Flyheel to crank bolts - correct torque?

[mangocrazy]

I've now reached the stage in my glacially slow engine rebuild where I can bolt the skimmed, lightened and balanced VX flywheel to the crank. I have one of Guy's 'how to' sheets and in there it states to lightly lubricate under the bolt heads with engine oil, add a small amount of copper anti-seize paste to the bolt threads and then torque up to 100 lb/ft.

Given that I've always believed that torque values are quoted 'dry' and that adding lube will mean that the effective torque is significantly higher, I'm thinking that 100 lb/ft is rather a high value.

Haynes (for what it's worth) quotes a torque value of 61 lb/ft for non-USA cars and 104 lb/ft for USA cars - quite a difference.

For the moment I've torqued the bolts up to 60 lb/ft. I realise that the flywheel bolts are probably THE most important fixings in the whole engine, so don't want to get this wrong. What values have you used when fixing flywheel to crank?

[rossocorsa]

Official figure for late is 145 nm (or 107 lb ft) GC always lost me a bit using imperial measures on a metric car! I don't recall if I used GC method or official one to be honest.
The Haynes figures are pretty much right for earlier cars as I checked an earlier tech data book but it is a bit ambiguous as it says 2000 - USA 1800 this may mean ALL 2 litre cars plus USA 1800s??
It looks like there are early and late variations on flywheel bolts

[SanRemo78]

Don't forget the locking plate!

[mangocrazy]

OK, 100 lb/ft (+/-) it is. The bolt are super tough 12.9 and I'm sure the crank is made of similar material, so it should be OK I guess. And yes, I've been sure to use the factory shim/plate. Guy's instructions gave dreadful warnings of what could happen if this was left out...

[SanRemo78]

Guy's instructions gave dreadful warnings of what could happen if this was left out...

I once had the pleasure of fitting a GC Volumex motor into Gerry Hawkridge's Alitlaiia Stratos replica. It came fully assembled with clutch fitted and aligned from the great man himself. All I have to do was connect the box and intermediate shaft and drop it in, plumb it and connect the driveshafts. About a day's work at the time.

Started on the first turn of the key and 20 seconds later we had a death rattle. Pulled the ignition lead off quick. Check through the inspection hatch on the top and removed the bottom plate and yup, flappy flywheel.

Rang Guy and got an "Ah, I wondered which motor that lock plate was from!" Fortunately no damage done, only a day's labour lost rectifying it

Guy (M).

[mangocrazy]

You can't beat a practical example! I wonder if that played a part in Guy (C) issuing multiple warnings in his 'how to' sheet...?

I also carefully measured the depth of thread in the crank vs. the length of bolt threads, as that was another of GC's dire warnings (risk of bottoming out).

[SanRemo78]

You can't beat a practical example! I wonder if that played a part in Guy (C) issuing multiple warnings in his 'how to' sheet...?

The engine was fitted, removed, fixed and refitted back in 1995 or 1996? If that fits with your timeline then probably! We had a very lucky escape!

[WestonE]

Unusual for Guy, but we are all human. Building engines properly is a terrifying business and I know in his recent years Guy ran a check twice and paint to confirm it is done up properly QA routine. His advice on starting with the full set of build components by assembly separated and counted has been very useful. As has finishing what you start with no interruptions allowed.

Eric   

[squiglyzigly]

As part of my job in maintaining high speed trains, it is a safety critical requirement that all fixings are torqued and paint marked. There are the obvious benefits for this but the added benefit of doing this when building engines is that you often build an engine several times to get the desired clearances and measurements. This is the point at which it is easy to assume you tightened it last time!
A final paint mark is your personal assurance to remove any doubt.
It also serves a future role of a visual check to see if something is working loose.

I was once asked  ‘don’t you trust yourself?’ when the paint marks where observed.
We’re fallible.

Paint pens are one of you’re most important tools.

Ian