![]() |
|
|
|
Registered
Join Date: Jan 2018
Posts: 878
|
Inspect rings or let sleeping dogs lie
I have purchased a piston and barrel set for my 2.0 S 901 \ 02
They are out off a rebuilt engine that was only run in.. No issues but more power was needed and it was converted to a 2.8 or something. I have bought these from a reputable shop and pistons where removed whilst in the barrel. Some have turned some in the barrel. Question is. Will my ring gap be in the correct place when I turn turn the piston to conect it to the rod. 2nd I just have this urge to pull the pistons and check ? Barrels were honed. New rings. Top ring land machined as it was not in spec. Any thoughts Lyndon Last edited by Lyndon302; 05-31-2020 at 05:28 AM.. |
||
![]() |
|
Registered
Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,471
|
Once you start the engine the rings will rotate in the piston to where they want to be, or continually rotate, I don’t know.
I have opened engines before after start up and the rings are not @120 degrees any longer Bruce |
||
![]() |
|
Registered
|
Agree with Bruce on the fact rings do rotate. If it were mine, I would be pulling the pistons out and making sure all is well. If the rings were seated, they still will be upon reassembly and you will also have full confidence in the job, as you did it.
__________________
1986 Targa Guards Red 2021 MT09 SP |
||
![]() |
|
Registered
Join Date: Feb 2004
Location: denver
Posts: 1,143
|
I always measure, clean and inspect any used part. Keep all the parts (rings, pistons, pins and cylinders) together. I would pull the pistons and measure cylinders for ovality and taper. Check ring to piston side clearance, end gap and piston to cylinder clearance. Clean all the parts so they look like new. At that point if everything checks out you can reassemble and install.
john |
||
![]() |
|
Registered
Join Date: Oct 2013
Location: Prescott, AZ
Posts: 1,062
|
I would also have a shop with proper equipment check the cylinder roughness. Apparently the cylinders were honed. If the surface was left too rough, the new rings will just wear out prematurely.
__________________
1990 964 Coupe 1986 Carrera 3.2 Targa |
||
![]() |
|
Registered
Join Date: Oct 2013
Location: Prescott, AZ
Posts: 1,062
|
My last comment was assuming the cylinders were Nikasil. If they are biral with iron liners, then would naturally be honed to a much different (rougher) speciification.
P.s. This is my 1,000 post! Woo hoo!
__________________
1990 964 Coupe 1986 Carrera 3.2 Targa |
||
![]() |
|
![]() |
Registered
|
Never trust new or used parts, check and measure. You are responsible for your build.
Rings move, and are supposed to. Only a 2 stroke have static rings due to a pin that holds them in place.
__________________
Magnus 911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI. 911T Coupe -69, 3.6, G50, "RSR", track day. 924 -79 Rat Rod EFI/Turbo 375whp@1.85bar. 931 -79 under total restoration. |
||
![]() |
|
Registered
|
This is all sound advise , If you don't know ... then you don't know . Check the info for yourself
Have fun Drive your car ian
__________________
Kermit, 73 RS clone, Just Part of the Team Chris Leydon ,Louis Baldwin ,Peter Brock ,Riche Clark Jerry Sherman ,Rob McGlade ,Donnie Deal Hank Clarkson ,Craig Waldner ,Don Kean ,Leroy Axel Gains |
||
![]() |
|
Registered
Join Date: Jan 2018
Posts: 878
|
Ok they arrived. 17 thousand on the top ring. 2nd ring is 80 thousand. 😦
The bore has been honed but has missed some low spots. Guessing they preferred to miss a spot than enlarging the bore. ??? Lyndon ![]() Last edited by Lyndon302; 07-02-2020 at 04:44 PM.. |
||
![]() |
|
Registered
Join Date: Jan 2018
Posts: 878
|
I have pulled all six now. I have installed my old rings out of the set that needed replacing and I have about 80 thousand gap on them. My conclusion is this shop has replaced the top ring. Fitted used 2nd rings. ( they look old as well ). The oil ring looks new as its a different type but has a gap of of 80 thousand as well.
Lyndon |
||
![]() |
|
Registered
Join Date: Jan 2018
Posts: 878
|
I am reading the specs are 15 to 45 thou for the rings and 100 thou wear limit on the gaps. Wayne's book does not spec the 2.0L. ( a mistake I think ) and does not even mention the S rings at 1.5 1.5 and 4 mm
Lyndon |
||
![]() |
|
Registered
|
80 thousands is a lot, on the other hand it dosen't do much compression sealing. Its job is to stop the gases escaping from the top ring gap and to wipe the oil.
__________________
Magnus 911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI. 911T Coupe -69, 3.6, G50, "RSR", track day. 924 -79 Rat Rod EFI/Turbo 375whp@1.85bar. 931 -79 under total restoration. |
||
![]() |
|
![]() |