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> 2270 Deck Height and CR, Pistons sitting proud of the deck, how many shims is too many shims?
vjb206
post Feb 26 2024, 03:52 PM
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Hey folks! I have the bottom-end of my 2270 assembled and spinning freely. Thanks to all who helped me get to this point!

(IMG:http://www.914world.com/bbs2/uploads_offsite/media.giphy.com-23760-1708984357.1.gif)

To quickly recap: I bought the 2257 kit from AA Pistons (78mm stroke, 5.158" rods, etc.). And when I threw a P&C on for a test-fit last weekend, I immediately noticed the piston sitting proud of the deck height at TDC (negative deck) by about 2mm.

(IMG:http://www.914world.com/bbs2/uploads_offsite/media.giphy.com-23760-1708984358.2.gif)

Before I overreact, or buy the wrong stuff, I thought I'd ping the community...
  1. Is this normal for a stroker set-up?
  2. Can you stack multiple shims when getting up into the .06 >> .09 range?
  3. (If no-stack) What's the best place to have custom shims cut?
  4. I recall Jake saying using large shims requires lots of advance, anyone have experience here? What am I looking to adjust for upon start-up?

Once I figure out whether or not this is normal (I.E. verifying that I don't have to backtrack), I'll get into the CR questions (just waiting on clear plastic from Amazon so that I can measure my CC volume this weekend) (IMG:style_emoticons/default/biggrin.gif)

Thanks!
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MikeK
post Feb 27 2024, 12:16 PM
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You can shim the cylinder base, use a copper gasket from the head to the cylinder, trim the top of this piston (not the full amount), use a shorter rod, or use a combination of those things.

You might want to consider using some rubber bands across the head studs and through the small end of the rod to keep them from slapping the cylinder sealing surface while you spin it.
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Jack Standz
post Feb 27 2024, 01:03 PM
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QUOTE(MikeK @ Feb 28 2024, 01:16 AM) *

You can shim the cylinder base, use a copper gasket from the head to the cylinder, trim the top of this piston (not the full amount), use a shorter rod, or use a combination of those things.

You might want to consider using some rubber bands across the head studs and through the small end of the rod to keep them from slapping the cylinder sealing surface while you spin it.


Sorry, must disagree with some of this.

A copper gasket between the head and cylinder won't fix the problem of negative deck height. You'll break the motor on start up.

A shorter rod isn't a good idea (and what size/where would you get one?) as the rod ratio is already 1.68 and going to a shorter rod would decrease it even more.

