Hurley engine out. My engine in...Help??

[Jonathan_F]

Igy is right about the lettering on the rotors, make sure they are the same, they are balanced and marked by Mazda for that reason.

I understand this but it is always possible to improve upon manufacturing tolerances. They are more cost orientated.

Thanks

[stuart wizy]

your dead right joe, always room for improvement on balancing on any mass produced crank, when you start talking about balancing to the nearest gram.
My crank assembled with rotors and weights and ligthened flywheel will move on its own weight between centres if i rotate it in a couple of possitions and just let go.
this means its not balanced without oil in the rotors.
to get it perfect you need to fill the rotors up with oil somehow

[Jonathan_F]

your dead right joe, always room for improvement on balancing on any mass produced crank, when you start talking about balancing to the nearest gram.
My crank assembled with rotors and weights and ligthened flywheel will move on its own weight between centres if i rotate it in a couple of possitions and just let go.
this means its not balanced without oil in the rotors.
to get it perfect you need to fill the rotors up with oil somehow

As I understand it the crank is 180°  (i thought it was 90° at the start of this thread). Therefore each rotor assembly balances each other. Now as the amount of oil in each rotor will be the same (neglecting acceleration/deceleration whn I understand it slops forward and back) and the seals/springs/corner seals will be in almost perfect balance due to their dimensional accuracy. That only leaves the cast rotors. Now mazda grade these by letter, I don\'t know the difference is mass across each grade but by simply balancing them the same as a pair then I can be certain i\'m improving the balance.
The counterbalances on the shaft are there to remove the secondary couple forces only from the rotating assembly (rocking forces).
Alhough these could be used to remove mass from when dynamically balancing the assembly. It is better to balance the rotor assemblies first.

[stuart wizy]

enquire about getting the full crank assembled with flywheel, rotors, counterweights, balanced at a crankshaft balancing specialist to get some good advice.
Im sure they wont have ever balanced a rotary ecentric shaft before, so it may be a novelty for them which normally creates interest.
something different from the normal crankshaft balancing on piston engines.

All i have ever balanced are grinding wheels and helical rotors between centres, but thats with just moving sliding bobweights around until the wheel or rotor doesnt move in any angular position on its own weight.
The rotors we made are for compressors, superchargers, pumps etc by the way at Holroyds machine tool and rotors.

[Jonathan_F]

enquire about getting the full crank assembled with flywheel, rotors, counterweights, balanced at a crankshaft balancing specialist to get some good advice.
Im sure they wont have ever balanced a rotary ecentric shaft before, so it may be a novelty for them which normally creates interest.
something different from the normal crankshaft balancing on piston engines.

All i have ever balanced are grinding wheels and helical rotors between centres, but thats with just moving sliding bobweights around until the wheel or rotor doesnt move in any angular position on its own weight.
The rotors we made are for compressors, superchargers, pumps etc by the way at Holroyds machine tool and rotors.

Yes. I\'ll have a look and see if I can call someone tomorrow. Time is short now if Pip gets my housings in tomorrow. Nice long weekend building and commissioning...
I\'ve got a nylon cutting board to chop into V-Blocks to check the final balance and a bit fabrication work to make a beam balance and i\'m done. Just the \'simple\' job of assembly after that.

I\'m thinking of clearancing the rotors now. I have a rotor that has touched the housing (oil pickup blocked (don\'t ask!) and lost the oil film at high revs) so I know where to relieve them.
It would be great to be able to pull 9000rpm in 1st. Great advantage at the strip perhaps if my porting is up to scratch.

Thanks for all the advice gents. Especially to a non-member  :rolleyes:

[Jonathan_F]

Right.
Well Pip got the goods in and I\'ve built the engine. I balanced the rotors to within 1 peanut at my local pet shop!!
Sounds dodgy but they were a £2k set of scales. Resolution was 5g so I improved that with peanuts. One of the rotors was about 8g heavier than the other.
I\'ll be installing the engine tonight and tomorrow.

Quick question. Do you fit the engine back in the bay with the engine mounts on or off? I had to remove the mounts before sliding the engine forward from the gearbox but the mazda manual has them on.
Do I need to jack the gearbox at the front to tilt it?

many thanks,

Jon

[G@NDY]

I have tried to help out on a few engine installs. And what people do is: jack the gearbox up, almost as far as it will go. Put the engine in with the mounts already attatched, and slide the fella in at an angle :p

[Jonathan_F]

Cheers. I\'ll try that tonight. I jacked the box up level last time and it was a struggle to get it to disengage.

[johnf]

Where in B\'ham are you?

John

[Bucky]

I think the best way to get the engine in with the mounts on is get the engine in the bay as far back as it\'ll go.  Then put the hoist around the bellhousing of the box and lift it and get a bar in under the engine and prise it back so it dropped into the cups for the mounts, worked for me with just about everything on the engine.

Taking it out I put the hoist around the bellhousing and prised it out over the cups where the mounts sit.

[Jonathan_F]

Hi Jon. I\'m in Sutton Coldfield. I\'m dropping the engine in tonight. Last night was R&R!
You don\'t fancy coming over do you? I would welcome your help.

Hi Bucky. I\'ll try that as it was a tight fit just to remove it.

Jon

[johnf]

Can\'t do tonight but I\'ll come over some other time it you need a lift or anything, but don\'t expect me to know what I\'m talking about.

John

[Jonathan_F]

Update!
She started up first time and ran like a good un...whilst pumping 4 litres of oil onto the floor!
After I\'d done up the oil pipe union she ran again. Very smooth. Then fouled her plugs and started running rough! ( 1 hour at idle)
All that 2 stroke oil in the fuel isn\'t helping but she\'s ok now.
I\'ve learnt alot so I\'m going to post a technical thread explaining it all.
Thanks for all the info over the past few months.
Jon

[Martiny]

excellent - congratulations.

[Jonathan_F]

Quick update. She\'s lost front rotor compression...all my whinging about Hurleys and my engine hasn\'t lasted more than 2000 miles!!

She does have phenomenal balance though. You struggle to tell she\'s running when you place your hand on the engine and no resonances up to 8k either.

Hasn\'t used any appreciable oil during this period and holds 7kg.cm² oil pressure with 5mm shims in the regulator.

I\'ll let you know what I find when I break her down soon. She was making a slight clicking noise from the block area so i supect I will have corner or side seal damage caused by my porting not being correctly radiused.

Jon