So I'm taking the motor down so I can send out cylinders and heads to be worked on for my spring 107 build. Look at the pics of the ring orientation. The front top and bottom compression rings about 10 degrees from each other. The rear cylinders top and bottom compression rings openings are lined up exactly! Wow. Never expected that. Probably asking that oil control ring to seal compression a bit.







Sent from my Galaxy Nexus

 

That is wacky- could be from assembly?
or have you measured the bore- could it be worn hourglass shaped?

Mike

 

From assembly I would guess. I'm not even going to fuss about it. My 107 jugs and pistons will be done correctly.... By me.

Sent from my Galaxy Nexus

 

Are you suggesting ring orientation caused uneven cylinder wear?? Or bad bore caused rings to somehow shift?

Either way, I say lazy engine builder. IMHO

 

Not sure but I have disassembled a lot of v8's and never saw the two compression rings gaps lined up.

Sent from my Galaxy Nexus

 

I can measure bit I'm not sure how accurate without torque plates.

Sent from my Galaxy Nexus

 

uneven wear can allow the rings to rotate look at the scuffing on the bottoms of the piston skirts

this can be the result of miles and normal use, or the "I break it in like I run 'em" strategy, or hammering a cold motor.

hour glass type wear is more likely with a bored cylinder- the piston is more able to tilt against the con rod ( and this is party why a small bore motor can rev higher, faster), the skirts are to prevent this tilt, but the rear skirt does appear to have a wear pattern.

not that it matters as the OP is doing the top end- but just a curiousity.

it could be from assembly, I don't know myself if there is a fixture to position the ring gaps when the TC's are assembled. but ring gaps positioning is really very basic

Mike

 

Where ya sending them? What ya gonna have done?

 

Right now the plan is a FM 107. If I had the extra $$ I would bite on their IC cylinders. Probably not gonna happen since I'd like to get head work done. Depending on funds heads could be big boyz basic port for 300.00, Dan Vance raised port head job for 750.00 or FM "b" heads for 850.00. So definitely 107 and head work but the level of work depends on funds. Already running stage 1 plus tw-555's.

Sent from my Galaxy Nexus

 

Its a fluke that when you took the cylinders off the ring gaps were lined up, its normal for rings to rotate around the piston during normal operation...(unless they are stuck) otherwise you would have vertical ridges in the cylinder and grooves in the piston ring lands where the end gaps were originally set at. No one would ever align the end gaps that close on purpose. I have also assembled 100's of engines and when this wrenching game is played long enough sometimes you have to take something with very little run time back apart, again I have seen ring gaps that although not lined up I know they had turned from where they were when I installed the pistons.