TwinCharged RX7

iTrader: (14)

Hi all, can someone (experienced engine builder preferably) explain how the end play is set? Specifically, how that places the rotors inside then engine relative to the irons, and also how that places the eshaft relative to the bearings in the irons.

I've taken a spare engine's front cover off and removed the eshaft bolt and counterweight.

The eshaft now has between 1/16" and 1/8" slop in it (if I push on the flywheel towards the front of the engine, the shaft moves forward a bit, if I then pull, everything moves towards the rear of the engine a bit).

When the shaft reaches the end of its movement, it hits something. Is this the lobe on the shaft hitting the iron where the bearing is?

If I had another way to keep the eshaft in place (not using the front bolt on the eshaft, thrust bearing, counter-weight, shims, etc...), would I want the shaft pushed as far forward inside the engine as possible?

RotaryEvolution

iTrader: (30)

without the thrust bearings in place the e-shaft lobes hit the center iron bore where it stops.

the rotor positioning has little to do with the thrust of the e-shaft, the shaft slides on the bearings so the rotors are basically stationary inside the engine while the shaft slides front and back.

the thrust plate on the front stat gear, bearing in front and rear as well as the collar all cinched down set the thrust slack. this keeps the lobes away from striking any surfaces inside the engine.


when you disassemble the engine you have to walk the center iron off the engine, this is the interference you're feeling without the thrust bearings. even without the stat gears on the engine you will feel the same slack.

if what you're asking is related to your 4 rotor project you will need to build the engine in halves and mate them together in the center carefully and then worry about your thrust figures. obviously with the shaft lobes 'centered' on your center irons after machining.

ultimatejay

iTrader: (1)

You have to check the end play with the front cover off and then put the pulley and bolt back on and torque it to specs. Then you use a dial indicator. I set it on the front counterweight. I do this on an engine stand with the front pointing upward so gravity will pull everything down. Then use a flat blade screwdriver and pry upwards on the front counterweight and check your reading. I set mine around .002"

TwinCharged RX7

iTrader: (14)

Thanks guys, appreciate the info.

RotaryEvolution

iTrader: (30)

i don't think the underlying question was how to check endplay but it's actual purpose. which is to prevent the internals from floating around and running on citical components as well it aligns everything in front of the engine like oil pump chain, CAS/OMP drive gear and balancer and additionally keeps the flywheel from hitting the stat gear(if it in fact can).

scathcart

Better to do it with the engine horizontally, and moving the stack by hand. Prying doesn't give a correct reading of endplay- it adds in an amount of deflection caused by bending the thrust plate.

TwinCharged RX7

iTrader: (14)

Exactly. I think I have a solution:
Bolt both engines together
Move both eshafts back as far as they will go (possibly by tilting the engine upright so everything slides to the rear.
Pin the shafts together.
Set the front engine's end as per fsm.

As long as the front engine's plates and housings are within a few thousandths of the rear, then the rear engine's eshaft should be in the right location and locked in place via the front engine that retains the stock eshaft bolt and spacers.

RotaryEvolution

iTrader: (30)

it really depends if you are going to build 2 engines and mate them together with a key or split the shafts and bolt them together with a through bolt design. each way you have to measure the centerlines of the e-shaft to their relative halves and/or shim them so that they are centered. at that point the e-shafts will be matched to the block(s) and then you just have to worry about the end play.