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MG MGB Technical - Blueprinting?

I am currently rebuilding the engine in my 78B. This was originally a US car that was desmogged (no emission laws at all in NZ!).

Currently it is off being machined and then I am having it line bored and balanced. I am fitting standard parts except for new pistons to replace the old LC ones. I want to do as much of the assembly myself as possible because 1, it saves money and 2, I've always wanted to build an engine!

I am not looking at any performance mods but do want to make the engine strong and smooth.

What exactly is involved in blueprinting an engine? As far as I am aware it means measuring everything and making sure it matches a specific set of specs. The question is where do you get the specs and instructions on what and how to blueprint?

Simon
Simon Jansen

You'll find that a lot of older engine parts have a certain tolerance built in. More modern engines do not have the same degree of tolerances. The way I have addressed blueprinting in the past is to get your hands on parts that will maximise say, the engine's capacity (shortest con rods), (perhaps) compression (longest con rods), breathing (largest ports) etc. By following this approach you will end up with a stock standard engine (and one that can be proven to be so) that has been built in such a way as to maximise its potential. Hope this helps. Obviously the larger the number of specific items you can pick and choose from, the greater will be your chances of finding the most appropriate parts for your project.
Lin Ison

Simon. The term "blueprinting" has no, real meaning. As you suggest, the term means to be built to some specification, a "blueprint" if you will. All factory engines are, by definition, "blueprinted". So is any other engine that is built up to any specification.

As the term has entered the vernacular, it referrs to "stock" engines which had tolerences built into them. Some of these tolerences worked for more power and some worked agaist more power. When building up a "stock" car, one determines which maximum and minimum tolerances will combine to produce an engine which will provide the most power, but still be "stock". This, then, becomes a "blueprinted" engine--one which will meet all of the specifications of a "factory blueprint", but has optimized within those limitations.

I have written a tech article on this subject, for our local Club newsletter, and have posted it on my website. It may be of use to you as it discusses the terms "balanced" and "blueprinted". The website is www.custompistols.com/ and the article is on the MG section. Peter Burgess' excellent book contains a number of "blueprints" for some fine engines. His "basic big bore" engine, the 1868cc built on the 18V block is my next serious engine project. Les
Les Bengtson

Simon,

I'm also building an engine at the moment. I think I'm a little further on than you, but I am doing it for the same reasons as you. However it will not save you money! I just keep spending! Pistons, machine work, nuts and bolts, gaskets, timing chain, seals etc. The money keeps going out the door! In the end I think it will cost me almost the same as a replacement stock engine, but I will get an 1868cc engine with piper270 cam out of it. Still, I have always wanted to build an engine, so at least that is happening!

Have fun
Iain

PS I'm trying to keep a track on my website. http://homepages.tesco.net/~rachel.cameron/
I D Cameron

Iain, I already figured out the not saving money part! I just don't want to get too carried away doing things that won't have much practical gain for me. I am not a racer so just a nice, standard engine will be fine! Anyway, it's a hobby so what can you do.

Les, I keep coming across your site and it always has interesting stuff on it. Unfortunately I don't really get a choice of parts (like Lin suggests). I will basically get back a machined block, head and a bunch of bits I will assemble myself. How much can I do given that limitation and where do I find the specs I should aim for?

I think I need to get hold of the Bentley book (called a local shop about it today, if they don't have it Amazon does). I have the Haynes of course and another Autobooks manual. I also have the Peter Burgess book. That book is dangerous. Gives a guy expensive ideas :)

Thanks!

Simon

Simon Jansen

Simon. I hope the website is of use to you. It started out as a series of tech articles for the local Club newsletter. Many of our members joined because they had purchased an MG and were looking for techincial guidance. Hence, some very basic stuff designed for the fellow who has never worked on a car before. Hopefully, some of it is of use to those of you who have a "beyond the basics" understanding.

The Autobooks series is a quite wonderful series of books. I picked up the ones on the MGA and, if I remember correctly, the one on the A-H 100, both of which I had at the time. Written by someone whose last name was Ball. They were excellent books, which, I thought then, gave me a much better understanding of what I was trying to do. They "got lost" in various moves when I was in the military. Wish I had them today so that I could see if they were as excellent as I believed them to be "back in the good old days".

