LA 360: Replacing the harmonic balancer...

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7milesout

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After this weekend, the Scamp will go back up on the auto-dollies, for some TLC. It's a 1972 Plymouth Scamp with a 360 & 727.

I can't set the timing because the weights / timing marker has slipped on the harmonic balancer. The car does run good. But it makes me nervous to not have the timing checked / set. And that's another thing. I'm told the cam is a 268, but I have yet to find timing settings based on that cam. I already have a replacement harmonic balancer provided by the previous owner. The smartest guy I know, so I have faith that it is the correct HB.

I'm imagining doing this job, removing the nut, pulling the existing HB off, etc. A couple questions:
  • Won't the engine turn as I'm trying to back that nut off? If so, how do I brace the engine?
  • I've not done this work before. I'm guessing I will at least have to remove the fan to get a wrench / socket on the nut. There's no fan shroud (yet) so I think it may be just the fan removal. Is that correct?
  • Are there timing tables I can refer to, in order to know the optimal timing to set?

7milesout
 
if the engine is trying to turn while you trying to remove the bolt that removes the damper....try this...get your breaker bar with socket on it so that the breaker bar is against the frame of the car or the ground...then hit the starter...should bust nut loose..

you can do it without removing the fan...
 
You will need to remove the fan blade and belts because you need to remove the crankshaft pulley. I was able to get the bolt loose with an impact wrench. Otherwise pull the starter and jam the flywheel with something.
Edit: at least I didn't have room to reach it with the fan mounted. Yours may be different
 
Another way to hold the crank is to remove the inspection cover behind the oil pan and wedge a tapered block of wood in-between the ring gear and bellhousing.

It will take a lot of torque to remove that bolt. And the torque when installing is 135 ft lbs.... a LOT. Applying that amount of torque is very important to make the damper actually damp the internal crank vibrations properly.

You will need a puller to pull off the damper and longer bolt to start to pull the new one onto the crank. Those things usually mean pulling the rad.

And yeah, replace this right away before the outer ring flies off and creates some REAL havoc in the engine bay!
 
70aarcuda - That was amazing advice. I put my torque wrench (it worked better than a breaker bar) on the nut, and some rags under the handle and against the body of the car. I had my son bump the starter a couple times. It was so easy, I can't believe it worked so slick. You guys are amazing. And the rest of the job went very smooth. The HB is off now, and tomorrow or the next couple days I'll get the new one put on. I know the HB bolt is 135 lb-ft, does anyone know the torque for the pulley bolts?
 
Use an impact gun. If you say "I dont have one" or "I dont have an air compressor? then what the hell are you doing working on an old car? No offense, but those items are must haves for people who own old cars.

It is a VERY simple procedure with all the correct tools.
 
If you say "I dont have one" or "I dont have an air compressor? then what the hell are you doing working on an old car? [/QUOTE] Hey a$$ wipe, he is already past that & iirc you gave me a scalding half page reply for no good reason back when I first joined. Just to make sure I got the right guy, some one n here commented (when that transpired) that you were a boat/naval officer or something similar & that alot of those guys are like that, yeah right.
 
Rapid Robert said:
If you say "I dont have one" or "I dont have an air compressor? then what the hell are you doing working on an old car?
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Hey a$$ wipe, he is already past that & iirc you gave me a scalding half page reply for no good reason back when I first joined. Just to make sure I got the right guy, some one n here commented (when that transpired) that you were a boat/naval officer or something similar & that alot of those guys are like that, yeah right.[/QUOTE]

Wrong guy. I've never served.
 
Thanks Robert. I am/was thinking the same thing. It's easy to go off on someone a bit prematurely as I think Rusty did. I don't feel compelled to load any more information into a post that what I think is necessary. I don't need to layout the tool schedule in my garage, as well as its floor plan. I actually have both tool mentioned. It's only an electric impact, but it has removed everything I've asked of it. And I have an air tank / compressor that would make some paint shops jealous.

But I have NO RUSH to do what I need to do to this car. So if I get ready to do something, and I don't have what I need, I shall procure it, or I shall improvise.

In this case, I doubt the impact wrench would have fit without first removing the radiator. And I'd rather not. I see NOTHING WRONG with improvising. Which I consider bumping the starter with a breaker bar on the nut, not just improvising BUT BRILLIANT. It worked like a charm, I think if a vehicle's available room and layout in this area would allow for it, you'd be a bigger fool to do it any other way.

