Here in the UK our F10s are cursed with having a mere 988cc to pull them along (unless you own the “big block” 1171cc coupe). Why Datsun decided that Europe only needed an A10 when the US got A14s I cannot begin to imagine. Maybe smog gear on US spec cars require the extra capacity to make up for the power loss?
My daily work horse is an F10 wagon (because nobody will steal it), which I decided was just way too slow, especially when loaded up with engines (no, I’m not joking), so I decided to fit an A12 for a bit more go. But what I really wanted was an A14. The only source for a proper front wheel drive A14 was an N10 Cherry coupe (sold as a 310 in the US), which aren’t exactly common, so I figured I’d try a RWD engine from a B310 Sunny (that’s a 210 in the US).
So, how did I get an A14 from a rear wheel drive sunny into it? Well, it’s not difficult at all. The first step is to haul the old A10 out. I left the transmission in place, so it was just a case of disconnecting the wiring, exhaust and fuel lines and unbolting the two top stabilizer bars and the mount attached to the sump. It makes life easier if you withdraw the input shaft from the clutch. This is accessed from under the right hand front wheel arch. Then it’s just the bolts attaching the transmission to the block and out it comes.
The A14 versus A10
Looking at the two engines, the most obvious difference is the alternator and distributor position. The A14 is the later style A series. A12s come in both styles, but A10’s are only the early style. This means that when the A14 is fitted, the alternator will sit up front, between the engine and radiator rather than mounted low behind the engine like the A10. The distributor is further from the front of the block too, although this really makes no difference. The A14 is taller than the A10 by possibly half an inch, which while not a huge hurdle, caused a few problems as I shall explain later. Finally the biggest difference is the position of the mounting bosses on the sides of the block. These are used to attach the engine mounts in a RWD configuration but in the FWD just the left side (manifold side) is used. This has a bracket bolted to it which attaches to the transmission. This bracket is very important, as the rear engine mount attaches to the transmission, but the front bolts to the engine’s sump, so this bracket is used to tie the two assemblies together to create a strong rigid structure.
Fitting the A14
The first job before fitting the A14 is to remove the RWD parts from it. These are the flywheel, backplate, sump and oil strainer, as well as the engine mounting brackets and studs. You will also need to change the water outlet pipe at the rear of the head and the thermostat housing. The major difference between the blocks lies in the sump attachment. The FWD engine uses 8mm bolts to hold the alloy sump in place where as the pressed steel sump of the RWD uses 6mm. To do the job properly I would recommend drilling and tapping all the sump threads to M8, but of course I didn’t bother. Only time will tell if it holds up. Next you have to fit the alloy FWD sump and the oil strainer from the FWD A10. Bolt on the A10s thermostat housing and to this and the rear of the head, attach the tie rod mounting brackets. I would recommend welding some strengthening to these brackets to cope with the extra torque of the A14. The rear of the engine requires the A10’s flywheel and clutch assembly (see notes further on about this) Once you have these items fitted then drop the A14 into place and bolt it to the transmission. Now you have to deal with the engine to trans bracket. The mounting position on the A14 makes the block’s mountings too close to the trans lug to use the original bracket. You may be able to acquire a bracket from an A14 equipped N10, but I decided to just make one. In the picture to the right you can see how it was done. Very simple although I did have to grind a little of the top of the lug away to fit the lower bolt into the block.
