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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hey guys, when I go to read timing on an engine I had built years ago, the timing mark on the balancer is at the 12 oclock position while my timing tab is at the 2 oclock position. the engine is a L31 vortec block 383 stroker. There's tons of threads of people having this issue scattered across a bunch of different small block chevy platformed vehicles but never any answer.
I've read a bunch of posts saying how there's three different balancers with differently clocked TDC marks, however, when I search for them I only see the same clocking as my current one. I've tried using a piston stop to remark the balancer but the spark plug angle in the heads and the dished pistons prevent the piston from ever making contact with the stop, you can just barely see where the piston kisses the threads of the piston stop, this kiss is not nearly enough to give a positive stop. I could modify it to make more contact but would honestly like to just have the correct balancer if at all possible.
My balancer is 8" diameter and has the mark clocked about 10 degrees to the left of the keyway (part number PB1050-N 8").
"10 degrees to the left of the keyway" is strange, but I'm not up on all available balancers.
First thing is, the key-way must be in line with the number one cylinder. IOW, rotate the crank clock wise until the key-way is at a 45° angle to the top of the block. This must be directly in line with the #1 cylinder. This is how crank key-ways are cut, which of course the damper also needs to be cut.
Now look at the TDC mark on the balancer, that will be 0° BTDC. And needs to match up with the timing tab 0° mark.
But start with the crank/balancer key way at 45° towards the driver side. That is in line with the #1 cylinder. This is the key (oh, bad pun). And is top-center #1, exhaust or intake, doesn't matter, the crank key-way has to be in line with the #1 cylinder.
"10 degrees to the left of the keyway" is strange, but I'm not up on all available balancers.
First thing is, the key-way must be in line with the number one cylinder. IOW, rotate the crank clock wise until the key-way is at a 45° angle to the top of the block. This must be directly in line with the #1 cylinder. This is how crank key-ways are cut, which of course the damper also needs to be cut.
Now look at the TDC mark on the balancer, that will be 0° BTDC. And needs to match up with the timing tab 0° mark.
But start with the crank/balancer key way at 45° towards the driver side. That is in line with the #1 cylinder. This is the key (oh, bad pun). And is top-center #1, exhaust or intake, doesn't matter, the crank key-way has to be in line with the #1 cylinder.
RBob.
I'll check this soon, gonna have to pull the pulley off again in order to see the keyway. My theory is that the mark on the balancer will be at the 12 oclock position once I do this, leaving me with having to get a 12oclock timing tab that will be unreadable beneath the water pump.
There is no 12 o'clock timing pointer - those came welded to the covers.
Use your current pointer and put a timing tape on your current balancer. I can take my degree wheel and lay it on a correct balancer, and tell you the correct position to cut a new keyway if you like.
Last edited by NoEmissions84TA; 02-12-2023 at 09:23 PM.
There is no 12 o'clock timing pointer - those came welded to the covers.
Use your current pointer and put a timing tape on your current balancer.
my issue is that i’m unable to locate tdc in order to put a timing tape on, i have a brand new 8” timing tape sitting in my tool box awaiting it. my piston stop doesn’t make contact with the piston in order for me to accurately locate tdc.
summit does have 12 o’clock timing tabs available but will be near impossible on these cars due to the water pump.
if you could provide that info that would be amazing
Do you happen to have the aluminum cover?
Here is how I do timing pointers. Here is what I do Tyler. This is with an aluminum timing cover. After finding true TDC, I mark the timing cover for a homemade pointer (from a stainless screw). Drill & tap, and Loctite. No bolt-on inaccurate pointers or timing tapes. There is no way of misinterpreting the reading in the future.
Gee, I told you this 2 years ago.
if you could provide that info that would be amazing
I will do it tonight. My cheap camera sucks, so I will have my neighbor take a clear pic with his smart phone tomorrow.
And you are correct - it takes a longer bolt than supplied with the piston stop to make good contact.
Then you have to be extra careful not to bend the bolt when the piston contacts it.
Last edited by NoEmissions84TA; 02-12-2023 at 09:38 PM.
Do you happen to have the aluminum cover?
