Mild Rebuild Ideas?

[Dex.e30]

Engine to be pulled for painting in the Fall, so I am considering a rebuild. I was thinking ‘stroker’, but for DD, and with another HP car already in the stable, the investment isn’t worth it.

Looking for a little more power, but just as reliable, clean running

So, what parts would you replace or freshen up?

Current status: M20 with ~150k on it

1. Springs
2. Valves
3. IE 'Performance 272 Cam for M20 (325i) reground' cam
4. block to be painted [black?, silber, white?]
5. all the seals, gaskets, etc., etc
6. timing belt & wp just done ~500 miles ago
7. spark plugs just done ~500 miles ago

Whatelse would you do with the motor out? TIA

[nando]

I wouldn't waste money on the cam. if you are going to keep it mostly stock, just keep it stock..

[Dex.e30]

What about rebuild parts? What would you do, and why?

[nando]

bearings, rings, seals etc. a stock rebuild :p

but really, are you sure it even needs a rebuild? I would consider just replacing the seals and leaving it alone. 150k isn't that much for an M20 - it will go to 200k easily. will you be keeping this car for another 50k? is it worth the time and money? maybe refresh the head, but I doubt that's even neccesary.

[Dex.e30]

bearings, rings, seals etc. a stock rebuild..

I can turn wrenches, but I have no idea about internals, so I appreciate any advice you can offer.

but really, are you sure it even needs a rebuild? I would consider just replacing the seals and leaving it alone. 150k isn't that much for an M20 - it will go to 200k easily.

Its been through at least 4 owners, all with different maintenance [and modification] habits, so I’d like to take the opportunity to start anew with known variables, freshen it up [was happy to see this], and add some additional reliability.

..will you be keeping this car for another 50k? is it worth the time and money? maybe refresh the head, but I doubt that's even neccesary.

I’ll be keeping the car indefinitely. I think its worth it. I mean, when am I going to crack open the engine again? Hopefully, like you say, not for another 200k, so why not take care of everything in one shot.

Could you expand on 'refresh the head'?

[nando]

okay then. are you planning on doing the work?

if you can turn wrenches and read a manual, you can put the bottom end together yourself. it's very simple..

the only things you won't be able to do is the machine work - have the block honed, cleaned (make sure they know about the intermediate shaft bearings) and polish your pistons. have the crank cleaned and checked out, but not neccesarily polished (unless it needs it). have the rods checked out, and have them press in new bushings if they are worn out. have the deck of the block checked for flatness, and surfaced if neccesary. Replace the rod bolts, but you can reuse everything else.

For the head, have it pressure tested, checked for cracks, and checked for flatness (and surface as neccesary). if the cam is in good shape, reuse it - but I'd replace the rockers with new OEM, as well as new eccentrics. The springs are probably fine left alone, but replace the valve retainers. Get new valve stem seals, and have the valve guides checked out - they are probably fine, but replace any worn out ones. Same with the valves - exhaust valves are cheap, so replace them if you want, but I'd just have the intake ones reconditioned, and get a 3 angle valve job done.

be sure to get a GOOD piston ring compressor - I attempted to use a cheap one at first and I ended up breaking a ring. that cost me a day and $75 to have one overnighted to me... there is lots of information out there on putting a bottom end together, and the M20 isn't very complicated. The bearings are matched to your crank - I'd call a dealer and give them your build date to get the correct ones from BMW.

I'd also replace the oil pump while you're in there, but if the old one is in good shape it's probably not neccesary - they don't really wear out unless the engine was seriously abused.

there's lots more I could type here but you're best off going to the library and getting a book on building an engine, or even searching online for a well written guide.

oh yeah, a good STOCk rebuild can put down ~150hp at the wheels... more than some people are getting with all the M20 bolt ons you can buy :p

[Dex.e30]

No, I won’t be doing the work [car will be at paint shop while motor at another shop, while I am ~3 hours away], but I’d like to know what components to purchase to hand over to my mechanic.

I mean, IE sells a few up-rated components that might be nice to have [reground 272 cam ‘m20cam272re’, smaller exhaust and intake valves, coated main bearings], but not sure if they are worth it for the kind of build I am doing.

