DIY 2.0 TC engine step-by-step rebuild with GC

[Guy Croft]

Crank inspection should include a thorough visual inspection and dimensional checks on flywheel driving flange, the main and big-end journals (the latter known as crankpins) OE data on crank sizes and runouts applicable to both the 2liter Fiat/Lancia TC 1800 and 2 liter (all models 131/2 thru -last of line 8v/16v Tipo/Coupe) is available at:
http://guy-croft.com/viewtopic.php?f=1&t=774
Measuring crankpins and main journals is done with a micrometer, imperial or metric though metric is more accurate to 2 decimal places than an imperial one is to three and thus preferable. With a micrometer reading in 0.01mm steps (0.0004") one can estimate the third decimal place, ie: to determine a reading in between like 52.985 which lies between 52.98 and 53.00mm. Stricltly speaking a measurement of that kind is outside the accuracy of the gauge but one must do it nonetheless, especially when recording crank sizes at build if they are a bit 'on the low side'. The micrometer must be checked/calibrated with a gauge block to ensure it's accurate (mine are done twice a year). Measurements done with inaccurate equipment are worse than no measurements at all.

Now you've measured yours which indicates that it's out of the block and the FW removed. Before we proceed - note: When you split a crank fw pair on any engine it is vital to record the position of the fw and this is best done by marking it with a pin punch and/or white dot at the TDC position of cylinders 1&4. On all the TCs the fw can be fitted in one of two positions and if you fit it in the non-original position there is a risk that it may be out of balance. Wherever possible balancing of two mating components should follow a STRICT regime which is simply 1) balance each part 2) balance the parts married together as an assembly. The risk of not doing doing this particularly on a 'used' crank/fw pair is significant enough for me to say quite firmly 'don't ever do it'. An out-of-balance, where the lighter/heavier section of the fw 'swashes' can fracture the bolts and lead to serious damage and injury.

Your fw - to me - looks quite heavily corroded. It needs beadblasting and crack testing, and at the very least and most thorough rub down with 80 grade and then 120 grade carborundun paper on the friction face and the mating face on the back needs 'stoning' with fine carborundun stone to assure a high degree of flatness. The sep from the friction face to the clutch cover locating periphery needs checking with straight edge and feeler gauge and must be 0.020" +/- 0.002". If it doesn't meet that tolerance, the friction face needs regrinding and the step remachined to the same diameter. Record the friction face diameter before giving it to any machine shop to do! Friction faces should ALWAYS be ground because most exhibit 'hard spots' as a result of high temperature and clutch slip and you'll never get rid of this by machining.

If you get a crack in the FW - usually in the central region - you must crack test the crank too. If a crank is going to break it will usually be near the rear flange or adjacent the center bearing. If in doubt test the whole thing and dye penetrant is the best way. If you employ magnetic particle dye method (Magnaflux) be sure to demagnetise the crank after (same applies to rods) or the thing will pick up every single piece of ferrous (iron/steel) debris in the engine and rub the bearings to pieces.

Now insofar as checking the runout (ie: the bend in the crank / amount by which the center main journal does not run true), the runout of the fw flange these can be done just as easily in the block (as shown below) as on Vee blocks. If you measure with Vee blocks ideally the one at the fw end should sit on the rear main (no5) journal rather than the rear flange because they can be a bit 'bumpy' and give a false reading. I would not check a crank 'between centers' in other words with rotating tapered centers in the ends of the crank because cranks don't rotate 'between centers', they rotate in bearing housings: The subject of relationships between 'centerlines' and journals in terms of datum relationships is far too involved to go into here but that bearing positioning determines the true rotational axis. So you can keep the thing mounted in the block for those checks. The OE spec for runout on the center main does, yes, say max 0.025mm but I've successfully run cranks with more, say 0.04mm without any problems, though suffice to say, the more it's bent the more significant the need for balancing because if the crank is slightly bent the fw flange will not be as er, 'perpendicular' to the crank rotational axis. It's imperative to check the flange runout and if it's really bad the crank needs to go to a grinder who will use a rotating center in the FW end and clamp on the crank nose, set it up to run true and then lightly dress the flange till it's perpendicular.

It is very important to use the micrometer to survey the full length of each journal, because you can get high and low spots on journals that cause damaging unequal wear on the bearings. You really only need to measure in one plane and that is the measurement shown in the photo, though if you think there may be an adverse history with your crank, check at 45 and 90 deg as well. Always keep a log of crank dimensions, because at strip down, you can refer back and see how much wear you're getting. Besides measuring the crank, get your magnifying glass out and have a good look at it, note particularly how the radii are formed where the journals meet the webs, and how the oil galleries are oriented and connected by diagaonal drillings down thru the webs, plugged off with nasty little press-in plugs. The MkI human finger is a marvellous device for assessing surface roughness on journals and seal diameters (front and rear). Used cranks often exhibit scoring and damage but this will very often disappear if lightly polished at 400 grade or finer without upsetting the general size of the journals.


