Jump to content

ignition upgrade


Recommended Posts

am new to datsun world and working on recently acquired 1978. rig runs well however want to improve preformance. have removed smog stuff and now am looking at ignition, wondering what can be done there. Is the ignition system worth upgrading (bang for the buck) or does it work well enough that other improvements are a better value? any advice appreciated. thanks.

Link to comment
  • Replies 21
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

id check everything if your shotting for performance.. ive always made sure there isnt vacum leaks or old hoses about to break.. replace easy gaskets get rid of oil leaks...

im rebuilding mine cause the motor is just old and tired... and im sure it will feel fast as shit when im done lol... =) but id make sure everything is running at its peak before you spend money to make it quicker and break something. =) just what i normaly do on any car.

Link to comment

The '78 already has a breakerless high voltage system in it. The same as used on the 280Z that year and was good to 7K on it. That's 11,500 RPMs on a 4 cylinder. It requires almost zero maintenance once the timing is set. A good set of wires, cap and rotor and you're good to go for as long as you will own it. Yes you can spend $200-$300 for an MSD wizz-bang thunderbolt flame thrower super nova laser beam ignition and coil but it won't run any better. Spend the money saved on tires, or a lowering kit, rims, shocks or anything that will improve your driving experience.

Link to comment

king rat - so appreciate your timely and complete response. did serach for ignition upgrades and found very little which now makes sense given the nature of the system.


Also understand your comments regarding driving experience and pls know that i am on that path already having replaced the tires and shocks as well as installing a front sway bar and brake system (repair and replace).


while i do intend to lower the rig and do those other things to enhance the driving experience, certainly part of this must be tweeking the motor. So i ask you king rat, what is your advice on the one, two or three (cost effective and moderately priced) upgrades i might consider to improve the engine performance (l20).


again, thank you for your comments on the ignitiion system.

Link to comment

start with giving it a proper tune up.


dont buy autolights and fram.... thats shithouse.


go get the proper NGK plugs, and NGK wires if you can find them, cheaper tune up parts anrt better.

gladstone nissan carried good nissan brand L series oil filters when i worked there.

id check in and see if they still do. (big blue canister)


and make sure to set your valve lash.

Link to comment


Well the Hitachi carb is rather complicated and although works best (when new or in good shape) for all around use it is a compromise for mileage, performance, pollution control and drive ability. You can't beat it . But if you are willing to give up some of these in order to improve performance, then get a new 32/26 Weber carb. Yes there are used ones on eBay but they are well used, old, probably rebuilt buy well intentioned owners that left parts out or mixed up jets and air bleeds. So why put something on that you have to trouble shoot? The Redline kit includes the adapter, gaskets, linkage and just about everything you need to plug 'n play. You should be able to get one for under $300... I know, not cheap, but they work out of the box and provide years of trouble free driving.


The L20B carb is adequate, the weber will flow more air and this will give more performance when revved up.



You'll probably be thinking header. Yeah if you had a race motor this might be an ok idea but for stock street motors I don't know which is more wasteful time or money. Any gains are far up the rev range and need more carb and a cam to truly show their stuff. What you can do is instal an earlier L16/18 exhaust manifold. The L20B ones are 4 into 1 with all cylinders jammed together in one outlet pipe. The L16/18s are 4 into 2 with the down pipe having the 2 into 1 and back to the muffler. The L16/18 is basically a cast iron header without the problems with one.

Muffler & Pipe

2" pipe is fine for the L20B. If you plan a cam swap maybe go 2 1/4" but large pipes lower the gas speed through them and this has to be balanced against restriction. Better to have the exhaust traveling fast as possible through a 2" then to slow it down with a 2 1/4". The exception would be a race engine making huge power at ultra high RPM with lots more exhaust to get rid of. Or if running a turbo. Both will have large amounts of exhaust and a 2" pipe may actually restrict the flow. Fr a street motor 2" is plenty.

For a muffler, the largest quiet one you can fit on. Turbo mufflers are good but louder. Avoid ones you can look through. I see these fart can for sale for $120!!! The rule is If you can see through it, why not get an 18" hunk of pipe from a muffler shop for $4.





Your exhaust down pipe will need changing to the 2 into 1 bend like in the picture.

Your head is a W58 casting and has round exhaust ports. The L16/18 exhaust manifold are square shape. Round port into square manifold is ok as long as you use a manifold gasket that is square. Early '75-'77 L20Bs with the U67 head had them. I picked up one of these manifolds for $10 a muffler shop should be able to bend up and weld a down pipe elbow for $25 bucks. Mklotz70 on here was selling the two hole flange for these a while back.



It isn't a header but for under $50? it's a steal.





You now have two of the necessary ingredients for better breathing that a cam alone can't give. Strength is built into the block, power is all in the head. The more air you can run through a head the morew power you can make. You have increased air available through a better carb. You have a good flowing exhaust manifold and system. Now all you need is something to make use of it. Here you can pick from a wide variety of cams but if you stay below 0.480" valve lift you shouldn't have to replace the stock valve springs. Duration of up to 270 degrees will not be too crazy. A rule of thumb is that for every 10 degrees of duration added the power and torque peak moves about 500 RPM up. As the L20B cam is a 248 duration this means that power peaks about 1,000 RPM higher. Under 7K for HP and over 4K for torque. Idle quality decreases as duration increases. So the more cam the more it affects the driving range you spend 99.999% of your time driving in.


