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Main : Mechanical : Engine Dimlight's turbo block

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Dimlight's turbo block
Dimlight's turbo blockPopular
Submitterdimlight65More Photos from dimlight65   Last Update2002/11/2 22:24    Tell a friendTell a friend
Hits9562  Comments10    0.00 (0 votes)0.00 (0 votes)
Here is the A-12 block bored out to accept A-14 pistons.  Oh, if you look closely, you might also notice the ARP head stud kit.

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The comments are owned by the poster. We aren't responsible for their content.

Poster Thread
Dodgeman
Posted: 2004/9/24 23:30  Updated: 2004/9/24 23:30
No life (a.k.a. DattoMaster)
Joined: 2003/6/27
From: Southern Tablelands N.S.W. Australia
Posts: 8287
 Re: Dimlight
The 1974 Competition tune up manual shows a 76mm flat top piston for the 1200 engine. [but not the larger 76.8mm one]
This book makes no reference whatsoever to any cautions, other than checking valve to piston clearance when the head has been heavily machined, & valve to bore clearance.

I also have a slightly later [B210] competition manual which has the larger piston listed, so i will try to find that & check for any cautions.

What is it that we can see at the base of each stud. I had assumed that they were flat washers, but maybee not.
Dimlight, would you care to bring us up to date with this engine?
Are the studs simply screwed into the parent metal, or has some additional work been done in the block?

Poster Thread
dimlight65
Posted: 2008/8/26 18:09  Updated: 2008/8/26 18:09
No life (a.k.a. DattoMaster)
Joined: 2001/2/7
From: Fort Worth, Texas, USA
Posts: 1003
 Re: Dimlight
I finally fired this engine up Sunday 08/24/2008. The water temp went pretty high pretty quick causing me some concern. When I told a friend how much we'd bored the thing, he got me thinking about this thread. I'm not ready to chuck it all and say, "Well, the walls are too thin" but it is my number one suspect. Has anyone else "hogged out" an A-12 for A-14 pistons and had it checked (like I should have done) and/or run successfully?

As for the studs, yes, those are the flat washers resting at the bottom. Sorry that reply took so many years, Dodgeman.

Poster Thread
rally1200
Posted: 2008/8/26 19:28  Updated: 2008/8/26 19:28
Home away from home
Joined: 2003/10/3
From: Perth
Posts: 287
 Re: Dimlight
Yes i have been using 76mm and 77mm pistons in my A12 with A14 cranks for years. full race applications (rally) up to 8500rpm sustained. never had a problem with bores. but did have lots of problems keeping it cool.

Poster Thread
dimlight65
Posted: 2008/8/26 20:44  Updated: 2008/8/26 20:44
No life (a.k.a. DattoMaster)
Joined: 2001/2/7
From: Fort Worth, Texas, USA
Posts: 1003
 Re: Dimlight
What did you have to do to keep cool?

Poster Thread
E10
Posted: 2004/9/24 23:06  Updated: 2004/9/24 23:06
Not too shy to talk
Joined: 2004/1/16
From: Ronse,Belgium
Posts: 32
 Re: Dimlight
In the competition manuals the 76mm piston is referred to as option 1 and the 76.8mm is option 2.There is an interesting line in the E10 manual (E10 was the first FWD cherry model) that says :'Though the wall thickness of the standard 73mm bore is 5mm,inaccurate casting and/or machining during modification may result in damage to the block'.So normally it works,but one could always be unlucky.....

Poster Thread
Dodgeman
Posted: 2004/9/24 12:04  Updated: 2004/9/24 12:04
No life (a.k.a. DattoMaster)
Joined: 2003/6/27
From: Southern Tablelands N.S.W. Australia
Posts: 8287
 Re: Dimlight
Well, i'm resurecting an old thread here, but it's a good topic.

There was some question about boring the 1200 block out to 76mm. Well i think that we all know now that a 1200 block without core shift will handle that on its ear, & then some. Nissan supplied a 76.8mm forged piston for these engines in the '70's, so they knew how much it could be safely bored. It was made this size so that engine displacement would come out at about 1297cc in a 1300cc class.

Why studs? A stud can be nice & securely seated at full thread depth BEFORE the slightest measure of tension is applied. I have never liked the thought of a high tensile steel bolt being screwed, unter great stress, into a relatively soft iron hole. I don't much like doing it with a coarse thread either, but the coarse thread is an absolute necessity in the softer iron casting.

