Author Topic: timing belt conversion on youtube  (Read 788 times)

gadget

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timing belt conversion on youtube
« on: December 04, 2020, 07:21:20 PM »
Anyone seen this mod or something like this? Looks like maybe a custom camshaft or is the housing removed to mount a belt drive sprocket on the end of the camshaft? Apparently this guy got tired of dealing with his idler breaking;

https://www.youtube.com/watch?v=NlXTeF0wOts


BruceM

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Re: timing belt conversion on youtube
« Reply #1 on: December 08, 2020, 07:50:12 PM »
An impressive timing belt conversion project.

The idler failure was sorted out by Dave (XYZer) over a decade ago. He found that errors in the idler gear bolt location where consistently causing grossly excessive gear lash.  Once people corrected that by offset idler bolts, which Dave most graciously had made in a variety of offsets, there has never been gear failure reported on any idler lash-corrected engine.  That was during the heyday of US listeroid/clone imports.




32 coupe

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Re: timing belt conversion on youtube
« Reply #2 on: December 09, 2020, 12:41:48 AM »
An impressive timing belt conversion project.

The idler failure was sorted out by Dave (XYZer) over a decade ago. He found that errors in the idler gear bolt location where consistently causing grossly excessive gear lash.  Once people corrected that by offset idler bolts, which Dave most graciously had made in a variety of offsets, there has never been gear failure reported on any idler lash-corrected engine.  That was during the heyday of US listeroid/clone imports.

Well said.
That and bronze gears.



« Last Edit: December 09, 2020, 12:45:15 AM by 32 coupe »
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gadget

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Re: timing belt conversion on youtube
« Reply #3 on: December 10, 2020, 03:59:49 AM »
An impressive timing belt conversion project.

The idler failure was sorted out by Dave (XYZer) over a decade ago. He found that errors in the idler gear bolt location where consistently causing grossly excessive gear lash.  Once people corrected that by offset idler bolts, which Dave most graciously had made in a variety of offsets, there has never been gear failure reported on any idler lash-corrected engine.  That was during the heyday of US listeroid/clone imports.

Well that is good news for us newbies. My 8/1 is still apart in my garage waiting for some free time to reassemble after I have given it its initial cleaning and painting. I checked my backlash and noticed it was maybe .010-.020 one way, and when I rotated it 90 degrees, It was tight. I'm guessing one of my gears is egg shaped.

BruceM

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Re: timing belt conversion on youtube
« Reply #4 on: December 10, 2020, 04:10:04 AM »
I don't believe tight gear lash or out of round gears have ever been reported here before.  Perhaps valve train pressure tricked you. Your finding certainly warrants careful checking.  Anything is possible in a Rajkot made engine.
« Last Edit: December 10, 2020, 04:13:17 AM by BruceM »

38ac

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Re: timing belt conversion on youtube
« Reply #5 on: December 10, 2020, 11:07:08 AM »
. "I'm guessing one of my gears is egg shaped."

assuming you had no valve spring load on the camshaft when you checked it is more likely the camshaft is bent or the cam gear was knocked crooked when the pin was driven in.
I am no fan of bronze gears. As Bruce said the fix is correcting the lash,  not a soft gear.
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32 coupe

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Re: timing belt conversion on youtube
« Reply #6 on: December 10, 2020, 02:02:34 PM »


I like the bronze gears, after the problem is located
and rectified.
I have made several offset bolts with success.

Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
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BruceM

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Re: timing belt conversion on youtube
« Reply #7 on: December 10, 2020, 07:20:59 PM »
38ac's advice on the CS listeroid/clone camshaft being bent (by Rajkot's "sledge that tapered pin after boring hole off axis") is right on the mark. I found it in the 1st clone camshaft I checked via dial gauge and hardwood vee blocks on my cast iron saw table deck. This just after he posted great info on this issue  about 5 years ago.  My intent here is just to amplify his understated advice for newbies.

