28 replies to this topic

[ACDodd]

If they did it it would have been on the bill. Busines charge by the hour, they would have put more time in the bill to do that job.

Ac

[purple_fly06]

If they did it it would have been on the bill. Busines charge by the hour, they would have put more time in the bill to do that job.

Ac

Pretty confident they did do it if I’m honest, see image https://imgur.com/qsvDzgu
It was one of the more time consuming parts for them when I would get updates.

[nicklouse]

The first thing I would be doing is checking for ID marks on the rods and pistons. As I would be shocked if they did not ID them if they did do a dummy build. How else would anyone be able to put it back together?

[OzOAP]

I take photos of everything. Parts as delivered, during machining/measuring process and when finished.
Customers can see what they are paying for and they feel like they're involved.

Edited by OzOAP, 09 February 2021 - 02:57 PM.

[mini13]

as said this sounds like a LOT of variance,

 

first thing i would do is note the  deck height of each rod & piston combination, and then swap them around as assy's, ( tallest with shortest) and see if the height follows the rod& piston or stays with the bore/crank.

 

If it stays with the crank/bore then Id be looking to try another crank, ( i dont suppose the mini crank will swap end to end will it? to check to see if it follows the big end journels )

 

its also worth measuring the actual stroke on each cylinder to see if any are off.

[purple_fly06]

as said this sounds like a LOT of variance,

 

first thing i would do is note the  deck height of each rod & piston combination, and then swap them around as assy's, ( tallest with shortest) and see if the height follows the rod& piston or stays with the bore/crank.

 

If it stays with the crank/bore then Id be looking to try another crank, ( i dont suppose the mini crank will swap end to end will it? to check to see if it follows the big end journels )

 

its also worth measuring the actual stroke on each cylinder to see if any are off.

 

Good advice, will do that. Could be that e.g. cylinder 1 has con rod 4 and vice versa.

[PoolGuy]

 

In the first instance you need to discuss it with Rob Walker 

Have you spoken to Rob Walker Eng?

[steeley]

I’d talk to the machine shop, it may be a simple fix

[PoolGuy]

I’d talk to the machine shop, it may be a simple fix

Agreed, at the moment they’re being made to look a bit shonky to be honest. 

[purple_fly06]

 

I’d talk to the machine shop, it may be a simple fix

Agreed, at the moment they’re being made to look a bit shonky to be honest. 

 

 

Agreed, I will give them a call if its not a simple fix. I'm not trying to throw shade at anyone as it could be a mistake on my part.

I'm just looking for advice in case I've missed something obvious. My plan is to take the advice given so far and if its still not correct contact RWE and see what they can do.

 

I'd rather try to sort it myself if possible as RWE is around 2 hours from me...

[mini13]

I will say Ive used Rob walker before and found him to be very good, but that is some years ago (maybe 10)

 

this dosent sound like a normal mix of components, ive found frm swaping bits around that you might see maybe 3-5 thou difference at the most, so unless you have a weird rod from the factory something sounds squiffy.

 

One other thing, is measurment accuracy, how are you measuring? and is it repeatable, I always measure in line with the gudgeon pin to eliminate piston rock.

[purple_fly06]

Thought I'd provide an update as to the outcome.

 

After taking it apart and re-evaluating I was convinced that some of the caps did not match the rods, this was emphasised by doing the dummy build when a certain rod was tightened it would pinch up on the crank or have tight spots.

I ended up taking the rods and caps out and taking them into work to check the concentricity of the caps and the rods to see if I could match them up correctly on the FARO arm and CMM... sure enough they were matched incorrectly.

I then re-matched them (once re-matched the chamfers and faces on the rods lined up perfectly), fitted new shells and installed them back in the engine. the deck height is now a very consistent 7 thou (was aiming for 5) which I'm very happy with. The engine now turns freely with no tight spots which is a relief...

 

The engine isn't far off completion (waiting on a few bits) but thanks for the advice and suggestions everyone 

Edited by purple_fly06, 19 March 2021 - 01:54 PM.

[PoolGuy]

My question now is, where the rods balanced like that? I find it incredible that the rods weren’t marked?

[Cooperman]

When rebuilding an engine, the first thing I do is to measure the existing deck height to piston tops.

Then the rods/pistons are removed and each rad/cap is marked.

When the new pistons arrive, the dimension from gudgeon pin to deck is measured and compared to the originals. This will give the notional dimension from new piston top to deck level and hence how much should be machined from the deck.  Personally I aim for 0.005" to 0.008" for a road engine, with 0.002" to 0.004" for a competition engine.

For a full-on competition engine it is good to have the crankshaft stroked and indexed to remove the diametric and angular tolerances and the rods accurately re-centred again to remove the BMC/Rover tolerances.

It is surprising how many crankshafts do not have the main bearing centres on the same centre line, i.e. the crank is slightly bent by a thou or two! Also the main bearing housings are not necessarily in perfect alignment.

Thus, as above, you get what you pay for. To have the crank stroked & indexed, the main bearing housings accurately aligned and the rods re-centred is not a low cost option and for a road car it is not necessary. Indeed, it is difficult to find a precision machine shop which is capable of that sort of work.