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PollyMobiles Rebuild

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pollyp

pollyp

Club Member
If you have a dremel you can get little felt polishing wheels, a bit of course lapping paste in the mix and you'll get it spotless in no time :)

pistons will be carefully slowly cleaned with scotch pad n carb cleaner, can't afford a rapid mistake there with a dremel.

valve heads will be scraped clean on pillar drill with a blade and polished with wet dry

cyl head chamber and exhaust ports will be wire brushed all over again with dremel
 

frank

Club Member
when the ends of expanders touch it is usually slightly larger dia than the bore in order to push the rings outwards. so they don't have a "gap" in the bore.
unless you mean how much their ends overlap on top of each other (preload?) when squeezed within the bore?

or unless u mean the oil ring end gaps. they were all set to 0.381mm


the end-gap paul, to see how much stretch you have in reserve :)

P5151030.JPG
 
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pollyp

pollyp

Club Member
wheels have arrived, thanks McCheung ;)
Mmm removing the packaging you can smell the paint solvent based environment its been from

DSC08640.JPG


first pair, ziptied together, have T1Rs with quite abit of meat left

DSC08641.JPG


little inside dirt and the outer face paint looks n feels solid and prob original coating. I presume these were the rear wheels.

DSC08642.JPG


2nd pair with avon/bridgestone tyres, 1mm left. these are likely the front set judging by heavy brake dust, worn tread and poor coating that it needed repainting at one point which is starting to peel away.

DSC08643.JPG
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one uses avon zv3

DSC08645.JPG


suppose these are the ones mentioned that have been painted championship white cos its peeling badly, loadsa bubbling separation

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very dirty insides

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other side are bridgestone turanza er300

DSC08647.JPG


again peeling paint

DSC08648.JPG


but insides are in a very bad peel.

DSC08649.JPG


stored in small garage. look at all those tyres!
I really need to get rid of those R888s, does anyone want 8x used R888 on BBS alloys? or suggest how or where I can sell em quick n easy n low cost?

DSC08651.JPG


so guess these are the abused trackday wheels but will require alot of work repainting em proper
 
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pollyp

pollyp

Club Member
Frank, help

I measured the oil ring tension are got 4kg, 3.5kg, 3.5kg, 3kg (piston 1, 2, 3, 4)
I placed the expander in the bore and it's snug so it zero expander gap.


but I can't figure how to stretch these expanders carefully and consistently.

tried finding a round cylinder thats slightly larger than the expander (baked bean tins just right),
marked the original distance between the ends (20mm)
tried to squeeze the ends together with pliers but is very difficult and it hardly budged but I don't wanna try too hard and possibly stretch/damage it too far

DSC08653.JPG


so left one is tweaked while right one is original, it's lost its roundness

DSC08652.JPG


fitted oil rings back on, retested and piston 1 is still 4kg drag

I'm stumped :oops:
 
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frank

Club Member
hmm, i had to do 2 more kart engines last week paul, and there was a 2 to 3mm gap when i pushed the expanders into the bore.
i just pulled them (with gloves on) in 3 equal areas, then roughly reshaped them circular, the gaps closed fully, and the the smoking ceased :)
 

frank

Club Member
and is that 4kg with the piston upside down paul ? without the skirt friction (using only the top 40mm of the bore)
 
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pollyp

pollyp

Club Member
hmm, i had to do 2 more kart engines last week paul, and there was a 2 to 3mm gap when i pushed the expanders into the bore.
i just pulled them (with gloves on) in 3 equal areas, then roughly reshaped them circular, the gaps closed fully, and the the smoking ceased :)
k I'll try that.
the JE expander is a different design to the nissan expander so may rest against the bore differently

and is that 4kg with the piston upside down paul ? without the skirt friction (using only the top 40mm of the bore)
upside down from BDC, pull up till it gets past the high static friction and measure the dynamic friction load of 4kg as it slides up (which was tricky to see as it stutters abit)
 