[nando]

no, they aren't worth it. I've said it a million times (and people will disagree) but stay away from regrinds. you're better off with the stock cam..

just stick to OEM parts. you can get stuff pretty cheap if you call bmaparts.com. I'd get the crank and rod bearings directly from BMW.

[dude8383]

okay then. are you planning on doing the work?

if you can turn wrenches and read a manual, you can put the bottom end together yourself. it's very simple..

the only things you won't be able to do is the machine work - have the block honed, cleaned (make sure they know about the intermediate shaft bearings) and polish your pistons. have the crank cleaned and checked out, but not neccesarily polished (unless it needs it). have the rods checked out, and have them press in new bushings if they are worn out. have the deck of the block checked for flatness, and surfaced if neccesary. Replace the rod bolts, but you can reuse everything else.

For the head, have it pressure tested, checked for cracks, and checked for flatness (and surface as neccesary). if the cam is in good shape, reuse it - but I'd replace the rockers with new OEM, as well as new eccentrics. The springs are probably fine left alone, but replace the valve retainers. Get new valve stem seals, and have the valve guides checked out - they are probably fine, but replace any worn out ones. Same with the valves - exhaust valves are cheap, so replace them if you want, but I'd just have the intake ones reconditioned, and get a 3 angle valve job done.

be sure to get a GOOD piston ring compressor - I attempted to use a cheap one at first and I ended up breaking a ring. that cost me a day and $75 to have one overnighted to me... there is lots of information out there on putting a bottom end together, and the M20 isn't very complicated. The bearings are matched to your crank - I'd call a dealer and give them your build date to get the correct ones from BMW.

I'd also replace the oil pump while you're in there, but if the old one is in good shape it's probably not neccesary - they don't really wear out unless the engine was seriously abused.

there's lots more I could type here but you're best off going to the library and getting a book on building an engine, or even searching online for a well written guide.

oh yeah, a good STOCk rebuild can put down ~150hp at the wheels... more than some people are getting with all the M20 bolt ons you can buy :p

Wow. Good info there.

I'm going to be rebuilding my spare M42 over the summer.

That just set a couple of things straight for me!

[Dex.e30]

no, they aren't worth it. I've said it a million times (and people will disagree) but stay away from regrinds. you're better off with the stock cam..

just stick to OEM parts. you can get stuff pretty cheap if you call bmaparts.com. I'd get the crank and rod bearings directly from BMW.

Cool, thanks again for the info. :up:

[Dex.e30]

Spoke with my mechanic this evening, and essentially agreed nando. Can't remember specifics, but will bascially clean up the block and head, check for any parts that might need replacing, replace some seals, and lastly paint. I'll procure another block and head for the work.

[BUDNUNTA]

Wow. Good info there.

I'm going to be rebuilding my spare M42 over the summer.

That just set a couple of things straight for me!

+1 thanks Nando
What do you know about M50/M42 rebuilds?
Im doing a top end and was wondering about replacing the lifters? is it nesessary there expensive and have seen them for sale used so probably just need realacing if needed? or as an upgrade to lighter ones(s50 S53 do you need the cam trays)?
Thanks Nando your the man


Hunter



Hunter

[dude8383]

+1 thanks Nando
What do you know about M50/M42 rebuilds?
Im doing a top end and was wondering about replacing the lifters? is it nesessary there expensive and have seen them for sale used so probably just need realacing if needed? or as an upgrade to lighter ones(s50 S53 do you need the cam trays)?
Thanks Nando your the man

Hunter

Hunter

You know, to tell the truth I don't know.

I bought M50 lifters for my rebuild because they hold more oil, not sure about them being lighter though.

If I was doing a top-end rebuild I'd probably buy new lifters either way.

Maybe Nando can chime in with some advice?

Sorry to thread jack.

[nando]

I don't have much experience with the M42 - but go read on www.metricmechanic.com on what they do with their M42 builds. there are some things you could take from them I'm sure. I believe that using the M50 lifters is common. The M42 is basically an M50 with two cylinders lopped off..