  • Like 1
Link to comment

king rat - thanks so much for the advice. the detail you provide is particulary useful as regards the trade-offs one must make when undertaking most performance upgrades. I will chose my path based in large part on what you have identified as upgrades to make. I will keep you posted on my progress and again, thanks so much so effort you put into your response. i have learned a lot.


ps - wanted to do something today so made up a set of msd wires (8.5mm) i had left over from a couple of other projects. Put them on car and while it probably made little difference with motor, it was fun to do.

Link to comment
  • 2 months later...



have continued to work on rig for last several months.


rebuilt/rehabed/repaired/restored or simply replaced - bench seat, tires, body and paint, heater, lights, radiator, starter, alternator, coil, plug wires, shocks, sway bar and a bunch of other stuff. Rig actually looks decent now.


up until recently, stock carb was doing fine but now am having problems (wont idle, secondary wont open, runs rough). no question carb is original and assume it has simply worn out. i do not assume i am adept enough to tackle rebuild and would enjoy performance upgrade and as per your suggestion. It is my plan to order a new weber conversion kit (redline). do you have any suggestions (or can you point me to a particular post )  that might help me make the change over go smoothly.  many thanks.

Link to comment
  • 1 month later...

Digging up the old to make a new!!


My truck, 1973 620, L16, all stock, even the dual dizzy. I know its a truck and treat it as such, I do not want power out of it but drivability and reliability. I plan to  do a lot of driving and car shows, so loooong highway driving is its main life. I never set my valves, and have a hard time getting it to run smooth, I think the float is buggered, but overall my carb is a disaster, the ignition is ok, a bit dodgey but meh?


I will buy the Redline Webber, do I just order kit #K 660? Does that have everything I need? Does it have a auto choke? Is it bolt up and is any tuning required? etc etc


Thank you Mike for letting me know my exhaust manifold is fine, right, thats what you said, riiiiight? Because my next question is what intake and exhaust manifolds could I buy to get the truck running better? It needs a new exhaust pipe and muffler and I know you were talking about a bigger L20 so I can only assume my L16 would need a smaller pipe like a 1 7/8? The exhaust will also need to be tucked in the tansmission tunnel because of my ride height. Is that an easy task? Do I have to hammer out the tunnel?


Mike, the '78 ignition that you stated above, can you explain every part I need to swap over and where I could find them in. Being in Vancouver BC I havent seen any dattos in the JY, just a 78? truck in Kelowna but I never grabbed enough :(


The other thing on my mind is the "engine swap" right now Im lazy and want to enjoy the truck. Is there any gain swapping to a L20? Are any parts interchangable between the two engines? (Intake/exhaust/bits?)


I think thats all.


Thanks again Mike for the driveshaft, you helped a lot!!

Link to comment

You may be able to order the down pipe for it or some places will bend one up right there from templates or do a custom job. 1 7/8 is plenty large enough. Get a muffler as large as you can fit so it's not restrictive but quiet.


Contact the Redline site. It should have all the info on the carb you want and need. The '73 has electric choke so the Redline should too, but you can check.


There were two styles of electronic ignition (EI) distributors (dizzys) The '78 was the remote igniter and the '79 and '80 L20B used the much simpler and desirable Matchbox type. Try to find a Matchbox, but failing that a remote igniter will work. Both work the same so one isn't better than the other just simpler.


The L20B has more displacement than the smaller L16 so more power and torque.  In the day I had an L16 521 and swapped a '77 L20B into it with no other changes. I don't remember it being any faster but it pulled much stronger at low speeds in higher gears. (torque) Strangely there isn't much that will swap between the L20B and the L16/18. Manifolds, dizzy, water pumps, oil pan, valve cover, oil pump, the head will swap but no reason to.

Link to comment

"had" an auto choke. the wire is there but I cant get a signal from it and the choke doesnt seem functional. Have the hardware is removed. Does the choke run off a positive signal? Would it be better off to have a manual choke?


Downpipe, you're talking about the 2 in to 1 after the split flange correct? Whats the point of that 2 hole flange btw?


So a '78-'80 L20 distributor is all I need? Do I just grab the assy or do I need to chase anything else down? Coil? Relays? Wires? Is it plug, time and play?


Other then a torque gain, I might as well stick with the L16 it seems. But I should look in to a 5spd.

Link to comment
"had" an auto choke. the wire is there but I cant get a signal from it and the choke doesnt seem functional. Have the hardware is removed. Does the choke run off a positive signal? Would it be better off to have a manual choke?


Downpipe, you're talking about the 2 in to 1 after the split flange correct? Whats the point of that 2 hole flange btw?


So a '78-'80 L20 distributor is all I need? Do I just grab the assy or do I need to chase anything else down? Coil? Relays? Wires? Is it plug, time and play?


Other then a torque gain, I might as well stick with the L16 it seems. But I should look in to a 5spd.



The choke should be powered by a relay that is only on when the motor is running and the alternator has output. You could supply and run it on any source that is on with the ignition too.



The L16 4 into 2 into 1 was as close to a long tube header as you can get. I think that's why as the L16 was also intended for racing.


'78-'80 L20B dizzy is what you want. Get the coil that goes with it as this will give the higher output. Be sure to unbolt the base of the dizzy called the pedestal, from the timing cover. It has two 10mm bolts in it. It's this part. Keep it.


Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.