Miura workshop, technical details

I've used oversize JE pistons, a good product. Rings came from Deves, if I recall correctly they were also the size for a Chevrolet Chevette.
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I'll see what I can find but it is quite a while ago.

 

I'd love to join in but unfortunately our last two motors were outsourced and I don't have specifics on pistons (I believe JE), etc. Next one (400gt 2+2) will hopefully be all mine...

But I'll keep watching, love the tech stuff.

 

Why 2 different intake cams, and 2 different exhaust cams - do they rotate counter to each other?

 

Hi, what number 400GT 2+2? Thanks!

Fred

 

My pistions/rods (bottom pix)

http://www.400gt.com/photos/engine_rebuild/EngRebuild.htm

I was advised "do not rebore" if you don't have to. That rebuild was 1983, car's still running like a champ, smooth as silt (ooops...I mean silk)

Cheers,

Fred

ps: more pix:

http://www.400gt.com/photos/engine_rebuild/EngRebuild2.htm

 

The cylinders are offset from one bank to the other and thus the cam lobes are in different places along the camshaft. The head gaskets are not interchangeable either.

 

That pretty much covers it.

You would never want to grind the crankshaft until you actually had bearings in your hand.

 

I got my first up close look at a window winder for an early Miura - looks to be far superior to the later all-cable system that I'm grappling with now. it looked to be so well conceived and easy to fine-tune that I first thought it was a clever retrofit of a 3rd party winder. Anyone know if these were home-grown or adapted 3rd party products (and if they can be found)?

 

whew doggies! I can look through my old receipts and stuff and see if there is any info there. Unlikely, but I always love a challenge

(don't hold your breath)

Fred

 

You have posed this same question in two different forums. The techniques used for building an engine aren't unique to Lamborghini (or Ferrari).

Are you expecting different responses?

The process of returning a worn/damaged engine to like new specs is documented in numerous automotive textbooks.

 

Thanks guys. I didn't factor the stagger into the equation.

Craig,
I think you're overthinking things a bit - experienced shops have simple methods for measurement and communication with sublet shops. Unfortunately, mistakes can happen no matter how well documented things are.

In the case of fitting pistons vs. fitting bearings, pistons are much more complicated beasts and its best to fit each piston to its respective bore before final honing. Bearings and their journal surfaces are simpler. Most everyday engines have their cranks cut to spec, are assembled, and clearances checked with plastigage. Clearances that are slightly out of spec can corrected by swapping bearings to even out the numbers, trying another set or brand, etc.

However, with high performance motors, it is advisable to mock up each bearing in the rod or main cap, torque, measure, and then grind accordingly.This allows not only a more exact clearance, but also allows for optimizing the 'looseness' or 'tightness' of your fit.

Does that help?

 

Fred- #0925...I think we've had pics on here somewhere. She's more or less a nice original driver with a repaint. Engine is starting to lose some oil through the rings I believe. Leakdown test is next on the list.

 

Some aspects are similar to a "BB Chevy", others relate to similar aluminum block/overhead cam motors. The technology dates from the 60s and was "state of the art" then but is "old school" today.

The specific operations required during a rebuild are the result of careful measurements taken during inspection. It is not uncommon for an aluminum block to need a "line bore" to make it straight again however it isn't always necessary.

One of the biggest differences between rebuilding a vintage Lamborghini 12 banger and a more "mass-market" engine is the cost and limited availability of some basic parts. If your Chevy has damaged cylinder heads, they would quickly be replaced with new (probably improved as well). New heads for a Miura or Countach or Ferrari Daytona are pretty rare items (not ruling out one left on a dusty shelf somewhere). Extensive repairs are frequently made to the original equipment. In many cases a combination of art and science.

Some items such as a crankshaft may need to be manufactured by companies like Moldex if the original can't be reused.

 

Craig it is best to have the bearings in hand because with Lamborghini you don't always know what is and is not available. Lamborghini unlike other manufactures does not always follow the normal standards that other manufactures seem to follow.

Take for example the bearings that are available for the 5 liter, 2-valve Countach. They are available in, standard size, first oversized and second oversized. The problem being is if one would assume that the first oversized set of bearings was 0.010" oversized like so many other manufactures typically produce they would be WRONG. As the first oversized bearing set is in fact 0.005" oversized and the second oversized bearing set is 0.010" oversized.

This is very good information to have before grinding the crankshaft. Maybe you can clean the crank up by taking 0.005" off from the journal diameters or maybe you can't. Or maybe if you assume that the first oversized bearing set is 0.010" oversized and you install them foolishly without checking them you have an engine without any oil pressure.

The later unfortunately happened to me at the hands of a self proclaimed Lamborghini expert by the name of Robert Ball owner of Supercars International Inc. Well this not only resulted in my Countach engine having no oil pressure. It also resulted in a lawsuit against Robert Ball and Supercars International Inc. This then led to eventual filing for bankruptcy protection by Robert Ball that took place exactly one year ago to the date.

Sincerely Vic