An early Datsun 240Z ITS race car at the July 2018 ICSCC meet, Pacific Raceways in Kent, Washington.

[SSGGeezer]

Isn't the 240z is worth more now than when it was new since they are so desirable for restoration and racing? Don't you have one or two around the house?

[Racer X 69]

Isn't the 240z is worth more now than when it was new since they are so desirable for restoration and racing? Don't you have one or two around the house?

Depending on condition they can bring a decent amount, but they don't go for really high numbers, save for low number first or second year 240's.

I could sell my race car for $15,000 to $20,000 if it was turnkey and ready to race.

And at one time I had 14, some early 240Z's, a few '76 through '78 280Z's, and a '79 280ZX. I think I'm down to ten or twelve now. Cut up a couple and stored the good bits, scrapped the rest. I need to go through the rest and do the same, saving the early 240's of course.

[SSGGeezer]

Depending on condition they can bring a decent amount, but they don't go for really high numbers, save for low number first or second year 240's.

I know that the 240's still hold their value better than the later Z cars, but since I lived in Minnesota back then, they were hard to find without terminal cancer.

[lesmore49]

Depending on condition they can bring a decent amount, but they don't go for really high numbers, save for low number first or second year 240's.

I could sell my race car for $15,000 to $20,000 if it was turnkey and ready to race.

And at one time I had 14, some early 240Z's, a few '76 through '78 280Z's, and a '79 280ZX. I think I'm down to ten or twelve now. Cut up a couple and stored the good bits, scrapped the rest. I need to go through the rest and do the same, saving the early 240's of course.

Down to 10 to 12 now ! I'm impressed. I still remember the first 240 Z I saw. It was parked over the weekend at an ESSO garage I used to hang out at with some other guys, buddies at the time. The group either had Camaros (two '70 1/2 Z-28's) one Nova SS350, one '66 Corvair, 4 carb, 4 speed...I had different vehicles back then...'61 VW Beetle, '69 VW Beetle 1500, couple CZ and one Yamaha YDS3 motorcycle(s), '67 Camaro RS 327 4 speed, '62 Volvo PV 544s. I went through a lot of vehicles in short time back then, the other guys tended to hang on to their vehicles.

We checked out the 240Z...I liked it a lot, and thought this is the death knell of the British sportscar. The other guys were more domestic iron/hot rodder types so didn't pay much attention to the Z, except the guy with the Corvair, but then he eventually became a Civil Engineer and could see the mechanical advantages of the 240 Z.

Nice car, well engineered, original thought in this sportscar styling and mechanics...ie; OHC in a car then...not common. I would say it was a game changer on several fronts.

[Racer X 69]

OHC in a car then...not common. I would say it was a game changer on several fronts.

And dual SU carbs.

150hp stock.

I have never had mine on a dyno, but it has a theoretical 250 to 300 at the crank.

With the SU carbs and a stock cast iron exhaust manifold.

[lesmore49]

And dual SU carbs.

150hp stock.

I have never had mine on a dyno, but it has a theoretical 250 to 300 at the crank.

With the SU carbs and a stock cast iron exhaust manifold.

I had twin SU's on my Volvo PV544's B1800s engine. An old design, but nice looking carbs.

I did not realize that the 240Z had SU carbs or are they after market on your 240Z? Your stock exhaust manifold must flow fairly well for that kind of power at the crank. However, when you think of it, the 240 Z (2.4 liter OHC four) must rev fairly high...can't recall the stock redline..guessing around 6500 RPM ? Have you done any port work on the engine ?

I thought the stock carbs on a 240 would be something like KEIHIN....I was assuming as Japanese carbs.

I can't recall the top speed on a stocker 240Z, but considering how windcheating the body was...also didn't have a 5 speed back then when a 5 speed was ultra rare coming from any manufacturer...it was fast.

They were cars ahead of their time and still look stunning and modern now.

My '67 Norton 750cc twin engine has a pair of Amal carbs. .

[Sailor]

I really like this "in your face" composition combined with strong colors.

I longed for one of these when they appeared in '69 or '70(????), but they were very hard to get - at least in Nashville. Later, while we were living in Boston, I nearly bought a 260Z (Big bumpers and other stuff added), but we decided to go with another Camaro owing to the fact that it had usable (if not comfortable) rear seats.

Jer

[SSGGeezer]

I really like this "in your face" composition combined with strong colors.

I longed for one of these when they appeared in '69 or '70(????), but they were very hard to get - at least in Nashville. Later, while we were living in Boston, I nearly bought a 260Z (Big bumpers and other stuff added), but we decided to go with another Camaro owing to the fact that it had usable (if not comfortable) rear seats.

Jer

I once rode over 800 miles in the middle rear seat of my sister's Early 70's Camaro, That was more miserable than a steerage class 24 hour ride in a military charter aircraft. (Flying Tiger.) Usable but for more than a quick ride, a way to get even with your so called friends.

