Hey Ito, What is the deal with the clearance tolerances? I mean to ask on a 60k mile 13B-rew that had collant seal failure is there a typical one to keep an eye out for that will get out of wack whe reassembling the short block?

I am refering more to the eshaft play and the bearings more that the corner seals and side seals.

How much attention to detail really needs to be paid here?

Check out the updated FAQ at the top of the screen.



There is a site just for you https://www.nopistons.com/forums/pub...DIR#>/moon.gif

i have a question about the apex seal the groove clearance

its supposed to be 0.0027-0.003" with a max of 0.004" every other fd motor we take apart is at 0.004" or more, they seem to run ok that way so how important is that clearance?



mike

Yea I have been through that site man. I was trying to get some discussion going on..

I like chatting more than just reading.

belie' dat!

Let's get a discussion going. Ask me what exactly you want to know and Ill try to give you some input on my experiences and great results on clearancing.

well we notice on say stock to mildly modded fd's that the apex seal grooves are in a v shape (particularly the corners), and that when you measure it its out of spec. how evever they seem to run fine with used (out of spec) rotors, what do think judge?



mike

I find it better to have a bit more clearance in the apex seal to rotor groove,then not enough. I have seen the V shape on the rotors by the corner seal also, but if measured deeper into the rotor groove the fit starts to get tighter.(basically, there's a tighter fit in the bottom of the groove and a wider fit at the top of the groove, I measure at the bottom of the groove) When I install the apex seal into the rotor groove, I make sure the apex seal is well in the groove, then I start to run my gauge well into the botton of the groove and get an even clearance from one point of the rotor to the other point. Considering metal expands under heat, is always good to extra clearance this areas a bit more. For that reason sometimes using rotors with a bit out of clearance will not hurt the engine but could prematurely hurt the apex seals from to much flapping back and forth in the excessive groove clearance from the rotors having to much V groove(clearance) by the corner seals. Let's keep this topic flowing. FD3Boost where are you? https://www.nopistons.com/forums/pub...IR#>/boink.gif

hmm so you mean if its even it should be ok? do you ever hammer the corners back? i like this kinda topic, i dont build that many motors



mike

Yes a nice even clearance from one side of the rotor to the other side. No hammering the corner seals, they should fit nice and tight but no hammering.

How about apex seal length and clearance of the side housing and apex seal edge? Seems like the after market seals I measured, atkins and hurley, are just a tad bit oversized in length. I am talking like 80.02 mm to 80.05 mm. Since the rotor housing width is right at 80mm, this means they will not be straight until the sides wear a little. Has that been your experience also, ito?

Im sorry I just checked back in..

I was wondering about the clearances of the eccentric shaft.

(I know I am gonna phrase this wrong) When you install the front spacer,thrust needle bearning,thrust washer/balance weight,sprocket and drive gear.

the manual states the tolerable play is 0.040-0.070 mm

The max being 0.09 mm.

In your experience is it common that a 93 with 60k miles on it will be out of acceptable levels.



How close do these actually come to being out of spec?

Yes sir. Now we are talking. Many people have had problems with the atkins because of this reason. Since Dave Atkins at first did not address the issue to measure his seals many people just installed the seals with out measuring and had many problems. I measure every single seal even the factory ones. I even measure brand new rotor housings. I know they are new but I just don't care, I want to know, I have perfect parts instead of hoping and guessing Im getting perfetc parts. Apex seal length has to be .0015 of an inch smaller then the rotor housing width. This way when the engine is assembled and under a load, the smaller tip of the apex seal will not push itself over the longer part of the apex seal and create blow by and loose compression.

Uhoo thanks for that bit of advice.

It's a no brainer but I am new and would have not thouht to measure even the stock parts.

If they are(apex seals that is) too long can they just be block sanded down to the correct length?

Besides regular bearing to eccentric shaft clearance, I have found that .0025 end play has brought me many great results with bearing life. When I write .0025 I mean 2 thousands and a half of end play. I have found some engines needing a different end play spacer after tearing the engine apart. I have found too much end play. Sometimes .004 and up too .006. Too much end play will try to make the engines main bearings walk away from the stationary gears.

Yes block sanded and check the apex seal length every 10 strokes. Your going to take a while but a really good and clearanced engine will make you a better engine builder and a happier one. And don't forget your giving a better reputation to the rotary engines reliability.

