L18 Help

[Steb]

Hello Ratsun folks. I just purchased a 1968 Datsun 1600 roadster that had an L18 5-speed engine dropped into it. I've owned Roadster's for over 30 years (currently have three) and have always only had the 1600 or 2000 original engines. I'm completely lost with this new motor and was hoping to get some help in identifying the exact year so I can do some research on the motor. It has aftermarket weber carbs and a header. I did find a web site that showed a 1973 verses a 74 L18 distributor difference and some specs on timing etc. If any one can help me identify this motor I plan on keeping it in the car.

 

Thanks

 

Steb

[datzenmike]

The L18 was only really available from mid '73 through '74 I believe so the specs for one is likely the same for another.

 

As far as a distributor back then, it had either single or dual points. The dual points had a second set that was late 4 degrees in opening and was turned on and off by the emissions system. When on, the motor was retarded 4 degrees from the static timing to reduce pollution during warm up. Best to disconnect them so your running static timing all the time. Better yet is to get the later EI (electronic ignition) breakerless distributor. Once installed and set you never have to adjust or change points again.

[datsunaholic]

While the L18 was only used for the 73 (610) and 74 (710 & 620) model years in the US, it was also used in other countries through around 1980 or so. Was a very common "Low Mile Import Replacement" engine back in the 80s.

 

The Japanese version had different specs (different compression), and never had 2bbl carbs (were either SUs or EFI). A JDM L18 is generally notable by having bolt holes machined in the block for an angled oil filter setup; an original US-market one won't have the holes tapped. Sometimes the filter adapter was left on the engine and sometimes it was removed when it got to the US. All JDM ones came with closed-chamber A87 or W53 heads, all US spec ones came with open-chamber A87 heads. All JDM ones had small-cap single-point distributors except the EFI ones; US spec ones were dual-point in 1973, and used a large-cap single point in 1974.

 

Of course, anyone could have made any number of mods since. Heck, I have a L18 (US-spec block) with an L20B "U67" head and manifolds from a '76 truck with the dist from a '79, bolted to a '83 280ZX 5-speed and all that stuck in a '76 King Cab. Complete mutt, but ran well.

[banzai510(hainz)]

L18s are EZ

http://olddatsuns.com/620tech.htm

 

read everything on here.

[Steb]

L18s are EZ

http://olddatsuns.com/620tech.htm

 

read everything on here.

 

 

I had found that web-site last week and looked at the engine firing order and plug wire set-up to distributor. My current engine plug to distributor dosen't match. The web-site spec. sheet shows the distributor on the drivers side of the engine and the following order:

 

Off engine Plug wire 1 to distributor, 9 O'clock position - My engine to distributor: Off engine plug wire 1 to distributor, 3 O'clock position

 

Off engine Plug wire 2 to distributor, 12 O'clock position - My engine to distributor: Off engine Plug wire 2 to distributor, 6 O'clock position

 

Off engine Plug wire 3 to distributor, 6 O'clock position - My engine to distributor: Off engine plug wire 3 to distributor, 12 O'clock position

 

Off engine Plug wire 4 to distributor, 3 O'clock position - My engine to distributor: Off engine Plug wire 4 to distributor, 9 O'clock position

 

So, when the spec. guy created the information on this engine was he standing on the driver's side or passenger side of the car? I'm getting very frustrated with the infirmation that's out here about this motor. Sorry for the venting but as I said before, I'm a 1600 2000 guy and this is new equipment to me and the info. isn't specific.

 

Thanks

 

Steb

[FoxyRoadster]

curious is the crossmember cut any to fit the L18 into the car?

[datzenmike]

Stand facing the motor from the left (driver's) side. 9 o'clock would be pointing to the rad.

 

There are several positions for the #1 plug wire mostly depending on which L series distributor is used. After 35-40 years many dizzys have been replaced with whatever was available. They all fit and are inter changeable but may have the #1 plug position in a different location. Add to this the spindle that turns the dizzy is gear driven off the front of the crank and there are 20 teeth (I think) so twenty different positions to set the distributor in. All in all it doesn't matter which way the rotor points, 10 o'clock, 1 0'clock whatever, as long as it's under the #1 plug wire and the dizzy can be rotated through a range of motion to properly set the timing advance.

 

To switch your 3 o'clock rotor position to 9 o'clock, remove oil pump and drop the drive spindle, rotate 180 and re-install. Distributor will now engage the spindle at 9 o'clock. Check that the vacuum advance is clear to move when setting the timing.

 

If it's running I'd just leave it.

[Steb]

curious is the crossmember cut any to fit the L18 into the car?