[Racer X 69]

I did not realize that the 240Z had SU carbs or are they after market on your 240Z?

SU carburettors were standard equipment on an S30 240Z. Two of them, one feeding the front 3 cylinders, one feeding the rear 3.

Your stock exhaust manifold must flow fairly well for that kind of power at the crank. However, when you think of it, the 240 Z (2.4 liter OHC four) must rev fairly high...can't recall the stock redline..guessing around 6500 RPM

Extensive work has been done to the engine, cylinder head, manifolds, carbs, all internals have been detailed and polished, and rotating bits weighed and checked for balance. I smooth and polish the inside of the cylinder block, paint it with Glyptal, polish the connecting rods and caps, the crank is knife edged and polished, the main caps smoothed and polished. I have extended the stock oil pan for more capacity, built a windage tray and baffles with trap doors in the oil pan.

The stock redline is indeed 6,500. I rev my race engine to 8,000. Much more and bad things start to happen.

? Have you done any port work on the engine ?

The cylinder head, intake manifolds and carburettors, the exhaust manifold have been on a flow bench, and had work done to the entire path, from the air inlet horns to the exhaust manifold outlet. I cheat on the exhaust valve clearances, running them a bit tighter, to get more valve lift. I also use a degree wheel on assembly and set the cam ad the perfect position in relation to the crank.

My cylinder head guy's motto on his business card is, "It's All In The Head!"

And he is mostly right, but I also did work on the cylinder block to improve airflow. The Intake valves are close to the cylinder wall when open, and the top piston ring stops a couple millimeters from the cylinder deck. So that leaves a bit of room to work with, and I do what is called eyebrow notching, laying back the block a bit to unshroud the valve as it opens. Each one has to be done perfectly, the exact same amount and shape for all six. That amount also gets measured and calculated when working out the combustion chamber sizes.

[Racer X 69]

I really like this "in your face" composition combined with strong colors.

I longed for one of these when they appeared in '69 or '70(????), but they were very hard to get - at least in Nashville. Later, while we were living in Boston, I nearly bought a 260Z (Big bumpers and other stuff added), but we decided to go with another Camaro owing to the fact that it had usable (if not comfortable) rear seats.

Jer

Thanks Jer!

The 260Z was only made for one year, and there were two models, the first half of the year with skinny bumpers like the 240Z, the second half of the year with the fat federally mandated 5mph safety bumpers like the 280Z.

Both models had the 2.6 liter OHC 6, with some weird Hitachi/SU mashup carburettors that were supposed to cut exhaust emissions.

But all they did was cause driveability and fuel economy issues, and didn't reduce emissions.

So many people retrofitted the early SU carbs from the 240Z, or used the Bosch fuel injection from the later 280Z.

[lesmore49]

SU carburettors were standard equipment on an S30 240Z. Two of them, one feeding the front 3 cylinders, one feeding the rear 3.





Extensive work has been done to the engine, cylinder head, manifolds, carbs, all internals have been detailed and polished, and rotating bits weighed and checked for balance. I smooth and polish the inside of the cylinder block, paint it with Glyptal, polish the connecting rods and caps, the crank is knife edged and polished, the main caps smoothed and polished. I have extended the stock oil pan for more capacity, built a windage tray and baffles with trap doors in the oil pan.

The stock redline is indeed 6,500. I rev my race engine to 8,000. Much more and bad things start to happen.



The cylinder head, intake manifolds and carburettors, the exhaust manifold have been on a flow bench, and had work done to the entire path, from the air inlet horns to the exhaust manifold outlet. I cheat on the exhaust valve clearances, running them a bit tighter, to get more valve lift. I also use a degree wheel on assembly and set the cam ad the perfect position in relation to the crank.

My cylinder head guy's motto on his business card is, "It's All In The Head!"

And he is mostly right, but I also did work on the cylinder block to improve airflow. The Intake valves are close to the cylinder wall when open, and the top piston ring stops a couple millimeters from the cylinder deck. So that leaves a bit of room to work with, and I do what is called eyebrow notching, laying back the block a bit to unshroud the valve as it opens. Each one has to be done perfectly, the exact same amount and shape for all six. That amount also gets measured and calculated when working out the combustion chamber sizes.

Very impressive engine work. I have a feeling the inside of your engine is as beautiful as the outside of a show car.

I still remember the first time I saw the 240Z engine ('71 I think) and thinking about it's specs. OHC, inline six with a couple of carbs...very sophisticated...more like a Jaguar's inline 6, DOHC than the Austin Healey 3 liter OHV inline six. All that technology on the 240 and it competed with the big MG's, big Triumphs, etc. Also like the fact that it was a closed coupe rather than an open car like most of the Brits.

A few questions, if you don't mind.

Do you have a rev limiter that cuts at higher rpm in the 7700-7900 rpm range ? What's the powerband like...power concentrated at the top end or...?

Race conditions can be quite stressful on an engine, how often does you engine need a rebuild of partial rebuild ?

