I am having a weird problem with my timing. I have a sb 350 in my 81 camaro and the timing is way out.
The car runs fine if i set the timing by ear, but when I check the timing with the vacuum advance unhooked at idle it's at 50 degrees, If I try and bring it to the 12 degree base timing it won't run. I have a mallory hei distributor with the gold(lightest) springs installed. Also have an msd 6AL and an ATI superdamper with the timing tab on the side. I was wondering if my engine needed the timing tab that goes on the top? how do you know which style tab you need?
any help is appreciated, thanks!

What do you know about the engine? Your balancer may have slipped.

You could use a piston stop and verify exactly where TDC is. I doubt a problem with the ATI superdamper and it can be rebuilt if so. My nickle is on a wrong timing tab.

sorry didn't see the part about the ati bet tap as well. piston stop is a good idea.

if you pull off the v-belt pulley on the crank,, which involves pulling out the damper bolt,,, you can see where the woodruff key slot is located/cut into the damper vs where the timing mark is. that's the trick to see if they match with very little work.

the older style that used the timing tab more inline with the #1 cylinder bank has the crank key/woodruff key in the damper almost inline with the timing mark on the damper. the newer style damper with the timing tab up top has the crank key about 35*-45* apart from the timing mark.

the key in the crank is at tdc for the #1 rod throw. so,, if you line up the woodruff key of the crank pointing in line with the #1 cylinder bank,, you can get a pretty good idea where true tdc really is compared to your timing tab. and you can find tdc cranking the engine by hand with a wrench on the front if needed with a small pocket screwdriver through the spark plug hole,, to reach for the piston top,, in a carefull manor.... hope it helps. andy

What Rat said. The more common 1:30 timing mark postion will have the TDC line on the balancer about 10* CCW from the position of the woodruff key- that kind of balancer will line up with a timing tab that sticks out next to the driver's side leg of the water pump. The less common 12:00 position timing mark setup will have the TDC line on the balancer about 45* CCW from the position of the woodruff key- that kind of balancer will line up with a timing tab that is welded to the front of the timing chain cover and is seen by looking straight down behind the water pump.

A common mismatch is to use an old/stock 12:00 position balancer (which were all the smaller 6-3/4" diameter, by the way) with a typical aftermarket timing tab that is held in place by 2 of the timing cover bolts (a 1:30 position timing tab). Such a mismatch results in timing that is off by about 35*.

yea, that may be the problem, The block and crank are from a goodwrench crate motor dated 1996 with the dipstick on both sides. I will take the pulley off and check it out.
now can someone describe how to do the piston stop thing? I have the tool to do it, but when the piston hits the stop, where do you mark it? at 12:00 or at the timing tab?

yea, that may be the problem, The block and crank are from a goodwrench crate motor dated 1996 with the dipstick on both sides. I will take the pulley off and check it out.
now can someone describe how to do the piston stop thing? I have the tool to do it, but when the piston hits the stop, where do you mark it? at 12:00 or at the timing tab?


if your timing tab is in the approximate location,,,, turn the crank counter-clockwise with a wrench till it touches the piston stop in the spark plug hole. then put a temporary mark on the timing tab where the damper line/0* line is.

then turn the crank clockwise till it touches the stop. put another temporary mark on the timing tab where the damper mark is.

then measure the distance between the 2 temporary marks,, and mark your 0* on the tab at the exact center between those 2 temporary marks. you're splitting the difference between both marks to find 0* true tdc on the timing tab. hope it helps. andy

you'll have to figure out the depth that allows it to touch just at a few degrees down from tdc to be able to not be off the edge of the timing tab for your temporary marks. andy

ok , I understand it now. thanks

sure thing,, good luck with it. andy

Damon,
I assume the tab that sticks out next to the drivers side leg of the water pump is the one that uses the 2 bolts from the timing cover right? I swore I hade the 10* CCW mark with the welded tab. I need to recheck that.

