Locked U20 5 speed and carbs

[SOUPY]

How about this....Loosen up all the rocker studs, remove the mouse trap springs and with a little pry bar on valve springs you can remove all the rockers! Don't forget to number them. Now you should be able to turn over engine slightly to get to your cam bolt stuck behind the evil L. And you won't do any more damage to rockers or cam. With all do respect to Gregs672000 and theunz, I would not take off the cam bearing caps and possibly warp cam or do other damage, or cut the timing chain! Good luck and keep us posted!

[david premo]

Just bend the L out of the way. Reach in from the top and bend it until you get enough clearance to take the bolt out of the cam. You could probably use a 10 or 12 inch adjustable wrench to bend it.
Dave

[redroadster]

Did you clean the engine internal parts? and was clean outside
Looks like a rebuilt eng. Maybe that didn't ever run , or siezed getting it running ? it had oil in it ?
see if the rods move back and forth
Play in crank thrust bearing ?

[mschel]

It had well used oil in it that was clean. I was trying to do the minimum teardown to free it up.

It does look pretty clean on the top end.

[Gregs672000]

Ok... you could try this first, but it probably wont give enough room, but it wont hurt anything...I'd first spray WD40 or similar on the cam lobes and let that soak in a little, back all the valve adjusters off as far as possible (takes some holding of the 19mm nut while you turn the 14mm until all the adjustment threads are not visible), pop the rocker springs off using a flat head screw driver to unhook them, then many of the rocker arms (numbered just in case) will slide or wiggle out... may need some leverage via a strong screwdriver pushing against the valve spring retainers and the cam. Remove the front tensioner inspection plate on the head, then use an extension and 10mm socket to remove the tensioner bolts and remove the tensioner (spring loaded). That will put slack in the chain and hopefully give you enough to rotate the cam to gain some space... maybe. Unfortunately it looks like the bolt couldn't be in a worse spot!

If that does not work, I'd see if the L would bend enough to allow removal, or cut the L off using a hack saw or thin cutting wheel where the L meets the head. As an aside, the L is known as the "evil L" as over time and due to a poor design it gets hit by the timing chain until it breaks off and destroys your engine (we have a fix for that). The solution in the past was to cut it off before that happens... mine was cut off 30 years ago. It's there to allow for easier head removal to keep the chains tight and in phase with the cam and crank, but there are other methods to do so and it's rarely used. The guides have also been remade so they can be replaced if desired. Or you could also cut the chain as it's best to replace them anyway as they stretch and we dont know how old it is (could compare replacement prices for either method via vendor's websites).

I also understand the concern about warping the cam, but I think things will be fine using the progressive removal of the cam caps so the cam is not being pushed hard by the springs in only one place (once the cam gear is off or chain is cut). With cam free of the chain, the springs will push hard enough to rotate the cam off those lobes, and with the other rockers removed or adjusted to full loose it will likely rotate enough by itself due to the tension until the cam pops free of the towers. As you are doing this, you may want to wiggle the cam a bit using vise grips or similar (unfortunately there is no designed spot for this unlike the later L-series cams... just clamp onto the middle of the cam)

In the long run I think the best method will be to cut the chain. Also, I have found a great spring compression tool to allow the removal and installation of the rockers with the head on the engine (often used on L-series engines) but I'm away from home for another 10 days and can't post a picture. I think I discussed it on some thread... I will see if I can find something on the internet or that post. Makes a big difference with my cam, may not be as important on a stock set up (?). Other options have been useless.

[mschel]

Thanks for all the detailed info. I might try cutting the L off.
I thought it had a mechanical purpose so was afraid to mess with it.


Will soak everything in penetrant regardless in case I need to pull the head apart later.

To me the chain looks very clean so trying to avoid cutting it for now.

Ok... you could try this first, but it probably wont give enough room, but it wont hurt anything...I'd first spray WD40 or similar on the cam lobes and let that soak in a little, back all the valve adjusters off as far as possible (takes some holding of the 19mm nut while you turn the 14mm until all the adjustment threads are not visible), pop the rocker springs off using a flat head screw driver to unhook them, then many of the rocker arms (numbered just in case) will slide or wiggle out... may need some leverage via a strong screwdriver pushing against the valve spring retainers and the cam. Remove the front tensioner inspection plate on the head, then use an extension and 10mm socket to remove the tensioner bolts and remove the tensioner (spring loaded). That will put slack in the chain and hopefully give you enough to rotate the cam to gain some space... maybe. Unfortunately it looks like the bolt couldn't be in a worse spot!