Back in those days, there was a book by a Brit named Colin Campbell called "The Sports Car Engine". (For the Scots, please forgive the "Brit", and I will forgive "The Campbells had ordered, King William had signed".) It is an excellent primer on sports car engines and has an excellent section on testing and troubleshooting. If my name means anything in the MG world, let it be used to get Haynes, or anyone else, to reprint this fine book.

To get back to your basic question. Peter Burgess' book is the current "bible" for most of us. Peter, like all of us, is still learning. However, I recently had Peter do one of his "Econo-Tune" cylinder heads for my daughter's car. Took a while. Peter mentioned that they had decided to hold a birthday party for the cylinder head before they sent it back. It did not, really, take that long, only seven months (but, I had told Peter there was no rush and it too me several more months before he engine was finished). The final result was an engine with .020" over pistons, .010" under main and rod bearings, and the Peter Burgess cylinder head.

What has the result been? A few oil leaks, which I will correct now. The newly installed OD transmission is not working. But, I will correct that problem or replace it with the one rebuilt by John Twist when I attended his seminar. But, for right now, the wonderful flexibility of the rebuilt engine is just a joy to drive. I have to keep reminding myself to limit the revs during the "break in" period.

My own 79 is currently being driven by my daughter. It has the same basic engine (mine is .040" over rather than .020" over pistons) with a cylinder head from an American tuner. Other than that, they are the same engines. My daughter's car, however, is much more crisp and responsive.

Thus, my experience suggests that, even with a stock cam, the Peter Burgess cylinder head makes a significant difference. Have the rest of the block built up as you wish. But, have Peter do the cylinder head. At that point, with a little tuning, you will have the finest running MGB that you can. Les
Les Bengtson

The best thing you can do is have your engine parts balanced. It saves your bearings and makes it much smoother. For a 4 cylinder engine it is generally about US$150.
Mike MaGee

Les
Isn't Peter Burgess in 'Jolly 'ol' ?
And that means some major shipping costs.
How much for shipping? And what does Peter charge to massage them?
Safety Fast
Dwight McCullough
Dwight McCullough

I always associated "mapping and blueprinting" with V8s fitted in American muscle cars.

In these applications, the idea was to get the stock motors to torque straight down on the front wheels.
Brad Batchelor

A Blueprint has exact measurements plus and/or minus a tolerance.

"Blueprinting" means eliminating the tolerance range, so generally if a clearance is 4 to 6 thou, then you build the clearance to 5 thou exactly, not a smidgen more or less.

If a part mates with another part then the alignment is made spot on rather than near enough - e.g. the rocker arm pads should be laterally central over the valve and centered longtitudinally on the end of the valve when at half lift.

Components are hand picked and matched so that they are all in balance - tappet weight, fitted spring height, load on the springs, etc., etc.

The centerline of the crank should be exactly parallel to the head face and the bores exactly at 90 degrees to both.

And so on......

Lightening componenets is not "Blueprinting" - it may help power though.
Chris at Octarine Services

Dwight. Yes, Peter is located in the UK and you may have to ship the cylinder head to him. (He may be able to pick up cylinder heads for certain cars over there and modify them for you.) You will, certainly have to pay to have the cylinder head shipped back. And, there will be a delay while waiting for the work to be done (mine took seven months). Whether the expense and the wait are worthwhile is a very individual decision. But, considering that a properly modified cylinder head is the basis for all engine "improvements", it was, to me, worth the time and expense. Les
Les Bengtson

I do carry a limited stock of Peter's MGB, MGA and midget heads for my engines, in standard unleaded, econotune, fast road and fully modified specs which I will sell outright - this will save you the cost of shipping your cylinder head to the UK, the wait for Peter (Sean, actually!) to work on the head and the risk that your head is cracked or unusable.

Don't all rush - the surplus I have is limited to one or two heads at any one time and getting good used heads for Sean to work on is getting harder and more expensive.

E-mail me if you want more details.
Chris at Octarine Services

I had always understood Blueprinting to apply to race classes with standard engines . People with money and a desire to win would have the engine rebuilt to maximise power , while staying within the original drawings so they would pass scrutineering when taken apart . I have not seen a genuine " blueprint" in the sense of a white line on blue background copy of an engineering original for about 30 years now .Wiring diagrams were a pain , cracks and scuffs in the original would print as a spurious wire !
S Best

Blueprinting is done in the machine shop.

