c1j bottom end tight? unsure on this one!

[raj]

ok ive started rebuilding an old engine i bought of djinuk:agree:

so to start with ive fitted the reground crank along with new main bearings and the crank spins freely as you would expect:agree:

then i fitted the conrods to the crank and all seem fine either side of TDC but beyond that i cannot move the crank without using a little force.

i removed the crank and refitted the conrods to the crank without it being fitted to the block, and all conrods are moving freely:agree:

* so when the crank is fitted to the block = OK
* with crank removed and conrods fitted, all parts are moving freely = OK
* conrods fitted to crank with crank fitted to block = seems stiff.


Now im unsure if it should actually be classed as being stiff,:scratch: do you think it may just be due to the fact the piston rings are gripping causing the stiffness feel..?

at TDC i can move the crank both ways up to a point,then it starts to become stiff(but moveable).
the crank turns easy enough with a torque wrench.

im bit confused:scratch:

[michael tierney]

prob seems to b one of ur big ends.....do one at a time!!

[Fordy]

* so when the crank is fitted to the block = OK
* with crank removed and conrods fitted, all parts are moving freely = OK
* conrods fitted to crank with crank fitted to block = seems stiff.

probably just the rings tight in the bores if the pistons are fitted the rods?
have you lubed up the bores with mineral oil ?

[raj]

probably just the rings tight in the bores if the pistons are fitted the rods?
have you lubed up the bores with mineral oil ?

im hoping it is just the rings, and yes the more are lubed:agree:


i cant think it could be anything else really, its just that either side of TDC is easy, but once you go past this on either side im really having to try and turn the crank via the crank weights, but once i try turning it with a wrench on the pulley bolt it turns ok with no real force applied.

[raj]

i think ive answered my own question:agree:

i refitted the crank and torqued it up etc = spins freely:agree::agree:
fitted the conrods to the crank without the piston rings = all spinning freely:agree:

so i can only assume that it is simply the resistance of the piston rings that is causing the stiffness.

[jamie_clioGTT]

my new rings had a fair bit of resistance mate, have you re-honed the liners?

[raj]

my new rings had a fair bit of resistance mate, have you re-honed the liners?

the liners are new mate,so already honed.

[raj]

ok, so im back on the rebuild,

and to sort this stiffness regarding the piston rings,
can anybody tell me what the piston rings end gaps need to be on the top 2 scraper rings?

ive checked the haynes manual but it states that piston rings come pre set.

im certain that the rings end gap clearances are too small as the rings,when fitted into the liner without the pistons the rings hardly have a gap and are almost touching end to end, thus leaving a slight score mark where rings have been pushing out where the two ends meet .

measurements please:)

[Ashy]

What gap are you seeing as they are mate?

[Tony Walker]

i think its somewhere around 15tho but thats not c1j specific

[raj]

What gap are you seeing as they are mate?

hmm, i think i may have fukced up the ring gaps. im unsure thou.:scratch:

i got annoyed and ground the ring gaps to make the gap slightly wider.

im seeing a gap of around 0.20 to 0.40 on all rings.
what is the maximum permitted gap size allowed?

i was under the impression that the bottom oil control ring has a slightly bigger gap than the 2 rings above it? my oil control rings where almost touching at the gaps.

now im not going to put the head on yet as im sure if ive fecked with the engines compression!

all i can tell you is that the engine turns easily without the rings fitted to the pistons, but once the rings are fitted the engine will not turn by hand, but it will turn only with a wrench on the crank pulley bolt without lot of force applied.

[raj]

if someone can give me the minimum and maximum measurements for the piston ring end gaps that would be great:agree:

from this i can see if ive over ground the end gaps or not.

i dont want to be fitting the head to find out im getting blow by past the rings and compression loss due to grinding the gaps too much.

[rs250nut]

I did once come across a online calculation for sizing the ring gaps let me have a dig about................. Here ya go

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

[modfather]

haynes manual say they come pre set

it does give the thickness tho

[raj]

haynes manual say they come pre set

it does give the thickness tho

what are the thicknesses? can you confirm?

[raj]

I did once come across a online calculation for sizing the ring gaps let me have a dig about................. Here ya go

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

thanks, but im pathetic when it comes to working things out:crap: and thats just lost me!

[modfather]

what are the thicknesses? can you confirm?


top compression 1.75mm
no 2 compression 2.0mm
oil control ring 4.0mm

[raj]

top compression 1.75mm
no 2 compression 2.0mm
oil control ring 4.0mm

thanks for that:agree:

the gaps are within them tollorences.:)

[modfather]

no probs mate glad i could help

[Ashy]

thanks for that:agree:

the gaps are within them tollorences.:)

He's talking about ring thickness not ring gaps... dont gap the rings to 1.75mm :eek:

Ive just done the ones on my F4R, which are forged pistons, the calculation for fast road applications was 0.004 x Bore Diameter.

Whats the standard bore on the C1J?

[Ashy]

I did once come across a online calculation for sizing the ring gaps let me have a dig about................. Here ya go

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

So, looking at the table that rs250nut found.

Assuming you are aiming for "high performance street / strip"

top ring = 0.0045" x bore dia.
Middle ring = 0.0055" x bore dia.

Bore dia = 76mm (from what i found on the web)

So ring gaps should be

Top ring = 0.342mm or 0.013" or 13 thou.
Middle Ring = 0.418mm or 0.0165" or 16.5 thou.

So given that info you should be able to work it out depending on what application you are building your engine for.

[raj]

So, looking at the table that rs250nut found.

Assuming you are aiming for "high performance street / strip"

top ring = 0.0045" x bore dia.
Middle ring = 0.0055" x bore dia.

Bore dia = 76mm (from what i found on the web)

So ring gaps should be

Top ring = 0.342mm or 0.013" or 13 thou.
Middle Ring = 0.418mm or 0.0165" or 16.5 thou.

So given that info you should be able to work it out depending on what application you are building your engine for.


thanks for that ashy:) when i was about to refit the rings i thought going into the mm's would be abit much for ring end gap:eek: luckily i logged on here and you confirmed my suspicions:agree:

im glad i didnt fit the rings i ground as i fecked them up.

ive got new rings and im seeing 15thou on the top ring, and 18thou on the middle ring.

im yet to refit the pistons etc, but hopefully all will go smoothly

:)