Irons lapping by a non-rotary specialist shop
 

Hi guys,

I would like to know what do you think about sending the irons to non-rotary specialist machine shop to lap the side plates?

Is there any advice like:
- Keep the plate straight.
- Don't remove more than X thousand of an inch.

I would like to send mines to a local machine shop but I'm affraid about the result.

Thanks,

Alex

The OEM Nitrate on the side plates are 3-4 thou deep. If you remove more than 3 thou , it will be wise to have your plates Re-nitrated. If that is not an option source some better condition plates.

The maximum anyone should grind or lap side plates is 4 thousands.

Hope that helps.

Thanks.

Do you think any machine shop can lap side plates?

I have a local machinist that has been doing mine for a couple years now. I usually don't go more than .002"
He uses a precision surface grinder that is accurate to the .0001" and has a true flat magnetic table so it stays straight. I have done quite a few engines now using this process and have not had any issues with it.
Here is a vid of a similar machine grinding a side plate.
http://www.youtube.com/watch?v=0pMG7EVxMkI

After this I use valve grinding compound and lap the faces together for a nice finish for the oil to mate to.

Very interesting. I think I will give it a try...

I have lapped sets that I can do exchange with.

You need to ship your set in to me, and then I ship you a set that are already done and ready to go.

Your set does need to pass inspection and be stock port and otherwise unmodified in any way..

You pay the lapping charge plus shipping only..

Good thread for the future

You'll want to consider the surface finish.

We had a local guy doing plates on a grinder as mentioned above. We measured a new stock plate at a finish of 12 RA. Our guy was able to produce a surface of 8 RA (smoother) with the grinder. That guy moved and the new guy that took over his equipment could only produce around 20 RA, which is essentially scrap iron.

Is the new guy just a retard at setting up the machine?

Or is he using the wrong grinding stones?

We grind until they clean-up and then we lap them.

2 different maschines

I always get OEM finish or better..

After grinding my machinist measured 16 RMS. However I was able to achieve a much finer surface after lapping the plates.

New guy was a retard.

i work at chipsmotorsports the surface finish is the smoothest like mirror finishing the problem is .002" deep in grinding the plates usually doesnt do much...some groove the rotor digs in from experience is close to .0045" deep on exhuast side and closer to .003" on average on the intake side the trick to chipsmotorsports is that we have the best surface finish in the indusry and we re nitrade them after doing the rough cut to take out all grooves and when they come back we take close to .00025" off the top so the engine break in time is eliminated. If your going to have a shop do your irons send them to chip he'll know what to do dont waste your time or money with non-rotary machine shops they dont know tolerances or RS/RZ finishes for the rotary.

yeah and when it's all said and done you'd be better off just buying a new iron or good used one, because the iron coolant seal walls do not gain strength over time, they lose it.

Are you trying to imply that irons should essentially be considered a "one time use" item, and throw away as soon as you experience any noticeable step wear??