Technical Engine rebuild, Stilo Abarth 2.4 manual

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Technical Engine rebuild, Stilo Abarth 2.4 manual

Abarth L

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Good day to all Fiat enthusiast's

My first post, surprised too see Stilo Abarth not under Abarth section??
Also surprised too see so little information on the Stilo Abarth and Uno Turbo's on an international Forum??

In short:
I am going to rebuild my Stilo Abarth 2.4 Manual engine, one off the valves on piston 2 has burned (no compression from compression test) I will be doing it myself to make sure all quality criteria is met, second hand or reconditioned motors even with warranty will not do.

Model: Stilo Abarth 2.4 Manual
Km's: 258000 (161250 miles)
Clutch & Flywheel replaced: 248000 Km's (lasted since new :) )



To do List: (Any comments/ suggestions welcome!!!):rolleyes:
  1. Remove engine or do it while in place? I am opting for not removing the motor.
  2. Remove RH Front wheel and plastic covers.
  3. Remove head, with both manifolds on(Outlet split where it go from 5 to 1), manifolds easier to dismantle and replace while on the outside.
  4. Remove Sump (Problem!! need to remove RH CV from gearbox, so will have to fill up gearbox with oil again) change to service RH CV??)
  5. Mark Pistons and Con rods and remove
  6. Lighten Con rods and pistons and must weigh better than factory spec "tolerances", (because factory spec is pathetic, worse than my 1993 Uno Turbo)
  7. Replace piston rings
  8. Measure and Hone cylinder sleeves(Clean with air and diesel)( diesel is oily and don't let your parts rust)
  9. Replace Con rod bearings(lubricate well with oil)
  10. replace Con rods and pistons(lubricate well with oil)
  11. Replace main bearings(lubricate well with oil)
  12. Main seal is a problem on the gearbox, don't think I will be able to do this, but seal on Timing belt end should be possible to change.
  13. If possible replace whelsch plugs. (don't till today know why it is made from Stainless Steel) (port used for grinding off moulding bumps after manufacturing)
  14. Replace oil pump
  15. Replace water pipes
  16. Head
    • Remove valves
    • Polish ports, a bit bigger and smoother THAT is ALL
    • Skim head by 0.5mm to increase compression. I think 1mm is too much?? Remember I stay 1500m above sea level so effective a 15 kPa drop in atmospheric pressure as compared to sea level, can even run a Turbo on low boost to compensate without changing any thing.
    • Replace valve guides
    • Clean valves
    • Lap valve seats with valves
    • Then I read someone is talking about a 3 degree valve seat as the optimum angle for some power gains, is this true? what needs to be done in conjunction with this?
    • Replace valves
    • New valve stem seals
    • Insert new seals
    • Replace intake and outlet manifolds
  17. New head gasket, no lubrication??
  18. Replace head (Problem!!! need special socket for head bolts??):confused:
  19. New head bolts Put oil on threat before tightening, or must it be grease??, but not to much it does not compress!!)(Use calibrated torque wrench on all, test calibration easily in bench with weights before any Torque work commence!!!)
  20. Replace Belts Aircon, Altenator & Timing)
  21. Set timing
  22. Replace RH Front wheel and plastic covers.

Modifications to be done:
  • De Cat, remove both catalytic converters and but in a mini cat to simulate Cat.
  • Lighten Pistons
  • Balance Piston's (all 5 must weight the same)
  • Lighten Conrods
  • Balance Conrods Top and Bottoms (All must weigh the same)
  • Polish ports on head
  • Skim 0.5mm off head
BOM:
  1. Head Gasket
  2. Exhaust Gasket
  3. Intake Gasket
  4. Tappet cover gasket
  5. 5x Piston ring set
  6. 10x head bolts
  7. 20x Valve seals
  8. Aircon Belt (Problem!! stretch belt, need tool to put on):confused:
  9. Alternator belt (Problem!! stretch belt, need tool to put on):confused:
  10. Timing belt
  11. Tensioner
  12. Tensioner bearing
  13. Main Bearings
  14. Conrod Bearings
  15. Oil Pump
  16. Water pump
  17. Water pipes (To and from radiator)
  18. Water bottle
  19. Cam seals
  20. Crank seal on Timing belt side
  21. What am I missing?? any suggestions??:rolleyes::rolleyes::rolleyes:
I will post more information and specs so we can have a details list etc.(y)
 
