Author Topic: Camshaft Adjustment  (Read 5065 times)

guest23477

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Camshaft Adjustment
« on: November 01, 2014, 02:52:43 AM »
Good evening,

I am somewhat new here, have been a member for a while, mostly read and when I have an issue I search the forum
and normally find the answer. This may end up as a double post, my first attempt failed for some reason, I checked back
and do not see it here so I'll try again.

As I said, I new to posting but NOT new to these engines, but I am still learning after 10 years of messing with these
things. I have several engines ......a 6/1 .....8/1's and a 16/2. Today I brought home an 8/1 Powerline that has been
at my mountain getaway for a few years ....has about 650 hours on it. I figured I would bring it to my hanger/shop and
look it over this winter. It Runs great but in all that time the intake lifter has never rotated well. I can spin it with my fingers
while running and it will turn about 3 revolutions and stop, it does seem to rotate back and forth about 20 degrees ......just
sort of jumps back and forth. It wants to rotate ......and I want it too ...lol.

As with my other engines I always pull and polish the faces of the tappets before start-up .......gets rid of the ugly finish
from the assemblers ......and because I cannot measure any real wear on the lobes I believe this helped. I have enough parts
to rebuild several of these engine ......and I compared a new camshaft to the one in the engine, made measurements and
find almost no wear and lobe placement is the same. I compared it to my 6/1 in which both tappets spin like crazy!

Upon closer inspection it seems my camshaft is shifted about .010 away from the IP roller lifter side of the engine. I think I need
to shift the camshaft towards the IP side of the engine to center the pump lobe, and I believe this would also offset the intake
cam lobe just enough to cause reliable rotation.   

Can anyone share their experience on this? The fix seems straight forward but would like to hear from others before I proceed.

Like I said the wear is not the issue ......I just want the dang intake tappet to rotate!! I read somewhere here where simply flipping
the locking collar on the opposite end of the cam could provide some offset, I may have to get some shims and solve the
problem that way. I'm sure whatever the mood of the day at assembly is where the hole was drilled in the camshaft and collar .....

This is the only engine I have NOT been able to solve this issue with ........thoughts??

Thanks for your time,

Les

cujet

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Re: Camshaft Adjustment
« Reply #1 on: November 01, 2014, 04:53:23 PM »
On my twin, I machined all the tappets flat, checked the camshaft lobe position, assembled and hoped for the best. All tappets rotated. However, after some time, one tappet is a bit reluctant to rotate. Turning the tappet guide helps. As they really are not machined with precision and even tiny differences can help.

Also, stretching an "O" Ring between the tappets to act as a rubber band/drive helps them rotate too. I'd guess that as long as the rubber band is not too tight, wear won't be affected much.

EDIT: The lobes should be slightly off center to facilitate rotation. That's the reason one of mine rotates slower. It's respective lobe is more centered.
« Last Edit: November 01, 2014, 04:55:40 PM by cujet »
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guest23477

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Re: Camshaft Adjustment
« Reply #2 on: November 01, 2014, 09:45:32 PM »
Thanks Cujet, that is my take on it as well. I completely understand how and why
these rotate, I sooooo HATE to disassemble this engine, it absolutely does NOT leak
anywhere .....starts on the first spin even when it's 25 degrees out ........and has been
completely reliable since 2009! It runs at 825 rpm and is very smooth .......

The tappets look good, the guides are good. Nothing like any of the horror stories I've
heard about .....I remember checking them while chucked up in my lathe .....everything
was round and ran true! I guess I did NOT notice the camshaft issue, I did not completely
disassemble the engine when it was new .......nothing during the inspection process
indicated I needed to ......

I have a good parts stock, I thought about just swapping the camshaft out but I have
never been the type to throw parts at things unless I see a reason. I thought I might
find some lobe wear for that tappet .......but there is none to speak of. When the engine
was new I did all the normal things prior to startup .......and one of them was to pull
and polish the tappet faces flat and to a good finish. It turns a 10KW generator head
4 to 6 hours a day during our visits to the mountains, and I change the oil every 3 or 4
months ...maybe 50 to 70 hours or so ......I've been happy with it!

I'm considering just letting it go .......and seeing how she does .......

My 16/2 at home is for backup use, it has gotten us through several hurricanes and
other power outages over the past 5 years, and all tappets spin very well! It also is
is of the Powerline brand .......has about 250 hours on it ........I have a small loadbank
that I check the health of the engine/gen a couple times a year .......best of all the
flipping tappets rotate ...lol. :laugh:

The camshaft needs to be shimmed about .010 towards the IP side of the engine,
fuel pump lobe is NOT perfectly centered under the tappet and that also does not
offset the lobe enough under the intake tappet to make it spin ......I was just hoping
someone else has already dealt with this .......will look on the McMasterCarr website for
some brass shims of a suitable size this week .......

Thanks for your thoughts .......

Fly level!

Les

xyzer

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Re: Camshaft Adjustment
« Reply #3 on: November 02, 2014, 12:57:28 AM »
Les,
I have done all of the recommended remidies and ended up with the same results. No reliable rotation! I did play with rotating the lifter guide and reclamping while the engine was running until I found the sweet spot that kept the rotation happening. I also learned the stamped sheetmetal clamp can easily be distorted from over tightening and apply hold down preasure to the inside of the guide causing the guide to tilt slightly with mushy gaskets. Your situation may vary.
Dave
Vidhata 6/1 portable
Power Solutions portable 6/1
Z482 KUBOTA

guest23477

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Re: Camshaft Adjustment
« Reply #4 on: November 03, 2014, 06:05:16 PM »
Xyzer,
Thanks for the reply, I'm thinking I just may leave this alone, does NOT
appear to be an actual issue at this point, no wear issues .....just my A-D-D
kicking in I think .....maybe I should just takes some meds for it .... ;D

By leaving it alone if I ever HAD to tear into it for some other reason I would
make the camshaft alignment correction. I know it's preferred the lifter
rotate ......but guess I'm making a problem when there isn't one .....guess
I'll get parts together and wait .......

