timing light and tac.

Thanks

Badcrank

Rather than buying a new timing light, try to borrow one.  Your current light may be just fine.  

I managed to find at the local pawn shop a craftsman Pro timing light for $30. it has a advance knob on the rear of the light.  I am assuming that if you turn the knob up to where it reads let say 25^ on the dial and you flash the HB mark and its flashing at 0^ on the tab, that I and running at 25^ adv. right?

Thanks

That is exactly how it works.It makes it easier to see exactly how advanced the engine is running without having to search for the mark .  

Mikeb55,  Thank you for that reply, that sure clears up a lot of mystery in respect to the lost timing mark.  I know it seams simple to all the master mechanics out there, but for the first time starters in the world of high performance chevy its invaluble info.  I can now put my 350 on the money instead of doing the by the ear thing.

Badcrank