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pollyp

pollyp

Club Member
ok so rather than trying to be cautious n fiddling about, I grab both ends and pull em apart in brief hard pulls in a straight line. then using the other normal expander as a roundness reference, I bend it bit by bit till it matches the shape.


so now the edge gap of expander 1 on my bean tin has shifted from 20mm down to 19.3mm

reinstall oil ring and the reading appears to be bout 5kg

also started to do piston 2 but can't read if its 4.25 or 4.5kg

the main problem is measuring the piston drag with these traditional spring-type gauges cos the massive springiness give makes the piston friction stutter n grabby so the reading goes all over the place between static and dynamic friction load and is very hard to read when it's also moving upwards and the eyes can't focus.

I need to buy a digital strain gauge that has no give for a smoother consistent measure
 
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pollyp

pollyp

Club Member
McCheung has refunded me £20 for the front wheels that require repainting, which is so kind of him :)

got a digital strain gauge type luggage scale from maplin

DSC08654.JPG
DSC08655.JPG
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so now I can measure the piston drag more easily & consistently . only issue is the 0.5s refresh rate but it'll do

DSC08657.JPG



remeasured the drag with the new scale reads:

cyl1 (expander stretched by 0.5mm) - 3.3kg
cyl2 (expander stretched by 0.8mm) - 3.3kg
cyl3 (standard expander) - 2.5kg
cyl4 (standard expander) - 2.5kg

I stretched the expanders abit more:

cyl1 (expander stretched by 1.1mm) - 3.5kg
cyl2 (expander stretched by 1.1mm) - 3.5kg

according to my quick calc, stretching the expander by 1.1mm increased the drag by 1kg so to increase the drag by 2.5kg to reach a total of 5kg drag I'd have to stretch the expanders by bout 2.5mm which is alot.

I can only do this an hour at a time before I get fed up n strained from the tedious labour intensive process

also need to figure a better way of stretching the expanders safely and harder cos its quite difficult to stretch/deform the links incrementally and carefully (without resorting to damaging brute force) while also preventing the serrated edges (that the oil ring sits against) from ripping by fingers apart

so frank, the new oil rings were originally tensioned to 2.5kg (maybe it was low tension, low drag racing rings?)
ya think I should aim for 5kg like yours? (estimate it'll require a huge amount of stretch and will stick out the pistons by quite abit before install)
or will 4kg be sufficient for the larger 72mm bores?
 

frank

Club Member
you,ll have to make a judgement paul, my kg figures were pretty ghetto tbh (same poundland gauge that you had :)) i tend to go by feel, you will literally feel the scraping of the rings, and see the matt finish in the bore when they are properly scraped.
you will know when you have overstretched the expanders, the piston will refuse to go in the bore !
 

frank

Club Member
the old cast iron oil control rings were never a problem paul, they had about the same "tension" as the compression rings, but these modern 3 piece ones rely heavily on the expanders for tension eh.
what KG readings do you get from each of the compression rings ?

finished_oil_rings.jpg
20111206234918.jpg
 
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pollyp

pollyp

Club Member
GAARGH :mad: kmn
disaster!

to stretch the expander further, I grabbed both ends with needle pliers and used the vice to slowly stretch it apart with help from dad.

that expanded it by 1.8mm


fitted it on the piston but cos it's now sticking out so far, its getting tricky to keep the oil rings straight on the ringland.
when I was clamping the compressor, something felt stiff and then pop? and piston was jammed stuck, hmm

removed the compressor and garghhh

DSC08658.JPG


so bloody careless :rolleyes:

what do I do now!?

had to ring sebastian at JE bout new rings (and conveniently its 2pm in california now)

after explaining the situation,
first Q: does he have a stiffer oil expander?
A: no my xc7150 came as a pre-set but he suggested maybe a bigger xc7200 ring set so the expander gets squeezed in harder? but wasn't sure if the oversized oil rings will stay rounder in the smaller bore.