Measuring tolerances/clearances can be done anywhere. Measuring tells the degree of accuracy.

It's my understanding that a blueprinted engine has parallel crank and camshaft centerlines, bores perpendicular to the crank centerline, and deck parallel to the crank, probably a lot of other stuff too - any allowable deviation from perfect is tolerance. Blueprinting is a matter of reducing the tolerances as much as possible.
Glenn

Hiya

Just to say Chris, we work in a holistic way on my heads...not just Shaun!

Peter
Peter Burgess

Well, bang for buck, I've found paying Peter's core charge for the spec head is cheaper and a shorter wait than sending one...or at least it was last time I did it.
vem myers

Hiya Peter,

.... and there's me thinking you just had fun on the rolling road and made the coffee ..... 8-)

.... yes, I know it is a team effort from blasting the heads through to lapping in the seats - and a very professional and knowledgeable team, too.
Chris at Octarine Services

Simon-
Chris and Les are correct in their explanations of what entails "blueprinting". However, the subject of balancing has yet to be covered in this thread.The effective length of the connecting rods (eye center-to-eye center distance) should be matched. If possible, have the connecting rods balanced end-for-end. This means that the Small Ends of the connecting rods should all be matched for weight and their Big Ends should also all be matched for weight. The total weight of each connecting rod should then be matched to the others in the set by removing metal from its shank. Have both the piston/ring/wristpin assemblies and the connecting rod assemblies matched respectively to within .10 of a gram. Pistons that use only three rings are lighter than the older-design four-ring and obsolete five-ring designs. The reciprocating masses having thus been matched, the crankshaft, harmonic balancer pulley, and the flywheel should then be dynamically balanced separately and subsequently checked for balance as a complete assembly. The flywheel should be balanced only after its clutch friction surface has been skimmed smooth. Advise the machinist that you would prefer that the dynamic balance of the crankshaft be achieved by wedging rather than by drilling. While more expensive than drilling, wedging will reduce both stress risers and oil drag and will greatly assist in prolonging main journal bearing life. In addition, the reduction in rotational mass produced by wedging will produce the same effect as reducing the weight of the flywheel. It is not only unnecessary to knife-edge the corners of the crankshaft counterweights of a street engine in an attempt to reduce windage loss, it is actually undesirable. Knife-edging can result in stress points which can lead to fracturing. Instead, a generous radius on each corner of the crankshaft will reduce both oil and air drag by approximately 90% of that attained by knife-edging. These procedures are fundamental to producing the smoothest running engine possible and will provide a bit more power that would otherwise be lost to the production of vibration, in some engines perhaps as much as 2 HP. It will also result in less main bearing wear due to more concentric running.
Steve S.

And I thought blue printing is what you got out of Laura Ashley,s

Pete.... Holistic? do you mean Realistic?

Cameron
Cameron

One version of 'blueprinting'

There was a rumour in NZ a few years ago in respect of 'homologated' cars that were eligible to race in a 24 hour race for 'production' cars.

A group of Fiat 125T's did very well.

The rumour was that although there were the necessary 100 cars built and sold to the public for homologation purposes, and that they were all the same, the tolerances on dimensions on suspension components was such that there was a great degree of scope for setting up the suspensions purely for the particular race circuit and drivers for each of the cars.



Ian Fraser

Just a small comment.

Depending on what you want to spend you can do most anything to improve what is already there.

As far as 'blueprinting' here is one that I might call 'beyond blueprinting'. When I lived in New Orleans, there was a very good local machine shop that regulary did BMW and Mercedes engines. What they proposed for my 'B' engine was decking, align boring the mains and using BMW or Mercedes main and rod clearances. This would reduce these clearances from 2 to 2-1/2 thou to about 3/4 thou via the accuracy of his equipment.

A friend of mine had an old Ford V-8 that this shop had done like that (reduced all the bearing clearances). When he was assembling the engine (crank and all rods and pistons in) he found that the torque to roll the engine over at this assembly point was a mere 18 lb-ft! When completed, he said that he had never had a rebuilt engine turn out as good as that one did.

You must, however, have an engine shop that is up to this task and be willing to shell out a few bucks.
Richard Smith 1

This thread was discussed between 24/05/2004 and 11/06/2004

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