Long Nose/Big Nose crank Info needed...

[FamiliaGT]

Im rather suprised at the lack of actual useful information on these situations. not looking for a "Look at the crank Bolt and Pulley" etc type answers. The B616 casting short nose crank I bought 4 years ago bit the dust, so Im in need of replacing the crank I have now. I purchsed a brand new crank from a friend of mine whos had it lying around for years. New Mazda crank set with bearings. Forging number B6S7 and part number b617-11-300 (long since superceded). Now that I have it, I spent the entire day digging for information on it, weather it was a big nose, or long nose crank and finally, after finding a post that displayed actual measurements of the snout on all 3 cranks, can say its a long nose new in the box. My issue now is finding the correct Timing Cog pulley, woodruff key and bolt for this crank. Mazda isnt much help as they list multiple part numbers for one thing. Is there anychance anyone knows the Part numbers for these items? Would be much appreciated.

Also think we need to start a list using Forging numbers off the crank to help with specific designation when its out of the motor and the bolt and pulley are not available to compare. Any thoughts?

[bman07]

Long nose and Short nose use same parts... Only Big Nose requires differnet pulleys, cog, key, oil pump, etc. Long Nose was just a temp replacement for 90-92 miatas..
Before they up'd the diameter from .875 to 1.063... If I remember right.. I too suffered my 1st crank nose problem... And am looking to replace the crankshaft.
I think i might just go Big myself.....

Brad

[bman07]

Here is a lil info for ya.. miata part #'s

Model Year Part Number

90-93 (short nose) B617-11-300
90-93 (long nose) B6S7-11-300A
94-05 (Big nose) BP06-11-300D (not sure if bp will fit thou..) mazdapartsunlimited claims all 1.6 & 1.8 cranks are interchangeable??? I don't believe this true...
I'll have to check out the BP block i tore outta my 92 escort gt last year.... Can anyone else confirm or deny this?

Actually the long nose 1 3/4 in. length nose and .865 diam.

and short nose is 7/8 in length and .865 diam.

BIG NOSE is 7/8 in length and 1.063 diam.

Brad

[Rocketman]

The BP is a longer engine so no. The rods, oil pump, water pump, timing belt etc are the same but the crank is much longer for the BP

[bman07]

Thats what i thought. Been a couple years since i worked on escort.... I was reading a post by moderator and he listed those cranks as a replacement to someone else...
Im really no GTX expert... I just am trying to figure out this pickle mazda left us with...

So if I go BigNose how hard would it be too find pulleys..
I suspose u'd have to look up cog, harmonic, pulley spacers, oil pump, power steering, water pump, a/c, and alternator pulleys...
Thats alot when you think about it. if i was to buy new it would cost a lot...
However could go used on accessory pulleys and just get harmonic and cog from dealership...


Brad

[FamiliaGT]

Thank you for the info Brad.
Heres where Im confused on my crank. The box part number is B617-11-300 which is for the small nose B616 forging numbered crank. The number on my crank is B6S7. Snout Diameter is 22mm and the keyway length is 27mm, with a noticebly longer snout. When I called my buddy at Mazda parts, the B6S7 number shows its for the big nose crank, although that number does not always coinside with the actual part number. This is where it gets confusing, so I am not sure what this is supposed to mean. Im assuming by the measurements that its the long nose, but I dont have a big nose to compare it with.

[FamiliaGT]

Correction. I found a website with a PDF that builds turn Key Spec Miatas and lists all the parts of the engine that have to confirm to SCCA rules as OEM, Including descripstion and Part Number. It states the B617-11-300 is the factory Miata Short Nose crank (NLA) and that B6S7-11-300 is shown to be the Long nose, which case, the casting number is a match. Only question is that crank apperently shows it requires a different pully, bolt and key, as well as the pully boss in the Mazda Parts Catalog. That sounds like the big nose, no?

[bman07]

Its showing a picture of the more common 1.8 BP. It says 1.6 & 1.8 in engine diagram.... Its only for part location reference. I believe big nose has a dowel of some sort sticking out of crankshaft Nose. much like reverse of whats on your camshafts.... If his snout diameter is 22mm = .865 its short nose or long nose. big nose is 1.063 in... long nose is supposed to be 1 3/4 long. 27 mm is only 1.06 in that cant be right. thats only lil over a 1/4 in longer than short nose...
Hmmm wierd.....
I believe Big Nose is b630XD forging number...??? xtra diameter?

