Page 2 of 4

Re: Bill's 200 20v,cyl#2problem

PostPosted: Thu Mar 09, 2017 9:47 pm
by audios
At the advice of Marc ( and many others ) i brought the head to the machine shop in rochester. The friend who brought it down to them just called me to tell me that the head is cracked. I didnt have time to get all the details, but I am wondering if that cracking could have been causing what seemed to be blow-by...I will call tomorrow to find out more details on exactly what is wrong with the head and on which cylinders.

Re: Bill's 200 20v,cyl#2problem

PostPosted: Fri Mar 10, 2017 5:39 am
by WOMBAT
audios wrote:At the advice of Marc ( and many others ) i brought the head to the machine shop in rochester. The friend who brought it down to them just called me to tell me that the head is cracked. I didnt have time to get all the details, but I am wondering if that cracking could have been causing what seemed to be blow-by...I will call tomorrow to find out more details on exactly what is wrong with the head and on which cylinders.


I'm curious to know as well.... and where the crack is?

Re: Bill's 200 20v,cyl#2problem

PostPosted: Fri Mar 10, 2017 4:13 pm
by audios
Kevin at the shop didnt tell me where the crack is but did say that it wasn't leaking but still woudnt want to rebuild it with a crack, as they obviously dont get smaller only larger... i am sending him down my extra 7a head with a few bent valves so he can make 1 out of 2...

Re: Bill's 200 20v,cyl#2problem

PostPosted: Fri Mar 10, 2017 5:21 pm
by audifreakjim
Yeah, like the crack they all have between the valve seats.

Re: Bill's 200 20v,cyl#2problem

PostPosted: Fri Mar 10, 2017 5:39 pm
by audios
do you think that the head could be good still? this is the shop Marc sends all his heads to.... ill definately be bringing it back home to take a look when this is all over.

Re: Bill's 200 20v,cyl#2problem

PostPosted: Sat Mar 11, 2017 8:09 am
by WOMBAT
Or the somewhat typical crack by the spark plugs.

Re: Bill's 200 20v,cyl#2problem

PostPosted: Sat Mar 11, 2017 11:44 am
by audifreakjim
audios wrote:do you think that the head could be good still? this is the shop Marc sends all his heads to.... ill definately be bringing it back home to take a look when this is all over.


Have them show you the crack, if it's just between the valve seats then it's not too much of a worry. If they know the heads, then they are probably talking about a different crack.

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Wed May 03, 2017 10:21 am
by audios
audifreakjim wrote:
audios wrote:do you think that the head could be good still? this is the shop Marc sends all his heads to.... ill definately be bringing it back home to take a look when this is all over.


Have them show you the crack, if it's just between the valve seats then it's not too much of a worry. If they know the heads, then they are probably talking about a different crack.


Got the head back today, here is a photo of the crack. Anything to be concerned about?Image


Sent from my iPhone using Tapatalk

Bill's 200 20v,head crack evaluation??

PostPosted: Wed May 03, 2017 10:21 am
by audios
audifreakjim wrote:
audios wrote:do you think that the head could be good still? this is the shop Marc sends all his heads to.... ill definately be bringing it back home to take a look when this is all over.


Have them show you the crack, if it's just between the valve seats then it's not too much of a worry. If they know the heads, then they are probably talking about a different crack.


Got the head back today, here is a photo of the crack. Anything to be concerned about?

Image


Sent from my iPhone using Tapatalk

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Wed May 03, 2017 10:23 am
by dana
I think thats a pretty normal 20vt crack to me. I would run it, thats just me.

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Wed May 03, 2017 12:42 pm
by WOMBAT
dana wrote:I think thats a pretty normal 20vt crack to me. I would run it, thats just me.


That's a textbook 20v crack. Apparently I would run it :P

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Wed May 03, 2017 2:31 pm
by audios
I'm thinking I should put some valve guides in before I throw it back together? What about reusing a head gasket spacer?


Sent from my iPhone using Tapatalk

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Thu May 04, 2017 7:45 am
by WOMBAT
Definitely go guides and seals, I never did them. I'd go new HG too, but have heard some people reuse them a bit.

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Sat May 06, 2017 3:54 pm
by PRY4SNO
That crack is within the Bentley spec, which (*I think) is no more than 3 threads.

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Wed Sep 06, 2017 1:58 pm
by audios
Per the bently :

"When repairing cylinder heads, small cracks in the head between valve seats or valve seats and spark plug threads are permissible.
Cylinder heads showing such cracks can be reused without reducing engine service life or performance, providing cracks are small.
Cracks may not be larger than 0.5mm (0.019") or cracks in spark plug threads may not be longer than through first coil of threads."


when it refers to not being larger than .5mm is that the width or the length?

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Thu Sep 07, 2017 10:52 am
by audifreakjim
I think it's the width

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Fri Sep 08, 2017 8:19 am
by audios
the only other issue i have before sending the head back to get rebuilt is the statement ' may not be longer than through first coil of threads.' is that the first full coil? it definitely seems to go a bit deeper that that....

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Fri Sep 08, 2017 10:37 pm
by mrdeye
Fix crack before reinstalling. Crack is not going to get smaller. Yes, head is going to crack in other combustion chambers in same areas. Buy unceacked head in near future. Just me. Good luck with project! :beer:

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Mon Oct 02, 2017 7:40 pm
by audios
Image

Progress is slow but engine is on the stand@ my house, will tear into it soon....

Re: Bill's 200 20v,head crack evaluation??

PostPosted: Tue Oct 17, 2017 6:04 pm
by audios
finally got to start with piston #1 tonite. Here are some photos, does the bearing wear look normal? I noticed the top ring and the middle rings were almost on top of one another, could that have caused some of the blow by?
Image

Image

Image


the ring stuff im doing at my house but up at the farm the body is still waiting to come down. I put it on 4 wheels to get ready :) i miss it....

Image

Re: Bill's 200 20v, rebuild underway

PostPosted: Wed Oct 18, 2017 12:23 pm
by mushasho
Broken links everywhere...

Looks like you're using Google Photos...

Here's the trick... Select the pics you wanna share(hotlink) from your main Photos screen. Then "create a shareable album"... you could then hot link THOSE pics from the new album created...
It's just that by nature all Photo Pics are private.

Hope that helps

Re: Bill's 200 20v, rebuild underway

PostPosted: Wed Oct 18, 2017 5:04 pm
by audios
ok i tried, thanks for the tip.... here are some more pics of the piston/rod, LMK if they are visable....

Image

Image

Re: Bill's 200 20v, rebuild underway

PostPosted: Wed Oct 18, 2017 9:40 pm
by mushasho
yup... Visible... Might need to do the same for the previously posted pics tho

Re: Bill's 200 20v, rebuild underway

PostPosted: Thu Oct 19, 2017 6:21 am
by Marc
the ring orientation is certainly not proper, but I think you have a catch can layout problem as well.

Re: Bill's 200 20v, rebuild underway

PostPosted: Thu Oct 19, 2017 6:52 am
by dana
I get that rings are supposed to be oriented correctly when installing, but what is to keep them from turning around in the bore once running? Two stroke rings cannot move because the ends of the ring would snag the ports in the cylinder walls, so they put a little pin in the groove to keep them aligned. I always just figured rings on a 4 stroke move around at will??