Q: ok so maybe use a xc7200 expander with xc7150 oil rings, do you sell em seperately?
A: no these custom special rings only come as a complete set per cylinder so I'd end up paying mega bucks for that option :/

bahh was a hard decision but I decided to order a full set of xc7150 rings $60 & $80post, so the replacement oil rings fit the bore as before (but will require regapping) and use the stretched expanders to correct the oil ring tension.

never thought I'd waste £80 on another set of custom rings.

...oh ffs just realised another mistake, I only needed to order 1 set of rings rather than 4 sets cos the other 3 oil rings are fine. jeez need to tell seb to change/cancel the order to the 1 set of rings but their lines busy.

this is really starting to challenge if I'll be able to make JAE at all :oops:

right, I need a cuppa tea to calm down tonight
 
OP
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pollyp

pollyp

Club Member
I'm guessing it's ok to keep the current bedded-in top rings and just replace the oil rings with stretched expanders and it'll seal alright?
 
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pollyp

pollyp

Club Member
k mom just convinced me to just resume ordering the 4 sets of rings cos it may be useful to have as spare (if I was that clumsy at wrecking all 4 sets of rings) and its only £80 rather than triple figures
 
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pollyp

pollyp

Club Member
Doh just realised another possibility.

I change the order to 4 sets of xc7200 (use just the bigger expander so they're all consistently tighter & won't need to mess bout stretching rings) and then add a single set of xc7150 to replace the one broken oil ring and reuse the other 3 oil rings.

Call or email him back tomorrow
 
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pollyp

pollyp

Club Member
ok status update

order has been changed to 4 x XC7200 and 1 x XC7150 ($16.65 each) and freight

so I'll be skipping this "stretching oil ring" stage of the engine build and resume next stage of checking end gaps and clearances

when the new rings arrive I gap the new XC7150 oil ring, test the bigger XC7200 expanders tension with XC7150 rings and reassemble hopefully before JAE
 
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pollyp

pollyp

Club Member
thx chris. lets hope things get better n smoother.

so lets abandon stretching the expanders and get on with checking the end gaps


the gaps are: (before - after break-in - difference)

Cyl 1
Top Ring (0.356 - 0.381) +0.025
2nd Ring (0.406 - 0.483) +0.077
Upper Ring (0.381 - NA)
Lower Ring (0.381 - 0.457) +0.076

Cyl 2
Top Ring (0.356 - 0.356) 0.0
2nd Ring (0.381 - 0.508) +0.127
Upper Ring (0.381 - 0.483) +0.102
Lower Ring (0.381 - 0.508) +0.127

Cyl 3
Top Ring (0.356 - 0.381) +0.025
2nd Ring (0.381 - 0.457) +0.076
Upper Ring (0.406 - 0.508) +0.102
Lower Ring (0.381 - 0.483) +0.102

Cyl 4
Top Ring (0.356 - 0.356) 0.0
2nd Ring (0.381 - 0.457) +0.076
Upper Ring (0.381 - 0.457) +0.076
Lower Ring (0.381 - 0.457) +0.076
 
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pollyp

pollyp

Club Member
K very rough calculations

Since the XC7200 is for a 72mm bore and XC7150 for a 71.5mm, the difference in circumference is bout 1.57mm

During my expander stretching tests I found the drag increased 1kg per 1.1mm so these XC7200 are estimated to increase the drag by 1.43kg to total of 3.9kg from original 2.5kg (156% tension)

Suppose all the expanders will be consistent rather than roughly altered by hand and the increased tension will help towards improving oil control.
 
