Help a flake (me) decide on which engine configuration.

My Datsun 1200 is currently running well but the dilemma is it is painful slow in its current configuration.

I've now taken to using my F500 for vintage racing so the car doesn't need to be competitive as it is a track day & back up race car.

Currently the 1200cc makes 80hp at the wheels, it is running well but it makes my  favorite portion of my home track much less of a challenge. 

I currently have a freshly bored 1500 block that is just waiting for assembly.

The only good head I have is on the 1200.

My spare head has larger valves bit it also needs repair.

Here is were the flaky part comes in:

The 1500 makes the car more fun on maybe 2 of the 22 turns at my home track so why take a perfectly good motor apart simply  to have have slightly more fun. It only increases the top speed by about 6-8mph, from 98 to 106.

BUT

If I repair the spare head I could install even larger valves in it ( roughly $1000) this would result in around 105-109 at the wheels

OR

The old me would have slapped together a motor with the sorts at hand. I could pull the head of the 1200 without disconnecting the intake and exhaust and simply drop it on the A15 bottom end. This would result in around 95 horsepower at the wheels.

BUT

I've had a couple of mishaps with A15s (overheated one, had one pop a head gasket) so I'm that's in the back of my mind.

So help a flake decide; I'm currently on slap it together but I keep thinking it would be nice to get a bit of extra power.......then I think that caught chase issues......sigh.

So a couple hundred in head repair gets you 15 HP.  Another $800 or $1000 in valve work gets another 10? I would leave the 1200 together as known good. Repair/replace bad head and put it on the freshened block.  Put the extra $800 into fuel and tires. If it is somehow still not enough fun, build a new head then. Are the $220 Autozone heads any good?

In reply to matthewmcl (Forum Supporter) :

The heads are JDM / Nissan race heads; they are $600-$800 used and then I spend about 20 hours porting them. A prepped race head is $2000.

In reply to Tom1200 :

Ah. So what do cheap heads put at the wheels?

matthewmcl (Forum Supporter) said:

In reply to Tom1200 :

Ah. So what do cheap heads put at the wheels?

Stock 1200 motors make about 40 at the wheels and 1500 motors make about 50.

The question is how much power do you think you want to keep yourself entertained?

I had two '77 B210s and two '80 210s.  The A14 in them was super reliable unless you overheated them.

How many carbs are you running and are they capable of blow through turbo?  How much heat can the stock cooling system dump?

Tiny turbo + low boost is cheaper than lots of head work and more power to boot.

In reply to Tom1200 :

I think you have problem fixation.  You need to step back and rethink the nature of the problem. 
     Last year you were thinking of a V8 because of your lack of power.  Well power is addictive. If you think 10 is enough, what about next?   Are you going to spend spend spend to keep going a little faster each time?  

is there an easy swap to something more modern for these? 

In reply to Rigante :

Sure but it removes it from vintage eligible. 

In reply to frenchyd :

The V8 swap is likely to happen at some point in the distant future; this would be for the near term (next 2-3 years)

As for vintage eligible there are a couple of motor swaps that are eligible in the catch all class that I sometimes run. With the 1200 motor I'm in C-sedan, with the 1500 I'm GTL (under 2.0)

@honch the car has 39mm flat slide carbs on it. With 99hp at the wheels it would keep up with regional level Spec Miatas on the straights.  I was mostly content with it at that point.

And to further add to the mix I may end up with a JDM twin carb L16 engine (at $500 it's hard to pass up). The L16 would be barely more than the A15 but it would run on pump gas and be longer lived than the A15. I get 50hrs out of an A15, which for me is about 4 years. Note I run the A12s for about 10 years between rebuilds.

In reply to Tom1200 :

I did something along those lines with my Black Jack.  TMI. I started out with stock engine. And over the first few years.   I gradually gained another 100 hp or so. But spent $15,000 in 1970's money. 
  A couple of decades later Vintage racing was serious and to be competitive with newer cars I went to a newer engine.  ( for a newer car)  It cost me less than $5,000 in 1990's money to make more than twice as much power. 
     My point is maybe you should set money aside and start buying pieces  for the V8 conversion?