Commenting one at a time on your measurements using engine builders' usual descriptions:
Main
No.1 52.984 - on bottom limit
No.2 52.979 - 0.005 (5 microns or 2/10thou") under bottom limit
No.3 52.979
No.4 52.979
No.5 52.985 - fractionally over bottom limit

I would assess these main journals as 'fit for further duty' and provided that the they don't exhibit and significant damage I would polish only. The impact on oil pressure and fit-for-use of fractionally undersize journals especially on such a rigid 2 liter crank as this (forged nitrocarburised EN40B - a nickel chrome moly steel) is negligible really. If any journal was 52.970 or lower I would tend to be looking for another crank, because I'd be concerned that the bearing leak-down rate (rate of oil bleed) would be excessive. Don't ever try and regrind these nitrided cranks, said it before, saying it again! Read;
http://guy-croft.com/viewtopic.php?f=3&t=520

Big End
No.1 50.795 - 0.013 over bottom limit (1/2thou")
No.2 50.796
No.3 50.795
No.4 50.795

Same applies as mains, light polish.

Action with crank now?
Set aside! For the future: unplugging, polishing (which must be done in the right direction), cleaning of thrust faces, possibly oilway mods, plugging-up, balancing.
Action with the FW now?
Get it beadblasted and crack tested and report!

GC time taken
On crank inspection and crack/fw cleaning and Xtest - 2.5-3hrs

Tools required
Micrometer 50-75mm with calibration gauge
Vee blocks or old block with decent bearings still fitted
Beadblaster or access to one. Best media is Guyson Honite 13 blasted at 90-100psi
Dye penetrant crack testing fluid and developer. This is extremely messy, red dye is best described as a 'mobile' liquid and it gets all over everything! You need a large tray to sit the FW in and a hose to wash off the dye after one hour.

Tips!
1. Lots more stripping and inspecting to do - apart from ops described above, don't embark on other work yet!
2) As the notable Brian Hart (owner of the former 'Hartpower', F1 engine manufacturers) used to say to his engine builders (incl me at one time), 'inspection and observation are more important than academic qualifications', which is certainly very true in part. Inspection and awareness of what's in front of your when you're engine building is SO important and the truth is the 'inspection regime' MUST continue right thru to where the engine is signed off for test/duty.

Next: stripping pistons and rods and bore checks.



GC

[Guy Croft]

Changed to a 'sticky' topic by GC

25th Jul 09

[Alan]

Hi Guy,

I calibrated the micrometer with a slip gauge just before starting measurements.

I should have the crack tester kit soon, the dye kit has greater appeal to having metal filings getting places they are not wanted.

With regard to the flywheel, the corroded one shown in my photos is from a FWD setup, and I don’t know if its any way similar to the RWD.
I do have the original flywheel and clutch from the 131 2.0 RWD engine, but its standard and my not be up to the task.
As I never marked the FW before removal, and also that I may be using a different one anyway, the lot may have to be balanced prior to use.

Before I go any work on the flywheel I must establish which one to use.

With regard to the journals, I am happy to continue as you have described them fit for further duty.

I am not familiar with the crank polishing procedure. Is this done on a crank grinder using a mop as opposed to a wheel?
Regards,
Alan.

[Guy Croft]

Good!

In short:

1. The FWD and RWD FW may vary only insofar as the locating bush/bearing diameter is concerned but whichever you have that in itself is not an issue. What does matter (very much) is that if using a CRANK from a FWD unit the RWD gearbox input shaft that goes thru the FW may bottom out in the end of the crank because FWD cranks have a shallow counterbore (the input shaft is shorter on FWD and does not penetrate the FW). There is separate thread on this if some kind reader has time to find it.
2. FW to crank swaps (they are factory pairs) and any weight alterations by lightening and regrinding call for a full crank Fw re-balance.
3. If the crank sizes are good you can DIY polish the journals to remove gum and varnish with fine Scotchbrite and MkI human finger with solvent like Jizer which is then water-washable and contains corrosion inhibitor. It's not hard on the skin so you don't have to wear cumbersome gloves (unless you've got sensitive skin). Scotchbrite is omni-directional unlike tape methods. Do the thrust faces too.
4. I have often remarked on the importance of unplugging these crossdrilled cranks to clean out the gallery that feeds the crankpins from the mains. They are full of sludge which will trap material form the polishing medium and wreck the new bearings. This op is imperative however you polish (and any good engine reconditioner can do it with lapping tongs in the crnak grinder though you have to tel him to use very fine abrasive - 500 grade or finer - and polishing with tape MUST be done in direction of rotation so it doesn't 'raise' the grain of the journal surface). replugging - well you can tap out GC style and I sell the plugs or you can buy the press-fit plugs from Fiat and stake them in yourself (not a method I like).

I do specialise in crank prep (I mean a lot of people send theirs to me with FW for full-spec overhaul) and so this is somehting you might want me to undertake.

GC

[Guy Croft]

I'm told this project is on-hold for the time being, sorry.

