The Great Pumpkin - '71 Duster
Engine progress! Got the rotating assembly installed and the cam is degreed.
The pistons and rods went in the block fairly easily. It's nice to have a specifc bore diamater ring compressor so you don't have to go through the process of loosenting and tightenting one of those clumsy adjustable ones sixteen times. The I.D. of it has a slight taper so you set the piston/rod assembly in it with a bit of the piston skirts hanging below. Place the whole works on top of the cylinder and knock it down with a dead blow hammer. Works awesome and makes the job a breeze. Worth every penny.
I ran into one issue at the end where I managed to put one rod cap on backwards. The whole rotating assembly was binding and there was no rod-side clearance on the last journal, I was like WTF! I had accidentally reversed the #7 cap so the chamfer side was in the middle. That's what happens when you're not paying attention. Flipped it over and all was back to normal. Sometimes I am my own worst enemy...
As stated previously, the goal this time was to keep things as clean as possible. I went through almost an entire box of blue paper towels and my hands were getting wrinkly from solvent. Absolute cleanliness is tough when you're trying to concentrate on something else like installing pistons. There were plenty of times when I had to stop and think about what I was doing to make sure whatever I picked up or where I placed something down wasn't dirty. It's all in though and I'm confident things are clean.
Speaking of clean, here are the Comp # 8043 solid roller lifters soaking in parts washing solvent. These things actually come out of the package still having the factory assembly lube on them so you have to clean them really well. It's all dried up inside so you have to soak them for a while to dissolve the stuff.
Here's the cam. Big boy solid roller. 263/268 @ .050", 108 on 104. .4125" lobe lift. Speak softly and carry a big stick.
Degreeing the cam was a bit of an adventure. I also had similar problems when I did it several years ago. I remember calling Comp Cams and they said run it but even after that I never was 100% certain it was right. Sure enough, same thing happened again this time. I must have tried it 100 times because I kept getting different numbers by like 2-3 degrees.
Ultimately, I called Bullet and asked them what the heck I was doing wrong. I had a long chat with Tim there and it turned out it really wasn't me. Like Comp Cams, he said run it. He told me the only sure way to know if it's in wrong will be to look at where the torque peak is and whether it's making an appropriate amount of torque at the given rpm. The cam is bigger than the last one I had so theoretically it won't make any less torque. This is the sort of thing that makes the case for putting an engine on a dyno. I have a lof of money and time invested in it and want to make sure it's right before I beat on it.
The answer to the problem was simple though. Basically, what I was seeing was a 'stack up of tolerances'. Things like timing chain slip, ratchet action on the crank, dial indicator vibration etc. The chain has only seen dyno time so it's basically new but by nature it does have some amount of slack. I tried a couple different degree methods over and over again but could never repeat the exact same number. I have a chain tensioner too but it still does not overcome that couple thousandths of movement.
I was able to prove the tolerance theory because at one point I went from a long-handle 1/2" ratchet on the crank to a long, solid 1/2" extension with a 90ยบ bend at the end. It's a home made tool I inherited a long time ago but I end up using it a lot. Consequently, the numbers got slightly more consistent because there was no ratchet gear slippage. It's almost imperceptible in your hand but it shows up on the degree wheel. Really, the only solution to eliminate those slight variations is to use a gear drive.
Unfortunately I failed to take pictures of the degree process but here is the aftermath. Yes, there was paperwork involved. Numbers and math too. Plus a lot of head scratching.
The next step in this rebuild process is to measure for pushrod length. I started by putting the driver's side cylinder head on which immediately presented another annoying problem. The front locating dowel was hammered and the top was mushroomed so the head would not go all the way down. Doh! This was another problem I ran into when the engine was first built but it was even worse this time.
The best thing to do would probably have been to pull the pin out and carefully install a new one but that's not my style. It was already ground down so it would have been a nightmare to get out. Instead, I carefully whittled it down some more so it would fit. Truthfully, the dowel hole on the head was a little tight which compounded the issue. I reamed it out with some sandpaper but that was minimal, don't want the pin to be swimming in that hole.
I put tape over the bores to prevent any shavings from going down into them. Dyekem was painted over the pin and I'd set the head down on it and tap it so there was some force acting on it and pull it off. The bluing would show where it needed to be filed. Took many rounds of careful filing but it finally went all the way down. What a PITA. Next time I'll take the pin out. I didn't take any pics of the dowel pin fiasco because I was so pissed at having to deal with such an annoying thing.