 

 

Yes, the crossmemeber was cut and a "home made" crossmember installed. Not a very good job. The most stunning modification was that the PO installed a racing gas tank in the car. The problem was that the tank was to tall so he cut a hole in the trunk so half the tank is in the trunk and half under the car. Of course the best way to secure the tank to the car is to put two 2" X 4"'s, one front and one back under the tank. Of course you wouldn't want to secure the wood to the car. Just let the tank hang there! I've already replaced the trunk floor with original metal and an original tank. I'm now working on the engine. The car won't run right. I can get it started but there is no power and it's missing like crazy. That's why I suspect that the wires aren't right and I can't proceed with setting timing and such unless the plug wires to distributor arrangement is correct. I'll keep plugging away.

 

Thanks

 

Steb

[Steb]

Stand facing the motor from the left (driver's) side. 9 o'clock would be pointing to the rad.

 

There are several positions for the #1 plug wire mostly depending on which L series distributor is used. After 35-40 years many dizzys have been replaced with whatever was available. They all fit and are inter changeable but may have the #1 plug position in a different location. Add to this the spindle that turns the dizzy is gear driven off the front of the crank and there are 20 teeth (I think) so twenty different positions to set the distributor in. All in all it doesn't matter which way the rotor points, 10 o'clock, 1 0'clock whatever, as long as it's under the #1 plug wire and the dizzy can be rotated through a range of motion to properly set the timing advance.

 

To switch your 3 o'clock rotor position to 9 o'clock, remove oil pump and drop the drive spindle, rotate 180 and re-install. Distributor will now engage the spindle at 9 o'clock. Check that the vacuum advance is clear to move when setting the timing.

 

If it's running I'd just leave it.

 

Thanks for the information. I will try it today and see if it improves the situation.

 

Steb

[banzai510(hainz)]

distributr fire order is the same on L motors 1 3 4 2 Counter clock wise.

 

its just when you dial a Motor to TDC zero on crank where the distributor rotor points that should be #1 plug wire. Should be ON a plug wire, Close enough to dial it in with the timming plate. when it llock down is #1 and then go 1 3 4 2 CCW.

 

On my vid on olddatsuns.com toward the end I install a couple different distributors and the rotor can point in different dirction depending on what distributor set IS installed. stock L16 to a Matchbox distributor

 

L motor is EZer than Roadster motors.

 

PS I dont go to the acutal drawings on the olddatsun dizzy set up. it more to show fire rotation.

[ppeters914]

Although the plugs and dizzy are on the driver's side for L-motors, and passenger side for R16/U20 motors, the cylinders are still numbered the same, the firing order is the same, and basic tuning info is the same, i.e. what datzenmike and hainz said.

 

Oh, and if it's still running points, get an EI dizzy.

[MicroMachinery]

... The dual points had a second set that was late 4 degrees in opening and was turned on and off by the emissions system. When on, the motor was retarded 4 degrees from the static timing to reduce pollution during warm up. ...

 

Not to thread jack, but I just want add to the above statement about how the dual points work. The dual points are set to work by retarding timing when in 3rd gear(via the 3rd gear switch in the transmission). They activate in 3rd gear, or when cruising in 4th. The idea here was to lower emissions in more suburban areas. When given full throttle, however, the Throttle Switch near the carburetor is engaged by the throttle linkage, thus canceling the effect of the retarded set of points, and switching back to the other(more advanced) set. I haven't seen a setup that works to retard the timing during warm up, but that's not to say it doesn't exist(I know that there were sensors and switches that are employed in the Canadian versions of the cars we got here in the USA).

[banzai510(hainz)]

Im sure Roadsters dont have 3rd gear swithces installed in the wireing.

So I hope he has a single distrinbutor in there already. If not just use the main point set if a L16 dual point set up. Use the one with the bigger capictor. dont use the 2nd set leave disconnted.

[racerx]

This sounds just like what I went through. Last year, I installed an L18 and was confused too because there were 2 timing 5 and 12 BTDC, after emails back and forth, I just set it to 12 and it runs good at this setting. Tried 5 and was too retard. I also installed a single distributor from 68-69 Datsun 510 then it got a little bit more complicated because there are different dist. pedastal and timing plates. Seen some on this site, thanks a la Hainz, and also visited Rod from Rod's discount parts and he shared stories about people changing engines, L series distributors,and things would get out of whack. As hainz said, when you use a distributor from a particular L engine and use another L engine, like L-16 to L18, take the pedastal and timing plate for that dist., they will fit but maybe you will not have any play with timing. With that said, also make sure you are at 11.25 time projection regarding your oil spindle....let us know what happened.

[ppeters914]

I'm sure Roadsters don't have 3rd gear switches installed in the wiring.

Correct.

 

So I hope he has a single distributor in there already. If not just use the main point set if a L16 dual point set up. Use the one with the bigger capacitor. Don't use the 2nd set leave disconnected.

Yeah, I've seen one post after another say the same thing, i.e. replace w/ EI (preferred) or single points dizzy otherwise disconnect the second set of points. Why complicate things?