Stock engine with bigger bores, small supercharger
with 32/36 or single 1.75inch su is going to be
cheaper and simpler from 70-100hp at the wheels
than most other modifications and make more torque
and driveability to boot. All of course unless you
are governed by strict road rules and emissions.

Im supercharging my a10 with a 500cc AMR and single su.
Its 59mm stroke makes no torque but with a supercharger
it will be perfect for an auto, economy and 70hp atw
moving a 650kg car.

Hey thanks... I was just looking at the "Extra-large Brakes for Datsun 1200s - Bolt On" thread and I'm intrigued...

So where are you finding the 175/60-13 tires? All I can find are 165/65-13 and 175/70-13. The tire sizes available in quantity (that match up to the original overall size) are 175/65-14 and 185/60-14. What do you think of these?I really don't want to go bigger.

And 13" wheels are not that common anymore for RWD vehicles. (Maybe obvious to those that have been here a while)

As for my last experience with Ferodo Race pads... I almost wet myself the first I tried to stop. No one told me they didn't work until they warmed up. That was 30y ago... I imagine they've improved them by now.

Flat top pistons with GX 29cc combustion chamber is 10-1. Dished piston are 8.5-1 (I think) so I'd guess flat tops with non GX head would be around 9.2 to 9.5-1............there are plenty of compression ratio calculators online.

Stainless lines are good for sure. As for brake pads IF you can find Ferodo pads get them, those work well. Porterfield might have something or worst case go with the Repco Metal Masters. I may have some decent pads in the garage. I use 280zx brakes so stock 1200's are of no use for me.

Tom

Thanks for the input Rally...
What you describe is the direction I want to go with my project. The carbs I have are 38mm Kenin CVK (semi-downdraft & semi-flatslide).

What do you recommend for flat top pistons?
What compression ratio do you get with them?

I picked up some stainless braided brake lines. What pads do you recommend?

I run an A12GX , with some basic porting, header, lighter flywheel & 39 MM FCR Flatslide carbs for my track only 1200. I'm probably putting out close to 100HP (73 at the wheels). One thing to consider is the powerband, the stock boxes drop near 3000 RPM's between 2 & 3rd. So I would go with a GX cam or something close to it. If the bike carbs are CV style than they would work fine if they aren't to big, I wouldn't go past 36MM. Here is what I always recommend for a 1200 street car: clean up the porting, use flat top pistons, GX cam, Weber 32/36, 2 inch exhaust.............after that get a set of sway bars, decent dampers, wider wheels with 175/60-13's and some upgraded brake pads. 1200's are not fast cars but can be quite fun to scoot around in with some basic motor and suspension upgrades.

Tom

Regarding the the open vs. closed head on the A12.
I remember reading that in the techwiki (great source if info BTW).

What I'm not clear on is this quote from the "A-series Cylinder Heads" section:
"A12 H39 Head

* USA B110, from April 1971
head has no casting numbers
* Same as H10 head, but with open chambers
* Compression ratio 9.0:1 with dished pistons"

From the "Engine Mechanical">"A12 Engine" section:
"Specifications:
* Bore: 73mm
* Stroke: 70mm
* Connecting rod: 121.5mm
15725.jpg
* Block Height: 189.1mm
* Displacement: 1171cc
* Compression ratio: 9.0:1 or 9.5:1
* Power: 68hp or 69hp (depending on year and country)"

I thought this (Compression ratio: 9.0:1 or 9.5:1) implied that the USA B110 Early 1971 model had higher compression. Most likely a result of the closed chambered cylinder head.

Thanks for the clarification.

Sounds like a plan.

Quote:
They are the same compression ratio with 27cc combustion chambers. The 1971 heads are closed-chamber, while the 1972-1973 are open chamber.

The change was made to lower NOx without reducing compression ratio.

Thanks all for the input. I'm not looking for the most HP (I have other vehicles for that). My intention is more for a daily driver. Something that is unique, fun to drive, deliver 20+ MPG and the over square dimensions (76mm x 70mm) appeal to me in a fast revving kind of way.

Having heard the motorcycle carbs on an A-series, I really want to use them.

Regarding the A14... I hear what your saying, however, I'm not seeing the 30+ year old A14 motors in the local wrecking yards. And since I have the extra A12, the bigger piston installation has some advantages as it doesn't require the H150 diff.

Thanks for the cam info. I was thinking about having my cam reground to GX specs. I'll definitely check out Isky.

BTW.. both of the A12s I have are the early front distributor type. My understanding is that the earliest A12s in the US had slightly higher compression due to the 'closed' combustion chamber. If I'm lucky, the head of the new engine would be that type. But It appears I won't know that until I take the head off.

I'm also planning on doing some minor head porting, more clean up actually. Making sure the gaskets don't protrude into the intake/exhaust stream. I've done this before with good results.

boost is the cheapest way to hp

turbo is the cheapest way to make the most HP -- if you fricate the plumbing yourself


Camshaft is available anywhere. Just call any camshaft company and they'll sell you a custom cam. They don't list them in their catalogs but they make them on order.

The GX cam was the best factory cam, better than the A14/A15 cam, but all of them of low-lift. Ordering a new cam from Isky will get you a better performing one

Nismo used to sell several high-lift cams, but no longer...

If you want an off-the-shelf cam, you can buy them in america from mail order japan. But they are hugely expensive like $400.