Trimming the pistons might work, but would not be the first area to consider to fix the negative deck height problem. Start with correcting the other problems and get the proper shims made.
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vjb206   2270 Deck Height and CR   Feb 26 2024, 03:52 PM
Jack Standz   1. It's all in the combination, what pin heig...   Feb 26 2024, 08:23 PM
r_towle   Did you buy the long liners? I’m guessing those ...   Feb 26 2024, 08:32 PM
Jack Standz   Strokers are a lot of fun but also a lot more work...   Feb 26 2024, 08:38 PM
Krieger   Why don't you call AA and see what they have t...   Feb 27 2024, 12:16 AM
VaccaRabite   You are asking the wrong question. Stop everything...   Feb 27 2024, 06:54 AM
Montreal914   Read! Here, on Shoptalkforums, other places…...   Feb 27 2024, 11:30 AM
cgnj   @vjb206 That looks like my motor did. It is curr...   Feb 27 2024, 12:11 PM
MikeK   You can shim the cylinder base, use a copper gaske...   Feb 27 2024, 12:16 PM
Jack Standz   You can shim the cylinder base, use a copper gask...   Feb 27 2024, 01:03 PM
MikeK   You can shim the cylinder base, use a copper gas...   Feb 27 2024, 03:35 PM
vjb206   @MikeK great idea! Don't want any scoring...   Feb 27 2024, 01:02 PM
VaccaRabite   [b]@[url=http://www.914world.com/bbs2/index.php?...   Feb 29 2024, 07:08 AM
Jack Standz   There's more to the compression calculation an...   Feb 27 2024, 01:14 PM
cgnj   @vjb206 I lied somewhere. I said my chamber volum...   Feb 27 2024, 04:31 PM
r_towle   You need to swap the short cylinders with the long...   Feb 27 2024, 06:09 PM
densible1   You'll need to shim bottom of cylinder to achi...   Feb 27 2024, 06:23 PM
technicalninja   [b]@[url=http://www.914world.com/bbs2/index.php...   Feb 29 2024, 09:39 AM
Geezer914   Almost 1/4" of shims, isn't that a lot? ...   Feb 29 2024, 11:26 AM
Jack Standz   +1 Yes, agree with post #18 from the ninja above....   Feb 29 2024, 11:42 AM
technicalninja   I'm planning on re-using the original Mahle cy...   Feb 29 2024, 01:10 PM
vjb206   Did some measurements this weekend! http://ww...   Mar 5 2024, 09:01 PM
Superhawk996   Have you fully researched the use of head gaskets?...   Mar 5 2024, 11:03 PM
vjb206   Have you fully researched the use of head gaskets...   Mar 6 2024, 08:30 AM
930cabman   Have you fully researched the use of head gaskets...   Mar 6 2024, 10:09 AM
technicalninja   Did some measurements this weekend! [img]htt...   Mar 6 2024, 10:00 AM
technicalninja   I missed a critical point! Check deck height ...   Mar 6 2024, 10:38 AM
Montreal914   Detail in the grand scheme of things in the curren...   Mar 6 2024, 03:09 PM
r_towle   I think you need the longer cylinders from AA.   Mar 6 2024, 05:49 PM
Jack Standz   Did some measurements this weekend! [img]ht...   Mar 6 2024, 10:27 PM
vjb206   If I'm 90 under and get a 90 shim I'll be ...   Mar 7 2024, 03:16 PM
Superhawk996   Can / should multiple cyl base shims be stacked ...   Mar 7 2024, 06:58 PM
vjb206   Just going to do some more reading before pulling ...   Mar 7 2024, 09:16 PM
Jack Standz   I think you need the longer cylinders from AA. ...   Mar 6 2024, 10:35 PM
crash914   Also don't forget: Pushrods will not be stock....   Mar 7 2024, 12:22 PM
vjb206   Definitely planning on getting deep into the valve...   Mar 7 2024, 03:13 PM
930cabman   My vote goes to NO head gasket   Mar 7 2024, 03:24 PM
technicalninja   Proper quench distance is far more important than ...   Mar 7 2024, 10:44 PM
vjb206   Proper quench distance is far more important than...   Mar 18 2024, 06:40 PM
cgnj   @vjb206 I used a .140 shim. No head gasket. I la...   Mar 7 2024, 11:31 PM
vjb206   [b]@[url=http://www.914world.com/bbs2/index.php?s...   Mar 8 2024, 04:11 PM
Jack Standz   Proper quench distance is far more important than...   Mar 8 2024, 02:27 AM
VaccaRabite   I'd say that if you got 60cc measuring with yo...   Mar 8 2024, 12:25 PM
vjb206   I honestly never thought about the pushrod tube le...   Mar 8 2024, 04:11 PM
GBX0073   Rubber bands were mentioned found this picture to ...   Mar 10 2024, 12:14 AM
vjb206   Rubber bands were mentioned found this picture to...   Mar 18 2024, 06:35 PM
technicalninja   [quote name='cgnj' post='3132716' date='Mar 8 202...   Mar 10 2024, 12:26 PM
vjb206   [quote name='cgnj' post='3132716' date='Mar 8 20...   Mar 18 2024, 06:36 PM
vjb206   Just to close the loop here, I ordered a few shims...   Mar 19 2024, 08:18 AM
technicalninja   I'd run 9.5-10 on that cam. It's a good s...   Mar 19 2024, 08:46 AM
technicalninja   Watch for evidence of exhaust back pressure if you...   Mar 19 2024, 09:31 AM
burton73   Here is a picture of Marks 2270 RAT built 2005 Eng...   Mar 19 2024, 10:37 AM
cgnj   @vjb206 Based on your measurements, I think your ...   Mar 19 2024, 11:02 AM
burton73   Mark to show shim on the RAT rebuild 2270 Bob B   Mar 19 2024, 11:58 AM
technicalninja   OOOHHHH! Pretty pictures! Thanks Bob! ...   Mar 19 2024, 01:04 PM
Jack Standz   Yes, noticed that too. We run phenolic spacers w...   Mar 19 2024, 01:25 PM
cgnj   I cut my own gaskets. CSP linkage threaded rods to...   Mar 19 2024, 02:38 PM
burton73   The picture of intake port is from the moment of t...   Mar 19 2024, 03:15 PM
VaccaRabite   The Windage tray modification was a RAT deal in...   Mar 20 2024, 05:22 AM
technicalninja   When I'm "finished" with port matchi...   Mar 19 2024, 05:21 PM


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