Incorrectly fitted timing chain?
10-31-2010, 04:39 PM
#1
Racer
Thread Starter
Incorrectly fitted timing chain?
Just fitted a cloyes double row chain,following cam install.
ok,says to line up the timing marks at 12 o'clock,so put the timing cover on and balancer (both temporary )to ensure it was pointing at TDC mark on cover.
ok removed the balancer and cover,mark on crank gear mark appeared to be at 12 o'clock and the cam gear mark also,each time I refitted the chain and run the straight edge through, seemed like the line between the two points was more likely at 11,oclock,while still keeping the cam pin at approx the 9 o'clock position and the imaginary line running through the centre of the cam.
So the question is can I continue,if this is out can I still compensate when setting the timing?
ok,says to line up the timing marks at 12 o'clock,so put the timing cover on and balancer (both temporary )to ensure it was pointing at TDC mark on cover.
ok removed the balancer and cover,mark on crank gear mark appeared to be at 12 o'clock and the cam gear mark also,each time I refitted the chain and run the straight edge through, seemed like the line between the two points was more likely at 11,oclock,while still keeping the cam pin at approx the 9 o'clock position and the imaginary line running through the centre of the cam.
So the question is can I continue,if this is out can I still compensate when setting the timing?
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SH-60B (09-13-2022)
10-31-2010, 05:14 PM
#3
Racer
Thread Starter
So by me putting the cam gear dot at the top,this is wrong? and I need to rotate gear 180 and have the cam dowel pin positioned at 3?
Last edited by Qiken; 10-31-2010 at 05:18 PM.
10-31-2010, 06:10 PM
#4
Tech Contributor
That's what is causing me the headache,The manual says the cam dowel pin is at 9.o'clock,if both dots are together the cam pin will be at 3.
So by me putting the cam gear dot at the top,this is wrong? and I need to rotate gear 180 and have the cam dowel pin positioned at 3?
So by me putting the cam gear dot at the top,this is wrong? and I need to rotate gear 180 and have the cam dowel pin positioned at 3?
10-31-2010, 06:45 PM
#5
Racer
Thread Starter
So I don't remove the balancer etc all again just to clarify.
Currently I have;
No1 TDC on compression stroke.
I installed the crank gear dot at 12
cam gear dot at 12(top of gear)
cam dowel pin positioned at 9.
This is good to go?
just a point whats the contradiction,FSM for the 89 says dowel pin at 9? and as there is only one dot on the cam gear if they are placed dot to dot that will put it at 3?,how does that work.
Sorry for the ignorance bit here,just trying to clarify in my mind.
10-31-2010, 06:57 PM
#6
Melting Slicks
No , on all small block chevys I can remember doing:
#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clock
crank sprocket with dot at 12 o'clock
in other words, both dots next to each other
plus, your crankshaft sprocket probably has three keyways;
one advanced (hp at high rpm)
one retarded (torque at low rpm)
and one just right (for most engines)
and if I'm wrong, someone please step in and help this gentleman before a very expensive blunder occurs.
#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clock
crank sprocket with dot at 12 o'clock
in other words, both dots next to each other
plus, your crankshaft sprocket probably has three keyways;
one advanced (hp at high rpm)
one retarded (torque at low rpm)
and one just right (for most engines)
and if I'm wrong, someone please step in and help this gentleman before a very expensive blunder occurs.
10-31-2010, 07:25 PM
#7
Racer
Thread Starter
No , on all small block chevys I can remember doing:
#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clock
crank sprocket with dot at 12 o'clock
in other words, both dots next to each other
plus, your crankshaft sprocket probably has three keyways;
one advanced (hp at high rpm)
one retarded (torque at low rpm)
and one just right (for most engines)
and if I'm wrong, someone please step in and help this gentleman before a very expensive blunder occurs.
#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clock
crank sprocket with dot at 12 o'clock
in other words, both dots next to each other
plus, your crankshaft sprocket probably has three keyways;
one advanced (hp at high rpm)
one retarded (torque at low rpm)
and one just right (for most engines)
and if I'm wrong, someone please step in and help this gentleman before a very expensive blunder occurs.
Yes I chose the normal key way position,
Can some one please step in to confirm,as I'm still very unsure which advice I have been given is correct.
10-31-2010, 08:44 PM
#8
Le Mans Master
Member Since: Aug 2000
Location: Sydney Australia
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Makes no difference to cam timing; both # 1 and # 6 pistons are at the top but if you drop the dist in with dot to dot setup to suit #1 compression stroke you will be 180 degrees out on dist timing
Most forget to rotate the crank over to get back to #1 TDC on compression stroke
Last edited by rodj; 10-31-2010 at 08:49 PM.