If that does not work, I'd see if the L would bend enough to allow removal, or cut the L off using a hack saw or thin cutting wheel where the L meets the head. As an aside, the L is known as the "evil L" as over time and due to a poor design it gets hit by the timing chain until it breaks off and destroys your engine (we have a fix for that). The solution in the past was to cut it off before that happens... mine was cut off 30 years ago. It's there to allow for easier head removal to keep the chains tight and in phase with the cam and crank, but there are other methods to do so and it's rarely used. The guides have also been remade so they can be replaced if desired. Or you could also cut the chain as it's best to replace them anyway as they stretch and we dont know how old it is (could compare replacement prices for either method via vendor's websites).

I also understand the concern about warping the cam, but I think things will be fine using the progressive removal of the cam caps so the cam is not being pushed hard by the springs in only one place (once the cam gear is off or chain is cut). With cam free of the chain, the springs will push hard enough to rotate the cam off those lobes, and with the other rockers removed or adjusted to full loose it will likely rotate enough by itself due to the tension until the cam pops free of the towers. As you are doing this, you may want to wiggle the cam a bit using vise grips or similar (unfortunately there is no designed spot for this unlike the later L-series cams... just clamp onto the middle of the cam)

In the long run I think the best method will be to cut the chain. Also, I have found a great spring compression tool to allow the removal and installation of the rockers with the head on the engine (often used on L-series engines) but I'm away from home for another 10 days and can't post a picture. I think I discussed it on some thread... I will see if I can find something on the internet or that post. Makes a big difference with my cam, may not be as important on a stock set up (?). Other options have been useless.

[Gregs672000]

Regarding the cam and rockers, it's almost certain that they will need to be at least surfaced, so I don't think you need to worry too much about some movement grinding away or doing a lot of damage to the lobes or rockers.

[Gregs672000]

With the L cut off it will be necessary to use a wedge to support the chain and hold it in place later on... do an internet search to see how that's done on an L-series engine.

[mschel]

Where is a good place to get that done if needed?

Ideal would be mid Atlantic area but could ship

Regarding the cam and rockers, it's almost certain that they will need to be at least surfaced, so I don't think you need to worry too much about some movement grinding away or doing a lot of damage to the lobes or rockers.

[mschel]

Will read up on it. Thanks.

With the L cut off it will be necessary to use a wedge to support the chain and hold it in place later on... do an internet search to see how that's done on an L-series engine.

[Gregs672000]

Only places I know are west coast as that's where I am... Isky cam in CA, and Delta Camshaft in Tacoma WA. Both are set up to do the rockers correctly if they need to be surfaced, and they have the specs for a B cam. Here's the link to the valve compression tool. It takes some configuration to work around the towers but it's a must have for me.

https://www.ebay.com/itm/394550621709?c ... 23EALw_wcB

[mschel]

Thanks, I think I read the owner of Isky cams was still grinding cams at like 100+ somewhere in the news.

Got the tool on order (found one on amazon with prime vs china) so should be here early next week.

Only places I know are west coast as that's where I am... Isky cam in CA, and Delta Camshaft in Tacoma WA. Both are set up to do the rockers correctly if they need to be surfaced, and they have the specs for a B cam. Here's the link to the valve compression tool. It takes some configuration to work around the towers but it's a must have for me.

https://www.ebay.com/itm/394550621709?c ... 23EALw_wcB

[Gregs672000]

When I get back home I'll post a picture of how you have to configure the tool to work around the towers and provide the leverage you need. It's a little fussy but it's the only tool I've found that works for the U20 with the head on.

[mschel]

Thanks, much appreciated.

When I get back home I'll post a picture of how you have to configure the tool to work around the towers and provide the leverage you need. It's a little fussy but it's the only tool I've found that works for the U20 with the head on.

[david premo]

The time chain wedge is only necessary for an engine that has a tensioner that cannot be accessed without the removal of the timing cover. All L series engines have this issue and has never been a problem with the U20 as it a twin chain engine. The tensioner for the upper chain is accessible through the cover on the cylinder head and therefore no need to wedge the chain. I used the put a piece of wire on the chain so it would not drop into the timing cover, but that’s not necessary as the timing gears on the jackshaft prevents it from dropping to the bottom of the cover. You can retrieve it with an extension magnet.
Dave