Greetings:

I'm at the point where the crankshaft is now in and bearing caps are tightened down. I've got the big bolt in the front of the crank and using a large wrench to turn it. Seems smooth enough but also seems pretty stiff. So it occurs to me that there might be a metric for this to let one know more or less if their workflow is ready for the next step- the pistons...

I used a new rope seal with the sizing tool, and had to do it twice as the first time I took someone's advice and soaked it in oil before install, causing it to swell and thus not seating properly so that it was waaayyy too tight. So now, before I move forward, it sure would be nice if someone out there has a torque wrench value for the naked crankshaft.

Much obliged,
Petrolero

 

I've never come across any torque value for this to check the rear seal. These engines were assembled by reasonably skilled fitters who used their own judgement. It was nothing like you'd see today on a production line. There was a lot of selective assembly in those days. If you used the correct sizing tool it should be OK. but needs oiling after it's assembled. I may have used a bit of grease when I did mine, but it's so long ago now, (1992), that I can't remember. It is very important that the seal is correctly sized, because if it isn't the heat generated by friction can cause the main bearing next to it to melt and then it's "End-of-Engine" time. Is there anybody near you who has rebuilt these engines ? Get a second opinion if there is.

 

This will be the second time for me rebuilding the engine - the last time was in 1987 when I got the car with 23,000 miles. I was quite a bit younger then and stronger also - but I don't recall it being this stiff without the pistons. I did use the sizing tool, again twice because the first time the oil-soaked seal wouldn't go down in far enough and it was VERY stiff turning the sizing tool. I redid the seal using a new dry set and this time was much easier so I'm not worried that the seal is too tight- but now am wondering if the bearings are oversize- I bought some powdered graphite and made a poultice of the graphite and grease to apply to the seal before the crank went down. The crank was checked by a reputable crankshaft shop in the city here and pronounced everything right at spec- I used assembly lube and liberal motor oil when assembling the bearing shells and caps- and yes, I do have the thrust bearings in. The bearings were marked as spec-

Next time I'm out in the shop I'll grab a torque value on this item...

 

Greetings chaps,

Something sounds "not quite right" here . . . I realise the term "stiff" is open to opinion, but you are right to question things as they stand. Talking of "torque" infers "too tight" in my book.

Burning question . . . no matter what shop said, did you check all journal bearing clearances using plastigauge?

I would back off two steps . . . (1) remove all journal bearing caps but not the thrust bearings and (2) remove the rear seal. Then clean any oil from journals and bearings, fit plastigauge, and torque down bearing caps.

WARNING . . . DO NOT ROTATE CRANK with plastigauge in place.

Remove bearing caps, measure width of plastigauge strips to verify bearing clearances. Only once confirmed you have correct clearances, you can progress to lubricating and refitting crank and rear seal. Our practice is to repeat the process on big ends, matching each rod to its correct cylinder and using the plastigauge strips to verify clearances. Same again for camshafts.

Once again, DO NOT ROTATE ROD ON BIG END with plastigauge in place. Check camshafts before mounting any valves.

So, why all the drama of using this method which, initially, takers a little longer . . . but saves all the risks of imminent failure. It is so easy for machine shops to be "tight" on their measurements and, if their job starts and stops at the crank, with you sourcing bearings, we have a recipe for the very symptoms you describe. Bottom line . . . guessing a "tight" crank is caused by the rear seal or bearings is really important. Early failure after a rebuild is a very real threat, so it's critical to get it right.

Yes, it may be a tight rear seal. In the day, that's why race engineers hated them and the after market bolt-ons enjoyed a hayday. But none, in our experience, ever relied on others when it came to verifying bearing clearances at each step of an engine rebuild.

Cheers and best wishes,

 

So after a few weeks- and laying hands on the requisite 33mm socket to fit the large bolt on the front of the crank- I've got some torque values:

It's of course different if the crank has been sitting for a bit as the thick build-lube and oil will grab the crank- but after breaking the crank free, I can report that the inch-pounds needed to get the crank to move is 140... Right near the upper limit for the inch-pound wrench.

As to foot-pounds, I can tell you that's at 4.5 or so - but here I can't be sure as the scale is not obvious. The last mark down the shaft of the wrench is 20- with the marks on the barrel running from 0-9.5. So when I back down below the 20 on the shaft, I only have another 10 to go - which puts me at 10-footpounds- so I guess I really mean 14.5 and this wrench won't go below 10.

To check this, I suppose I should convert inch-pounds to foot-pounds and see.

140 inch-pounds converts to 11.6667 foot-pounds using the online widget- Close to the 14.5.

Let's just say 13 foot-pounds is what it takes to turn this crank after mains are torqued down AND before pistons added.

Next step is to check bearing clearance with plastigauge as recommended. I understand one looks for about a thou per inch of crank diameter- which means 3-thou for these, plus or minus.