10-31-2010, 08:57 PM
#9
Racer
Thread Starter
Dot to dot is TDC on # 6
Makes no difference to cam timing; both # 1 and # 6 pistons are at the top but if you drop the dist in with dot to dot setup to suit #1 compression stroke you will be 180 degrees out on dist timing
Most forget to rotate the crank over to get back to #1 TDC on compression stroke
Makes no difference to cam timing; both # 1 and # 6 pistons are at the top but if you drop the dist in with dot to dot setup to suit #1 compression stroke you will be 180 degrees out on dist timing
Most forget to rotate the crank over to get back to #1 TDC on compression stroke
So I can continue as I am "as I mentioned above" with the cam gear dot position at 12 #1 TDC on compression stroke and drop distributor back in as marked when I removed it?
Last edited by Qiken; 10-31-2010 at 09:10 PM.
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jazfe (09-13-2022)
10-31-2010, 10:55 PM
#10
Pro
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Location: North Bay Ontario
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...one more thing while you're in there and before you bolt it all back to gether - check for clearance between your new double roller chain and the block casting behind the cam gear. The double roller chain can come VERY close and sometimes touch the casting. Some will say - "not a big concern" because the harder steel in the chain will just wear a groove in the casting, but when I did mine, I just ground a little casting away because I didn't fancy the idea of my brand new TC acting as a metal grinder...
10-31-2010, 11:11 PM
#11
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11-01-2010, 04:50 PM
#12
Le Mans Master
[QUOTE=mtwoolford;1575787396]No , on all small block chevys I can remember doing:#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clockcrank sprocket with dot at 12 o'clockin other words, both dots next to each otherQUOTE]
No, that's not correct. Re-check what you wrote. When "both dots next to each other" the #1 piston is NOT on the compression stroke. The #6 (SIX) is.
Don't feel badly, lots of members on all the different Forums get confused on this; happens all the time.
The diagram shown in the manuals is part of the problem when it shows the "dot to dot" method.
When both dots are close to each other (crank dot at 12 o'clock and camshaft gear dot at 6 o'clock) the #6 (SIX) piston is on the compression stroke - NOT the #1 piston.
Naturally, when (1) the two dots are close to each other (cam dot at 6 o'clock and crank dot at 12 o'clock) the camshaft dowel pin will be at the 3 o'clock position. But when (2) both cam dot and the crank dot are at the 12 o'clock position the camshaft dowel pin will be at a different position - 9 o'clock.
In the case of (1) the #6 piston is on the COMPRESSION stroke and in case (2) the #1 piston is on the COMPRESSION stroke.
The reason the diagram is shown that way is only to make it easier to align the dots so the gears won't be that dreaded "one tooth off". Just makes it easier to see that's all.
A couple of manuals I've seen have, in small print below the diagram, an explanation that the #1 piston is on the EXHAUST stroke, but many guys fail to read down that far, so they miss it.
Then when they install the distributor and have the rotor tip pointed at the #1 terminal in the distributor cap the timing will be 180 degrees out of sync - 180 out. So the engine won't start and run and will back-fire and have the installer scratching his head trying to figure out where he went wrong.
The #1 piston is on the COMPRESSION stroke when the camshaft gear dot is at the 12 o'clock position and the crankshaft gear dot is at the 12 o'clock position also/too. Both at 12 o'clock.
I hope this explains it better. Last thing I want to do is to confuse you more. LOL You may have to read this explanation a few times to become comfortable with how this works.
Jake
cam sprocket with dot at 6 o'clockcrank sprocket with dot at 12 o'clockin other words, both dots next to each otherQUOTE]
No, that's not correct. Re-check what you wrote. When "both dots next to each other" the #1 piston is NOT on the compression stroke. The #6 (SIX) is.
Don't feel badly, lots of members on all the different Forums get confused on this; happens all the time.
The diagram shown in the manuals is part of the problem when it shows the "dot to dot" method.
When both dots are close to each other (crank dot at 12 o'clock and camshaft gear dot at 6 o'clock) the #6 (SIX) piston is on the compression stroke - NOT the #1 piston.
Naturally, when (1) the two dots are close to each other (cam dot at 6 o'clock and crank dot at 12 o'clock) the camshaft dowel pin will be at the 3 o'clock position. But when (2) both cam dot and the crank dot are at the 12 o'clock position the camshaft dowel pin will be at a different position - 9 o'clock.
In the case of (1) the #6 piston is on the COMPRESSION stroke and in case (2) the #1 piston is on the COMPRESSION stroke.
The reason the diagram is shown that way is only to make it easier to align the dots so the gears won't be that dreaded "one tooth off". Just makes it easier to see that's all.
A couple of manuals I've seen have, in small print below the diagram, an explanation that the #1 piston is on the EXHAUST stroke, but many guys fail to read down that far, so they miss it.
Then when they install the distributor and have the rotor tip pointed at the #1 terminal in the distributor cap the timing will be 180 degrees out of sync - 180 out. So the engine won't start and run and will back-fire and have the installer scratching his head trying to figure out where he went wrong.
