Twin Cam Engine Book Great!

[promotor]

Pete
What were the deliberate mistakes.

A miles wilkins book owner

Distributor specifications are quite confusing for one thing - they aren't consistent and need to be taken with a pinch of salt! He mixed up crankshaft RPM and distributor RPM in some advance plotted graphs - this has an affect on where the advance is shown to start, where the two advance springs start working together, and where the distributor stops advancing or by how much. I ended up taking the info from various Ford workshop manuals.

Not sure if this was an error based on a mistake Lotus also made, but it's definitely not right.

Yes this distributor advance mix up originated in the Lotus Manuals

cheers
Rohan

Thanks for the info.

Al

The OEM (eg. Ford) books are the best for data, specs. and numbers. Also included is stuff the manufacturers deemed important that the Johnny Come Lately's deemed unimportant - eg. how to tighten the sump bolts in the correct sequence so the sump and cork seals don't leak.

The MW book is a very interesting read about the development history of the Lotus Twin Cam engine. That kind of information you can't get elsewhere. The section on how to time the camshafts is good. The rest of the stuff is stuff you can get elsewhere or at times it's not quite right information. The section on the head rebuild for example. Are you really going to have a go yourself at removing the valve seats or are you going to hand over the work to a good machine shop that you trust? I know what I'd do. A dropped valve seat can absolutely smash an engine.

The Brian Buckland book. I don't have the book. I didn't need the book. However I did read on this forum how he recommends cutting a gasket for your timing cover to go between the cover and backplate instead of relying on the metal to metal with sealant advice from the original manufacturers. Seeing that kind of advice I don't think I'll be rushing out to get this book.

One thing that is always difficult and where sometimes you really can't get all the information you need from books is making judgements about what needs to be replaced and what's OK to reuse. Every engine is different in that regard. Judging wear on things and identifying parts that aren't quite right can take a bit of a developed eye and experience. As can use of appropriate sealants - a stand alone topic with many opinions!

Some good points made.
The hard bit is picking out which manuals to use for what info - manufacturer's own info is always the best starting point for me.

[rgh0]

All the books and manuals have issues with some of their detail. Its hard to be perfect The books are written by experienced rebuilders not engineers and some of their conclusions and observations are erroneous but not radically wrong

One day when I have time after I retire I will do a detailed analysis of them all and try to identify and correct some of the issues and I am sure some will disagree with what I write also

Just a couple of anorak teasers for now.

They all say make sure you have the V belt not overly tight to avoid water pump bearing failure. What none of them say is you must check this with the engine hot as the belt tightens significantly cold to hot

The first photo in the engine section of the Buckland book shows a "Mk2" engine with the post 68 cam cover with Lotus on the front - but it has an early die cast head !

Finally fitting a gasket between the timing cover and back plate is one approach and not a problem as there are no critical dimensions that it affects so I would not write of the Buckland book based on this. I dont do it as modern anaerobic sealants work just as well in this application and dont leak. This metal to metal join back in the 60's with the sealants available then was much more problematic.

cheers
Rohan

[englishmaninwales]

Pedant alert!
MW book - centre photo P115 - assembly of the crankshaft thrust washers - the thrust washer being fitted is the wrong way around, with the oil groove pointing away from the crank thrust face.
TBF the text on page 118 is correct!
An easy mistake with hundreds of pictures to take, organise, proof read etc. But a serious error if one didn’t carefully follow the written guide.
Malcolm

[2cams70]

Finally fitting a gasket between the timing cover and back plate is one approach and not a problem as there are no critical dimensions that it affects so I would not write of the Buckland book based on this. I dont do it as modern anaerobic sealants work just as well in this application and dont leak. This metal to metal join back in the 60's with the sealants available then was much more problematic.

Being an anorak too I've got to disagree on this one. Having two gaskets in a clamped together joint is not good engineering practice when you only need one. Fibre gaskets relax over time and having two gaskets means they relax twice as much. It also increases the chances of the flange warping. You'll hardly ever see a gasket in a modern engine and there's good reasons why not. Hylomar as originally recommended is still quite a good sealant although of course there are other alternatives these days. I do agree with you however that I was probably being a bit unfair writing the whole book off on that basis without having read it.

Good pick up on the MW book about the thrust washers. That's an extremely important one.

[Craven]

Part No 026 E 0005 Gasket, Timing Case. Very thin paper IIRC.

[rgh0]

Technically there is no problem with multiple gaskets in a bolted joint if it is designed right. Gaskets are designed to operate in their elastic range in combination with the bolts and metal components in the joint . Once the gasket is compressed the desired amount to seal by the bolts and the cover when cold it then experiences multiple compression and relaxation cycles as the alloy covers heat and expand while being constrained by the bolts, that being steel expand less. The bolts stretch slightly and the alloy cover and gasket compresses slightly all in their elastic range during these cycles.

Whether adding a gasket between the front cover and back plate in addition to the gasket between the back plate and block is a good idea or not you can argue theoretically about and do lots of design calculations about but it appears to work in practice and not result in leaks. As i said there are other ways to assemble that also don't leak

BTW Modern engines use fewer gaskets for a range of reasons

1. More accurate machining of components meaning joins don't need compliant gaskets to take up surface variation as much
2. Modern sealants that can be easily and cheaply computer applied on an automated production line
3. More moulded plastic components that are sealed with O-rings and other rubber profiles rather than gaskets due to their flexibility.

cheers
Rohan

[2cams70]

Technically there is no problem with multiple gaskets in a bolted joint if it is designed right. Gaskets are designed to operate in their elastic range in combination with the bolts and metal components in the joint . Once the gasket is compressed the desired amount to seal by the bolts and the cover when cold it then experiences multiple compression and relaxation cycles as the alloy covers heat and expand while being constrained by the bolts, that being steel expand less. The bolts stretch slightly and the alloy cover and gasket compresses slightly all in their elastic range during these cycles.

But to put it in plain English simple terms if you don't need to use a gasket you don't use a gasket. Gaskets have a bad habit of losing their elasticity over time. Modern engines don't use gaskets because they add cost, aren't as reliable and aren't as stable dimensionally as using the correct grade of sealant (and yes you can have both cost down and performance up co-existing together -Ford was very good at that. That's smart engineering and design. Getting more out of less)

Hylomar as originally specified for that joint is a good sealant. But like any sealant it has to be applied correctly. You can achieve the same result applying by hand as any production machine. You do need to have some idea of where to apply it and how much to apply however.