Stag engine rebuild

[flying farmer]

I was hoping to continue the welding on the Stag, but an unfortunate accident (twisted my ankle getting off a tractor in the dark) has left me with a black and swollen ankle so I will not be crawling about under that for a while.

I am able to stand (and sit) still though, so have launched myself into rebuilding the engine that seized its jackshaft last year. As usual I am not giving myself an easy time, as I want far more BHP than a standard Stag engine will provide. I also need to get it assembled so I can finish of the EFI inlet manifold project.

Once again I am photographing the job and sticking the photos on photobucket, just in case there are any useful points I may have discovered and would benefit anyone else rebuilding an engine. This is intended as a similar specification to the engine fitted to the TR, but with a bit more compression which makes the job even more difficult:?.

Photos here

http://s740.photobucket.com/albums/x...ine%20rebuild/

More to follow in a few days

Neil

[StagnJag]

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Fascinating stuff.

One day, when I have a garage I intend to have a go at this engine building malarky. Reading stuff like this is hugely educational. Please keep up the good work .

(I think you should seriously consider writing this up for the magazine as well).

Rgds

Dave

[singapore stag]

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Ditto!,I too sooner or later will need to have the knowledge to rebuild the TV8 myself. That to me is the fun of owning a classic,..

Sukh.

[Giles]

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really interesting Neil - thanks for doing this

[new to this]

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Neil

where do you find the time with all your projects

Great stuff keep the pictures coming

Dave

[Andy Rundell]

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Nice one Neil, always enjoy reading/seeing your projects ........ sorry to hear about your ankle-mishap !

............Andy

[flying farmer]

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More time has been spent on the engine rebuild. It is a slow job involving much measuring and calculation, but for once something has worked easier than expected. I needed to produce valve cut outs in the pistons due to the heavily skimmed heads, high compression pistons and skimmed block. A scrap head and old inlet valve were used and it turned out to be a quick, simple and accurate way of producing the desired results

More photos here

http://s740.photobucket.com/albums/x...ine%20rebuild/

Neil

[flying farmer]

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More progress has been made on the engine rebuild. The combustion chamber volumes have all been measured and equalised, finally ending up with a theoretical compression ratio of 10.3 : 1

More pictures here

http://s740.photobucket.com/albums/x...ine%20rebuild/

I have now got as far as fitting the left hand head and am working on the cam timing. Initial measurements show it is about 2 degrees retarded, so tomorrow I shall redrill the sprocket. I have actually measured the cam timing this time. When I built the engine for the TR I just used the timing marks on the cam, which are pretty accurate for 3 or 4 degrees, but more guesswork for 1 or 2 degrees. It seems these cams have a duration of about 294 degrees against 256 for standard, timing is approx 34 80 80 34 . IIRC the 150bhp TR engines were timed 30 70 70 30, 180 degrees duration, but of course they were a long stroke low revving engine. More to follow in the next day or so

Neil

[V Mad]

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Hi Neil

I am rebuilding an engine for a friend, and I am doing the heads at the moment.

It is not a blueprinted rebuild; we just want to achievea reliable 'cooking' engine.

Before I read your post I had been working on the camshaft bearings as one head was tight. Now I have read your post, I will be reviewing what I have done, and looking more carefully at checking the bearingsfor fit as you have certainly focused my mind on how head warping can affect the bearings. One camshaftappears to turn freely but I have not checked to see of there is excessiveclearance,but now I will be doing just that.

I like your pragmatic approach. Some people will just send the heads off to a specialist, or buy a recon head, trusting that it will all be good.Maybe they will in some cases, but I am sceptical, and would much rather check it all myself. I hadassumed that the cam bearings could only berectified by a machine shop, but I think something like your methodsshould work at much less expense.

Thanks again for your informative posting.

Cheers

[V Mad]

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Just an update; I used Neils method of grinding the cap base to tighten up a loose bearing, and the socket wrapped in 400 wet/dry to loosen up a tight bearing. All the bearings now have a small clearance, enoughto allow oil film to protect the bearings without being excessive enough to cause rattle or valve timing errors. On refitting the camshaft, it turns nicely by hand now; very sweet!

[flying farmer]

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Well it is nice to know that my post has already been of use to V Mad, because as he says, just because it looks all clean and shiney it doesn't always mean it has always been done correctly, and Stag engines can be a huge money pit at the best of times (and don't I know it )

I have now finished timing in the left hand cam, more photos here

http://s740.photobucket.com/albums/x...ine%20rebuild/

Tomorrow I shall hopefully fit the right head but owing to a mix up on parts ordering I have recieved a couple of door catch retaining clips instead of the two 1/4inchUNF by 2 inch bolts that hold the right timing chain tensioner in place so I will have to re order those tomorrow. Someone added a zero to the end of the part number:?

At least when I have the head fitted I will be able to start assembling the two halves of the EFI inlet manifold

Neil

[flying farmer]

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I have more or less finished the engine at last, more photos here

http://s740.photobucket.com/albums/x...ine%20rebuild/

Now I can get on with finishing the EFI manifold, as I have something to bolt it on to

Neil