Let me know more lets figure this out! Cause I need to know more. Cause i thinking of going BIG!
Might be cheaper than a $580.00 Mazda oem long nose... This whole situation is making my stomach sick..
Not that i can't fix it... Just the misinformation you get from web,parts vendors, and the likes...
I need to know and understand everything about my much loved 88 323 GTX...

Brad

[Rocketman]

The original "short nose" crank uses a pulley/harmonic balancer that bolts directly to the timing cog. The timing cog is retained to the crank by the main bolt.

The later "Big Nose" as you call it uses an intermediate hub. The hub sandwiches the timing cog to the crank using the main bolt, and is drilled & tapped. The hub retains the timing belt & must be removed in order to change it. The balancer & pulley have less offset and bolt to the hub using a different bolt pattern, and use a small dowel to index vs a keyway. There is no dowel in the crank itself, just in the hub.

[FamiliaGT]

Thanks Rocketman. That helps paint a picture. My crank is identicle to my short nose, but appears to be longer. I get paranoid about this stuff when Im unsure of what I have. I will post pics of the crank snout to give you guys an idea. With all my knowledge on this motor and car, I just havnt seen anything other then a short nose crank, so Im unfamilure with the differences.

[bman07]

I was wrong the b630xd is another longnose? Why are there so many part #'s and forge #'s??? Its almost makin my head spin.....

1989 - 1988 Mazda 323 1.6L L4 1597cc Turbocharged. DOHC. B6. Neck approximately 1 3/4" long and .865" in diameter.. Casting Number : B630XD

& more info...

1.6 4 86-94 B6 323, Tracer SOHC engines. Neck approximately 7/8" long and .865" in diameter. B616, B630
1.6 4 88-93 B6 323 GT Turbo & DOHC engines. Neck approximately 1 3/4" long and .865" in diameter. B630XD
1.6 4 92-95 B6 MX3, Miata, 323. Neck approximately 1 1/4" long and 1.063" in diameter. B6S7, B616, B630, B61K
1.6 4 99-02 ZM 99-02 Protégé B6S7, B616, B630, B61K

FamiliaGT this makes sense now.... you have the Big nose and your diameter is 27 mm which equals 1.063... length of yours would have to be 1 1/4 in = 31.75 mm.
according to your casting #

Brad

[Rocketman]

I have spares of both engines on hand here. When I get some time I'll take some pictures to show the differences in design.

[FamiliaGT]

I don't think that's right. My crank, I can slip a small nose crank Tbelt pulley on it and the bolt threads right in (they mabe the same thread pitch and size, don't know). Im assuming by the Diameter and size difference that the Big nose would not fit the small nose pulley?

Also, no where on the nose of my crank does it measure 27 MM diameter. This is getting frustrating. there just isn't any good solid info on this issue!

[FamiliaGT]

Brad, theres a flaw in that last post...

"1.6 4 92-95 B6 MX3, Miata, 323. Neck approximately 1 1/4" long and 1.063" in diameter. B6S7, B616, B630, B61K"

B616 I know from experience is the small nose crank. It cant be a Big nose, so this information is not trustworthy. Where did you find this?

[bman07]

That was from :

https://www.crankshaftsupply.com

I just want to get a crankshaft.... I don't know or care what to look for anymore. Theres so much mis info. every auto part store has a diff dimension or forging number...

Screw it... I am losing my f'n mind over this crap..... Can someone point me to a Big Nose or a short nose or a long nose. i don't care anymore. i want 1 bird in the hand. i got zero in the bush right now...

Or at least give me a part # or forging # that makes sense. I'm not even sure which pulleys need to be changed if i go bignose besides harmonic. i hear they have serpentine belt alts and does the a/c, water pump and power ster. have to be changed at all???...

I am losing all hopes. i don't even want to look for cranks anymore cause it leads to false hopes: different diameter n lengths, forged and not forged , 4 counter weights or eight, six gazillion different part #'s and forging #'s.... Its mislabeled everywhere and I feel like i ate a bad bunch of mushrooms or something....

When i am looking in my merkur xr4ti shop manual it labels each part# and forging # in the corresponding picture or description...
Something that is highly lacking in the mazda 323 shop manual.

HELP ME!!!!! I DON'T KNOW Which end is UP anymore...

With knowledge comes power and confidence....

The more i did into this.... The more powerless and fruitless my endeavors become.....

Not a gleaming Mazda owner at the moment....

Someone show my the mazda candle light and lead my mind home please....

Im Begging on two knees here.....

Brad