Connecting it up
First re-install the input shaft to the transmission and replace the cover under the wheel arch. It is advisable to fit a new clutch when upgrading to the A14 as it gives the little A10 clutch a pretty hard time. Attach the upper tie rods to the brackets on the head. Due to the block being taller you will have to adjust the tie rods to lengthen them a little and of course they are forced up at an angle a little. Not a problem though. The wiring for the alternator is long enough to reach over the top of the engine if you unclip it from the bulkhead. All the hoses go back as they were, but make sure the upper radiator hose is well clear of the alternator pulley and fan. The wiring to the sender units and distributor are easily re-connected, although you will need to lengthen the temperature sender wire and fit the angle adaptor to the oil pressure switch, otherwise it’s too close to the fan shroud to get the connector on. So far so good. Now we get to the awkward bit…
Carburation and Exhaust
Ideally the entire exhaust should be replaced as the stock one is about the size of a McDonalds drinking straw. Great for low end torque, but totally strangles the engine above about 4000 rpm. At the time I was converting my F10, I didn’t have time to do this, so I had to use the original exhaust manifold with the A14 intake. The two bolt together but the A14 and A10 use different size bolts. The A14 manifolds are bolted together with 8mm bolts whereas the 100A are 6mm. This means you have to use the two 6mm bolts that point downward through the inlet into exhaust and drill the Exhaust manifold hole out to use the 8mm one that points upward. Does that make any sense? It’s necessary to use the A14 inlet not just for correct Carburation but because the intake has a different bolt pattern where it attaches to the head. Also bear in mind that some A14’s have oval intake ports rather than round. Unfortunately using the RWD inlet means the carb doesn’t sit level as the engine is angled down toward the rear in the RWD application but sits level in the FWD, however it doesn’t seem to affect it’s running at all. The biggest pain in the butt, is that due to the extra height of the block, the air filter assembly won’t fit under the bonnet. You could make a custom filter or possibly adapt a remote style one from something like a Nissan Vanette. I eventually managed to modify an A10 air filter assembly to fit although this is only temporary. The extra block height also means the stock exhaust is too short to reach the manifold. This was temporarily cured on mine by detaching the clamp at the bottom and pulling the downpipe up to meet the manifold although this means the clamp cannot be re-attached. It would be preferable to use the RWD A14 manifold and fabricate an exhaust to fit it. At least then you can have a larger bore size for the downpipe as well as the system.
So, what’s it like?
Great! Totally transformed from the slug it was before. The torque difference is huge with the A14. The A10 flywheel and clutch assembly is quite small diameter and fairly light so the response from the engine is instant. Acceleration is very rapid now, although the tiny exhaust somewhat restricts it at higher RPM, and a lot more torque steer is present. The low gearing is very apparent now, so I have fitted 15 inch wheels which helps a little. Top speed is now around 105mph with 80-90mph cruising (ear defenders recommended). The best thing is, in spite of a low final drive, the car is still very economical both on long trips and around town.
As I mentioned earlier, those tie rod brackets need beefing up as I found out when mine bent after about 150 miles of abuse. The left hand bracket not only bent, but broke the thermostat housing too as it worked loose. Mighty A14 power! I also replaced the large bush at the engine end of the rods with a spherical “rose” joint to take a bit of the engine movement out. This helps to stop the rubber drive train feel that most FWD cars have. The clutch died rather quickly on it too, but it was fairly worn to start with which is why I recommend fitting either a new A10 clutch or better still a KF10 clutch as outlined below..
Top of the list is a new exhaust system. For this I’m going to fabricate a header which will use long primaries going into a two inch system with one muffler at the rear. I have a set of GX twin SU carbs to fit which will get round the tilted carb and air filter problem, as well as help the engine to breath better at high RPM. My A14 head has round intake ports, so they will have to be ported to match the GX intake. While the head is off, it would be good to have a bit shaved off it to raise the compression, as the stock compression is only 8.5:1, and with our cool climate and 95 or 98 octane fuel it could stand a good deal more.
A five speed transmission from an N10 coupe would be nice, although no gain will be made in either top speed or economy as the fifth gear is still 1:1 on these five speeds.
The A10 clutch isn’t really man enough for the A14, so an upgrade is in order there too. Both the Datsun 120A (F10 coupe) and N10 have a larger diameter clutch with a different flywheel, which would be ideal. I plan to also machine the area of the flywheel that the clutch cover bolts to, back about 1mm to create a higher clamping force.
As for the rest of the car? Maybe lowering, little more castor on the front suspension for better stability and possibly a brake upgrade, although I have absolutely no idea what brakes can be made to fit. Ah well, that will make another tech article in the future.