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Timing mark at 11 o'clock at idle, what's the possible causes?

708 Views 25 Replies 11 Participants Last post by  Edlanta
Hello All,
My new Chevelle has a 350 gm crate engine (2017 model) in it and it runs pretty good. I was adjusting things in an attempt for a better tune and noticed the timing marks are at the 11 o'clock position when facing the motor. That is with the vacuum advance disconnected. Does that mean the harmonic balancer has slipped or could there be another reason? Also there is no timing marker coming off of the timing chain cover, for what that is worth???
Thanks in advance for the help!
Ed.
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You should probably roll the engine up to top dead center on #1 cylinder. Do this by hand with engine off. With number 1 at top dead center the timing mark should be on or near zero. If it is your timing is just retarded. If not something else is going on.
 
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11:00 is odd. Is there any evidence there was a timing tab, scarring on paint on bolts etc. You will need to find TDC and maybe redo the wirring on the dist. Doing what blm said the grove or mark on the ballancer should be pointed toward the #1 exhaust or close. Pull the disc cap to check rotor with #1 wire. I have seen engines rigged to run at 180^ out. With no marker tab to go by, and if dist is at #1, mark the timing cover with a paint pen or nail polish.
Locating TDC can be tricky. If you have access to a bore scope or plumbers camera that will help.
Rick
 

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If its a new style damper, that is where tdc is. Are you sure there isnt a timing marker at 12 oclock ? Look straight down behind the water pump. There might also be a little "tube" to put a magnetic sensor in for setting the timing at the factory.
 

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How about taking a picture and posting it here? If you want people to help diagnose an engine issue over the internet, pictures are usually a good idea. If it's the typical stock replacement vibration dampener with the two pieces being bonded together, ( I think those kind really suck) then it may have come apart and moved. I've had that happen before with one of those, and it also destroyed the camshaft and the mechanical fuel pump I had on a SBC 350 engine, since the dampener was no longer dampening the damaging harmonics from the crankshaft.

So if I were you, I wouldn't even run the engine anymore until you rule that out, IF you have one of those type of dampeners. If you're not sure what type it is, then a pic or two will help.
 

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Thanks BillK, I did not know that. When did they go to that ?
OP is a little off.
Rick
1980 or so ? Not sure if the cars where like that but I know the trucks were. My 85 Blazer had that type.
 

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BTW, unless the timing mark is set up to be on the 11 O' clock side like Bill K has mentioned, there's no way your engine would be running very well with the ignition timing that much retarded. That's why I mentioned the possibility of the bonded stock type dampener coming apart, since that would be another possible explanation.
 

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Discussion Starter · #10 ·
Great information! I'm heading home from work now. I know there is no timing tab where the original 350's where so I kind of hope the tube is there so I don't have bigger issues.
Question: Is it possible that the distributor could be off a tooth or 2 and the timing advanced or retarded to compensate giving the funny timing mark location? Logic tells me no but I have been wrong before at diagnosing.
Thanks!
 

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1980 or so ? Not sure if the cars where like that but I know the trucks were. My 85 Blazer had that type.
By 1979 they started using the timing tab at 12 oclock and all the cars and trucks had that tube for the magnetic pickup. In addition to the slash for TDC there is also a wider slot in the OE balancers that is 9.5 degrees off TDC (for Chevy/GM) or zero for the magnetic pickup to read.All the big 3 had there magnetic slot a set number of degrees off center IIRC Chrysler had the largest # of degrees off center.Those slots were a little away from that timing slot because I believe the timing slash would throw off the mag pickups reading.
I still have a copy of the user manual for one of the "big box" diagnostic machines that were so popular in the late 70's 80's and at the start of the 90's.
To the original poster if it has a slot thats about 1/4 inch wide that isn't TDC.The slash for TDC is still about 1/16th like a normal balancer would have. The other thing to watch out for is the balancer and the timing chain cover are a pair as the timing marks on the cover must match your balancer.
 

