3.1 litre stroker: Getting Started
When starting any project you need to have a game plan. A good starting point is to ask yourself this question "How fast do I want to go?" Since how fast you go is directly related to how much money you spend, this is a good starting point. Unless your last name is Gates or Trump you will need to set a budget. This will let you know just how much you need to lie to your spouse. It will also serve as a reality check (Cobb's rule #1: Building a 3 liter engine has no basis in reality!). Another major dilemma is can you do it yourself, or do you pay to have it done. I have a moderate amount of technical ability, but I didn't have any of the necessary tools. So I did a mix. Eric and I decided to build his engine and mine side by side. This allowed me access to Eric's knowledge and some really cool tools. My advice is to ask club members and others with more technical ability than you have. Another source of excellent information is what Eric and I call the sacred tablets (the Nissan Shop Manual and "How to Modify Your Nissan/Datsun OHC Engine"). Both of these books are critical to engine modifications and assembly. These publication are available through several sources. The tools and technology required to do this type of work will require the services of a machine shop. How much you send to the shop depends on your access to specialized tools like pneumatic grinders, valve spring compressors, and mic gauges.
Building a high performance engine is a lot like cooking. The right ingredients, blended together correctly produce a great end product. Locating the necessary parts to send to the machine shop is a project by itself. The single hardest used part to locate will be the diesel Maxima crank. Nissan only produced this option for a few years. Because of that they are few and far between. I chased down three people with these cranks. The first was a person who wanted $500 (I don't think so!!!). The second was a junk yard. The car had burn to the ground and because of the heat, the crank was warped. Finally, I located a crank out of a car with only 54,000 miles on the engine for $150. This single task took over six weeks. You could also go to a Nissan dealer and purchase the crank and rodas new for $450. Next plan to purchase a 1975-1978 280-Z engine, unless you plan to use your own engine. I bought a complete 1976 engine with the correct head (N42) for $250. I sold the fuel injection and manifold to a club member for $50. While you are at the junk yard, pick up a set of 240Z rods. Remember there are two different types of rods for the 240Z. One has 8mm main bolts and the other has 9mm bolts. You will want the 9mm bolts for the added strength.
Now is probably a good time to make a few hard decisions. Since some of these parts will take three to four weeks for delivery, the first decision is where do you plan to drive the car? This simple question will help determine the correct parts to order. There are trade-offs when making these decisions. As an example, if you plan to drive this car on the street all of the time, then a milder cam and lower compression would work best. On the other hand, if low speed drivability is not an issue and you want more power, then you may want to get a little more aggressive on the cam and increase the compression. At this point start thinking about improving your ignition system and your life insurance. Now if you're tired of listening to your bitchy neighbor talk about how fast his 5 liter pony car is (yawn), then a cam that kicks in around 4500 to 5000, triple 44mm Mikuni carbs, competition valves and matching springs and a different piston to your compression up to around 10.5:1 would be the ticket. Oh by the way, your can kiss ever using pump gas good-bye. You're now an octane junky. Remember its only money (Cobb's rule #2: You can never go too fast!). The bottom line is simple. How will the car be driven? Then build the appropriate engine. There are many sources for the right recipe. Talk to people in the club that race. Parts suppliers like Motor Sports in Orange CA, offers cams with good information on driveability and RPM ranges. Some of these companies also offer their own 3 liter kits. These kits offer convenience not flexibility. As for the three engines that Eric and I built, we used an aggressive cam with 510 lift and 300 duration. Attached to the cam are Nissan swirl cut and tuliped valves with hardened competition valve springs. The intake manifold has been extensively ported and polished (see the "Machine Shop Section" for more details). At one end of the manifold are triple 44 mm Mikuni carbs. And at the other end are six JE forged pistons with moly rings. The compression comes in around 10:1 (93 octane or higher required). The factory ignition system was replaced with the Electromotive Crank fire system. At one end of the crank is a HKS eleven pound flywheel and the other end is a Fluid Dampener harmonic balancer. The lubrication system uses a 90 PSI high volume oil pump sucking oil from a 9 quart competition oil pan (Cobb's rule #3: Keep telling yourself, ITS ONLY MONEY!).
You don't have to use parts produced by NASA to build a fast engine. The early SU side draft carbs (1970-1972) can be modified to offer good performance at a reasonable price. Cast pistons instead of forged can be use to help cut cost. The factory ignition system and many other OEM parts will work fine. Which parts you use are up to you. Now you need to decide how far to bore your engine. Up until now I have used the term3 liter generically. Lets define just what I mean. I bored my block 40 thousandths over stock to get a 3.0 liter engine. Eric on the other hand bored his to a 3.1 liter or 120 thousandths over stock (3.0 uses 87mm pistons and a 3.1 uses 89mm pistons). So order your pistons now because the machine shop will need these to bore the block.
Now that you have ordered the correct parts. Its time to disassemble
the 280 engine and prepare it for the machine shop. When I was a kid, I
could take apart anything. Putting it back together was always the hard
part. I always had extra parts left over when I was finished. This part
of the project is fun and does not require special tools. However, it does
require some organization. Because some of these parts may be used again.
You will need some type of parts organizer. You can buy an engine organizing
tray from a parts house or use milk jugs, heavy-duty 8"x10"envelopes
or coffee cans. Once you remove a part label or tag it. You DO NOT need
a hammer to disassemble an engine. The head is aluminum and the block is
cast iron. Both are brittle, and do not react well to being hit with a hammer.
Since the newest engine you can use was built in 1978. The use of liquid
wrench is recommended. The bolts for the water pump and timing cover will
snap if forced. The use of penetrating oil will help removing these bolts.
There are two very important parts to label (the cam towers and the main
baring caps). As you take one off label the location. These parts look identical.
They are not! These parts must go back into the same location you took them
from. Parts like the old cam, crank, timing chain and gears do not need
to be kept. Spend a few minutes inspecting the head bolts, cam towers, and
main bearing caps for damage. Thoroughly clean all parts with a automotive
de-greaser. This will make the inspection process much easier.
The Machine Shop
Cranking & Debugging