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it all sounds good
but unless you own or have access to a pretty good machine shop or engine rebuilding business you just wont have the equiptment to do all the stuff you want and buying good enough equiptment will cost many times more than getting an engine builder to do the whole job or even parts to your spec.
someone was looking for abarth head porting last year search and see if you can find if they got anywhere.
then youtube a few videos on crankgrind , piston lightening, conrod lightning and balancing etc and see the sort of tools you need(and experience)
even the gead porting , without expensive depth of material sensors you can easily poke into a gallery and scrap your head without a bit of knowledge or experience.
good luck however you do it.
try autolusso they rebuild alfa engines to high spec,should be similar parts
 
Sounds like a rather lot of work planned but sounds like you have a good plan. keep us up to date with pictures.
Thank you "mariocing", yes a lot of work but truly worth it, done it previously on my Uno Turbo, will still post all detailed procedures and pictures I created under the Uno section at a later stage.
I will definitely post pictures and guides that I used on this thread.
 
Thank you "sussexa" for your input.

However,
You don't need expensive equipment or an engineering workshop for 98% of the work!
Unless you are going to re sleeve/change valve guides or change vlave angles you can do everything else with basic hand tools.
Piston/ con rod lightning can be done in your garage, you just need to know how, and the best part is, you do the quality control.
Head port polishing is more know how and hard work than anything else, if you want to go bigger or change port angles then you need to know the limits and the effect of your decision, so NO un informed work!!!
I will show how in detailed descriptions and pictures, and I have done it very successfully with my Uno Turbo.
 
fair enough you have previous experience, and we will guess time is no problem.
ill stick these here for others benefit
ok you can end to end balance conrods like this with good set of scales(0.1g) and a few made up jigs

you got a lathe you can lighten a bit more like this

I like this guys vids

im not sure what shape abarth conrods are but this is diy able drill press

heres a half descent vid of 3 angle valve job

compression ratio calcs

a crank check measure

a crank journal refurb

porting

piston clearance

conrods again

flywheel lightning and balancing


crank and flywheel balance

measuring equiptment

I suppose this is doable cylinder hone


maybe get away with flex hone

and I suppose plastigauge would save on tools but not better tolerances than oe


lube for torqueing bolts might be worth something like this arp lube

for pre lubing on final assembly id be thinking more dedicated lube than just oil

and you might want to run a break in oil before switching to a good synthetic to speed up ring sealing etc
 
Thank you "sussexa"

Constructive criticism is always welcome, and your input is highly appreciated(y), thank you for the info I will for sure look it over tonight.

1. I used a cheap mono grade oil on my rebuild on the Uno Turbo for the running in period (2000km's) draining every 400km's and replacing oil filter. Then used fully synthetic after the running in period, my question on the 2.4 engine is how mono grade will affect the cam's during the run in period? (I read somewhere the correct oil is very important)
 
you can always just add something like this
http://www.opieoils.co.uk/p-59393-red-line-engine-oil-break-in-additive-zddp-additive.aspx
to a cheap supermarket or autotrade oil of the correct spec to be sure.
not sure how good the eper links are nowadays heres some screenshots that may help from 2014 eper

abarth shell brgs.png

abarth con rods.png

abarth rings.png

abarth cambox.png

abarth valve gear.png
were all here to help if we can,
I do wish you well, appologies if it came across negative but you have a lot of work there not many would even entertain.
from what I gather from here say on here the crank area appears to be the weak spot of the engine maybe search what they failed I seem to remember a lot of knocking bottom end stories at fairly low miles.
if you can mod something down there while your at it you may extend life.
 
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I have searched but I cant find the thread on here or alfaforum but someone had posted up a tip for the piston and ring pack to mod a groove or hole or something like that , it wasn't specific to stilo abarth but the alfas seem to have the same thirst for oil that the abarth has the reputation for especially the jts engines.
I thought more abarth owners would have posted some mods or engine tricks by now. even the oil spec has a varied recommendation from 10w40 to 10w60 as I recall.
ive seen a few detailed posts by alexgs in the past and hes had a few abarths and a lot of other fiats and alfas.
https://www.fiatforum.com/stilo/86868-excessive-oil-use.html
have a search of his other posts.
id still think about letting a head place skim the head , valve guides and do the 3 angle seats. have you thought about a cam profile grind? are you aiming for high reving more hp top end ?
found something about it
http://www.alfaowner.com/Forum/engines-ts-jts-jtd-and-v6/694953-excessive-oil-use-156-2-0-jts.html
heres one with a link to aftermarket piston rings(no idea if they do stilo abarth)
http://www.alfaowner.com/Forum/alfa-147-156-and-gt/655857-jts-engine-rebuild.html
 
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Hi all

Mod (Decat) completed (y)- opted to add new flanges so if I want I can just bolt the original back without any welding or cutting required.