The #1 piston is on the COMPRESSION stroke when the camshaft gear dot is at the 12 o'clock position and the crankshaft gear dot is at the 12 o'clock position also/too. Both at 12 o'clock.
I hope this explains it better. Last thing I want to do is to confuse you more. LOL You may have to read this explanation a few times to become comfortable with how this works.
Jake
09-12-2022, 08:40 PM
#13
1st Gear
Member Since: Sep 2022
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[QUOTE=JAKE;1575796186]
Okay I'm not a dummy but I did exactly what what you just said explain whatever my doctor dot crank up cam down dowel in the 3:00 position rotor pointing at number 6 and that's all fine and dandy it starts but soon as I step on the accelerator and gear it black right on his nose.... Help I like the forms and all but I'm trying to get this thing running and not have anything you know poking me in my backside so my phone number is 320-217-3488
No , on all small block chevys I can remember doing:#1 piston at TDC compression stroke
cam sprocket with dot at 6 o'clockcrank sprocket with dot at 12 o'clockin other words, both dots next to each otherQUOTE]
No, that's not correct. Re-check what you wrote. When "both dots next to each other" the #1 piston is NOT on the compression stroke. The #6 (SIX) is.
Don't feel badly, lots of members on all the different Forums get confused on this; happens all the time.
The diagram shown in the manuals is part of the problem when it shows the "dot to dot" method.
When both dots are close to each other (crank dot at 12 o'clock and camshaft gear dot at 6 o'clock) the #6 (SIX) piston is on the compression stroke - NOT the #1 piston.
Naturally, when (1) the two dots are close to each other (cam dot at 6 o'clock and crank dot at 12 o'clock) the camshaft dowel pin will be at the 3 o'clock position. But when (2) both cam dot and the crank dot are at the 12 o'clock position the camshaft dowel pin will be at a different position - 9 o'clock.
In the case of (1) the #6 piston is on the COMPRESSION stroke and in case (2) the #1 piston is on the COMPRESSION stroke.
The reason the diagram is shown that way is only to make it easier to align the dots so the gears won't be that dreaded "one tooth off". Just makes it easier to see that's all.
A couple of manuals I've seen have, in small print below the diagram, an explanation that the #1 piston is on the EXHAUST stroke, but many guys fail to read down that far, so they miss it.
Then when they install the distributor and have the rotor tip pointed at the #1 terminal in the distributor cap the timing will be 180 degrees out of sync - 180 out. So the engine won't start and run and will back-fire and have the installer scratching his head trying to figure out where he went wrong.
The #1 piston is on the COMPRESSION stroke when the camshaft gear dot is at the 12 o'clock position and the crankshaft gear dot is at the 12 o'clock position also/too. Both at 12 o'clock.
I hope this explains it better. Last thing I want to do is to confuse you more. LOL You may have to read this explanation a few times to become comfortable with how this works.
Jake
cam sprocket with dot at 6 o'clockcrank sprocket with dot at 12 o'clockin other words, both dots next to each otherQUOTE]
No, that's not correct. Re-check what you wrote. When "both dots next to each other" the #1 piston is NOT on the compression stroke. The #6 (SIX) is.
Don't feel badly, lots of members on all the different Forums get confused on this; happens all the time.
The diagram shown in the manuals is part of the problem when it shows the "dot to dot" method.
When both dots are close to each other (crank dot at 12 o'clock and camshaft gear dot at 6 o'clock) the #6 (SIX) piston is on the compression stroke - NOT the #1 piston.
Naturally, when (1) the two dots are close to each other (cam dot at 6 o'clock and crank dot at 12 o'clock) the camshaft dowel pin will be at the 3 o'clock position. But when (2) both cam dot and the crank dot are at the 12 o'clock position the camshaft dowel pin will be at a different position - 9 o'clock.
In the case of (1) the #6 piston is on the COMPRESSION stroke and in case (2) the #1 piston is on the COMPRESSION stroke.
The reason the diagram is shown that way is only to make it easier to align the dots so the gears won't be that dreaded "one tooth off". Just makes it easier to see that's all.
A couple of manuals I've seen have, in small print below the diagram, an explanation that the #1 piston is on the EXHAUST stroke, but many guys fail to read down that far, so they miss it.
Then when they install the distributor and have the rotor tip pointed at the #1 terminal in the distributor cap the timing will be 180 degrees out of sync - 180 out. So the engine won't start and run and will back-fire and have the installer scratching his head trying to figure out where he went wrong.
The #1 piston is on the COMPRESSION stroke when the camshaft gear dot is at the 12 o'clock position and the crankshaft gear dot is at the 12 o'clock position also/too. Both at 12 o'clock.
I hope this explains it better. Last thing I want to do is to confuse you more. LOL You may have to read this explanation a few times to become comfortable with how this works.
Jake
