30 replies to this topic

[nicklouse]

But what should I do if it are not the right caps? Will check for the marks etc

Spend money new block with correct caps.

Caps are block matched.

[Dusky]

But what should I do if it are not the right caps? Will check for the marks etc

Spend money new block with correct caps.

Caps are block matched.

Hmm, can i rebore it to 1330 without offset boring? Already got my pistons..

[Guess-Works.com]

You don't NEED to offset bore at +60, however if the current bore will allow I would recommend it. I've been offset boring @ +60 for a while and makes for a much better spacing of the bores maintaining the gap between 2 and 3 therefore increasing head gasket reliability. Also means you can go to 73mm and then 73.5mm on future builds before the block would need to be linered back to standard.

Edited by Guess-Works.com, 19 April 2015 - 06:42 PM.

[Dusky]

Will be a long time before i have to rebore, and as offset boring would be more expensive... what should I do with the other block? Scrap it as there are no caps?

[dklawson]

Offset boring and the crank issues are completely separate.

 

If you have already paid someone to bore this block for the pistons you have, then you may want to discuss line boring the block for the crank.  Take whatever price they quote you against buying another complete block (with proper caps fitted) and having it checked and bored for your new pistons.  Whichever is less expensive is the way to move forward.

 

For future reference, as is stated in all service manuals, you are supposed to stamp or otherwise mark each bearing cap prior to removal so you can put it back in the correct location and orientation.  The reason you are having issues appears to be because the engine came to you in bits and the caps were not marked prior to removal.  You don't know which one goes where or even if they all came from the same engine.

 

I don't want to rain on your day further, but you said this engine came to you in pieces.  If the person who took the engine apart did not mark the bearing caps for position and orientation... they are likely to have skipped this important step with the connecting rods as well.  I hope this is not the case.

 

Clean all the parts as best you can looking for orientation marks (1,2, 3, 4 numerical stamps... or perhaps a series of center punch marks (1 dot, 2 dots, etc).  Check the connecting rods for the same.

[Dusky]

I have a block with caps fitted ( and already tested it with this crank and hot no problems with locking things). Si the only comparison is line boring vs re boring. (Dont know the prices of line boring?)

In lucky enough that the conrods came with the caps fitted i guess( hopefully these are still the right ones though )

[69k1100]

Just out of curiosity have you measured the crank and earing shells prior to assembling this engine? It may not lock up because the crank journals could be undersized. I don't want to be a p*sser but if you want to stand any chance of getting decent trouble free mileage from the engine you're spending time to build (time you can't get back) then you really need to have your wits about you and be methodical about your approach.

I've never built an engine before, only because I feel I have to learn considerably more before I can proficiently build one. Working my way up from bodywork to gearbox assembly then to the big boy stuff.

[Dusky]

Yes, i did measure the journals ;)

[peter-b]

How about some plastiguage around said troublesome journal, might shed some light.

[mini13]

pull the crank out, bolt the troublesome cap on and feel the "joint" where it meets the block, if the alignments good you should nto be able to feel a ridge. if you can slacken it off and see if you can move the cap about with those alignment collars in. also check the collars to see if they fit tightly, if they are slack replace them... swiftune do some nice billet ones that fit really snug for about 15 quid.

 

also check the back of the bearing for any raised areas, somtimes the stamping can cause issues, and check the ends of the bearings for raised bits. it dosent hurt to go over all the exteriour edges with a fine file and pit a slight bevel on them.

 

the fact the crank turns then locks up sugests a bend, can you check this?

 

also its not the crank hitting the cam is it?

[Spider]

I did read your post last night (our time!) and wanted to sleep on it a little.

 

Sometimes these can near do your head in to track down, the running clearances are fairly fine on these engines.

 

This is some stuff to check, but not in any particular order.

 

But what should I do if it are not the right caps? Will check for the marks etc

 

Now, is the Crank an A or A+? They are ever so slightly different, often can be interchanged but on a few engines combinations, not always. If it's A+ and un-ground, there were 3 'grades', there'll be a dab of paint on one of the webs, what colour is it?

 

OK, if you look near the where the water pump goes, you'll find 3 or 4 numbers and maybe some letters stamped there. These same numbers should be on the caps. Then you know you have matching caps, that's a big start!  (how they ever get mixed up in the first place is one of the mysteries of the Universe!).

 

I nearly always fit new hollow dowels, it doesn't take much distortion of these to put the cap out.

 

Do a final clean of the caps, bolts, dowels with thinners.

 

Check the spot facings on the caps where the bolt heads come down on. These need to be flat, smooth and it is essential that they are perfectly perpendicular to the bolt hole. If they are not, have them corrected by a machine shop.

 

Assemble the caps without the bearing shells and torque up (oil the bolt threads and under the heads). Check there is no 'lip' between the mating parts. Measure the tunnel for diameter and roundness. The diameter for the tunnel is 2.1460" to 2.1465".

 

Check the Tunnel alignment between tunnels. This needs to be +/- 0.0005" (half a thou).

 

If all that checks out, clean the bearing shells with thinners and measure the thickness of the shells. For stock size shells these should be 0.072" thick.

 

Assemble the shells in to tunnels 1 and 2 (with thrusts) torque up. leave the cap off no. 3 and check the crank for wobble on no. 3 journal. While you're at this point, check the bearing shell crush or nip on bearings 1 & 2. Must be between 0.003" and 0.007".

