Engine experts please chime in.
Thread Starter
Instructor
Joined: Aug 2004
Posts: 174
Likes: 0
From: Roskilde
Engine experts please chime in.
This engine came from T&L engines and has serious problem with detonation and strange sounds, we pulled one of the heads and found these issues:
Shouldn't the piston be square to the engineblock, there's a .011 difference on number 2 cylinder ?
this is cylinder 4 with less than 100 miles on it:
cylinder 2 when piston is at the top, notice the cylinderwall clearance:
when the piston is at the bottom at cylinder 2 it looks like this, the cylinderwall clearance looks bigger:
Shouldn't the piston be square to the engineblock, there's a .011 difference on number 2 cylinder ?
this is cylinder 4 with less than 100 miles on it:
cylinder 2 when piston is at the top, notice the cylinderwall clearance:
when the piston is at the bottom at cylinder 2 it looks like this, the cylinderwall clearance looks bigger:
Melting Slicks
Joined: Aug 2006
Posts: 3,429
Likes: 20
From: Kingston Ontario
I can see a slight difference top to bottom but there shouldn't be any side to side. If it looks like there's more gap when the piston is down maybe the taper is just way too much. What did T&L say about your situation?
Instructor
Joined: May 2009
Posts: 180
Likes: 1
From: Prairieville Louisiana
The piston crown is a usually a lil smaller than the skirt. If the block was not zero decked, it is normal for the piston to not come all the way to the top pf the cylinder. I dont see a problem in thses pics (IMO). BB72, I think the difference you see is looking at the reflection on the cylinder wall that you cant see when the piston is on top.
Last edited by Sho'nuff; Aug 14, 2009 at 01:24 PM.
Thread Starter
Instructor
Joined: Aug 2004
Posts: 174
Likes: 0
From: Roskilde
Instructor
Joined: May 2009
Posts: 180
Likes: 1
From: Prairieville Louisiana
If you mean the piston is .011 below the block surface, that is about normal. It will not be exactly the same if it hasn't been zero-decked. Check your T&L paperwork and see if they give you that measurement.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Um, that bottom picture looks more than a little wacky. Yes, pistons have slight barrel to them and they do rock in the bore, but the gap I'm seeing in that bottom pic looks crazy - it looks like you can see a good bit of the ring; is that what I'm seeing?
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Team Owner
Joined: Jan 2007
Posts: 53,648
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From: Southern Cal Ca
St. Jude Donor '22
I won't claim expert, I do not see evidence of detonation.
I do see a dirty assembled engine.
Proper measuring is needed to see if you have piston slap or
rod knock ect.
How do the bearing shells look?
Bummer
I do see a dirty assembled engine.
Proper measuring is needed to see if you have piston slap or
rod knock ect.
How do the bearing shells look?
Bummer
Racer
Joined: Jul 2006
Posts: 277
Likes: 0
From: Big Spring TX
I see poor machine work, and poor assembly work, and I see a company that needs to send you a new engine.
The wear in that cylinder is atrocious, the deck of the block should not be that far off from one point to another, not to mention just that one cylinder, the bore of that cylinder is definately way off base, but I agree that I see no signs of detonation.
Whoever machined and assembled that block must have been off their meds that day. I would kindly get a new engine sent to me, and they pay the freight, or a total refund and learn never to do business with them again.
Let us know how it turns out.
The wear in that cylinder is atrocious, the deck of the block should not be that far off from one point to another, not to mention just that one cylinder, the bore of that cylinder is definately way off base, but I agree that I see no signs of detonation.
Whoever machined and assembled that block must have been off their meds that day. I would kindly get a new engine sent to me, and they pay the freight, or a total refund and learn never to do business with them again.
Let us know how it turns out.
Le Mans Master
Joined: Dec 2006
Posts: 5,557
Likes: 9
From: Oquirrh Mountains
St. Jude Donor '09
The deck shouldn't be off that much across the bore. The factory gets them straighter than that; factory is typically around 0.020" below the deck. The surface looks like a typical factory broached deck. It definately hasn't been cut at a machine shop. Are you sure you're getting an accurate measurement? IE - the 'straight edge' is actually straight or there is gasket material interfering with the measurement?
The cylinder wall looks tapered & I don't see any marks on the pistons indicating an overbore size. I can just about guarantee this was a typical KRYLON rebuild. Maybe you got lucky and yours actually has new rings & bearings.
The cylinder wall looks tapered & I don't see any marks on the pistons indicating an overbore size. I can just about guarantee this was a typical KRYLON rebuild. Maybe you got lucky and yours actually has new rings & bearings.
Last edited by Ben Lurkin; Aug 14, 2009 at 09:07 PM.