32coupe made a very nicely turned offset idler bolt for my neighbor's 8/1 propane conversion.  A great kindness!
That engine has been working hard and trouble free as an off grid power and air compressor for 4.5 years now.

gadget

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Re: timing belt conversion on youtube
« Reply #8 on: December 12, 2020, 04:18:03 PM »
My 8/1 parts are boxed up at the moment and it will be a while before I can check again.  I had to move everything out of the shop I was working in last spring and haven't had any free time since.

There was also mention that the problem with excessive back lash is the snap back from the camshaft from exhaust valve going down to intake opening? Is there not any valve over lap on these motors or maybe some wrong lobe placement? I guess it could also be during intake closure or the injection lobe.

It seems like poorly made camshafts are a problem source on these motors. I'm curious to test the valve timing on my camshaft.

38ac

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Re: timing belt conversion on youtube
« Reply #9 on: December 12, 2020, 07:37:31 PM »
The lash problem has nothing to due with overlap, although there is overlap in a CS cam. Every revolution of a CS type cam the direction of force on the teeth changes 6 times, pushing the valves open and then the springs pushing them shut, same with the fuel pump. A small amount of extra lash multiplies the excelleration, aka gear bang by many times.  Extra lash is what breaks the gears, not inferior gear metal. This problem exists in the Lister built engines also. I have one in the shop with gear issues and it sure isn't the first one.

 
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32 coupe

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Re: timing belt conversion on youtube
« Reply #10 on: December 12, 2020, 10:05:46 PM »

Butch,
That is interesting.  I didn't think those problems would exist in the original Listers. I must
admit I have never seen an original Lister.

So is the "fix" the same as the clones ? Offset ider bolt ?
Just curious.

Gary

Metro 6/1 turning a ST 7.5 KW gen head
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38ac

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Re: timing belt conversion on youtube
« Reply #11 on: December 13, 2020, 01:36:11 AM »
The Listers have the idler bolt properly located. While history of operation seldom comes with the engines that see my shop it's a pretty easy guess what happens. The gears wear over the years and when they reach that critical point of excessive lash and accerations the  forces break the gears. Much more common in the twins but singles suffer to a lessor extent also.
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32 coupe

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Re: timing belt conversion on youtube
« Reply #12 on: December 13, 2020, 08:32:51 PM »

I keep forgetting about the "slapback" in the gear train.

I remember a fellow here awhile ago that posted a pic of a bronze gear with the teeth worn to a razor edge.

That appeared to be a definite case of the idler bolt being in the wrong location. Funny thing is I offered to
send him an offset bolt but he never got back with me.

I think the list of problems with the clones is endless. That is the reason when I got my twin I didn't even
try to run it. It was completely torn down and rebuilt.

On my twin the bore for center carrier in the block for the cam was large enough for excessive play. I repaired
that with a brass shim that wrapped around the carrier  I JB welded in the block. I used material that gave
the carrier a snug fit when in place. A pin holds the carrier in place and it seems to be fine so far. I haven't
run the engine much ( maybe 75 hours or so ) so I guess time will tell.

Again, on the clones everything has to be checked. One of the heads on the twin had the valve guides reversed !
And yes they are different.


Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

38ac

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Re: timing belt conversion on youtube
« Reply #13 on: December 13, 2020, 09:39:41 PM »



I think the list of problems with the clones is endless.

No way!  They all come with a sticker that says PASSED??????
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gadget

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Re: timing belt conversion on youtube
« Reply #14 on: December 13, 2020, 10:54:32 PM »



I think the list of problems with the clones is endless.

No way!  They all come with a sticker that says PASSED??????

I picked up an 8/1 "KIT" last year from D.E. Tore it apart and hot soaked. Blocked looked pretty good, no holes! Found I had a steel piston and used cylinder bore. Also, one of my lifters has an unusual chatter type pattern on the face surface. Also, my back lash feels way off. Everything else passes visual inspection

I ended up going with one of their stamford type gen heads. I figured I would have enough on my plate getting the lister polished and just wanted a turn key gen head. It looks really well built!



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