 

Check the crank end float, I think the books say 0.002" to 0.003", but I have found this nearly always gives trouble, I go for 0.003" to 0.005" in a stock type build, a little more in something that's going to be reved. Just while we are here, I always rub the backs (steel side) of the thrusts on a diamond stone. The are all stamped with info and the stamping is always proud of the surrounding material, so makes them sit 'high', at least until they get hammered flat! Best take them off at the start.

 

Disassemble, fit shells in to no. 3 tunnel, torque up and then check bearing crush.

 

Reassemble and then check journal to bearing clearances, Plasti-gauge is handy for this. Dead set smallest you'll want to see is 0.001" but a good clearance is 0.002. Maximum clearance (on a bad day) is 0.003".

[Dusky]

pull the crank out, bolt the troublesome cap on and feel the "joint" where it meets the block, if the alignments good you should nto be able to feel a ridge. if you can slacken it off and see if you can move the cap about with those alignment collars in. also check the collars to see if they fit tightly, if they are slack replace them... swiftune do some nice billet ones that fit really snug for about 15 quid.

 

also check the back of the bearing for any raised areas, somtimes the stamping can cause issues, and check the ends of the bearings for raised bits. it dosent hurt to go over all the exteriour edges with a fine file and pit a slight bevel on them.

 

the fact the crank turns then locks up sugests a bend, can you check this?

 

also its not the crank hitting the cam is it?

 

 

I did read your post last night (our time!) and wanted to sleep on it a little.

 

Sometimes these can near do your head in to track down, the running clearances are fairly fine on these engines.

 

This is some stuff to check, but not in any particular order.

 

But what should I do if it are not the right caps? Will check for the marks etc

 

Now, is the Crank an A or A+? They are ever so slightly different, often can be interchanged but on a few engines combinations, not always. If it's A+ and un-ground, there were 3 'grades', there'll be a dab of paint on one of the webs, what colour is it?

 

OK, if you look near the where the water pump goes, you'll find 3 or 4 numbers and maybe some letters stamped there. These same numbers should be on the caps. Then you know you have matching caps, that's a big start!  (how they ever get mixed up in the first place is one of the mysteries of the Universe!).

 

I nearly always fit new hollow dowels, it doesn't take much distortion of these to put the cap out.

 

Do a final clean of the caps, bolts, dowels with thinners.

 

Check the spot facings on the caps where the bolt heads come down on. These need to be flat, smooth and it is essential that they are perfectly perpendicular to the bolt hole. If they are not, have them corrected by a machine shop.

 

Assemble the caps without the bearing shells and torque up (oil the bolt threads and under the heads). Check there is no 'lip' between the mating parts. Measure the tunnel for diameter and roundness. The diameter for the tunnel is 2.1460" to 2.1465".

 

Check the Tunnel alignment between tunnels. This needs to be +/- 0.0005" (half a thou).

 

If all that checks out, clean the bearing shells with thinners and measure the thickness of the shells. For stock size shells these should be 0.072" thick.

 

Assemble the shells in to tunnels 1 and 2 (with thrusts) torque up. leave the cap off no. 3 and check the crank for wobble on no. 3 journal. While you're at this point, check the bearing shell crush or nip on bearings 1 & 2. Must be between 0.003" and 0.007".

 

Check the crank end float, I think the books say 0.002" to 0.003", but I have found this nearly always gives trouble, I go for 0.003" to 0.005" in a stock type build, a little more in something that's going to be reved. Just while we are here, I always rub the backs (steel side) of the thrusts on a diamond stone. The are all stamped with info and the stamping is always proud of the surrounding material, so makes them sit 'high', at least until they get hammered flat! Best take them off at the start.

 

Disassemble, fit shells in to no. 3 tunnel, torque up and then check bearing crush.

 

Reassemble and then check journal to bearing clearances, Plasti-gauge is handy for this. Dead set smallest you'll want to see is 0.001" but a good clearance is 0.002. Maximum clearance (on a bad day) is 0.003".

Hollow dowels are very snug, was a pain to get them out to test if it would work with the dowels removed.

It indeed turns, then locks up and then turns again. Will check tomorrow for a bend.

 

The color on 1 of the webs seems to be a splash of green paint ( probably BMC engine green?

Crank is supposed to be from a MG) metro. Will check on the cap faces etc tomorrow when th esun shines again ( well hopefully it wont rain!).

Previous owner wasn't too sure if the caps match th eblock anymore too, so the misallignment issue probably lays there.. Now I'll try to see what woudl be fastest, boring my other block or lien borign this.. AS I had that über imprtant meeting on sunday.. Busy days ahead!

[Spider]

The color on 1 of the webs seems to be a splash of green paint

 

 

OK, size is 2.0009" to 2.0013". The Green Cranks actually have more clearance than the most of the others, there's only one other that has more.

 

One obvious thing I did forget to ask, have you looked at the bearings for witness marks?

Edited by Moke Spider, 19 April 2015 - 10:50 PM.

[Dusky]

The bearing that locks up has witness marks from locking it and then trying to turn.

 

Checked the clearance with the other ( Red) block and everythign is okay.

 

I guess the blue block will become a table... Red block is out for a rebore, hope I'll get it by wednessday /thursday. Howlong do you think it will take to buildup the engine?

[Jordie]

With right tools n stuff. Clean work area and everything prepared to fit....its a couple hrs.