Shawn- yeah, that's right.

Now, I've heard of some 12 o'clock position timing tabs that ALSO use those 2 bolts to hold them on to a plain timing chain cover, but they are aftermarket timing tabs. All factory 12 o'clock position timing tabs are welded to the cover.

The woodruff key on all SBC cranks is always lined up with the #1 crank throw so when #1 is at true TDC the woodruff key is always pointing 45* CW from stright up. To line up with a 12 o'clock position timing tab there must be a 45* spread between the keyway in the balancer and the 0* timing line on the outside of the balancer to get the two of them to line up and show TDC properly.

What Rat said. The more common 1:30 timing mark postion will have the TDC line on the balancer about 10* CCW from the position of the woodruff key- that kind of balancer will line up with a timing tab that sticks out next to the driver's side leg of the water pump. The less common 12:00 position timing mark setup will have the TDC line on the balancer about 45* CCW from the position of the woodruff key- that kind of balancer will line up with a timing tab that is welded to the front of the timing chain cover and is seen by looking straight down behind the water pump.

A common mismatch is to use an old/stock 12:00 position balancer (which were all the smaller 6-3/4" diameter, by the way) with a typical aftermarket timing tab that is held in place by 2 of the timing cover bolts (a 1:30 position timing tab). Such a mismatch results in timing that is off by about 35*.
i went thru the same thing on my 81 it 12 straight up

http://img.photobucket.com/albums/v243/shawntmartin/4-Stroke-Engine.gif
I got one for you... tell me if this would work. Find the compression stroke with your (thumb in #1 cylinder) then tear apart a spark plug or buy a spark plug adapter and connect it to a vacuum/psi gauge. Screw the plug/plug adapter into the hole and slowly crank the engine by hand. As the piston continues to reach TDC you'll see psi on the gauge. Continue to crank the engine past TDC and you'll the psi start to drop. Crank in reverse now that you went past TDC and you'll see psi go up again. Do this a few times and you'll see what your max psi reading is. The point at which you *just* reach max PSI is you TDC.Any opinions?

You can't rely on that- cranking slowly by hand compression bleeds past the rings too quickly to give you anything approaching an accurate reading.

Looking in the plug hole with a little mirror and a flashlight you can watch the top of the piston and get a fairly accurate idea if you go back and forth near TDC a few times.

The mirror and flashlight would definately be the easiest. My last post was a modified version of something I read.... Tell me if this would be unreliable too: Do the same exact thing as I posted before but instead of vacuum gauge you would use a long clear plastic tube that goes from the (air tight) spark plug hole into a jar of light oil. As you reach TDC you will see bubbles in the oil, when you go past TDC you will see the oil get sucked up into the tube from the vacuum the piston creates going down into the cylinder. Crank back and forth and TDC will be at the point right in between where the bubbles stop and the oil gets sucked up into the tube.
Just thought this was clever but didn't know how reliable it was. this was on Wikipedia.
But, yes a mirror and flashlight would be a lot easier....

The mirror and flashlight would definately be the easiest. My last post was a modified version of something I read.... Tell me if this would be unreliable too: Do the same exact thing as I posted before but instead of vacuum gauge you would use a long clear plastic tube that goes from the (air tight) spark plug hole into a jar of light oil. As you reach TDC you will see bubbles in the oil, when you go past TDC you will see the oil get sucked up into the tube from the vacuum the piston creates going down into the cylinder. Crank back and forth and TDC will be at the point right in between where the bubbles stop and the oil gets sucked up into the tube.
Just thought this was clever but didn't know how reliable it was. this was on Wikipedia.
But, yes a mirror and flashlight would be a lot easier....

to be honest,, a piston stop is a really decent way to be alot more exact. the piston actually dwells up at tdc for about 3*-5* without moving due to the rod geometry of things. the longer the rod to stroke ratio,, the longer the dwell time.

