1991 Camaro 5.0 swapped to 5.7 litre tpi,113heads comp camp 168. My car had a no start problem after sitting over winter, so I set the base timing and it was cranking good I changed the dizzy cap and spark control module and it started up so I set the base timing using a timing light unplugged the tan wire and it was idling really low around 600rpm and sounded like **** like a bad misfire, I have the original 305prom and a stage 2 corvette chip piggyback. The plugs were changed last year wires were too.

I was wondering since my crankshaft in the engine is out of like a 88 truck block or something when the engine was built the truck crank and block were used would that timing mark on the balancer be different from what I need, so I think im setting the timing right with the mark on the cover and the balancer but can it really be off or something?

 

The cranshafts are all the same- the location of the dampener keyway is unchanged since the small block Chevy was born in the 1950s.

Balancers.... different story. A 3rd gen TBI balancer would have lined up properly with a timing tab in the 12:00 position (viewed straight down behind the water pump). A 3rd gen TPI balancer, however, would line up with the the older location 1:30 position timing tab (viewed from the front, just under the driver's side leg of the water pump).

If you use the old TBI balancer (designed to work with a 12:00 position timing tab) with a TPI timing tab (1:30) you'll be off by about 30*.

Also, when you set base timing, you need to disconnect the "timing wire" to get an accurate baseline timing reading. After you set the base timing, then you plug that wire back in and the timing you observe will be whatever the ECM commands it to be over the baseline setting (which will be significantly advanced over the base timing at idle).

 

I have no idea what the balancer is from tbi im guessing it was a 92 truck when i turn crank and feel pressure from spark hole it does line up to 0 on cover, i did buy a march pulley kit for crank awhile ago maybe i should change the balancer during the pulley install to be safe

 

So with a timing light i set the current setup so the white mark is at approx the 12 oclock position just to see if it helps and it sounds alot better but is idling high around 1500-2000 rpm. Ive ordered a new balancer in to set a more accurate timing and hopefully some of the shaking will go away. I will have to search how to adjust IAC in the haynes manual or something and see if i can get it down to 1g

 

If you advanced the timing so the mark was up near the 12:00 position (timing wire disconnected to set intial) and it ran better, that's probably where your balancer is indexed. Otherwise it would be so over-advanced (ike I said, about 30* difference) it would probably not want to run and probably kick back HARD against the starter while cranking as well.

Just a little thing to check before you replace the balancer....

The amount of "offset" there is between the crank keyway and the TDC mark on the balancer is EASY to spot by eye if you remove the crankshaft pulley. Take it off and look at the angle between the crank keyway inside the hub of the balancer and the TDC mark on the outside ring. If it's a balancer designed for a 1:30 position timing tab, there will be 13* of angle between the two. If it's a balancer designed for a 12:00 timing tab, there will will be 45* of angle between the two. Pretty hard to mistake the two for eachother once you're laying eyes on it in such a direct way.

 

Ok i will check that tomorrow.