tight crank

[Mjg1705]

im am in the process of fitting the newly ground crank and versized bearings in to my major engine- i have found that even when the bearing caps are only finger tight - the crank is basicaly siezed and will not rotate. so what are my options- i have contacted the engine comapny who ground it and they argue that it is 20 thou ground. and the shells are also 20 thou. so can anyone advise me as to the reason of my crank "siezing" when tighnend and also when torqued - please note that its only being torqued to 60 ib nm - so not even tight. any suggestions !?!

[Broadspeed]

Have You checked the straightness of the crankshaft bore in cylinder block?

Are the thrust bearings correctly in place?

[Dandy Dave]

Yes, You cannot mix the bearing caps. They need to go in the places and directions that they came from as they are line bored as caps and block together.
Other than that you will need to get a micrometer and measure things to see where the problem is. Dandy Dave!

[Mjg1705]

hi. ive spent all morning messing around with it- the caps are all correct- the thrusts are correct- ive had the crank in and oit about 5 times ! so getting a bit fustrated as cant see to pinpoint a problem ! vbut the block aint been used much so cant see that that would be out of line or anything so dont know !

[Fixersteve]

Hi Mjg, Have you tried the crank with just the mains done up and without the big ends attached?? Did they take 20 thou of the whole crank? or just the mains or big ends??
Was it Cornwall Engine Company that did the work??

Cheers
Steve

[Mjg1705]

yeh steve i have - 20 off the mains 10 off the big ends- and yes it was unfortunatly ! ive already given them amouthful down thge phone this morning over it but they ar ademant they have ground it spot on - but looks like they may have under-ground it !

[Pavel]

From engine no.1483140 the radius fillet [the curved sides of each journal] was increased and to accommodate this the bearing widths were decreased by 0.080 thou. You may have older width bearings which are not correct for a later crankshaft. Compare the widths with the old shells.
Both big ends and mains were altered.

Pavel

[Mjg1705]

Hi pavel, when I both the bearings - the only options were super 63/64 so I was assuming that the company would know what's right ! So I bough these bearings in the knowledge that they would fit my 08C engine ! But after this morning I don't think they do- or at least fit the journels - the company who ground it have offered to measure it but if it comes back correct then I'm still stuck - as I'm would be £70 down in bearings as I can't return them ! but the shells seem to perfectly fit the caps/block casting- so they would appear correct - even a local ag engineer can only think that it's the grinding that is at fault as everything else is correct - this is a bit of a blow as it was all going so well !

[Fixersteve]

my engine number is 08c967812 in 63 Super and i ordered +10 Mains and bigends from Agriline and they were spot on. Also had the crank done at cornwall engine company. Have you but a verneier on the crank to see what its coming up at??

[scoobyjim]

so what size does the crank measure compared to the bearings? Is the crank smaller?

Have you installed one cap at a time o see if you can narrow it down to one spot?

as already said if a cap is 180degrees out, it will sieze. Takes only a thou or two out of line to lock it up.

[Timeee]

Hi
The previous suggestions to do one bearing at a time to try and isolate which one is causing the problem are sound. A silly thing, but something that has caused me grief when asked to find out why a crankshaft was binding is to ensure that the backs of the shells and the bearing caps they sit in are scrupulously clean. It only takes a few one or 2 thou smidgins of "dirt" behind the shell bearing, to lock it up when torqued up. In one case, the chap had used cotton waste to wipe everything off and had caught a small particle/strand of the fibre behind the shell bearing.

Good luck

Tim

[Mjg1705]

Yeh I didn't order mine from agriline - wish I did now . As to size - if I put the shells around the crank - they don't meet "butt" which leads me to think the crank ain't ground enough other wise the shells wouldn't be jamming the crank between the caps - and yes I have individually placed on cap at a time aswell. Tbh I havnt placed a vernier gauge - but didn't have one with me ! but I think that crank is bigger than 20 thou - as like you say - only take 1 thou to jam it up.I have also spent literal days cleaning the block and in behind the bearings ! So it is spotless ! As that did also come to mind - So going to collect the crank tomorrow and see if I can measure it home here and find a result ! I hope this is the only problem I will have ! !!

[scoobyjim]

Thats the problem.
When the shells are sat on the crank they sgould meet at the end and have no gap. This enables a though or two around the journal.

Either the shells are small or the crank is big.

How much of a gap do you have.

[Mjg1705]

yes scoobyjim thats what me and anothe engineer thought ! they should both meet ! but if i butt one end together i have a good 1MM gap on the other side ! didnt measure it but it was clear to me that when i was trying to suround the crank with the shell i could tell that they must be jamming it up once torqued together - so just need to find out what the crank measures at - the bearings are defo oversized 20thou - and not cheap either ! but im just hoping that they have underground it otherwise i cant figure any other reason !

[Dandy Dave]

If I read what you wrote correctly, The center bearings are 20 under and the big ends are 10 under size. Under size is the correct term as the crank has been ground to a smaller diameter. To make this work you need 10 under for the Big ends and 20 under for the others. A 20 under size bearing is too small for any journal on the crank that is ground only 10 under. Dandy Dave!

[Mjg1705]

hi dandy dave - almost read correct ! swich around !! crank has been ground down- and i have over sized bearing so crank is 20 down with 20 up bearings to compensate. and same for the big ends.