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I'll see if I can find one of the pages that describe the mag pickup for the timing tab.


Here ya go this blurry picture shows one at about 12:30 and kinda explains the magnetic pickup
 

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just for the heck of it.you are on the front plug wire on drivers side? if you take the firing order 18436572 at top dead center cyl 1 and 6 would be at about 2 o'clock number 8 and 5 would be around 5 o'clock number 4 and 7 around 7 o'clock and 3 and 2 would be around 11 o'clock .so if you went off the front pass side plug wire(2) it would be around that 11 o'clock position.
 

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just for the heck of it.you are on the front plug wire on drivers side? if you take the firing order 18436572 at top dead center cyl 1 and 6 would be at about 2 o'clock number 8 and 5 would be around 5 o'clock number 4 and 7 around 7 o'clock and 3 and 2 would be around 11 o'clock .so if you went off the front pass side plug wire(2) it would be around that 11 o'clock position.
But that is not the case. It is simply the way the front cover is made for all of the late model engines and the damper that goes with them as I showed in the picture above. Look at reply #4
 

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There were different locations foe timing tabs, therefore, different locations on the balancers as well.

When I went to weld my tab on, I found I had ordered the wrong balancer. I wanted the 2:00 position, so I welded the tab there and then cut another groove in my brand new balancer.



A 2:00 balancer. Crank key way approx 2:00 as well.

Locking hubs Wheel Rim Automotive tire Gas




A 12:00 balancer. Crank key way approx 2:00 as well.

Automotive tire Motor vehicle Rim Locking hubs Wheel






Here's the new line I made with a hacksaw as I prefer this position.

Wheel Automotive tire Motor vehicle Alloy wheel Locking hubs
 

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Great information! I'm heading home from work now. I know there is no timing tab where the original 350's where so I kind of hope the tube is there so I don't have bigger issues.
Question: Is it possible that the distributor could be off a tooth or 2 and the timing advanced or retarded to compensate giving the funny timing mark location? Logic tells me no but I have been wrong before at diagnosing.
Thanks!
As long as you're on the number 1 plug just check to see if the timing tab on the cover s just past 12 oclock on the timing chain cover.You'll know if it's one of the ones with the magnetic pickup tube on the cover if the marks are easily visable looking down between the water pump with your timing light it's easy to see.
If the timing tab is sitting at around 4 or 5 o'clock then maybe what you're saying is possible.
 

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But that is not the case. It is simply the way the front cover is made for all of the late model engines and the damper that goes with them as I showed in the picture above. Look at reply #4
Here's one of them all mudded up and in post #8 is a timing tab that's all cleaned up




two good pictures of the timing tabs that are mounted around 12 oclock and right behind the water pump.
This last one I posted has got some good explanations and 2 off the wall explanations that totally missed the "bulleye" ;)
 
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The only truly accurate way to find top dead center is with a piston stop. Pull all the plugs and disconnect the battery first. Then rotate by hand the engine one way to the stop then mark it on the balancer. Then rotate the other way to the stop and mark it. Halfway in between is TDC.
 

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The only truly accurate way to find top dead center is with a piston stop. Pull all the plugs and disconnect the battery first. Then rotate by hand the engine one way to the stop then mark it on the balancer. Then rotate the other way to the stop and mark it. Halfway in between is TDC.
Yes yes Yes everything that Bill k Pugsy and 350 ss said plus the nice pictures that Pugsy posted. Pugsy you should have been on Candid Camera nice pictures . You will notice Pugsy,s lat picture with the repositioned timing mark that was pre 70 at TDC the way they used to be . I always set up all my builds the old fashioned way. i also made a jig so that i could re mark the dampener easily and hack sawed the new mark then painted white. The other ways are ok i supose that was one of my quirks call it a professional Idiosyncrasy for an idiot LOL . Alex
 

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I'm dyin for the update from Ed! Tab or no tab! ? Guys who really don't want to work today, really want to know!
 
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