|
By Jeff - 12 Years Ago
|
After approximately 10K miles since I put my '57 wagon with 312 and automatic on the road, it was starting to run a little ragged so I figured a tune up was in order.When I put the car together I replaced the wires, cap, rotor and installed a Pertronix ignition. When we purchased the car it showed 100K, but the speedometer wasn't working so the actual mileage is unknown. Some time back I had the pan off to replace the rear main and everything was surprisingly clean so I am assuming that the engine has had some major work some time in it's past. It is also fairly clean in the valley and under the valve covers.
So I installed new plugs, while the plugs were out I thought I would also adjust the valves. I was somewhat surprised at how far off some of the adjustments were but I attributed that to sloppiness on my part. So I hook up the tach and timing light and start the engine. Now the valves are quit noising. I let it warm up and the idle drop down and I can't find the timing mark with my light. After a bunch of checking and head scratching I see the that timing marks are 2-3 inches ahead of the pointer (like it would way advanced, I think). I removed the number one plug and using a remote starter button and my finger in spark plug hole, I can repeat the same scenario as with the timing light.
The pressure goes by my finger before the marks on the dampener reaches the timing pointer. The car had been running fairly well, adequate power, no pinging or over heating.
My question is it possible for outer ring of the dampener to shift or change and if so it there a means for testing this or is it possible for the timing chain to jump teeth? Are the timing sets all metal or do they have a fiber covering that can wear and possibly allow the chain to jump.
I am hoping you guys can help me figure this out.
Thanks
Jeff
|
|
By Daniel Jessup - 12 Years Ago
|
|
it was starting to run a little ragged so I figured a tune up was in order....So I installed new plugs, while the plugs were out I thought I would also adjust the valves. I was somewhat surprised at how far off some of the adjustments were but I attributed that to sloppiness on my part. So I hook up the tach and timing light and start the engine. Now the valves are quit noising. I let it warm up and the idle drop down and I can't find the timing mark with my light. After a bunch of checking and head scratching I see the that timing marks are 2-3 inches ahead of the pointer (like it would way advanced, I think).
The pressure goes by my finger before the marks on the dampener reaches the timing pointer. The car had been running fairly well, adequate power, no pinging or over heating.
My question is it possible for outer ring of the dampener to shift or change and if so it there a means for testing this or is it possible for the timing chain to jump teeth? Are the timing sets all metal or do they have a fiber covering that can wear and possibly allow the chain to jump.
I am hoping you guys can help me figure this out.
Thanks
Jeff
Jeff, can you explain how it was running ragged? hard to start? decreased power? had the ignition been intermittent or something? I would imagine that the best thing to do would be to examine those old spark plugs that had 10K miles on them and see how they look, oil fouling? wet? gasoline smell? burnt orange? dark brown? etc. Reading plugs will tell you a lot about your ignition. There are some good charts on the internet if you google it.
It does sound like the dampener rubber ring has allowed the outer circumference to "slip" around, but this would not have caused the "run a little ragged" part. Also, I would expect that if the engine would have jumped time, you would have found the decrease in performance immediately. Personally, I have owned several Y block powered cars and trucks and have never had one jump time. By the way, the only gears I have ever seen are all metal. (that doesn't the count the Overhead Cam setup I saw at Dennis Carpenter's museum, lol!!!) 
IIRC, Ted Eaton, or another Y blocker on this site may have a CAD diagram of the angle measurement of the timing TDC on the outer ring in relation to the key way on the dampener assembly. I would suggest removing the assembly and checking it over.
Did you have a chance to do a compression test on your cylinders as well? Any increase in smoke through the tail pipes?
|
|
By speedpro56 - 12 Years Ago
|
|
Jeff, there are three wide spokes on the damper that cannot move. In the middle of one of the spokes is 12 degrees. Since you can't see the keyway to see which spoke is correct just start putting a mark in the middle of a spoke until you get the right one and you should be good to go. Be sure to unplug the vacuum advance and plug the ported port on the carb when setting the timing while idleing at 500 to 600 rpms.
|
|
By pegleg - 12 Years Ago
|
 Also, number one is on the right side! you would not be the first guy to get that wrong!!
|
|
By Ted - 12 Years Ago
|
|
I’m assuming you have the vacuum advance unplugged while setting the initial timing? The harmonic damper outer rings are prone to slipping when they get a number of years on them so that’s high on the list. As far as the noisy valve train, are you sure the valves are on the heel of the camshaft when you are setting them? Here’s a past link on the various methods for setting the valves. http://forums.y-blocksforever.com/Topic8614.aspx As far as running ragged, I’ll suggest a compression test to insure the valves are all seating fine. If you don’t have hardened seats at the exhausts, then ‘worn before their time’ seats is a possibility. And here’s the link to the thread showing the TDC location on the damper in relation to the crankshaft key. http://forums.y-blocksforever.com/FindPost21693.aspx
|
|
By Jeff - 12 Years Ago
|
Thanks for the feed back, Daniel, what I meant by running a little ragged is that the idle wasn't as smooth, especially when cold, starting a little harder. The plugs all looked pretty decent, but worn. They all looked consistent with each other. I did a compression test when I got the car 10K ago and all the cylinders were up with no wild variation between them.
Pegleg, thanks for the reminder on number one cylinder and it's the front one, correct? (a little Y block humor).
Gary, I did have the vacuum advance disconnected and plugged at the carburetor.
Ted, I was relying on TDC on the dampener so if it is off then that would help explain why I found the unusual gap when I checked my previous work and probably why they are noisy now. Thanks for the valve adjusting link.
Jeff
|
|
By Ted - 12 Years Ago
|
|
I’ll add that a quick check for a slipped damper is to get both the valves on either the #1 or #6 cylinders at equal opening at overlap. That’s where the exhaust valve has almost closed and the intake valve is just opening. Then check that the TDC mark on the damper is close to alignment with the timing pointer. It’s expected to be within 5° either way if not dead on.
|
|
By Archangel007 - 12 Years Ago
|
Ted (2/22/2013)
I’ll add that a quick check for a slipped damper is to get both the valves on either the #1 or #6 cylinders at equal opening at overlap. That’s where the exhaust valve has almost closed and the intake valve is just opening. Then check that the TDC mark on the damper is close to alignment with the timing pointer. It’s expected to be within 5° either way if not dead on.
Another bit of gold right there, thanks for sharing that Ted!
|
|
By RodgerF - 12 Years Ago
|
Thanks for that piece of advice! I need to check the one on my '56. Would this apply to any engine using #1 cyl? Reason I ask is I suspect hte damper on my '66 Mustang 289 is off too.
Thanks
Rodger
|
|
By Ted - 12 Years Ago
|
|
RodgerF (2/23/2013)
... Would this apply to any engine using #1 cyl? Reason I ask is I suspect hte damper on my '66 Mustang 289 is off too. ...This does apply to all V8 engines in that #1 and #6 cylinders share the same TDC on the damper regardless of make or firing order.
|