Jump to content

a12 rebuilding tips


kinetisist

Recommended Posts

Well I got the old a12 out of my 1200 today. That was way easy compared to other cars I have worked on..maybe 3 hours total including removal of the cylinder head to inspect why my engine died. I found that the top of the pistons on the exhuast side were all chewd up. I can even see the compresion ring on #2 and #3 and alot of scratches on the cylinder walls..some one really did not know how to take care of an engine. Any way I am really considering rebuilding and putting in bigger pistons, a better cam and a GX head with a single weber sidedraft. I am tying to get my 1200 reliable and alittle more peppy but I don't want to do a ton of alterations to shoe horn in a bigger engine. If anyone has a good engine that is cheap and you are near Redding California I would be interested in an engine. If you have some suggestions on sources for cams, pistons, and the like ...this would be very helpful.

thanks

Link to comment
  • Replies 11
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

I can even see the compresion ring on #2 and #3

That sounds like detonation-caused.

 

 

Any way I am really considering rebuilding and putting in bigger pistons, a better cam and a GX head with a single weber sidedraft. I am tying to get my 1200 reliable and alittle more peppy but I don't want to do a ton of alterations to shoe horn in a bigger engine.

 

All that and you will have the same peak power as a stock A14, but with less horsepower below 6000 RPM. If it was me I would swap in a good used A14, it's an easy swap no shoehorning required.

 

If you want to go with the hop-up route, there are no single-carb manifolds for the GX head. Instead use an A14 head, it's a bit smaller but will work on an A12 with slight modification. Call Iskenderian for a custom grind cam (better yet less expensive than new a stock cam), tell them the RPM range you want to run it at. For pistons, call Wiseco and order custom pistons about $100 each. Flattops will make the most power and still run on pump gas. Go with a 76mm bore which will work your A12 out to about 1300 ccs. If you do the work yourself, parts and machining will be around $1200.

 

Tip: Don't replace the cam bearings. But do use new lifters with the new cam.

Link to comment

Thanks for the input .. keep them coming .. I have a buddy that has an engine shop so the machine work is a little more reasonable than regular rates. I am just trying to sort out where to get all the parts from. I do have a standard gasket set ..

 

does the 12a head gasket work with the a14 head or gx head?

Link to comment

If your heart is set on an A engine then rebuilding an A14/15 will cost the same as an A12. Go bigger.

 

Better would be an L20B and 4 speed swap. About 90 hp and tons of torque. How long is your current 4 speed? This will determine which L 4 speed to use.

Link to comment

A-series 4-speeds are the same length as shorty L-series 4-speeds (26.3 inches). L20B running gear from 1977-1979 200SX fits with the shifter coming up in the stock 1200 location and will use the stock 1200 automatic driveshaft. You can even re-purpose the rear axle assembly which is 2 inches wider.

 

12a is a Mazda engine. A12 is a Datsun engine.

Link to comment

A-series 4-speeds are the same length as shorty L-series 4-speeds (26.3 inches). L20B running gear from 1977-1979 200SX fits with the shifter coming up in the stock 1200 location and will use the stock 1200 automatic driveshaft. You can even re-purpose the rear axle assembly which is 2 inches wider.

 

But what about weight?? what to do about that ...My guess is that the L20 is double in weight ... and I don't have a auto driveshaft ..

what about rear diff ? .. been told it won't take the power from the L20 ...

what about the length for the engine compartment?

Link to comment

Sounds like you are not prepared for a big engine swap. In that case stay with the A-series engine. See Datsun 1200 A-series Engine Swaps

 

thanks for the input...I am not up for modifying the entire engine bay .. If I were to do that I would put a s12/s13 engine and redo the rear end but I am tring to do this on the cheap right now

so I am looking for things that have been doen to the a12 engine that work well and keep it reliable and easy to keep it tuned.

Link to comment

The engine bay does not have to be modified to fit an L20B.

 

 

things that have been doen to the a12 engine that work well and keep it reliable and easy to keep it tuned

That is called a stock engine. You could fit a Weber 32/36 and pick up some HP above 5000 RPM. Those are reliable. Also can the contact-points and install a matchbox distributor -- far more reliable.

 

But generally hopping-up reduces reliability For example, if you fit a header, reliablilty goes down. The stock manifold never cracks, never leaks, never rusts out. I have both a highly modified A14 in one 1200, and a 100% stock A12 in the other. Guess which one never gives any trouble?

 

 

things that have been doen to the a12 engine that work well

 

The traditional hot-rodding that works for a Chevy V8 also works for an A12. Porting, high compression, etc. The sky is the limit.

 

Bigger pistons, a better cam and a GX head with a factory twin carburetors is very reliable, and will make it more peppy. An A12 with these will have stock HP at 3000 RPM, but more at 6000 RPM. It about as much HP as a stock A14, when both are revved to 6000 RPM.

Link to comment
  • 2 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.