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pollyp

pollyp

Club Member
last time I ordered new rings it took 10days to arrive. if its the same this time, then it'll arrive the week after and that'll just give me under 3wks to rebuild the engine, clean up the bay, fit and check the engine and finish everything else off before JAE. gonna be tight

lets measure the bores, shells n pistons


most of the cylinders are round, straight and close to 71.50mm spot on

piston 1 slight scuffing, prob during cold runs from the loose piston-bore clearances

DSC08659.JPG


piston 2 the same

DSC08662.JPG


piston 3 exhaust side is abit scuffed

DSC08664.JPG


but ohh ehh look at the inlet back side of piston 3. the lower edge of the skirt has made heavy contact at one point and can definitely feel the flat section by hand. worrying

DSC08666.JPG


piston 4 slight scuff

DSC08670.JPG


other than a strangely worn skirt lip on piston 3, all the pistons r fine and all the piston skirts measure 71.375mm (previously 71.4mm before break-in so its worn by 0.025mm)

looking at the bores

DSC08672.JPG


cyl1

DSC08673.JPG


cyl2

DSC08675.JPG


cyl3

DSC08677.JPG


cyl4

DSC08679.JPG


bores appear fine

now here's piston 1 big end shells.

DSC08681.JPG
DSC08682.JPG


piston 2 big end

DSC08683.JPG
DSC08684.JPG


piston 3 big end

DSC08685.JPG
DSC08686.JPG


piston 4 big end

DSC08687.JPG
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does that appear to be insufficient oil pressure and the upper shell (under compression/combustion) is rubbing on the journals?
all the lower shells have this repetitive wear segment, badly seated? loose vibration?

main shells

DSC08689.JPG


main shell 1

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main shell 2

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main shell 3

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main shell 4

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main shell 5

DSC08694.JPG
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the upper main shells not under much stress but the lower stressed shells show signs of slight contact near that hole dimple where oil pressure might be lower?

the front thrust bearings not under much load and its 1.94mm
while the rear thrust bearing under load from the clutch is down to 1.93mm

DSC08701.JPG
 
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Does seem like a lack of oil of the 'big ends' :/
And that piston 3 with the flat edge? Concerning. The bores look ok to me though. Any sign of damage?
 
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pollyp

pollyp

Club Member
just googling into types of bearing shell wear and that stuttering look on the big end shell might be slight contact from vibrations caused by Oil Whirl/Whip?
 
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pollyp

pollyp

Club Member
haven't looked too detailed at the bores but they look and felt smooth.
what shell rubbing?

work has changed priority so now all my total effort is to finish programming 2 of the demo apps for boss to take to london to gain clients/contracts to get the business going, so I may have to put this engine on hold for now.
this means there's only a very slim chance I'll be able to make JAE:(

best case is I assemble the car within few days and skip painting the aesthetics
worse case is either I'll make the sunday or not at all
 
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pollyp

pollyp

Club Member
the big-end shells look like too much clearance to me paul, have you tried plastigauging them ?

too loose? bah, cant do much bout it at short notice suppose, can just continue runnin eh?

no didn't plastigauge em. thought machinist grinded it down precisely n specified 0.25 oversize, so thats what I fitted and run.
don't have bore gauge small enough to measure and dunno where to get plastigauge locally or quickly
 
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pollyp

pollyp

Club Member
i shave a couple of thou off the caps, then lap the clearance with fine paste :D

thought u meant it was too much clearance, too loose n vibrating about? so if I was to fix it I'd have to thicken the shells rather than lap it thinner?

anyway 1st task is to find some plastigauge to find the facts before any diagnosis
 

frank

Club Member
thought u meant it was too much clearance, too loose n vibrating about? so if I was to fix it I'd have to thicken the shells rather than lap it thinner?

anyway 1st task is to find some plastigauge to find the facts before any diagnosis
i,ve stripped some high milers that still had the matt grey factory finish on the white metal coating in the shells paul, your shells look pretty scuffed to me.
maybe its the breaking-in oil ?
 