so,, all those ways would get you "in the ball park" with it,, but the piston stop,, or degreeing the cam with a degree wheel and dial indicator is the most prefered way if i have to do it. the latter of the 2 ways is when shortblocked of course. piston stop if the heads are on it. but you can use a deck mounted piston stop as well when the heads are off. hope it helps.
andy

Can you guys give me a the instructions for using a piston stop. "kindergarten" level preferred. I've never had to swap out an old balancer for a new one that had a different timing mark, so I've never had to use a piston stop.

shawn,, see post 5,6,8, and 9 on page 1 of this thread. 8 and 9 tell the story. pretty "low tech" really. you can do it. it's no biggie. hope it helps.
andy

yea I've read that a few times but its the little details that I have questions about. Like, is there a spec on how far in the piston stop needs to be screwed in? Does the piston have to be on the compression stroke? Because it reaches the top on the exhaust stroke too.... How do you measure the distance between the marks? A regular old tape measure like used in tayloring clothes?

yea I've read that a few times but its the little details that I have questions about. Like, is there a spec on how far in the piston stop needs to be screwed in? Does the piston have to be on the compression stroke? Because it reaches the top on the exhaust stroke too.... How do you measure the distance between the marks? A regular old tape measure like used in tayloring clothes?

yeah,, you'll have to juggle the depth to get it where it puts the damper mark within range of the timing tab. like where it makes the mark within about 2*-4* on each side of the 0* mark on the tab, without going off the edge. doesn't matter which stroke of tdc it's on. just like you can use your timing light on #6 or #1 with a sbc for example. crank is in the same basic position either way. or 1st and 5th in the firing order on a v-8 engine.

the closer the mark is on each side to zero,, the less variation you'll have measuring arround the curved radius of the timing tab. just splitting the difference or averaging the 2 distances on each side of the 0* mark to find true tdc. when it's that close with the 2 temp marks,, you can pretty much eyeball the center of the 2 marks. but measuring with a flexible tape is good too. or a piece of paper layed over the timing tab to help in duplicating the marks arround the curved surface of the timing tab,, then laying it flat on a table to measure for the center.

just that it eliminates the piston dwell time trying to use the pumping vacuum/liquid method. it uses a fixed reference of the piston stop repeating for each side of the 0* mark.

just to make sure you don't slip up. use a wrench on the crank to turn things. having all the plugs out makes for easier turning. and don't forget the piston stop is in there and accidentally hit the key to crank the engine!! ooooops. maybe take the battery cables off while doing this,, so no one else will come by and hit the key with the piston stop in there. hope it helps.
andy

Sound to me like you got a 305 balancer from the original motor used on the goodwrench motor (which comes w/o balancer). The 305 bbalancer is 12* off fron a typical 350 balancer/tab setup. I had same problem.

Alright guys.... update and last question...

I pulled the old balancer off and set it on top of my new balancer, lined up the keyways and ...Whahoo! The "0" TDC mark on my new balancer lines up with the timing mark on my old balancer. The old one just has a timing mark. My new one has the whole engraved timing tab. So now I have two timing tabs..(the other being the one welded on the timing cover that I used with the old balancer). Since I never changed my timing from 14*, then the "0"TDC mark on the new balancer should be at the 14* on the old timing tab when checking the timing with the light, and the 14* thats engraved on the new balancer should be at the "0" onthe old timing tab... right? I know I can find this out when I get home from work.. but I just thought I'd post this and see what you think.
Next step is checking the distributor curve, checking the fuel pressure at WOT, and checking vacuum at WOT to see if the carb is restrictive. And then buying that expensive ass Wideband

but I just thought I'd post this and see what you think.

once you have (like the new one) a degreed damper,, you can find your true tdc on the timing tab,, then cut the timing tab to a point at the true 0* mark. then a normal light will give you your marks on the damper in reference to the 0* mark of the timing tab. yep. you're there now shawn. hope it help'd.
andy