Tip!! Make sure you put Lambda sensors/mini cat's on inside of a bend or on top the exhaust, if you put it on the outside or bottom it will clog eventully with oil and carbon;)


BOM
  1. 1x Mini Cat
  2. 2x connection adaptor (threaded washer, where mini cat or Lambda sensor will turn into the exhaust)
  3. Expansion piece
  4. 4 mm plate for flange to be cut from template made from old flange
  5. 76mm pipe
  6. 4x bolts with 8 nuts the extra 4 is to lock(Think it were 10 x 30mm)
  7. 2x Standard 3 bolt exhaust flange with 3x bolts and nuts.
  8. small piesce of steel to make bracket under sump with 2x bolts
Procedure ( I had this done by an exhaust service centre who can still work from scratch and not just want to take from shelf and fit, I had to go to 9 different shops to get to the one who will do what I want)
  • Remove Lambda sensors
  • Remove both catalytic convertors
  • Make template from old flange to created new flange where manifold go 5 to 1
  • Bent exhaust pipe to form
  • Weld on expantion piece
  • Weld new 3 point flange on exhaust remainder and new piece
  • make 2 brackets where exhaust will mount under sump
  • Spray to eliminate future rust
 

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Hi "sussexa"

Thank you for the links you are almost more exited than me :)

I agree with you on letting an engineering company do the head skimming and valve guides, quality is what's going to determine who I chose, on my Uno Turbo the skimming was so bad because their machine had play, I had to manually use sand paper on a marble table using the figure 8 technique to remove un even areas.

I am going to keep the cam profile the same, I like the torque at lower revs, and according to me profile change will only result in higher performance in a short rev range, and also can result in un even idling if over done.

I have read the same thread about the piston ports but like you say no confirmation on the Abarth, my previous Abarth used 1l for about 6000km's, but this one used 1l every 2000km's, but lately 10l for 400km's(really time to do the motor?)
 
Hi all

Some progress on the Head ad interesting facts, please comment??


  • Sourced complete head which were modified for Group N racing (R6500\ +-470 Euro) it was a spare which they prepared for changing between races if something happened.
  • Group N, modifications according to Head racing mechanic was valve seat angle, and small cam shaping, and cam balancing. a bit confused, thought Group N said no modifications only e.g. balancing??
  • No porting were done so I asked how is this possible since the Group N racing car develop 185kw x1.36 = 251.6 bhp, so he told me the head was developed perfectly by FIAT but the intake and outlet system(exhaust etc. were made smaller to comply to CO2 emission laws. So no port polishing or bigger port work is required, just optimize your intake and outlet, unless you want more then 185kw/250bhp.
  • The head has got the markings from van Der Linde racing and the number, so I phoned them and they confirmed according to their records it has been prepared for Group N racing series.
  • I will measure valve angles and cam lift etc. and share.
  • I don't trust the job, although I opened the wrapped head as stored from modifications, I could see 2 non standard bolts on the cam brackets, so I will rather change them to standard/ re torque all and change all seals.
  • Do I need to polish the ports? Yes I think so, as you can see they head is brand new, but valves looked to be "used" although clean.
 

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What an epic post by Sussexa, some very very helpful links in there since I am just starting to port polish and match my first two heads.


Keep up the good work Arbarth, following this closely to see how you get on.
 
Head bolts special Tool sorted:D

Ok, so this was on my hit list, since I did not know what Socket will fit this rare head bolt.

So it is called a "Ribe" type of spline but different, much stronger corners.

Ribe nr 13 to be precise, I paid R65/+-47Euro
 

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hehe, When I bought the head bolts etc a year ago in anticipation of the project I saw it the first time.
 
Cleaned work area and setup some tools and tables for project.(y)
 

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