Yes, i know, the industry has been doing it this way for a century, which shows the power of economics over the wisdom of engineering. Simply put, bolts are 'good enough'
Much better is to have the stud firmly & fully seated, ready to share its load on ALL the threads in the block first up, rather than reaching down for another turn as it is being tightened under high stress.
The much more gentle application of tension of a high tensile nut, gently gliding along the fine thread of an equally high tensile stud is, in my view, a more sound proposition. This system is also capable of safely applying an even greater clamping force if this is ever deemed necessary.

Can anyone else add some constructive input.

Poster Thread
ddgonzal
Posted: 2004/9/24 15:50  Updated: 2004/9/24 15:50
Moderator
Joined: 2001/5/3
From: 48 North
Posts: 31575
 Re: Dimlight
Quote:
Nissan supplied a 76.8mm forged piston for these engines in the '70's, so they knew how much it could be safely bored.
Nissan also added this caution:Quote:
[A12/A13] Cylinder wall thickness should be checked by sonic testing when increasing initial bore size in excess of 1mm/.03937". Standard bore size for the A12 or A13 block is 73mm/2.874".

reference: Nissan Competition Parts catalog, 1984 editon
The catalog shows 76mm "Arias Forged Racing Piston" or "Cosworth Forged Racing Piston" for the A12A/A14 and a 76.75mm "A14" piston of Arias manufacture.

Poster Thread
b310gx
Posted: 2002/11/5 12:15  Updated: 2002/11/5 12:15
No life (a.k.a. DattoMaster)
Joined: 2002/7/19
From: sydney australia
Posts: 1858
 Re: Dimlight
did the stud kit come with a reduced shank bolt for oil feed to the rocker gear,cause i'm interested in getting a set for my next a15 build up.it doesn't look it from the photos,but i seem to remember a12's had a different feed system to the a12a's,a14's & a15's.maybe there's a different kit for a14's & a15's.

Poster Thread
1200rallycar
Posted: 2002/11/5 13:05  Updated: 2002/11/5 13:05
No life (a.k.a. DattoMaster)
Joined: 2002/3/20
From: Melbourne, Australia
Posts: 8221
 Re: Dimlight
whats the deal with the stud kit, what does it do? how is it diffrent?

Poster Thread
ang94541
Posted: 2002/11/3 7:15  Updated: 2002/11/3 7:15
No life (a.k.a. DattoMaster)
Joined: 1999/12/6
From: Castro Valley,CA USA
Posts: 1191
 Re: Dimlight
Did boring out the cylinders this much make the walls paper thin? I've been thinking of getting an A15, but doing something like this to the spare A12 I have sounds interesting.

Poster Thread
dimlight65
Posted: 2002/11/5 17:58  Updated: 2002/11/5 17:58
No life (a.k.a. DattoMaster)
Joined: 2001/2/7
From: Fort Worth, Texas, USA
Posts: 1003
 Re: Dimlight
I will try to answer all three questions.
1) Did boring the block make the walls paper thin? I don't think so. We, my machinist & I, felt around in the water passages at various points around the cylinders and feel pretty confident that the walls ar OK. Big gamble, I know. Hey, it's only money.
2) Does the stud kit come with a reduced shank stud for the oil passage? Yes. It is the one in the center of the picture, closest to you. Look really closely and you can see it is thinner than the others. ARP also makes a kit for the A-14/15 that has a different part number.
3) What is the deal with the head studs? This is an issue that could take pages and pages to discuss. Basically, studs are better than bolts because they... well they just are! Carroll Smith wrote a very good book called "Nuts, Bolts, Fasteners and Plumbing Handbook" that explains it in great detail. Corky Bell goes into in his book "Maximum Boost" and Smokey Yunick actually says in his book "Power Secrets" that "If you're building a racing engine and you're serious about it, using bolts to hold the main caps or the cylinder heads in place is just plain dumb!" I know this doesn't answer the question so I'll try to.
Studs, when installed properly in the holes, will reduce the stress in the block's threads by inducing some preload in compression that the torque of the nuts counteracts before inducing stress in tension. That is a summation of Bell's reasoning. The other two authors go on to mention that the repeated disassembly of a race engine is also an important factor. The studs don't have to be removed from the holes every time.
I'm going with Bell's reasoning and Yunick's warning about not being dumb to justify it in my mind. Besides, Summit Racing Supply had ARP studs for A-12s and A-14s in stock. How cool is that?
Sorry to go on so long.

Poster Thread
dattoman_1000
Posted: 2003/2/8 15:53  Updated: 2003/2/8 15:53
No life (a.k.a. DattoMaster)
Joined: 2002/8/11
From: Perth
Posts: 2689
 Re: Dimlight
I can't find a part # for the A14 kit anywhere and our local performance boob was hard pressed to know what an A series was as it didn't have 8 cylinders.
Could someone furnish me with the part # for these ??