i can addmitt to my mistakes. my mistake is not putting the words EARLY A12 BLOCK in my thread.....hum i feel better now.... there is 2 diffrent a12's early & late [our diffrent terminollogy]..I DID NOT SAY THAT A A12 WAS A A12A. i said on later model a12a no need to drill, ...& buy the way they did get sold here technickley in the forms of sole eng importers,car sales imports & the wreckers....and if you read my thread right i !!WORKED!!there & IF YOU COME WANTING A A12 YOU WILL BE ASKED EARLY OR LATE ENG & where it was i have known them over 30 years and i use and still do go there to buy & compare parts for interchanging etc..preveios owner leased but most of the workers have been there for years,and know i like my datsuns.go speak to a few exp eng builders to get a broader opinion & you will find that you won't get the same life out of a bored eng....my old school terminology for cam's is 25-65=mild,30-70=wild,40-80=race,50-90 full house...yes 30-70 is a good streetable cam if you go to race you it will lump & and if in top gear at 60 k's [4sp] it'll be like you are running it on kangaroo jucie,so it's 3rd gear operation with alittle lump at 60k's if you pick race.''''I SPOKE TO CAM TEC TO DAY IN MELBORNE ABOUT GRINDS & SHE SAID THEY HAVE CHANGED THE WAY THEY ARE PROFILED & RATED,SHE'S KNOWS BEEN THERE 20 PLUS YEARS. WITCH I NEW ANYWAY. P.S, AFTER 23 YEARS OF WORKING ON A SERIES I KNOW THIER CAPCITY'S.THANKS .YOU ALSO HAVE ALOT MORE OFF THE SELF GRINDS TO PICK FROM NOW

TO G1;= IF THE GRIND SELECTED IS TO LARGE THEY WELD YOUR STD CAM[AS SAID BY KILLER 1200] THEN MACHINE IT DOWN BUT IF YOU WAN'T FULL ADVANTAGE FROM THE GRIND SELECTED I SUGGEST YOU BUY WHAT IS CALLED A BILLET CAM SHAFT BUT IS WORTH A LOT MORE MONEY...YOU WILL ALSO NEED A FULL LIST OF YOUR ENG MODS INCLUDING EXHAUST & FUEL UPGRADES AS WELL.SO THEY CAN MATCH A GRIND TO SUIT HAPPY MOTORING

Whitelightning
It looks like we are both old timers when it comes to Datsuns. I started my apprenticeship as a mechanic over 41 years ago & left the trade when I was the fleet manager for Telecom in the Goulburn & ACT areas during 1994. I ran the workshops in both Goulburn & Canberra back then & the whole operation was shut down nationally in February & March. It wasn't 'core business'.

I got involved in small Datsuns in 1980 & I still have my 1968 sedan, although it has passed it's 'use by' date & has been 'converted to components'.

No wrecker ever asked me 'early or late' when I was looking for A12 stuff because I always made it clear from the outset, but obviously, this would be a common question for most Datsun customers. 'Early or late' would be the appropriate question too, but in all fairness, it's only since the introduction of the internet that knowledge of overseas models has become readily available & most would not know about the real A12A.

One of the things that I hold dear is the acceptance that factory engineers were NOT complete idiots, so when they publish recomendations that it is safe to overbore a 1200/ A12 engine by 3mm, I accept it as being 'the good oil' & when they recomend a specific minimum overall thickness for cylinder heads, I realise that there are two reasons.

Firstly, they need to keep compression within limits that will ensure that the engine still complies with smog laws, & secondly, that there is a point at which the thickness of the gasket face starts to become insufficient to guarantee a reliable seal under all normal operating conditions.
I do not know what that point is, but I suspect that machining 2.25mm or more from this relatively soft aluminium gasket face would be testing the limits.

The only 'hard' bores that I have personally encountered are in my 1957 Dodge Hemi & that is because these 50's era Hemi blocks are cast from a high nickel content iron. They are so hard that reconditioners were advised to reduce the cutting depth of their boring bars by half to avoid problems with their equipment.
Reconditioners do not modify the depth of cut from their standard settings when boring Datsun blocks,[at least they didn't on any I have had done] & this suggests to me that these blocks are not significantly different from any other block.

Wow...one guy have 23 yrs experience in A series...and another have 41 yrs experience as a mechanic..!!!...How old are u guys actually....i feel im the youngest here..23...hehe

**excuse me for the irrelevent post in this thread...im just curious..

dont worry g1 im younger than you lol so would i get away with having an 40-80 as a street car. Would i regret doin this? would it make it any more tolerable with a heave duty clulch, or will this not afect its drivablity?

hi datsun guy, chance you could reget it .have you got exp with moded eng's if not i'd say not.because your gunner know that you have a 40-80.it'll be pretty lumpy when idlerling,doey down low &and go like a cut snake when it comes on. you will have to upgrade clutch & gearbox & also diff other wise they will s..t them self if you get serious with the power it will have,even only being a a12you have 69 hp app now after mods around 100+hp

Ok I pulled the head from my engine and it has oval ports on the intakes and square ports for the exhaust, looks like it already has double valve springs I looked for a casting number on the heads but could not find any.

Just curis if i understand from the previous posts, this head would be good to use on a a-15?

Also it has water passages below the intake

if your head has humps over the intake ports then it is a gx head which has a good cc. refer to the gx head in the tech and engine id page. it would be a good head to use for your a-15 build up

Quote:

yeah itll go alright.

double valve springs u say. its fairly easy to see if they are or aren't.

measure the valve diameters and try to find some info in the tech section to see if you cant identify the head more accurately...

Quote:If your head has humps over the intake ports inside the rocker cover, then you have the Nismo race head. The 1200 & A12 GX head had larger ports than the A14/15 heads, but no humps inside the rocker area.

If your head has 37mm inlets & 30mm exhausts, then it would be an A14/15 head & if the double springs are original, then it would be an A14 GX head, which I believe is based on the standard Japspac A14 head casting anyway.
I do not think that there ever was an A15 GX.

The Japspec A14/15 head casting is a good base for any improved performance A series engine.