Lapping Irons?

[Grizzly]

What is the general Opinion on Lapping irons?

I relies the standard FD irons are Hardened and that helps reduce the wear, so removing it is not that clever but at the same time early Rotary\'s weren\'t Nitrided or so i believe, So does it make that much difference to a motor that might do 50k between builds?

The Problem i have is i have seen plates with Excessive wear in the past that was put down to Lapping, but can\'t say i have rebuilt a motor using Lapped plates and 3k later its out of spec. So i don\'t know if the wear is simply old age or Lapping.

[Grant Monkhouse]

if plates are lapped and .003 of an inch, or greater, is removed then the plates should get re-nitrided
 
the ports have to be re chamferred too as it leaves a sharp edge, not good for the seals.  or port them afterwards if you have standard plates.

[Grant Monkhouse]

Grizzly did you get hold of the Apexi GT IC? if not Matt P is selling one so get on it quick;)
 
i was searching rx7club last night about lapping, some goodish info on there, have a look, just type in lapping

[Grizzly]

Grizzly did you get hold of the Apexi GT IC? if not Matt P is selling one so get on it quick;)
 

Yeh cheers, i must have upset him because he doesn\'t reply when i PM\'d him (on the dark side ) but we\'ll see.

[Grizzly]

if plates are lapped and .003 of an inch, or greater, is removed then the plates should get re-nitrided
 
the ports have to be re chamferred too as it leaves a sharp edge, not good for the seals.  or port them afterwards if you have standard plates.

I have had Plates resurfaced a few times before but after having a chat with an Engine Builder i know who uses Chip\'s i\'ve been put off having anything at all taken off the plates. The reason i put this up was to see what peoples first hand experience of this was because it all seems to be a mate had really bad wear or they where told the engine had been resurfaced and that\'s what they blame the wear on etc.

For me if its close to spec i usually just buy a decent second hand plate of Tim but its a bit of a Pita when i have to recut Ports etc.

[Grant Monkhouse]

if the plates are withing tolerance then i would say lapping isnt needed, but if they have wear marks, like 2 plates i have got then lapping needs ding to make them useable.

[Grant Monkhouse]

I would say poor lubrication would be the culprit for excessive wear not lapping of plates, providing the nitriding hasnt been removed.

Racing beat plasma spray their alli plates BTW, no noticeable wear at all after being in a race engine

[Grizzly]

I was told by a good source the Corner seals make a big difference to wear too, the Stock seals are Chromed so the face is very hard and reduces friction which in turn reduces Wear, but if you use softer Solid corner seals they tend to accelerate the wear as the Friction Increases.... Allegedly... Its just common to have the Plates lapped at the same time as a rebuild and the engines that get opened most often are the higher HP etc.

[Grant Monkhouse]

2 materials with different wear rates is always going to cause problems. For example rubbing sandstone against granite, one won\'t last right long.

With the correct coatings used after lapping then nothing should really wear faster than the other, I\'m sure iv seen people use ceramic corner seal?? Along with normal metal seals.

[Grizzly]

Yeh corner seals are just like Apex\'s every one has a different view but from my personal experience OE are the best hands down (even though its very common for them to split in half) but i do use Atkins solids on Higher hp motors simply because most other corner seals put square the bottom of the Apex Groove which is just asking for cracks imho but you trade off the extra plate wear against the extra strength.

TBH i would not have anything Ceramic in a motor of mine i have seen the consequences.

[ceylon]

Does anyone offer these services (And have exp with rotaries) in the UK?

[HaywardRotary]

I used to lap plates but not anymore.
The Nitriding was first done on 1st gen RX7 12a engines.
Its about 4 thou depth and lapping takes close to that amount off so your better of using good used plates with some wear than lapping in my opinion.
Having seen wear rates of more than 4 thou in less than 1500 miles on lapped plates by other engine builders and that are really smokey  with high oil consumption due to the wear that\'s the reason not to do it.

[HaywardRotary]

Stock Mazda corner seals have a diamond like hard coating over the chrome which is also really good for low wear. This type of surface material is used extensively in F1 engines for skirts of pistons.

[Grant Monkhouse]

I used to lap plates but not anymore.
The Nitriding was first done on 1st gen RX7 12a engines.
Its about 4 thou depth and lapping takes close to that amount off so your better of using good used plates with some wear than lapping in my opinion.
Having seen wear rates of more than 4 thou in less than 1500 miles on lapped plates by other engine builders and that are really smokey with high oil consumption due to the wear that\'s the reason not to do it.

after lapping have you not had them re nitrided? would this stop the excess wear

[HaywardRotary]

after lapping have you not had them re nitrided? would this stop the excess wear

Yes I have but the cost and hassle negates all the value of just using good used plates.
To nitride you have to remove all other metals in the parts otherwise they contaminate the process. There are quite a few blind holes with brass in them that have to be removed and refilled after.