Hello Everyone 1st post here - I’ve done a lot of reading on this forum and think I’m ready to jump in.....but I need help/support. Sorry for the long post I wanted to get the basics covered in one post.
Car History:
I have a ‘66 Mustang convertible 200 Sprint that was my Dad’s and has been in the family for 45 years. He purchased it with about 40k miles in ‘75. It currently has 105k miles and has been sitting for about 5 years. The interior/exterior was redone in late ‘88/'89 and was relegated to parade and Sunday afternoon drive duty - no engine work was done. My Dad kept it in a heated garage until I brought it to Arizona (still garaged) about 15 years ago. Engine ran and drove good for many years. I drove it occasionally on weekends until about 5 years ago when the engine started making a knocking noise at idle. I didn’t have time to do anything with it so it has sat in my garage since. I recently retired and would like to bring this old girl back to life.
What I want out of the car:
Not a daily driver but something my wife and I can take reliably to a local small towns (1 to 1 1/2 hour away for lunch and a day out), country roads so very little if any highway (60 - 65 mph max) - do want to have 2-lane passing power, grocery getter - yeah when I want to drive it and local around town fun to drive car.
Observations & Actions:
I drained the fuel and put MMO in the pistons. Manually turned it over - no sound that I could hear and turned smoothly. Rebuilt the carburetor (1100), new fuel-filter, new battery, new plugs, rotor & cap, already had pertronix and fired her up. It started without much effort. Ran it for 5-10 minutes. Adjusted the idle a little but would not idle below about 700-800. Still making a knocking noise at idle. Sat for a couple days. Ran a compression test. Dry (1-6) was:160, 170, 170, 175, 174, 169. Wet (1-6) was: 165, 175, 175, 179, 179, 175. I think this is promising - Yes? Pulled the valve cover (at some point adjustable rockers had been installed - who knew?) and found several severely worn and deformed pushrods. Cups were deformed and very loose (no preload). Could this be a lifter problem or did they just bleed down? Upon further investigation I found the rocker arm shaft to be severely plugged with gunk. After some cleaning all the rockers rotate with some drag but they bind with minimal side pressure. Could this be the cause of the knocking sound? Oil pressure gauge has always read in the normal range. In addition, I found the PCV all gunked up (no rattle either) and the vacuum line & grommet crumbled when I removed the valve cover - vacuum leak - could this be part of the idle issue?
Thoughts on next steps:
New rocker arm assembly (or rebuild existing), new push rods, maybe lifters (not sure I’m looking forward to pulling the head). Eventually a new oil pump (gasket is leaking and needs replaced anyway) and timing chain. I checked the slack in the chain and it is 4-6 degrees (back and forth) of crank rotation to observe any rotor movement. I’m not sure I have the ability to pull the engine (don’t have room or hoist/lift) and do any block work. Maybe pulling the head and oil pan will decide for me once I can see the cylinders.
I did purchase the handbook and have read it cover to cover several times. Just not sure of my abilities for doing an engine rebuild. It has been 40 years since I have done anything like this.
Questions:
1) Thoughts on lifter replacement - Part of the knocking? Just bleed down? Replace anyway?
2) Could the rocker arm assembly condition cause the knocking?
3) Should I just purchase a new/rebuilt rocker arm assembly vs trying to rebuild existing?
4) Could the timing chain slack cause the knocking or wear on the rocker arm assembly? Could this have caused Piston/ring damage?
5) Should I pull the head? If I do what else should be done - only want to do this once.
6) If I pull the oil pan what should I look for to determine if additional block (piston/ring, cylinder, crank, bearing) work is required?
7) Anything else? What am I missing - I’m sure a lot?
Thanks for your help.
Car History:
I have a ‘66 Mustang convertible 200 Sprint that was my Dad’s and has been in the family for 45 years. He purchased it with about 40k miles in ‘75. It currently has 105k miles and has been sitting for about 5 years. The interior/exterior was redone in late ‘88/'89 and was relegated to parade and Sunday afternoon drive duty - no engine work was done. My Dad kept it in a heated garage until I brought it to Arizona (still garaged) about 15 years ago. Engine ran and drove good for many years. I drove it occasionally on weekends until about 5 years ago when the engine started making a knocking noise at idle. I didn’t have time to do anything with it so it has sat in my garage since. I recently retired and would like to bring this old girl back to life.
What I want out of the car:
Not a daily driver but something my wife and I can take reliably to a local small towns (1 to 1 1/2 hour away for lunch and a day out), country roads so very little if any highway (60 - 65 mph max) - do want to have 2-lane passing power, grocery getter - yeah when I want to drive it and local around town fun to drive car.
Observations & Actions:
I drained the fuel and put MMO in the pistons. Manually turned it over - no sound that I could hear and turned smoothly. Rebuilt the carburetor (1100), new fuel-filter, new battery, new plugs, rotor & cap, already had pertronix and fired her up. It started without much effort. Ran it for 5-10 minutes. Adjusted the idle a little but would not idle below about 700-800. Still making a knocking noise at idle. Sat for a couple days. Ran a compression test. Dry (1-6) was:160, 170, 170, 175, 174, 169. Wet (1-6) was: 165, 175, 175, 179, 179, 175. I think this is promising - Yes? Pulled the valve cover (at some point adjustable rockers had been installed - who knew?) and found several severely worn and deformed pushrods. Cups were deformed and very loose (no preload). Could this be a lifter problem or did they just bleed down? Upon further investigation I found the rocker arm shaft to be severely plugged with gunk. After some cleaning all the rockers rotate with some drag but they bind with minimal side pressure. Could this be the cause of the knocking sound? Oil pressure gauge has always read in the normal range. In addition, I found the PCV all gunked up (no rattle either) and the vacuum line & grommet crumbled when I removed the valve cover - vacuum leak - could this be part of the idle issue?
Thoughts on next steps:
New rocker arm assembly (or rebuild existing), new push rods, maybe lifters (not sure I’m looking forward to pulling the head). Eventually a new oil pump (gasket is leaking and needs replaced anyway) and timing chain. I checked the slack in the chain and it is 4-6 degrees (back and forth) of crank rotation to observe any rotor movement. I’m not sure I have the ability to pull the engine (don’t have room or hoist/lift) and do any block work. Maybe pulling the head and oil pan will decide for me once I can see the cylinders.
I did purchase the handbook and have read it cover to cover several times. Just not sure of my abilities for doing an engine rebuild. It has been 40 years since I have done anything like this.
Questions:
1) Thoughts on lifter replacement - Part of the knocking? Just bleed down? Replace anyway?
2) Could the rocker arm assembly condition cause the knocking?
3) Should I just purchase a new/rebuilt rocker arm assembly vs trying to rebuild existing?
4) Could the timing chain slack cause the knocking or wear on the rocker arm assembly? Could this have caused Piston/ring damage?
5) Should I pull the head? If I do what else should be done - only want to do this once.
6) If I pull the oil pan what should I look for to determine if additional block (piston/ring, cylinder, crank, bearing) work is required?
7) Anything else? What am I missing - I’m sure a lot?
Thanks for your help.