Do you agree with this???
07-07-2008, 06:22 PM
#1
Melting Slicks
Thread Starter
Do you agree with this???
Got this off of the Hotrodders Forum. I am not sure this is correct. Anybody have any opinions as the factual nature of this guys statement???
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"That actually sounds like it is correct.
If you did have the cam sprocket 180 degrees out the engine would not run at all.
With the distributor aimed at the #1 plug terminal in the cap and the #1 piston at TDC on the firing stroke (the timing mark on the crank (harmonic balancer) will be very close to the '0' mark, then the cam sprocket should be at the 12 o'clock position.
For small block Chevy engines, when you are doing the installation of the cam the key in the crank will be at approximately the 2 o'clock position and the '0' mark on the crankshaft sprocket will be at 12 o'clock. At this point the cam sprocket will be installed at the 6 o'clock position. The piston that is at TDC at this time is the #6 piston.
If the crank is then rotated until the #1 piston is at TDC on the firing stroke and the rotor in the distributor is pointing to the #1 plug terminal, the crankshaft sprocket will be at 12 o'clock and the cam sprocket will also be at 12 o'clock.
Confused yet? Most are but that's the way the engine was designed."
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"That actually sounds like it is correct.
If you did have the cam sprocket 180 degrees out the engine would not run at all.
With the distributor aimed at the #1 plug terminal in the cap and the #1 piston at TDC on the firing stroke (the timing mark on the crank (harmonic balancer) will be very close to the '0' mark, then the cam sprocket should be at the 12 o'clock position.
For small block Chevy engines, when you are doing the installation of the cam the key in the crank will be at approximately the 2 o'clock position and the '0' mark on the crankshaft sprocket will be at 12 o'clock. At this point the cam sprocket will be installed at the 6 o'clock position. The piston that is at TDC at this time is the #6 piston.
If the crank is then rotated until the #1 piston is at TDC on the firing stroke and the rotor in the distributor is pointing to the #1 plug terminal, the crankshaft sprocket will be at 12 o'clock and the cam sprocket will also be at 12 o'clock.
Confused yet? Most are but that's the way the engine was designed."
07-07-2008, 06:29 PM
#2
Le Mans Master
For small block Chevy engines, when you are doing the installation of the cam the key in the crank will be at approximately the 2 o'clock position and the '0' mark on the crankshaft sprocket will be at 12 o'clock. At this point the cam sprocket will be installed at the 6 o'clock position. The piston that is at TDC at this time is the #6 piston.
If the crank is then rotated until the #1 piston is at TDC on the firing stroke and the rotor in the distributor is pointing to the #1 plug terminal, the crankshaft sprocket will be at 12 o'clock and the cam sprocket will also be at 12 o'clock.
If the crank is then rotated until the #1 piston is at TDC on the firing stroke and the rotor in the distributor is pointing to the #1 plug terminal, the crankshaft sprocket will be at 12 o'clock and the cam sprocket will also be at 12 o'clock.
07-07-2008, 07:57 PM
#4
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100% correct.Remember, the cam turns 1/2 rotation for EACH FULL rotation of the crank. Soooooooooooooooo, both marks are 12 o'clock for #1, 12 and 6 o'clock for #6.
When installing a cam, MOST people (including myself) install the timing gears 12-6 o'clock because it is much easier to ACCURATELY get the timing marks EXACTLY opposite of each other.
07-07-2008, 10:07 PM
#5
Melting Slicks
Thread Starter
Thanks for the replies. I was totally confused with this and still am!!! Oh well, I'll get over it, I hope.
Steve
Steve
07-07-2008, 10:11 PM
#6
Melting Slicks
Thread Starter
100% correct.Remember, the cam turns 1/2 rotation for EACH FULL rotation of the crank. Soooooooooooooooo, both marks are 12 o'clock for #1, 12 and 6 o'clock for #6.
When installing a cam, MOST people (including myself) install the timing gears 12-6 o'clock because it is much easier to ACCURATELY get the timing marks EXACTLY opposite of each other.
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Question??? If I install the cam at 6:00 and the crank at 12:00 where do you install the distributor? Since you are timing No 6 by this method, you can't put the rotor at No 1 or can you?
Steve
07-07-2008, 10:33 PM
#8
Melting Slicks
Thread Starter
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God, have I been doing it wrong all these years. I have been setting the marks at 6:00 and 12:00 and installing the dist. at No 1 in everything I've done. No wonder nothing seems to run correctly for me. I even looked in the Corvette Rebuilding book and they simply state to install the timing gears at 6:00 and 12:00. They don't say anything about rotating the crank 360 degrees and then installing the distributor.
Steve
07-07-2008, 10:48 PM
#9
Le Mans Master
You're not the first. When I first started wrenching, I did the same thing. I thought that when the timing marks where at 6 & 12 and the #1 piston was up, that was TDC and you put in the dizzy. WRONG. I'm sure we're in good company.
Jim
Jim
07-07-2008, 11:25 PM
#11
Melting Slicks
To eliminate confusion and guesswork, I always feel for compression as #1 approaches TDC. If the timing mark is close then you KNOW it's #1!
BTW, it is always good to check TDC and damper marks when the heads are off...or else you will never be 100% sure where the timing is
BTW, it is always good to check TDC and damper marks when the heads are off...or else you will never be 100% sure where the timing is
07-08-2008, 12:08 AM
#12
Le Mans Master
You are right. Just time the distributor to #6. #1 is TDC of the stroke, just not the ignition point.
if you think that is bad, I had a timing gear that was wrong once. The dimple was 90 degrees off. They had a lopsided 0 for the mark, the dimple wasn't supposed to be there. Unfortunately, it was my first solo engine. Screwed me up ever since.
07-08-2008, 12:39 AM
#13
Melting Slicks
100% correct.Remember, the cam turns 1/2 rotation for EACH FULL rotation of the crank. Soooooooooooooooo, both marks are 12 o'clock for #1, 12 and 6 o'clock for #6.
When installing a cam, MOST people (including myself) install the timing gears 12-6 o'clock because it is much easier to ACCURATELY get the timing marks EXACTLY opposite of each other.
07-08-2008, 05:57 AM
#14
Le Mans Master
100% correct.Remember, the cam turns 1/2 rotation for EACH FULL rotation of the crank. Soooooooooooooooo, both marks are 12 o'clock for #1, 12 and 6 o'clock for #6.
When installing a cam, MOST people (including myself) install the timing gears 12-6 o'clock because it is much easier to ACCURATELY get the timing marks EXACTLY opposite of each other.