More to come.
Engine progress! Got the rotating assembly installed and the cam is degreed.
The pistons and rods went in the block fairly easily. It's nice to have a specifc bore diamater ring compressor so you don't have to go through the process of loosenting and tightenting one of those clumsy adjustable ones sixteen times. The I.D. of it has a slight taper so you set the piston/rod assembly in it with a bit of the piston skirts hanging below. Place the whole works on top of the cylinder and knock it down with a dead blow hammer. Works awesome and makes the job a breeze. Worth every penny.
I ran into one issue at the end where I managed to put one rod cap on backwards. The whole rotating assembly was binding and there was no rod-side clearance on the last journal, I was like WTF! I had accidentally reversed the #7 cap so the chamfer side was in the middle. That's what happens when you're not paying attention. Flipped it over and all was back to normal. Sometimes I am my own worst enemy...
As stated previously, the goal this time was to keep things as clean as possible. I went through almost an entire box of blue paper towels and my hands were getting wrinkly from solvent. Absolute cleanliness is tough when you're trying to concentrate on something else like installing pistons. There were plenty of times when I had to stop and think about what I was doing to make sure whatever I picked up or where I placed something down wasn't dirty. It's all in though and I'm confident things are clean.
Speaking of clean, here are the Comp # 8043 solid roller lifters soaking in parts washing solvent. These things actually come out of the package still having the factory assembly lube on them so you have to clean them really well. It's all dried up inside so you have to soak them for a while to dissolve the stuff.
Here's the cam. Big boy solid roller. 263/268 @ .050", 108 on 104. .4125" lobe lift. Speak softly and carry a big stick.
Degreeing the cam was a bit of an adventure. I also had similar problems when I did it several years ago. I remember calling Comp Cams and they said run it but even after that I never was 100% certain it was right. Sure enough, same thing happened again this time. I must have tried it 100 times because I kept getting different numbers by like 2-3 degrees.
Ultimately, I called Bullet and asked them what the heck I was doing wrong. I had a long chat with Tim there and it turned out it really wasn't me. Like Comp Cams, he said run it. He told me the only sure way to know if it's in wrong will be to look at where the torque peak is and whether it's making an appropriate amount of torque at the given rpm. The cam is bigger than the last one I had so theoretically it won't make any less torque. This is the sort of thing that makes the case for putting an engine on a dyno. I have a lof of money and time invested in it and want to make sure it's right before I beat on it.
The answer to the problem was simple though. Basically, what I was seeing was a 'stack up of tolerances'. Things like timing chain slip, ratchet action on the crank, dial indicator vibration etc. The chain has only seen dyno time so it's basically new but by nature it does have some amount of slack. I tried a couple different degree methods over and over again but could never repeat the exact same number. I have a chain tensioner too but it still does not overcome that couple thousandths of movement.
I was able to prove the tolerance theory because at one point I went from a long-handle 1/2" ratchet on the crank to a long, solid 1/2" extension with a 90ยบ bend at the end. It's a home made tool I inherited a long time ago but I end up using it a lot. Consequently, the numbers got slightly more consistent because there was no ratchet gear slippage. It's almost imperceptible in your hand but it shows up on the degree wheel. Really, the only solution to eliminate those slight variations is to use a gear drive.
Unfortunately I failed to take pictures of the degree process but here is the aftermath. Yes, there was paperwork involved. Numbers and math too. Plus a lot of head scratching.
The next step in this rebuild process is to measure for pushrod length. I started by putting the driver's side cylinder head on which immediately presented another annoying problem. The front locating dowel was hammered and the top was mushroomed so the head would not go all the way down. Doh! This was another problem I ran into when the engine was first built but it was even worse this time.
The best thing to do would probably have been to pull the pin out and carefully install a new one but that's not my style. It was already ground down so it would have been a nightmare to get out. Instead, I carefully whittled it down some more so it would fit. Truthfully, the dowel hole on the head was a little tight which compounded the issue. I reamed it out with some sandpaper but that was minimal, don't want the pin to be swimming in that hole.
I put tape over the bores to prevent any shavings from going down into them. Dyekem was painted over the pin and I'd set the head down on it and tap it so there was some force acting on it and pull it off. The bluing would show where it needed to be filed. Took many rounds of careful filing but it finally went all the way down. What a PITA. Next time I'll take the pin out. I didn't take any pics of the dowel pin fiasco because I was so pissed at having to deal with such an annoying thing.
More to come.