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pollyp

pollyp

Club Member
i,ve stripped some high milers that still had the matt grey factory finish on the white metal coating in the shells paul, your shells look pretty scuffed to me.
maybe its the breaking-in oil ?

dunno. been using 20w50 mineral to break-in.
gonna use the last 4L once it's back together, run abit more to see if it stops drinking oil and then go to usual 10w40 semi.

can't afford nor can be bothered to buy another set of bearing shells at £80 a set :/ run it till it breaks :p
tis at the point of being a money drinker and I say fookitall, it runs
 
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pollyp

pollyp

Club Member
God I feel your pain man. Just get her boosting and safe then enjoy it.

aye, just wanna finally fix it up, ignore the minor itsy bitsy issues, up n running for JAE and burning nice n dry inside for MOT emissions in few months, but work and money gets in the way of luxuries.
if the oil still burns, then this engine won't pass MOT and ain't sustainable and will have to buy and downgrade to a normal 1.3L and yet more hassle.

we'll see each other on the other end of this progress bar \\\\\\\\\\\\\\\\\\\\.......
 

SirChris

Educated Bodger
aye, just wanna finally fix it up, ignore the minor itsy bitsy issues, up n running for JAE and burning nice n dry inside for MOT emissions in few months, but work and money gets in the way of luxuries.
if the oil still burns, then this engine won't pass MOT and ain't sustainable and will have to buy and downgrade to a normal 1.3L and yet more hassle.

we'll see each other on the other end of this progress bar \\\\\\\\\\\\\\\\\\\\.......
Tell you what I won't go if you don't go. I really want to go so if you fail us I will be well unhappy. Best not disappoint me
 
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pollyp

pollyp

Club Member
my target will still be to get it to JAE whether late or early, presentable or in a mess. will be working on it with any energy I have left till I can get there. if I can't get it ready by the last day, sods law theres always another JAE.

but right now, finishing these demos at work by 5th sept is important to ensuring the future of the company & my job and has 1st priority over any hobby. once thats done, then I can focus on finishing the car (if the rings arrive in time)
 

Enuo

Glorified Electrician
dunno. been using 20w50 mineral to break-in.
gonna use the last 4L once it's back together, run abit more to see if it stops drinking oil and then go to usual 10w40 semi.

can't afford nor can be bothered to buy another set of bearing shells at £80 a set :/ run it till it breaks :p
tis at the point of being a money drinker and I say fookitall, it runs
20w50 might be to viscous for your oil pump to efficiently move around the engine, it's pretty thick stuff meant for older engines with more generous tolerances...
 
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pollyp

pollyp

Club Member
20w50 might be to viscous for your oil pump to efficiently move around the engine, it's pretty thick stuff meant for older engines with more generous tolerances...

during stone cold starts with 20w50 on this forged engine I do notice the oil light goes out bout a millisec slower than a stock engine with 10w40 semi.
maybe its during the cold state with massive clearances that the pistons and big ends are banging away n rubbing shells hence the dieselly noise until it all warms up n tightens up?

I'll first sort the rings, run with 20w50 last time, double check it's stopped soaking the piston and then move back to 10w40 semi n see if it drinks the thinner stuff
 
20w50 seems a bit thick to me?
Like you've said. Use it up and carry on with 10w40
Your missing an oil range of 10-20 which is specified :/ so it must need it
 

Low Rider

Poindexter
Founding Member
Moderator
Club Member
Damn, those shells don't look happy after that long :(

Issues aside, are you using 20w50 because it's purely mineral based Paul or just easy to come by/cheap?

I always run Millers 10w40 CRO for tuning and 500miles post tune before switching to synth based lubricants. We followed that on the '62 e-type engine and it runs sweet.
 

SirChris

Educated Bodger
Paul what is your reasoning to this oil changing? I saw hood reaper changed oil for his dyno run with new turbo? Is there anything I am missing?
 
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pollyp

pollyp

Club Member
I was advised by my cousin to bed the new engine in with 20w50 mineral like halfords classic then change to normal stuff
 
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