GC

[andygriff]

A very interesting thread indeed... It's been a useful guide during the strip of my own 130TC "rally" engine.
I hope that the project will re commence soon !

[Alan]

Hello to all who have been following this post.
My apologies for the long absence, life in general can sometimes get it the way of these projects and they can get pushed to one side.
Thank you to Guy for understanding and allowing me to continue with the thread.
I hope to do it justice by getting my engine back together and screaming again soon!

At this point I am going over the whole topic again to revise on what I have done, and what I have yet to do.
I hope to continue with pictures and information as soon as possible.
Best regards,
Alan.

[Alan]

Hi Guy, I did a little this week, got some crack tester and applied it to the block.
I don’t see any obvious cracks so I am hoping all is ok.

DSCF3096.jpg (183.44 KiB) Viewed 9321 times

By all accounts, I will have to get the bottom end rebalanced, and as I am converting to RWD I will be using a different flywheel so they will no longer be a matched pair anyway

The FW is a standard 2.0 131 type, so might need to be lightened?

With regard to the crank plugs, can these be replaced with grub screws and a thread lock compound?

Thanks,
Alan.

[Guy Croft]

It doesn't need to be lightened but I would because the standard 131 FW is unnecessarily heavy. Balance of both that and crank individually and as a pair is imperative.

Get the FW reground to 'clean' and then machined with the 20thou step. Must be done before balance and make sure you crank test it after cleaning with beadblaster or a good scrub with Scotchbrite.

Threaded plugs for the crank, yes I use 7/16 UNC but you might struggle to get them, I have them made for me, buy from me.

There's no cracks on that block as far as I can tell.

G

[Guy Croft]

Those photos are MASSIVE! Sorry, just don't have time to edit.

G

[Alan]

Hi Guy.
I got the RWD FW cleaned up and crack tested, nothing obvious anyway, and I have contacted my local engine re shop and they can grind it.
I will drop it off this week.

DSCF3659.jpg (90.29 KiB) Viewed 9163 times

DSCF3660.jpg (89.69 KiB) Viewed 9163 times

I weighed the 2 FW’s, the standard RWD is 8.15kg, and the lightened FWD is 5.341kg.

While on the subject, what are the main benefits of lightening the FW?
Is it required to balance the entire rotating mass or just crank & FW?

With regard to the lightening, I will get this up onto a lathe soon and get that done too.
I have done some searching for a company in Ireland that can balance the bottom end, but as of yet have not found any.

What tolerances do you recommend for balancing?

I need to get grubs for the crank op too, I will PM about that.
Alan.

[pastaroni34]

Is it required to balance the entire rotating mass or just crank & FW?

Definitely balance all the parts that you can on the rotating assembly, especially since you have the engine apart. The additional cost is very small because when they have the crank on the machine, the majority of the setup time is already done. Some clutch pressure plates are balanced from the factory but the vast majority I have seen are not. These can easily be more out of balance than the flywheel itself.

What tolerances do you recommend for balancing?

Balancing to a tolerance is a very tricky thing. It is very hard to find a shop that has an accurate balancing setup. The standards that I am familiar with are set by ISO 1940/1, typically for a 4 cylinder fast engine (8000rpm) a G40 specification will suffice. Most shops will say "balanced within X.XX grams" which means very little because X grams at the center of the rotor axis is a very small force, and X grams 100cm off the axis is a large force.

[Guy Croft]

Alan, hi

you categorically don't get involved in balance tolerances, even I don't do that. You engage a well-known name that you know is good because everyone uses him and those people will be owners whose FW don't explode. He will be doing virtually full-time because it is a dying art.

There are commercial tolerances and there are finer limits used by the little-known world experts on balance like the guy who does mine, ex balance foreman at Laystalls and over 20 years in private practice doing little else except race balancing. You don't need to know limits because you_can't_check them. I see limits, sure, I know what folk use and none of their work will cause a problem. Balancing is like flatness, there is no such thing as perfectly balanced, only degrees of it.

Unless you know how to balance in which case you know your limits, in the truest sense. If you buy a balancing machine it will likely be a Schenck and they will teach you too.

Alles klaar?!

G

[Alan]

Guy,
I have not found anyone locally that provides a balancing service.
There are plenty based in the UK, but I would rather go with one of you recommendations than Google!

I popped out the oilway plugs in the crank and used a 7.8mm and 4.9 to clean out the gunk. There was very little and most of it was stuck to the plugs themselves (inertia I suppose).
I would imagine what was there was bearing material, or at least that’s what it looked like.
I wont tap the holes until I get the grubs, so to get the thread length to match.

131 crank.JPG (91.53 KiB) Viewed 8950 times

They will go on the shopping list of parts that I will need from you so not much point getting them on their own.
Alan.

[Guy Croft]

Yes, there is a problem with balancing over there. Dr K sends his to me to do.

RU sure that is the right crank?

I did not know they used single crankpin oilway on the early 8v TC. It looks like an Integrale type, let me have a shot of the crank nose.

G