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Christoph
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PostPosted: Sat Mar 12, 2005 10:30 pm 
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Same thing has happened again... roughly the same distance too. Ive only had time to take the head off so far, big blow in the same place. Ive used copper gaskets both times. Also the gasket between 3-4 looked a bit discoloured, but not blown i suppose this is a bit of a hot spot. Now im thinking maybe the deck is **** and might need machining. The bores seem a bit worn also... the pistons will move back forward at TDC and seems more than a little bit.
Im tempted to go rebuild the flattop 998 i have sitting round and wack the 295 back on it and possibly fit a decent cam etc. From what ive read the 998's are one of the nicest running A-series and are naturally pretty revvy. I know they lack torque but i dont have time or money to source a 1275 donk.
How hard/whats involved in fitting a centre main strap? and also what kind of revs will it handle with/without centre main strap.
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drmini in aust
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PostPosted: Sat Mar 12, 2005 10:34 pm 
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Christoph wrote:
Same thing has happened again... roughly the same distance too. Ive only had time to take the head off so far, big blow in the same place. Ive used copper gaskets both times. Also the gasket between 3-4 looked a bit discoloured, but not blown i suppose this is a bit of a hot spot. Now im thinking maybe the deck is **** and might need machining. The bores seem a bit worn also... the pistons will move back forward at TDC and seems more than a little bit.
Im tempted to go rebuild the flattop 998 i have sitting round and wack the 295 back on it and possibly fit a decent cam etc. From what ive read the 998's are one of the nicest running A-series and are naturally pretty revvy. I know they lack torque but i dont have time or money to source a 1275 donk.
How hard/whats involved in fitting a centre main strap? and also what kind of revs will it handle with/without centre main strap.

A few people on here have had trouble lately with copper 998 gaskets- Gafmo, Mini Mad, kazjim.. all have since fitted ACL gaskets and no more problem, they all ran the dyno day too.
p/no of this ACL head gasket (VRS set) isCP250MT. Available from Repco etc. :wink:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:
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kazjim
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PostPosted: Sat Mar 12, 2005 10:43 pm 
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I was fine while i ran a pair of the copper (AF070 ?) ones and then i went to a single for some reason (cant remember.....) Bam, Bam, Bam three failures in a row ....

ACL now and no problems... since the dyno day, i'm running more power than ever and its still holding nicely !

J

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9YaTaH
 Post subject: Deck
PostPosted: Sun Mar 13, 2005 8:29 pm 
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Christoph wrote:
Same thing has happened again... roughly the same distance too. Ive only had time to take the head off so far, big blow in the same place. Ive used copper gaskets both times. Also the gasket between 3-4 looked a bit discoloured, but not blown i suppose this is a bit of a hot spot. Now im thinking maybe the deck is **** and might need machining. The bores seem a bit worn also... the pistons will move back forward at TDC and seems more than a little bit.
Im tempted to go rebuild the flattop 998 i have sitting round and wack the 295 back on it and possibly fit a decent cam etc. From what ive read the 998's are one of the nicest running A-series and are naturally pretty revvy. I know they lack torque but i dont have time or money to source a 1275 donk.
How hard/whats involved in fitting a centre main strap? and also what kind of revs will it handle with/without centre main strap.


Hi Chris, sounds like you really need to examine both mating faces....don't panic just yet....determine the flatness of the deck and the head :!:

Listen to the Doc re gasket choice etc

You will get there!!

PS are you using a Torque Wrench to tighten in stages???

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drmini in aust
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PostPosted: Sun Mar 13, 2005 8:42 pm 
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The so-called `copper' gasket (used to be copper-asbestos, once) has nothing inside any more, they burn easy.
The ACL gasket is a composition one similar construction to the black BK450 `turbo' gasket used on 1275s. :wink:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:
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Christoph
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PostPosted: Mon Mar 14, 2005 10:56 pm 
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Oh ok so the new copper types are basicly POS apart from the fact they are easy to clean up. Ill wack one of those ACL ones on and leave it for now.

Does anyone know about fitting centre main straps to small bore blocks?[/img]
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drmini in aust
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PostPosted: Tue Mar 15, 2005 6:13 am 
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You normally have to grind or mill the cap flat first, this weakens it to start with. And on a small bore watch it's not too wide or the thrust washers won't clear it.
I have one on my (now dead) 1310, but the new 1360 won't be getting one. GR reckons no need. Lots of race motors running without them. :wink:

Standard smallbore and 1275 centre caps are pretty strong. I only ever broke one once, in `67, running my hot 1098 on a mixture of petrol and diesel.. :shock: OK, so I was an apprentice (broke) and the old man had a drum of diesel on the farm.. :cry: :lol:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:
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kazjim
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PostPosted: Tue Mar 15, 2005 3:09 pm 
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So centre strap gets the thumbs down from Big Rev Kev ?

Was thinking about one too .....

Centre pickup on the list now.........
J

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drmini in aust
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PostPosted: Tue Mar 15, 2005 4:19 pm 
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The one I made, I stepped it so it fits on a nearly stock 1275 cap. Then I gave it .0015 " preload.
Might fit it again, on my next stroker motor, if I can find decent bolts- all I could get last time were Grade 5's. :shock:
Could not find Grade 8 bolts or Unbrakos (Grade 12) in 7/16" UNF, the right length.

BTW I took the big journal crank to get stroked today. It's std/std.. :P
The guy crack tested it (`ping!') OK, and said of the last 5 he got to do, 3 were cracked already.. :cry:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:
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gafmo
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PostPosted: Tue Mar 15, 2005 5:04 pm 
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drmini in aust wrote:
The one I made, I stepped it so it fits on a nearly stock 1275 cap. Then I gave it .0015 " preload.
Might fit it again, on my next stroker motor, if I can find decent bolts- all I could get last time were Grade 5's. :shock:
Could not find Grade 8 bolts or Unbrakos (Grade 12) in 7/16" UNF, the right length.

BTW I took the big journal crank to get stroked today. It's std/std.. :P
The guy crack tested it (`ping!') OK, and said of the last 5 he got to do, 3 were cracked already.. :cry:


Dr wan't thier another avenue for the Bolts
And I'm sure you did the Bushi's and congrats on the perfect Crank..I hope mine is :?

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drmini in aust
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PostPosted: Tue Mar 15, 2005 6:14 pm 
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Gaf, these are main bearing bolts not rod bolts. When I needed some (coz block had none), nobody had new Mini ones, even stock length- or Grade 8 etc. I guess I could have fitted ARP main stud$ and nut$... :roll:
So.. I just used Grade 5 hex bolts, revved it regular to 8,000, nothing broke.. not even the old stocko S rod bolts. :lol:
New 1360 motor has ARP `S' rod bolts. Couldn't find BB Ford ones. :cry:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:
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gafmo
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PostPosted: Tue Mar 15, 2005 6:17 pm 
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:wink:

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9YaTaH
 Post subject: Crank Whip
PostPosted: Tue Mar 15, 2005 10:24 pm 
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drmini in aust wrote:
Standard smallbore and 1275 centre caps are pretty strong. I only ever broke one once, in `67, running my hot 1098 on a mixture of petrol and diesel.. :shock: OK, so I was an apprentice (broke) and the old man had a drum of diesel on the farm.. :cry: :lol:


Hmmmm most A Series are known to "whip" their cranks.....do you mean the centre main strap does not dampen down these destructive oscillations :?: :?:

Do you routinely balance everything as part of a rebuild Doc.....crank and rods to flywheel :?: :?: :?

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