Questions...
I did something to my engine that is making an ugly knocking, I've been told it's a bearing or something. I'm gonna have it torn apart, so I'm not really asking what is wrong with it.

If I get an A12GX cam, do I need different rocker arms?
Do those nismo light weight lifters come in sets of 8?

Will oversize bearings help or is that just for when bearings have failed several times.

what am i going to want to have done to the block to have it be trouble free for a while again?

A12's have the distributor in a different place than the other A's. The distributor gear won't be in the right place. Oversize bearings are for worn crank or rod journals. If they have to grind the crank, you'll get oversize bearings.

I don't know anything about lightweight lifters. But I wanna!

My old a14 had a bad knock. pulled it apart yesterday to see what the problem. Turned out to be a broken ring. Is it making the oil go black or anything like that. If so it is likely to be a piston problem. ie cracked skirt, broken ring

Is this as a result of an over rev? Check the flywheel bolts when you pull the motor out.

1. GX Cam:

You do not need special rockers for a GX cam. Although I have seen some very nice roller rockers. If the lift exceeds 7mm you need to concern yourself with valve spring height, retainers, and pushrods.

From Nismo:

When installing any new A-series camshaft new lifters must be used. The GX camshaft can use any A-series lifter.

Due to increased valve lift, the race cams can only be used with the oversize cam lifter (13231-78201) which has a 33% larger surface area. The lightweight lifter (13231-M0820) weighs 24 grams less than the OE unit.


Block:

If your motor is knocking that bad then you dont need to concern yourself with bearings, you probably need the crank ground or a new one and the machine shop will mic the crank and install the proper bearings.

Have machine shop check both the block and the head surfaces where they meet for trueness. (Not warped)
This is paramount.

Hot tank the block. Hone or bore cylinders, New pistons or rings, Rod and Cam bearings. . Freeze out plugs. Obviously a new crank and crank bearings

Head:

The condition of your head will tell you what must be done to it. ie valve guides, seals, reseat valves, porting etc. With a high performance cam I would have damper springs installed.
(spring within a spring)

The items I have mentioned are standard for a machine shop. It all depends on haw far you want to go with the motor$$$$$$$. For more detailed work and information the gentleman listed below is very knowledgable and does great work.

Les Classic Datsun Motorsports.
760-940-6365.

Good luck



P.T.T.P.

Quote:

To clarify
While the Datsun 1200 engine is an A12 engine, it is diferent in a number of ways from the later A12 engines, so i tend to call this family either 1200 engines [from a 1200 car] ... or A12's [from anything after the 1200 model]
The 1200 GX had a foward mounted distributor [above the oil pump], so the cam from this engine can not be used in the later A12's which require an additional gear to drive their rearward mounted distributor. It can however, be used in the A10 engine.

The GX engine was continued into the 1974 [& later] B210 series, known here as the 120Y models & this A12 engine had the same basic configuration as the A14/15 engines. This A12 GX cam CAN be used in other A series engines & i will be using my spare A12 GX cam in another engine for my son's B210. With any luck, it will go into the spare [big bore] A13 block that we have here.

So be carefull when speaking of A12's as there are two types, & both were offered in a GX variant. Better to call the early ones "1200" engines as it describes both the nominal capacity, & the car model that used it.

P.S. You should be able to use the later A12/14/15 cam in the earlier 1200 & A10 engines. In this instance the rearmost drive gear on the camshaft is no longer used as the 1200's distributor uses the front one, & the fuel pump eccentric will not line up with the 1200's fuel pump, so you would need to use an electric pump instead, but it does fit & work.

Dodgeman, I just realized that we may have some confusion because you're in Aus and I'm in the US. Someone correct me if I'm wrong, but I think the 1200 A12 ended here in 1973. In 1980 or so, we got the A12a. The only GX engine I'm aware of here was the 1978 B210GX with an A14.

So now I'm wondering if the A12GX cam will fit an A14? There's been one on ebay lately.

Why dont you just get your current cam ground to gx specs. That will save you the confusion about wether it will fit or not.

Chowdozer
Yes, 1200/ A12 engines were sold here in B110, B210 & B310 models while the US got larger displacements from '74 onwards. This club is international, & it's easy to forget that diferent model names & specs were sold into diferent markets, so advice from one country may not always be accurate in another. It's one of those things we need to keep in mind sometimes, so yes, A12's were made in two configurations, which is why i refer to them by diferent designations, & yes, the A12 cam [as distinct from the 1200 cam] will physicly interchange into the A14/ 15 engines, however, you should be able to get your old cam reground.

If that proves to be a problem, you may want to contact Feral at Datrats He should be able to help you out with all your needs.

I think all the A12GX engines have been imported to the US.
The A12 cam should not fit but the A12a,A13,A14 cams should.
Now, could you have the A12GX cam used as a master for reginding an A15 cam? I'm not sure how cam grinders do it or what they use as masters.