Yes block sanded and check the apex seal length every 10 strokes. Your going to take a while but a really good and clearanced engine will make you a better engine builder and a happier one. And don't forget your giving a better reputation to the rotary engines reliability. [/quote]

Hey Im just trying to learn as much as I can for my car incase a nuclear bomb explodes and the only survivors are me and my Fd https://www.nopistons.com/forums/pub...#>/biggrin.png

Yes block sanded and check the apex seal length every 10 strokes. Your going to take a while but a really good and clearanced engine will make you a better engine builder and a happier one. And don't forget your giving a better reputation to the rotary engines reliability. [/quote]

Hey Im just trying to learn as much as I can for my car incase a nuclear bomb explodes and the only survivors are me and my Fd https://www.nopistons.com/forums/pub...#>/biggrin.png [/quote]

I wish I had some info. like this many good websites when I was learning. I created a couple of bombs myself when I first started. Especially in the engine timing department. But that was 15 years ago. Thank god I was loyal to this little engine and did not give up.

wow thats some good stuff judge :bigok: its always great to see someone who actually wants to build good motors, i used to work at a dealership, and we used to look at all the mana motors with a flashlight, mostly junk



mike

When I sit down to assemble any engine, by the time im done with all the clearance my back hurts and it usually takes about 4 hours or more. But is all well worth it.

Ito, the interesting thing on the length is that the 86-88 factory manual has a spec length of 79.9 to 80.1 mm. So I am assuming you can get a factory one over 80 mm also. I was told by a few "experts" that the 0.0015" clearance you stated was for one piece seal only. The 2 piece seals have zero clearance because the small linear expansion is taken up at the split not the sides. It is very strange that mazda manuals of any year don't have any info on the clearance of side plate to apex seal. By the way, when I told hurley about the length, his advice was to not clearance the edges in any way since the sides would wear themselves in and fit perfect after break-in. Personally, I don't see a downside to giving a little clearance up front except it is very hard to keep the ends square when you sand it.

By the way, he also said NOT to super glue the corner piece of the seal.

Do you use super glue??? And yes, using any kind of glue makes the length even longer!

That is the whole problem with the aftermarket seals like Hurleys and Atkins. I have seen .0016 of metal expansion when the engine warms up under a load. If you don't make the seals a bit shorter,(even though is a 2 piece apex seal) the shorter piece of the apex seal will slip over the larger peace when the engine is under some serious temperature,(because of the metal expansion promblem) and create some blow by or leakage from one chamber into another.I have talk to many people that did what Hurley recommended. Not to clearance the seals and all I could say is many ,many people are not using Hurleys seals anymore. I took a 2piece 2mm Atkins apex seal and measured the seal, then I heated the seal with my acetylene torch, I had the apex seal turn cherry red and let the seal cool off and re-measured and I had an apex seal that was .0016 of an inch larger from side to side. If you have a rotor housing with a width of 80mm and start with an apex seal with 80mm your going to have problems. becuase this apex seals grow like Chia Pets under some temperature. Stock seals have a totally different hardening and do not grow like the after market ones do.

Getting back to Hurley for a minute. One time I had Eamon Hurley machine some 93Fd rotors that had broken the factory 2mm apex seals. he machined the rotors to fit the 3mm apex seals. When I recieved the rotors back, they were fully assembled with all the seals on.(like side seals corner seals oil seals and apex seals) I talked to Eamon and he told me the rotors were clearanced and ready for assembly.I decided to check the side seal clearance apex seal clearance oil seal ring location. and to my surprise every single measurement was way off. I'm writting here and giving some proven tips from my personal experience. Not some word of mouth from people like hurley. Basically I'm writting and giving tips on proven and reliability performance. I have build many engines that consistenly get tortured at and over 11,000rpm and they live to fight another day and another day and another season. By the same token I have seen some engine builders build engines for a one day event. after that day the engine is burned out, no compression, warpped apex seals like a banana shape. And some very disappointed racers. Now you do the math..

What did atkins have to say about this? They do sell an awful lot of engines with their own seals in them. I take it, this problem arises in high performance t2 applications and not N/A ones?. You are correct in the fact that a softer metal will have a higher coefficient of expansion than hardened metal. But if you and I know this and they do also I don't understand why they continue to sell oversized seals.

