I'll take some tonight , I also have new OEM rods in the Nissan boxes

Tom

after iburnt out my a14 in my s/wag i fitted a a12[not a12a] into it with a oval port head being a a12 i had to redrill oil gallery and plug hole.on later model a12a no need to. do what you said but don't forget to use manifold to suit carb/s,if using adaptor weld on & open up its throat wild cam & shave the s##$ out of the cyl head must be no less than 90 thou run copper gasket & use v.h.t cooper gasket spray, don't forget dual valve springs[come std on a14 gx twin carb head balance it &she'll pull 8000 no worries.if you wan't life from block don't bore unless needed nitetrited from factory

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OK, lets see if I understand this.

You 'burned out' your A14 & you replaced it with an A12 engine [Is it a 1970 to '73 model 1200 engine, or the later 1974 to '82 type?] but not the North American A12A [1237cc] from the 1979 to '82 US model 210 [B310]
So far so good?
The A12A engine was never used in Australian models, so, without importing one, I don't know how you would get one anyway.

You used an oval port head, but you needed to modify it by drilling & pluging so that it can be used on the A12 engine. This would suggest that you are using a cylinder head from the 1974 to '77 Datsun 120Y-GX, or more likely a head from an A14 or A15 engine on Datsun 1200 block [front distributor] as this mod is only required on the 'late head to early block' conversions.
The A12A head is the same as all of the other 1974 & later heads in regards to the rocker oiling system, so it too would need the same mods if used on an early block.
[Edit] Or did you mean that the 1974 & later head would not need mods if used on the US A12A block, which would be a correct assumption.

You also recomend machining at least 2.25mm from the head & seem to feel that this will not seriously weaken the deck, or the gasket face, of the head, but you recomend against boring, unless necessary, as the bores in a cast iron Datsun A12 block are 'nitetrited' at the factory.

Is this similar to the nitriding on crankshafts?

All I can say is that I bored my 1971 Datsun 1200 block 3mm oversize & I used this engine in a 'sporting way' for many years untill I eventually wore it out at about 100,000 miles. [160,000 km] I rebored it again to 76.5mm & pressed it back into service after a comprehensive overhaul, then used it for a lot more miles again. That engine is in pieces now, but the bores are still within service limits &, with a light hone & a set of rings, would give many more years of reliable service.

In the Datsun 1200 Competition Tune Up Manual, the factory recomended a 3mm overbore in the 1200 blocks to bring these engines closer to the 1300cc limit of the class that the 1200's seemed to compete in back then, & they provided the pistons for it too [I used A14 pistons], so the serious overboring of Datsun A series blocks is a long held, & factory recomended, tradition.
That nitetriting must go pretty deep I think.

As for the head, I recomend that machining be kept to within factory limits as the factory seems to have been concerned about head reliability on just a stock engine, yet you recomend going well beyond this in a performance engine.
I suggest that more compression should be gained through more moderate maching & the use of suitable pistons instead.

The recomended 'wild' cam will have serious & detrimental affect on lower speed operation & driveability, so if all you're after is a paltry 8,000 rpm, then this can be achieved with a cam of much more sensible specifications. After all, even the stock engines were red lined at 6,500, so how 'wild' does it need to be for such a relatively modest improvement. Talk to a reputable cam grinder for more realistic recomendations.

Just my 2c worth.