[Dandy Dave]

Get one of these if you do not have one. .... http://www.ebay.co.uk/sch/i.html?_trksi ... &_from=R40

Digital Vernier Calipers are easy to learn to use and are invaluable doing mechanical work on engines and such and the lesser ones are not that expensive. Dandy Dave!

[Dandy Dave]

hi dandy dave - almost read correct ! swich around !! crank has been ground down- and i have over sized bearing so crank is 20 down with 20 up bearings to compensate. and same for the big ends.

The bearing are also considered under size. If you have a crank journal that is 3.000 inchs in diameter as a standard, and it has been ground 0.010 an inch under, the crank would then measure 2.990. The inside diameter of the bearings will measure around 2.992 Plus or minus 0.001 leaving several thousands of an inch for oil clearance. Dandy Dave!

[low253]

agree with the need for some digital verniers to confirm the journal diameter- cheap and very useful to have. The next step, and other side to this is to install the caps with the shells in place, but without the crank in situ, torque caps to spec, and beg/borrow/steal an inside micrometer to measure each and every main bearing shell pairing. This will tell you 100% whether there is indeed an issue with the machining of the crank journals. Remember to take into account the recommended clearance for a fordson main bearing. If that checks out, then it is likely to be the radius on the shoulder of the journal...IMHO (However, have never rebuilt a fordson, but built plenty of small block V8s at home over the years- the theory is the same)

[Mjg1705]

Thanks dandy dave will have to invest in a pair ! - hmmmm havnt tried that - but will have to try that Tuesday when I'm on it again - will do the crank Tuesday morning and then will have alook over the bearings when I get back to the engine ! As it's not at my home.

[Pavel]

Remove the crankshaft [you must be an expert at that by now]. Fit a shell to the block and one to the bearing cap. Bolt together. Using a digital vernier, set on inches, measure the internal diameter between the 2 shells. Lock the resultant measurement in place with the small screw on top of the sliding jaw. Fit the locked jaws around the crank journal -- there should be just a hint of freeplay. Check all the journals likewise. Make sure you hold the vernier gauge exactly at right angles to the journals.
You could, of course, do it the other way around -- measure the journals first and then the bearing's internals.
If you have the old shells, measure their width and compare it with the new ones.
Then, all being well, make sure there is no build-up of carbon on the block and bearing cap surfaces that the shells fit against.
Also, don't forget the thrust washers -- their measurements altered as well. In fact I would be inclined to fit the shells without the thrusts and check for tightness, first.

Pavel

[Mjg1705]

Ha yes pavel - change of career I thinks ! -ok will try all that advice - It did make me wonder if it was the thrust washers jamming it - but seems then when the crank was just sitting in the shells before and caps with shells it did sorta turn "easy" but still but tight - so can't see that it was thrust washers - I'm assuming as to what dandy dave said previously that if I measure this crank ATM it should measure 2.980 - as it's been ground 20 - saying the crank was 3 inch - is it 3 inches as standard ?! anyone ?! - but I can only imagine the problem lies with mistake in the grinding ! After all as said - only takes a thou oversize to make it tight !

[super6954]

Hi
I would not mind betting that your shells are possibly 10 thou + out from your crank or there is no oil clearance I have heard of that once as well. . I had a motor here once that had a reman plate stuck on the side with re grind shell sizes, so just went and got the shells that it said from my storage shelf, was kinda in a hurry and didn't look at the back of the shells that came out. It was one of those not good paying stuff it together and get it to run jobs, for a local guy .
It turns out that info was for at least 2 cranks before what is in this engine now with re grinds, and a replacement .
It was like yours with a gap between the shell halves before it was tightened in the housing so i knew it was wrong at the start. I read the old shells and found them stock, put new stock back and it turned fine . Maybe they gave you the wrong info on the re grinds it can happen .
Regards Robert

[Mjg1705]

Hi Robert - that's unlucky - well when I poke to the company - as fixersteve will back up - even he had had a crank done there so maybe they gave me his measurements - or I was wondering if they got them the wrong way around and it's 10 off the mains instead of the stated 20 !?! If so then they owe me big time !!

[Dandy Dave]

Ha yes pavel - change of career I thinks ! -ok will try all that advice - It did make me wonder if it was the thrust washers jamming it - but seems then when the crank was just sitting in the shells before and caps with shells it did sorta turn "easy" but still but tight - so can't see that it was thrust washers - I'm assuming as to what dandy dave said previously that if I measure this crank ATM it should measure 2.980 - as it's been ground 20 - saying the crank was 3 inch - is it 3 inches as standard ?! anyone ?! - but I can only imagine the problem lies with mistake in the grinding ! After all as said - only takes a thou oversize to make it tight !

I was just using that as a for instance to give you a general Idea of the theory. I may be able to look up the dimensions in my manual for you.
Ah yes, More info...

The increase in the Fillet started with Power Major engine # 1483140 with a 0.080 increase as stated before.

Standard on the rods is 2.500. Giving 2.4997 to 2.0005 as an allowance.

Standard on the mains are 3.000 inches. Giving 3.0002 to 3.0010 for an allowance. What a guess!

0.020 under should indeed measure around 2.980. Dandy Dave!