But I was also very cautious, I removed all belts (of course) and bumped it a few times with nothing on it to make sure nothing additional was going to happen that I wasn't account for. It was just so ingenious, that is the power of these forums. And I give a big salute to you guys for offering the idea up.

Moving on ... I was going to go ahead and put the new HB on, but I was thinking about timing tape. And it occurred to me ... why don't I put the timing tape on the new HB *BEFORE* I install it? Duh. So I held off putting the new one on. I'm in no rush. So, today on the way home I'm going to pick up timing tape for a 7.1" O.D. HB.

What bugs me now is, I've read that even the new HB's TDC marker may not be exactly accurate. So, I'm kinking around the idea of doing the #1 piston TDC locator process, and scribing the new HB, and using those scribe marks to locate TDC on the new HB.

What do you guys think about that? Is doing that a waste of time?


7milesout
 
"Which I consider bumping the starter with a breaker bar on the nut, not just improvising BUT BRILLIANT. It worked like a charm, I think if a vehicle's available room and layout in this area would allow for it, you'd be a bigger fool to do it any other way."


I was so Brilliant was I was a young boy, My Mother call be Son.........
 
7milesout said:
What bugs me now is, I've read that even the new HB's TDC marker may not be exactly accurate. So, I'm kinking around the idea of doing the #1 piston TDC locator process, and scribing the new HB, and using those scribe marks to locate TDC on the new HB.
Click to expand...
Your're spot on in doing it this way. You need to know the TDC is very accurate as it will be a baseline for a lot of other work that you do... like ignition timing.
 
So, I'm kinking around the idea of doing the #1 piston TDC locator process, and scribing the new HB, and using those scribe marks to locate TDC on the new HB. What do you guys think about that? Is doing that a waste of time?
Click to expand...
Not a waste of time at all & in fact it is one of the solid "basics" that should never be omitted especially since as you noted that quality control on aftermarket parts is questionable & in fact you might even check the timing tape. dia X 3.1416" gives the circumference then 360 divided into the circumference gives the dimention for (1) degree. If desired you can confirm TDC & omit the tape then make 4 or 5 paint marks on the dampener for say 15/17.5/20 and your total with the can capped (35 is a good SB #). if you use the timing tape clean the surface well then stick it on then spray it with clear lacquer & let it dry well cuz they have a tendency to fly off & need extra glueing. EDIT diameter is 7.25". (1) degree is 0.0632683" around the dampener circumference.
 
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Well - I finally got what I needed, plus time to do it, and made some progress. Last night I put the new HB on and tightened it only enough to get the engine to turn. But that amount of tightening drove the HB far enough on, I'm going to have to borrow the puller again. But it should pull off really easy. I made the marks last night.

Tonight I will make the center / 0° mark and apply the tape. I've got some "gel" superglue, so I'll add a few dabs to hold it in place.

It was slick to break the bolt loose with the starter, but who's going to tell me a SLICK means to hold the engine still so I can achieve 135 lb-ft, when torqueing that bolt back in place? :D
 
back a piston down slightly a bit from TDC compression (you want the valves closed) & feed some white nylon 3/8 rope into the cyl then bring the piston up till it locks then torque away. Or use you TDC tool in the plug hole & I always use one of those colored vac caps on the end of it to protect the piston. Ace hardware has em for pennies each, they are called "thread protectors" red/yellow/black/green for the different sizes (mine was yellow)
 
I reckon I'll go get a thread protector (Home Depot has them, hopefully in the correct size though), and do it that way. Doing via the TDC tool, I don't have to figure out where the valves are. Right?
 
7milesout said:
I reckon I'll go get a thread protector (Home Depot has them, hopefully in the correct size though), and do it that way. Doing via the TDC tool, I don't have to figure out where the valves are. Right?
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Yes no worries on valves with the tool. Yeah a guy mentioned once that potentially a piece of the rope could get wedged between a valve & its seat so I figured I'd better toss that in. For my tool a yellow cap was the right size & I'm sure HD has something, I'd take it in with you. Actually if you went real easy with turning the crank it ain't likely you will make a sharp ding in the piston top which could be a preignition point but I just like to be proactive (Mr Murphy is ALWAYS lurking nearby in this hobby).
 