What displacement is your engine ? Are you restricted to a certain amount of cc's for your car's racing class ?

I've always had a fascination with engines of all kinds from 2 strokes to OHV V-8 to high winding OHC engines.

[Racer X 69]

A few questions, if you don't mind.

No problem Les.

Do you have a rev limiter that cuts at higher rpm in the 7700-7900 rpm range ? What's the powerband like...power concentrated at the top end or...?

Yes. I have a rev limiter that accepts chips for various rev limits. I use an 8,300 rpm chip, as I expect to rev to 8,000 before shifting up.

The power comes on at about 1,500 to 2,000, climbs rapidly and pulls hard from around 3,000 all the way to 8,000, where I decide it is easier on the valvetrain to shift and let the engine begin another climb.

Race conditions can be quite stressful on an engine, how often does you engine need a rebuild of partial rebuild ?

The guys who ran them back in the Trans Am days said they would teardown after every race weekend. But they had nearly unlimited sponsorship budgets.

I change the oil after each race meet, and clean the oil screen (yes a screen, no paper spin on filters here). I watch the screen and oil for signs of impending failure and base my decisions for when to do a teardown. The L series engine block is quite stout. A main bearing between every rod, and one at each end. The crank centerline is a couple inches above the oil pan rail, so the block has skirts to help support it. Nissan designed a very good package, so it doesn't really require a great deal of extra prep.

Still, it is a long crankshaft, and does not tolerate any out of balance conditions.

What displacement is your engine ? Are you restricted to a certain amount of cc's for your car's racing class ?

The original class I ran was a production based group, and I was required to have an L24 engine (2,400cc) with whatever cylinder head was available for the years the L24 was produced. The head to have is the early E31 head, and I have two versions, one has a smaller combustion chamber (higher compression!).

I currently have an L28 bottom end (2,800cc) bored 1m over, with the small chamber E31 head, with bigger valves installed (described in another post), but there are so few guys running the production classes anymore that no one complains. I also run GT2 (albeit not very competitively), and SPM (again, not very competitively), for extra track time.

The last two classes are for more prepared cars, think full tube frame, very high strung dry sump racing engines costing $25,000 to build, fiberglass bodywork, wide racing slicks, and 400 to 600 horsepower (or more), depending on the class and level of prep.

GT2 cars are prepared to the SCCA GT rules. Engine must be the same make but it doesn't have to be the same as came in the Z. For instance I could run a 300ZX (3 liter V6), 350Z (3.5 liter V6) or 370Z (3.7 liter V6) engine.

SPM is Super Production M (for cars with engines under 3 liters and over 2 liters if memory serves me). Anything goes, the only rule is there are no rules, save for the displacement grouping, and all cars must comply with the safety regs, seatbelts, harness, fire system, helmet and nomex suit, window net.

Turbocharging increases the displacement calculation by a factor of 1.4.

Some pretty exotic stuff.

Still, they don't always finish.

I ran the full regional season in 1997 in GT2 and the production class. I finished 3rd in the production class.

I won the championship in GT2 because I finished every race and even won one when all the real GT2 cars dropped out.

Kinda like the tortoise and the hare.

I've always had a fascination with engines of all kinds from 2 strokes to OHV V-8 to high winding OHC engines.

Me too!

I keep toying with the idea of building a custom 4 rotor Wankel engine for a Z, using Mazda rotary stuff. I talked to a friend about it just this past weekend. Rotaries are essentially two stroke engines, and by design have no rev limit. I think physics or something my present a maximum rev, but having driven a few RX7's in race trim I can tell you it gets pretty high, higher than the tachometer will read.

[lesmore49]

Thank you for the information about your racing car, the racing series you participate in and the engine prep you do. Fascinating stuff.

I recall the Trans Am series in the late '60's fairly vividly and of course the Can Am cars. I do recall attending a Can Am race in Edmonton in the late 1960's and I was very impressed with the quality of cars raced.

Back in the '60's we had some local sports car racing in and around my burg and had some interesting cars. Mostly British stuff at the time...Mini Coopers, a few Lotus 7's ( a few were sold here), Tr 3's, MGB's, MGA', etc. Because of our climate ice racing has been very popular. Back in the 1960's that meant mostly Austin Minis...some Coopers...due to traction advantages of FWD.

Two strokes have always had an appeal for me since I got my first motorcycles back in the 1960's...for their ease of maintenance, power potential , tune ability, etc. Very interesting book I would recommend on classic race engines...motorcycles...though...The author is Kevin Cameron, the title, Classic Motorcycle Race Engines, Expert Technical Analysis of the World's Great Power Units.

Thanks again for all the time you put into your response. I very much appreciated it.

[link81]

wonderful shot.
really makes me miss my old 78 280. Converted that car from FI to SU carbs. was a ton of fun. Alas, i had to sell it when i moved from WA to NY...

still have the carb tuning spark plug, and a few crank tower shims somewhere in my toolbox(es)

One day i'll get another one.