what's stated in my first three lines answers your first 2 paragraphs,except where they come from seeing you that you don't know [don't know why you seem to think you know everything else going buy what i have read]..they call it auto wreckers out of late 120y's or sunnys & also vanetts[so you don't get confused i have worked at the wreckers]p.s no assumption fact......NEXT; nitetriding more ifo for you it's called case harding thats why you can run app.. 3 sets of rings on avg before boring.then if you want it to last you can't drive as hard & have to run s**t black ring's,or pay the buck's & renitetrid to run chrome,factory or hasting rings etc,then you can flog it... most jap eng's were done up until app 1992 so i have been informed this is the reason you can't run chrome or simliar hard rings in aust made fords or holdens...you say keep within factory limits yet you go well beyond that when you are boring & risk the BORE FLEXING , OVER HEATING & PICKING UP OF THE PISTIONS. [re;you stated on another post]....NEXT;factory limt for cyl head is from memory is app.. 9 thou.so don't let it get hot because in your opinion throw away head.*** THIS WILL BLOW YOUR BRAIN *** on my own eng's i run std pisitons thats why i take off 120 thou,my saying is bang for your bucks,yes the pisitons do hold up to it try it you'll get a surprise.just make sure tunning is right, little on the rich side i prefer so you don't risk cooking the pistons,make sure you go colder in the spark plugs.... i go 2 ranges for street use .no the cyl head does not warp or crack neither.i use n0;13 bolt same as gx twin carb & pull down a extra 5 lb,using copper gasket & vht copper gasket spray not hylomar spray.at the moment i won't mention the other cyl head mods i do it'll be to much....NEXT;wild cam hummm 30-70/70-30 [old school they called it 3/4 race] sounds wild to me .... now lets see i have a old school a series eng in block cam and only 2 OHV valves per cyl no roller rockers heavily modded cyl & it's. n/a no hairdryer or police attracting p****er valves here.[sorry but i don't like blow off valves dump it into the exhaust i say].torque dose not raise it's head not even in the a15's[persernol opinon] so you need to be at 4200-4500 & above to get any sort of grunt...A PALTRY 8000 what a joke i said PULL REPEAT PULL TO 8000 thats far from paltry to me by the it'll rev a lot further & if you can't understand it's out of it's power curve any higher. technickly you should pull up at 7500 with this cam.SORRY EVERYBODY BUT THE SARCASIM IN THE HIS LAST PARAGRAPH GOT TO ME..........BY THE WAY IN 1992 I THINK 92 /93 CROW CAMS PUT A MOD SHEET IN FAST FOURS YOU COULD FILL IN STATING YOUR ENG MODS THEY REPLIED WITH 30-70 FOR A REALISTIC 7500 REPEAT 7500 RPM FOR MY ENG'S....GOOD NIGHT IVE TAKEN TO LONG NEW AT THESE KEY BOARD & INTERNET THINGS.

This is an international club & the A12A [1237cc] engine was sold in some models in some countries, but not here. Refering to the 1974 & onwards A12 engine [1171cc] as an A12A simply confuses the issue as it is simply not right. This is why I call the front distributor version of this engine the 'Datsun 1200' engine, since it was used in, ummm , well, .... Datsun 1200's, while the later engine is refered to by me as the A12, ... which it is.
Obviously the wreckers that you have dealt with in the past have got it wrong.

EDIT
A12 engine, 73mm bore x 70mm stroke =1171cc
A12A engine, 75mm bore x 70mm stroke = 1237cc








I had no problem with the boring bar in my Datsun engines since the 3mm overbore is a FACTORY RECOMENDED modification. There have been more than a few that have run their 1200 & A12 engines at bore sizes out to 77mm without any problems. My own 1200 GX engine is currently at 76.5mm & the bore shows no sign of abnormal wear. Bore service life seems to equal that of original/standard bores too.
Obviously these 1200 & A12 blocks were cast with the intention of allowing them to be overbored by at least 3mm for competition engines. After all, successfull racers are good for promoting product & selling new cars.

Cams. Well, we have a difference of opinion with the terminology. I would not use the term 'wild' to describe the 30/70 cam. That this is a performance cam is not in doubt, but 'wild' seems to be overstating it.
Tighe cams refer to their 31/70 cam as a 'Fast Road' cam profile, & it is the milder of the two 'Fast Road cams that they offer.

Wade cams also offer a similar cam & their comments say only that "Needs springs, twin carbs, good midrange" That doesn't sound very 'wild' to me, but is probably a good choice anyway.

Hey greasemonky here is a link to the pics of the a15 disassembled.

PHOTOBUCKET

Guys, sorry to interrupt...its regarding cam grinding...i have no idea how its done..
Im planning to run a 285deg on my A15...

Can anyone pls explain how its done. Actually i need the simplest, yet effective method. High precision CNC milling will cost alot...so, are there any guide for a "hand made" cam profiling?....Thank u all.

well what in your guys opion is a wild cam? For a bored out a12 to the 77mm like said befor a twin side draught weber and 4in1 extractors?

Have a look at the Tighe list for the A series & see what they say about each different cam.

The cam you use should be governed by the use that the engine will be put to.

If you plan to actually DRIVE the car, on the street, then stay away from cams that are recomended for competition use only. These will make the most power, [while the engine lives] but you will very likely regret it from day one.

If necessary, talk to your cam supplier & be guided by his suggestions.

For me, a 'wild' cam would be a 'race only' cam. That's about as 'wild' as you can get.

g1
To successfully re-profile a cam, you would need a cam grinding machine. Think of it as being the same for crankshafts. To regrind one of these, you need a crankshaft grinding machine.

If you can't get it done properly at home, then it might be an idea to e-mail either Wade cams or Tighe cams to see what's involved in sending them your old one & having it done properly over here.

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They weld on the cam first.