Rapid Robert said:
Yes no worries on valves with the tool.
Click to expand...

Again, brilliant. I went and got the TDC bolt condom, worked slick as could be. HB installed, to 135 lb-ft. Crank pulley installed, 6 bolts to 17 lb-ft. Belts, they look really good, so I reinstalled them. Spark plugs reinstalled to 20 - 21 lb-ft. All but 1 are indexed (not a big deal to index them, but why not). Fan reinstalled, no room for the torque wrench dagnabbit, or they would have got 17 lb-ft also. I am OCD about torqueing properly.

If I have time tonight, I'm going to put the timing light on it and see where it is.


7milesout
 
Not to fret you but.... I would not ever think of using a piston stop on a piston to reach that torque level on the crankshaft. 135 ft-lbs on the crank will require many, many times that number of lbs on top of the piston near TDC to create 135 ft-lbs in the opposite direction. The rod and piston body will take it, but that is a lot of concentrated force at one point on the piston top.
 
That is very risky! Cracking the piston is highly likely!:eek: so it is best to find method of holding motor from turning. Maybe @ the converter ring gear?:popcorn:
 
Hey nm9stheham & QuickDart - Thanks for the concern, but you guys are too late. I torqued using the suggestion to hold the piston. But before I did so, I considered EXACTLY the things you guys mentioned. I figured that if I held the piston very close to TDC, the leverage from the crank would be enormous. So I would be better off to torque the HB with the piston at mid-stroke. The best I could do though was to insert the TDC tool, and run it down as far as it would go. I did that, and checked the position of the piston on the timing tape. I want to say it was at about 35° BTDC. That was good enough for me. So I did it. It worked. When I pulled the TDC tool out, I check the tip. It had some carbon on it, but it wiped off easily. So my thought was that as easy as that carbon wiped off, I likely didn't do anything detrimental.

And since finishing that, I've cranked it up (ran fine) and set the timing. I came back here (now) to post about that (the timing). See below. I post it because if you guys think I would be better setting the timing differently ... I'm all ears.

I found the initial timing running at ~18° BTDC. The P.O. had just set it by ear due to the slippage on the original HB. I set it to ~8° BTDC. And with mechanical advance it tops out right at 35° BTDC. About perfect, at least based on a stock engine.

I will say it seems like there is less vibration with the engine (I don't think I'm just imagining it), it starts easier now, and when I'm cruising, it just "feels" more free. Meaning, every little slight push on the throttle, and it responds very linearly. It seemed to be held back before. Almost as if when you're in your car pulling a moderate grade, and you give it a slight bit more throttle, and you barely feel any gain in power. That's how it felt before. And while I was out in it Friday night, I topped off the fuel tank. Previous tank 11 mpg. I'll come post here one more time, but I expect the mpg will increase. And now, when flooring it, no pre-ignition noise!

The replacement of the HB, and setting the timing seems like a complete success. Thanks to you guys with the GREAT advice.

I am now changing gears ... this coming week I'm going to get the wiring of the tach straightened out (have a thread on FABO going for that). It's been a while since I messed with it, but now, I have a plan set. The current wiring is jacked-up, but I'll save that info for that thread. And as soon as possible, I'm redoing the ENTIRE exhaust. I have a thread started for that as well here on FABO. While replacing the whole exhaust, I'm going to weld in a bung for a wideband and dial in the carb once the exhaust is finished.

Gonna have this thing running SWEEEEEET. I've already had a guy come up to me at the bmx track and said, "I took a picture of your car and texted it to a buddy ... he's going nuts blowing my phone up asking me to ask you if you'd sell it..." It is quite a nice car. I want it to crank and drive as close to a daily driver as it can be. Not that I will daily drive it (I won't), but I don't want a hassle for 20 more hp. Give me an enjoyable experience, and I'll spend my time fixing all the small imperfections and just have one SWEET ride.


7milesout
 
Glad it is all working well. Interesting that less advance on the ignition timing seems to be more responsive.....it is usually the other way. But, I suspect the timing was kinda unknown before.

FYI, the vibrations that the damper damps is something you will never feel; they are torsional vibrations, where the crank is twisting back and forth internally. The frequency is very high. But of the rubber is rotted and the damper ring shifts around, then the original balance of the damper gets thrown out of whack and THAT you may feel.

Sounds like you have a good plan for making things better and better!
 
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