Machining and Balancing
Turbo Mini Forums

I have the cash to get my engne sorted now so am ready to start re-assembling it! Im not sure whats involved in the following or what you guys have done but opinins/reccomendations would be great!:

1. What is involved in the installation of new big end bearings? Ive heard machining is necessary is this true?


2. Are "big end berarings" the shells that are in the rods and end caps? Or just on the ends of the block


3. What else should be replaced/looked at when rebuilding a block? (ive got new cam followers)


4. Is rod and crank balancing crucial or can it be left out? (im not sure how expensive this is)

Sorry for the questions, im still learning hehe!

1. Providing the big ends have not stretched then no, machining will not be required. It will just be a case of installing the new shells

2. The term "big end" refurs to the big end of the con rod. The bearings in the block for the crankshaft are called main bearings.

3. You may want to consider new cam bearings depending on the state of the ones that are in there.

Is the block warped?

Is the top face of the block completley flat or will it need a slight skim?

Have you had it re-bored, if not are the tollerances ok just to use new rings?

I would take out the core plugs and give the inside oil ways and water ways a good clean. Also may be worth modifying the water pump end as per vizards book to improve water flow the the 4th cylinder end of the block.

4. Balencing is not as crucial on our engines as it would be on a 9000rpm miglia engine.

Cost wise - my flywheel and clutch assembly was balanced up for £25 quid - so its not particularly expensive

Dan

Brilliant, that clears a few things up! And you make it sound as if it doesnt cost so much! I love you! haha thanks Dan

Rich

Have just been looking through my MiniSpeed catolouge and in there machining section it says about Big-end re sizing. What do they do when they do this?

Also on the avonbar site i was lookng at the big end and main bearings they do, they have oversized ones like +020 and +030 etc. how do i find out if my end caps and rods have been mahine before? What are the standard tolerances? Is it possible to identify what crank/rods i have using the codes, if so where are the details of the cast number?

Are metro turbo engines pre A+? Im not sure what year my engine is either, is there a way of finding tihs out too?

You need a Haynes metro manual as this has all the Mains and Bid-end data (and other stuff i think you need to read...) and a digital caliper so you can measure stuff.

Rods and main journals (big ends and mains) are not machined oversize btw - the crank is the part that is machined. ie the bearing 'shells' all have the same Outside diameter - the ID (and hence crank OD) is what gets progressivly smaller as the 'oversize' numbers grow...

10 thou is as near as dammit to 0.25mm incidentally.

I suggest you purchase a book that has been described on here a few times about engine blue-printing. I've got a copy - but can't remember the author or title for the life of me....

Edited by turbodave16v on 6th Apr, 2006.

Found it!
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7385

Des Hammil...

WWW.TURBO-MINI.COM

also should say on the back of the shells if it says std then stanard or +20 for just that ect

always looking for them bigger bunches of bannanas