Here is how I do timing pointers. Here is what I do Tyler. This is with an aluminum timing cover. After finding true TDC, I mark the timing cover for a homemade pointer (from a stainless screw). Drill & tap, and Loctite. No bolt-on inaccurate pointers or timing tapes. There is no way of misinterpreting the reading in the future.
Gee, I told you this 2 years ago.
I don't have an aluminum cover, its stamped steel. my life went wild for the past three years and I've only recently been able to get back to working on the car lol. it was actually held hostage from me for a year.
My issue still stands at finding TDC, I'll have to modify my piston stop in order to make contact with the piston it seems. I just cant understand what I'm missing regarding the balancer differences, how could this balancer read 2oclock on someones engine and 12 oclock on mine?
Just don't do anything until you get the pics.
I think that I still have the longer bolt in my piston stop.
I will get you a measurement and pic of that also.
Just don't do anything until you get the pics.
I think that I still have the longer bolt in my piston stop.
I will get you a measurement and pic of that also.
No pics, and the ones on the internet are confusing.
But I did get the numbers for you.... I checked 3 balancers.
Looking from the front, a 12 o'clock balancer has the TDC mark 9 degrees before the keyway.
A 2 o'clock balancer has the TDC mark 38 degrees before the keyway.
Piston stop - make one from an old spark plug and threaded rod.
Smash all the porcelain away so that all that remains is the base.
Thread 3/8-24. Round one end of about a 5" length of threaded rod.
Use the rounded end to contact the piston.
You don't want to bend the rod, so all spark plugs should be out and remove the accessory drive belt(s).
Don't move the piston to the rod by rotating the crankshaft -
get the piston to where you think it might be close enough for the rod to touch it
and screw the rod in to contact. Make a mark in relation to whatever pointer you are using.
Then you will have to very carefully rotate the crank in reverse to touch the rod again.
Make your second mark. You don't need a degree wheel, just a tape measure.
Halfway between your marks is TDC.
Yep, centerline of the keyway.
My 1984 LG4 305 balancer has the 38 degree measurement.
And I just found another on my 1980 267 SBC.
It originally had the 12 o'clock position (which I hate), but I used a different cover
and the usual chrome bolt-on timing tab with a timing tape on the balancer.
I double checked that balancer with the degree wheel - also 38 degrees.
Last edited by NoEmissions84TA; 02-14-2023 at 05:36 AM.
thanks again for all your help. unfortunately no matter how much i modify and add to my piston stop, it does not contact the piston. i can’t add any more weld to the end of the stop otherwise it won’t fit through the spark plug hole. this engine is fighting me every step of the way.
i’m sure this is a dumb question but can i run a 6-3/4” balancer on a l31 vortec 383?
That all depends on how the rotating assembly was balanced.
Let's not get into that - it's a whole nuther can of worms.
But IF your current 8" balancer does not have any extra weights and the outer ring is totally round and symmetrical (inside and out), then it is a NEUTRAL balancer.
Then you would be able to swap to a 6-3/4" of the same configuration.
Last edited by NoEmissions84TA; 02-16-2023 at 05:34 PM.
That all depends on how the rotating assembly was balanced.
Let's not get into that - it's a whole nuther can of worms.
But IF your current 8" balancer does not have any extra weights and the outer ring is totally round and symmetrical (inside and out), then it is a NEUTRAL balancer.
Then you would be able to swap to a 6-3/4" of the same configuration.
i think i just figured out my issue.
i used a boroscope to watch the piston come up to TDC. when i noticed the piston dwell at the top of the cylinder, i looked at the balancer and saw the mark line up with zero.
i then looked at my distributor and saw the rotor was well past the #1 post and was closer to the next post.
i pulled the distributor and re stabbed it so the rotor lines up perfectly with the #1 post while the balancer mark is at zero tdc.
it’s too late to fire up the car and check timing now but i will be doing it the second i get out of work tomorrow. it looks like all my issue has been because of me being too far off when installing the distributor. definitely feel like an idiot
ran the car today and was surprised to see that it liked to be at 18° initial, all in at 36°.
the engine is a 383, comp cams xe282hr cam, 195cc aluminum dart copy heads, edelbrock 750 carb with an rpm air gap intake manifold. it’s making around 14lbs of vacuum and is running well. hot starts definitely kick back on the starter a little.
02-12-2023, 02:36 PM
We have all been there.