Many thanks Dave!

Les
Helicycle, RV-4, 16/2, 8/1's, 6/1


 

listard-jp2

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Re: Camshaft Adjustment
« Reply #5 on: November 03, 2014, 07:52:11 PM »
Others on this forum have devised an offset bolt to adjust gear tooth backlash. Hence thinking along similar lines, it would not be difficult to modify the existing cam follower guide, so that the bore is eccentric respective to the locating diameter. This would then allow for the offset to be adjusted until the required degree of lifter rotation is obtained.

Fortunatly I own only genuine Lister CS engines, so do not have to rely on frigs such as this to correct manufacturing deviations ;D

buickanddeere

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Re: Camshaft Adjustment
« Reply #6 on: November 03, 2014, 10:47:33 PM »
  By the reports of these miss timed cams that have the lobes wedged or pinned together roughly in the correct location. It's not that expensive to send the cam to shops that re-grind cams for two cylinder Deere pulling tractors. 

guest23477

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Re: Camshaft Adjustment
« Reply #7 on: November 05, 2014, 03:47:50 AM »
Thanks for the input guys, and having a camshaft made is not out of the realm of possibilities for sure. Before I did something
like that I would first want to know that everything else was in good shape, straight and true .......I had a couple of custom cams
made for some experimental aircraft engines and the cost was surprisingly reasonable.

But, I have good news!

I decided I would pull the camshaft and try and correct the issue previously discovered (cam lobe not centered on IP tappet
roller). So yesterday I pulled the camshaft, and after some measurements I decided I would shim the camshaft 0.010 towards
the IP side of the block. I knocked out the pin on the camshaft collar, removed some material from the collar and then added
.010" shim to the inside of the engine/camshaft which line up the fuel pump tappet roller perfectly with the corresponding lobe!
I put a grade 8 bolt and lock nut back where the taper pin came out of the camshaft collar, so a camshaft should be a breeze
in the future. Some red locktite on the nut will assure it stays in place.

It did of course move the lobe under the intake lifter tappet as well .......good! So I checked for gear-train interference and found
that all looked good. I decided to get on the lathe and make two tools that fit the tappet guides that had a pin that would go
down and touch the corresponding camshaft lobes, the purpose was so that I could make some measurements and what I found
was that the intake guide was NOT vertical, it was a couple degress off from the vertical plane ........the shoulder of the tappet guide
was true and the bore was where it should be ........but the lifter is actually sitting sideways! I pulled the exhaust guide and put
a steel ruler across the block ......and in short I found a casting flaw with the block right where the tappet guides seat. The exhaust
side was straight and flat but the area around where the intake guides sits was not flat ......there was actually a low spot about halfway
around the hole in the block where the guide sits, back near the cylinder, with the guide in place you really did not see it. So the
intake tappet guide actually sat at a slight angle ........not flat like it should have.

So I could either make a custom guide that would correct the problem or fill the low area of the block.

I decided to remove all the paint and get down to good metal and lay down some filler, I used JB Weld and after heating the area
with an industrial heat gun so the JB Weld would thin out and flow evenly I filled the low area and let it cure overnight. Today I sanded it
and test fit the intake guide, it fit like it should, I re-inserted both guides then my two lifter pin tools and verified that the guides were now indeed
parallel with one another, I polished the tappets faces and I painted things and put every thing back together! You cannot tell this work was done!
I'm sure if I bead blasted the crankcase I would find lots of body filler .......but the JB Weld will be there forever!!

When I turned the engine over by hand the intake lifter now rotates about 75 degrees every time the tappet lifts ....YES! I exhaust side
spins a little faster but it does that on my other engines as well.

While I had the camshaft out I compared it to a NEW spare camshaft and there is no wear, I would have thought that with the tappet
face riding the cam lobe at an angle it would have worn the lobe face that way too .......but it did not! The lifter face barely had a mark
on it after 600+ hours (652 hours to be exact). I guess the low spring pressures, 800 rpms ...plus clean oil prevented that!

So anyway I ran it this afternoon for 2 hours with 4kw on it (I have a small suitcase load-bank) and I made several transitions to
5kw and it ran perfectly ....and both tappets spinning like all-get-out! I am satisfied.  ;D

So, I'm NOT sure if the camshaft adjustment made the tappet rotate or fixing the block so the tappet guide sat flat made it rotate. If I
had to guess it was fixing the block so the tappet sat correctly and allowed the tappet face to meet the cam lobe squarely. The camshaft
needed to be corrected ......so the IP tappet roller or cam lobe did not wear abnormally, so I'm giving credit to both!   ;)

Xyzer you sort of pointed at that very thing in your post ......thank you for the guidance.   

I have had great service from this engine for 650 hours, I'll be happy to get that many more!

Thanks for everyone's input and comments!

mauicole

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Re: Camshaft Adjustment
« Reply #8 on: November 14, 2014, 11:15:21 PM »
I like easiest, cheapest first... half gaskets are your friend.... 8)
1972 Lister SR1
DES 8/1 w/iron piston & 6/1 cam
1983 Ford F250 6.9L Diesel