Thanks Ito. We all really appreciate your contributions to the forum :bigok:

Damn am I glad I followed good advice and stayed with the stock seals.



How can they manage to stay in business with such a shitty product?

Damn those Brits! https://www.nopistons.com/forums/pub...IR#>/boink.gif



I have another question about Hurley seals, let me jump on the correct thread.

Atkins Rotary has gotten MANY negative criticizm about his apex seals. Many tunners did not get a chance to tune an engine when the seals collapsed. I started to use the Atkins seals since I build alot of N/A bridgeport and P-Port engines with Nitrous Oxide. When I had my first engine failure with the Hurleys. I liked the seal before I had the failure so I decided I wanted to find out what was going on with the Hurley seals. Then I noticed the metal expansion, and noticed the Hurley and Atkins seals were made of a softer metal then the stock cast Iron seals. I had a choice of using Racing Beat carbon seals(which I dont like for nitrous engines) and the Atkins metal expanding seal. I decided to correct the Atkins seals and use them. What I do, is tell the people that buy my seals,(mostly speed shops) to make sure and measure and clearance this seal. I just try to spread the word. I have talked to kathy Atkins about the metal expansion and she said they were going to address the problem. I always talk to Kathy, because in my opinion David Atkins is not the smartest cookie. Over all I like the stock cast iron seals for turbo application. But I cannot use the stock seals for bridgeport engines.

actully now that you mention it, how are the carbon rb/mazdacomp seals for an na non nitrous, either bp or big streetport motor? i gather if you set them up right (clearances) that they will run fine for about 40-60k maybe lacking a little low end power over a steel seal. i like the fact that they dont do any damage when they go, and i'm thinking that a big plus.



mike

Ito san.. https://www.nopistons.com/forums/pub...#>/biggrin.png What kind of side seal to corner seal clearance do you run on higher hp turbo engines? I'm assuming that a long side seal will expand more than the apex seal does.. I usually run a .015mm cleance and I've had no problems with blow by, but I've also heard that a tighter clearance will pick up 10 hp or so..

you can tell a tight side seal motor from a not tight side seal motor spinning it by hand



mike

Dragon I see you want to get the good info. Side seal clearance is responsible for some nice equal compression on both rotors and extra power. I clearance side seals according to the application. N/A or turbo application. Ill reply later with my specs I need to surf to pineapple racings website for some pineapple racing 6port better flowing sleeves. Ill be back. Im building a bridgeported 6 port engine and using the stock auxilary sleeves with the 5 and 6 ports bridgeported also. Ill make sure to take pics. So far it looks like a wicked port.This engines is going to have 12 port openings using the 5 and 6 port sleeves for low rpm torque and opening at around 5,500RPM. I want to see how much power increase the bridgeported 5and 6 port will add to this engine when they open.

lol.. give me spec's Ito.. :yum: and hurry up and get a damn digital camera.. https://www.nopistons.com/forums/pub...#>/biggrin.png If you need $, I'm sure vosko's gone and broken somthing else on his car by now.. https://www.nopistons.com/forums/pub...#>/BURNOUT.gif

doesnt vosko have a reserved parking space at the shop?



mike

haha, i knew it. i'm happy iget to build a 12a soon, and i'm gonna actually tke my time and build a really good one instead of "good enough"



mike

Uh humm, clearance spec's.... https://www.nopistons.com/forums/pub...#>/biggrin.png I'm waiting over here on the other side of the plannet... https://www.nopistons.com/forums/pub...IR#>/boink.gif

ito is gonna fix my car soon. he wants to see me do another monster burnout in front of the shop with the FD. this time it will videotaped though :bigthumg:

sweet, aks his what he sets his side seals too



mike

itos neighbors must be used to the smell of burning rubber. I've seen plenty of videos of huge burnouts in front of his shop and those are only the ones that were videotaped and uploaded https://www.nopistons.com/forums/pub...DIR#>/wink.png

Alright, Jude Ito, your honor, how do you keep the apex seal end square when you are reducing the length? Any tricks you know? I was extremely careful and it seems quite square but not perfect. I am assuming the ends wear in after break-in so it is not extremely critical to have it perfect. Any thoughts?.........