User Login    
 + Register
  • Main navigation
Login
Username:

Password:


Lost Password?

Register now!
Fast Search
Slow Search
Google Ad



Browsing this Thread:   1 Anonymous Users





A15 block decking
Home away from home
Joined:
2015/11/10 17:48
From Fort Worth, Texas
Group:
Registered Users
Posts: 206
Offline
Its been a while since I have posted. Finally got my engine back from the machine shop. I noticed the engine block deck is pitted in certain areas. Do I need to deck the block or will the head gasket take care of any imperfections? Machine shop never brought it up to me and I didnt notice it till I set it on the engine stand. Also need to find a supplier for piston rings and bearings. Piston bores were within tolerance as well as the crankshaft. Block was not hot tanked so that I could reuse the cam bearings. One of the images (A15block4) shows a brass plug in the center. This is stock from the factory or was the block modified?

Attach file:



jpg  A15block.jpg (86.10 KB)
20677_57550171036fa.jpg 1088X816 px

jpg  A15block1.jpg (61.33 KB)
20677_5755017ee2995.jpg 816X612 px

jpg  A15block2.jpg (42.55 KB)
20677_575501892af41.jpg 816X612 px

jpg  A15block3.jpg (13.78 KB)
20677_575501933d14f.jpg 408X306 px

jpg  A15block4.jpg (46.54 KB)
20677_5755021664e0d.jpg 1088X816 px

Posted on: 2016/6/6 5:57
Transfer the post to other applications Transfer


Re: A15 block decking
No life (a.k.a. DattoMaster)
Joined:
2003/12/3 7:56
From Christchurch NZ
Group:
Registered Users
Posts: 3704
Offline
It will probably be alright.

Might just be a trick of the light, but the honing marks look quite horizontal?

Posted on: 2016/6/6 10:29
_________________
Forced Induction!
Because everyone knows you don't bring a knife to a gunfight!
Transfer the post to other applications Transfer


Re: A15 block decking
Home away from home
Joined:
2015/11/10 17:48
From Fort Worth, Texas
Group:
Registered Users
Posts: 206
Offline
You got me thinking about the machine work quality. Here are some closer images of the bore. I spoke with another machine shop and they said a hone should be about 33 degrees. If the angle is too much, then the oil may find its way down thru those hone marks. The images do show a slight angle. I'm not an expert here so any additional feedback is welcome. Thanks for bringing this to my attention.

Attach file:



jpg  Engine bore.jpg (69.89 KB)
20677_5755beb618ebd.jpg 1088X816 px

jpg  Engine bore1.jpg (86.42 KB)
20677_5755bec59a9c2.jpg 1088X816 px

Posted on: 2016/6/6 19:20
Transfer the post to other applications Transfer


Re: A15 block decking
Home away from home
Joined:
2015/11/10 17:48
From Fort Worth, Texas
Group:
Registered Users
Posts: 206
Offline
I found this on the Ratsun Forum regarding cross hatching:

CROSS HATCH ANGLES

The correct angle for cross hatch lines to intersect is approximately 45 degrees. Too steep an angle promotes oil migration down the cylinder resulting in a thin oil film which can cause ring and cylinder scufflng.
Too flat a cross hatch angle can hold excess oil which conversely causes thicker oil films which the piston rings will ride up on or hydroplane. Excessive oil consumption will result.
The diagrams will illustrate cross hatch angles.

My honing looks more like the "Too Flat" image. Is this something to have redone with the 45 degrees if that's possible after its been honed already? Any comments are welcome.

Attach file:



jpg  cross hatches.jpg (11.22 KB)
20677_5755ec00001b7.jpg 450X194 px

Posted on: 2016/6/6 22:36
Transfer the post to other applications Transfer


Re: A15 block decking
Moderator
Joined:
2001/5/3 7:04
From Gone to Maui
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31390
Offline
The block deck looks fine to me

Yes, most engine builders say 45 degrees. I think a flatter 30 degrees is fine too, just don't go flatter than 30. Whether it can re-honed depends on the measurements of your pistons, use a ball-hone for least wear and aim for 0.0009-0.0017" piston-to-bore clearance (Nissan factory specification).

Be sure to clean the honing with soapy suds before assembling the pistons. Honing leaves metal particles that need to be removed

Posted on: 2016/6/6 23:28
Transfer the post to other applications Transfer


Re: A15 block decking
Home away from home
Joined:
2015/11/10 17:48
From Fort Worth, Texas
Group:
Registered Users
Posts: 206
Offline
Thanks DD. So based on the two close up images I should rehone it to get closer to 45 degrees?

Posted on: 2016/6/7 2:02
Transfer the post to other applications Transfer


Re: A15 block decking
No life (a.k.a. DattoMaster)
Joined:
2002/10/28 6:49
From on my stationary Earth @ 0 km/h
Group:
Registered Users
Posts: 10857
Offline
texans out of all peeps have access to deck reclamation technology as used by farmers
just in case you go too far :)

Posted on: 2016/6/7 13:51
_________________
"Australia" is formed by all its geographically listed territories on official maps "including" Norfolk, Christmas and Cocos Islands. The word include excludes all else before it therefore you have no rights in Terra Australis
Transfer the post to other applications Transfer


Re: A15 block decking
Home away from home
Joined:
2010/3/20 12:20
From Sydney Australia
Group:
Registered Users
Posts: 238
Offline
Hint having been an engine machinist in the past this is how we did it and why.

We were given 6 months use of a fancy boring bar machine much like a vertical mill out of Italy, the long column we found allowed the machine to chatter with the result we needed to leave about 4 thou and finish hone on the sunnen honing machine to make sure there were no boring marks left,the increased cost of hone stones meant we went back to our old original setup.

With either method because of the heat involved in boring you did say cylinder one then cylinder three then allowed it to cool before doing the remaining cylinders so the heat from machining did not adversely affect the next bore

The original setup was a strap on Van Norman boring bar but we also had a jig for the mill which we clamped the block onto the main bearing tunnel and then refaced the top of the block which the portable boring bar sat on when installed.

By doing it that way the bores were guaranteed to be square to the crank line, We had a fresh surface for the gasket to seal on and because the strap on did not vibrate like the vertical mill style boring bar the finish was so much better we only needed to leave one thou for finish honing and had no boring marks left to deal with, Sometimes the older methods and machines are better when used correctly compared to high throughput modern methods.

Yes it was quicker to just mount the block on the pan rails and just wind the table along to do each bore but it was neither as accurate nor cost effective in the long run, These are pertinent questions to ask your machinist when getting any engine bored is does make a difference when everything is as per design blueprints and the bore and block deck are all square to the crank.

Posted on: 2016/7/10 0:23
Transfer the post to other applications Transfer






You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.

[Advanced Search]