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#1 A14 vs. A15
teretonga Posted on: 2000/3/10 3:32
Thanks for all the great information everyone. I have a question for CA18DET_man regarding his A14. Did you choose to build your race motor from the A14 for a reason? Could
you have had better results from an A15? The reason I ask is your engine builder obviously knew what he was doing - did he choose to do the A14 instead of an A15. Cheers.


#2 Re: A14 vs. A15 (long)
ca18det_man Posted on: 2000/3/10 7:33
I have had both A14 and A15 race engines over the years with same head. The A15 was 40thou over giving a capacity of around 1540cc it was a good grunty motor.I sold the bottom end to a freind
who had blown his stocker I kept the head as it is a work of art:) I purchased a rally car several years later with lots of bits and pieces to my suprise in a box was a set of A14 120thou
over pistons and a A14 crank with linished rods ect. The block I use at moment is actually a A15 there is no difference in A14 & A15 block anyway so I had it bored decked ect and fitted all
the good bits in. I used a different experimental cam this time with heaps better results. (cant remeber the exact spec) anyway once it was all together I was suprissed with the amount of
torque even with the more radical cam power peeked at 7000rpm and would rev to 7500rpm all day long.The A14 also has what is called a square bore withthe 120thou oversized pistons it had same
stroke as boresize.
All in all even though the A14 had a smaller capacity of 1510cc it was a heaps better engine maybe the cam helped could have also been the different jetting and chokes in webbers.
I actually have a freind who spent over $6000 on a A15 total capacity of 1608cc even though it had more work done it didnt quite have the same hp its strange how some engines are just freaks
of nature. Anyway I hope this info helps I hope I havnt dribbled on too much if you want to know anymore give me a yell.


#3 Re: A14 vs. A15 (long)
Errrnstak Posted on: 2000/3/11 3:34
My dad and I both have 1200 coupes. My dad's has a rebuilt A-14 with stock pistons, a mild cam, and everything's been balanced. The head was rebuilt with a 3 angle valve job, etc. He also had
a Weber DGV, header, and 2.25" exhaust w/turbo muffler. His seems to pull hard past 2500 rpm to 7500 rpm and we don't know where the redline is because the tach only goes to 8 grand. He has
stock valve springs too. Wanting to whoop my dad out, I got an A-15 for my 1200. I rebuilt it, put 20 over pistons in, balanced it, and got a slightly more wild camshaft. The head has been
rebuilt the same way with stock valve springs. My car has a Weber DGV and an ported manifold with 2" exhaust and straight through glasspack muffler. My car seems to have good power between
4000-7000 rpm, but it just doesn't feel like as much get up and go as my dad's A-14 has. On the highway, his just keeps pulling strong, mine doesn't pull like his on the highway unless I'm on
a slight downhill or something. Somedays it seems my car just takes so long to pick up speed on the highway. So anyways, we both just got SU carbs, and I'm getting a header, 2.25" exhaust, and
a Turbo muffler. So basically we will have the exact same setup the only difference being his is A-14 and mine is an A-15. This summer we will see who's is faster. I was thinking that maybe
the rear end I have may not be 3.9:1 like the stock 1200. I got the rearend from a 78 B210 auto...of course it may be from a different model B210 also knowing Datsuns...So does anyone know
what the rearend ratio is for a 78 B210 automatic??????


#4 Re: A14 vs. A15 (long)
sagemanone Posted on: 2000/3/12 12:55
Hi Andy,
My B210 had a set of 3.77's in it with the factory 4 speed and I traded them for 3.889's from the "75" 4 door Parts car,also a 4 speed. Those are the only two common ratio's I know about
although there was supposed to be some 4.11's in early B210's But the wreckers I've talked to said they hadn't seen any.
Lack of "Pull" is a torque problem and is hard to
track sometimes. Two things come to mind,one is very do-able and that is re-curving the Distributor. When I did that right, it woke up my A14. The other is the cam degreeing,and is almost
impossible without an adjustable gear set up. One note is, most cams are designed as they get more radical to have a header to work best and you will be there soon, the sidedrafts will
change the torque a bunch too. When it is all on the engine THEN re-curve the dist to suit the combination,try several different advance spring tensions and see which gives the best seat
of the pants kick, or better, is to dyno test it, if you can find a shop for that.
Hope that wasn't too long!
C-Ya Steve


#5 Re: A14 vs. A15 (long)
Errrnstak Posted on: 2000/3/12 4:55
I don't know anything about recurving a distributor. My engine has the electronic distributor from the A-15, can I still do those
tricks to it?


#6 Re: A14 vs. A15 (long)
sagemanone Posted on: 2000/3/13 11:55
Here is the 1-2-3's of re-curving a distributor.
First assuming you know how to remove and replace
it from the engine,pull it out and get to a well lighted area. My dist. is electronic too. There is a dust cover under the rotor,pop it out and loosen the screw to seporate
the shaft halves. Note that the plate has notches to re allign it when putting it back. Remove the screws holding the pickup coil
and the vacuum advance rod and the holding screws
for the plate and the plate with the top half of the shaft should come out of the housing.
At this time you should see some two small springs
mounted on grooved pins and they limit the centrifical timing advance. Higher tension springs
mean less advance at higher rpm (retarded timing )
weaker springs means more advance at higher rpm.
When at higher rpm's the vacuum advance is cut out because the engine is eating all the manifold
vacuum so the advance weights take over.
Your cam will need more advance because it provides a better charge in the combustion chamber
and will need to fire the plugs sooner as rpm increases to make better torque. The cam grinder
may have tested to see what the optimum max advance ( timing light varification) gives the best power output. My guess is 34 to 39 degrees.
I would check it at the rpm the cam is supposed to make power and see what it is at before you start.The vacuum advance should be adjustable to
get the idle where you want it, but most power cams have lower rpm vacuum losses because of lobe
configurations.
Hope your not totally confused now!
just go slow and you should be fine, a little
trial and error will make you a better tuner!
Try the dealer for spring assortments,I just scrounge them wherever I can.
Good luck
Steve


#7 Re: distrib advance
ang94541 Posted on: 2000/3/15 12:16
I bought a Mr.Gasket HEI distributor advance kit at Kragen or whatever. I replace the springs with the lightest pair in the kit.
Before the timing would begin to advance at about 3K rpm. Now It starts to advance somewhere around 2K and is all in by 3.5K.
Dude, it made a huge difference.
I would suggest that when you change the springs, leave everything else unchanged at first. Make sure to set the timing the same as before. This way,if something is right or
wrong, youll know its the springs.
angelo






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