Finishing touches 78 620

[Bayou620]

I have been lurking on Ratsun and considering buying a 620 for over two years and finally bought one I love at the end of December. It is a very good starting point and just needs a little freshening up.

 

Please help me with a few questions to start out with:

1. Why do most of the KA trucks have the intake routed to the driver’s side? Is it just because most people do not want to relocate the battery or is there a less obvious reason? I have already relocated my battery and think I’d like to free up the space behind the radiator and get the intake tube away from hot radiator.

 

2. Has anyone actually tried any of the Viking coil overs on a 620 yet?

 

3. Any secret tips to removing bed liner? The floor of the truck has Berliner and I’d like to do Lizard Skin. I think it’s best for Lizard Skin to have contact with metal instead of trying to put it over this bed liner material.

[datzenmike]

1/  Sticking the MAF too close to the throttle body can cause some running issues. It's always better to put some distance between them. I think the intake pulses need space to damp out. Insulate the intake runner from rad heat, and make sure the air used comes from in front of the rad support. I don't know a good way to do this other than removing the driver's side high beam and using the hole.

[flatcat19]

^ That; intake pulse.

 

Vacuum created by (intake volume) could affect the Mass Air Flow reading were it to be too close to the throttle body.

 

The air tube you see across the top of the radiator is the way the 240sx was routed originally in the engine bay. It has nothing to do with it being a truck install.

 

 

 

So...you just bought a truck you've been dying to have. And know you want to put it under the knife before the honeymoon is even over? Get it running in stock form and rock it. Best to shake out the bugs before you introduce a whole new can of worms to the mix.

 

78 already has EI dizzy, IR alternator, disc brakes, ball joint, and an L20B. Hopefully you got a 5 speed too. Really there is not much more you could ask for from a Datsun truck.

[Moist Lightning]

1/  Sticking the MAF too close to the throttle body can cause some running issues. It's always better to put some distance between them. I think the intake pulses need space to damp out. Insulate the intake runner from rad heat, and make sure the air used comes from in front of the rad support. I don't know a good way to do this other than removing the driver's side high beam and using the hole.

Do you know what kind of symptoms this would cause. As i have my intake where my battery was. Is there something I should look out for?

 

Edit: just read flatcats response. still wondering what the symptoms would be though.

 

bayou620 - is there something special about the viking coils that would make them ideal for a 620?

[flatcat19]

Do you understand how the MAF sensor works?

 

 

It detects air intake volume to determine how much gas to inject. If the MAF feels a lot of air coming in...more gas.

 

Now...being close will trick the ECM into thinking more air is going in having MAF too close...false lean condition. ECM will correct by dumping fuel. O2 sensors will get all buggy trying to correct this now over-rich condition but ECM will still see MAF/air volume and override 02 logic. Constant rich. Bad gas mileage. Poor performance. Catalyst damage.

 

 

As clean as it looks to just loop the air tube down in to the passenger well, the end result is just not worth it.

 

I've had this argument before. Nissan engineers are way smarter than you or I. They got paid big bucks to make a pretty good engine. Don't begin to think we're smarter than they are.

[Bayou620]

Sorry I didn’t start out by figuring out how to upload pictures which may have helped. I bought the truck with a KA, 5 speed, mono leafed, minimal rust... very nice truck!! Thus “finishing touches”

 

I too have done a bit of automotive engineering, but for the Germans and a startup. However, I am no master tech, have no automotive education, and there are many many things I do not know. I do understand intake pulses but have done no analysis. A quick Google image search shows many KA swaps with intake on passenger’s side and this is exactly why I asked before swapping sides (mostly 510s and maybe they have trouble?) So might I be so bold as to ask if you KNOW it causes problems? I’m not dead set on moving the intake, but it would be nice to free up the space. As I said initially, I thought most people went to drivers side because they liked the battery where those smart Nissan engineers put it.

 

You are right about the bugs and worms too. The truck and I had ... minimal trouble driving 3000 miles from Seattle to Louisiana in the 3 days after I bought it but the wiring is a mess and that is my first priority. Next is getting the fuel pump off the frame and into the tank.

 

I do appreciate your responses.

[Bayou620]

For the Viking coilovers, I’ve just seen a couple of other threads where someone has been advocating for them but I haven’t seen where anyone has actually tried them on a 620. They seem to be gaining popularity on muscle cars.

[FrankRizzo]

Plus - the KA-D IACV needs metered air (after the MAF) and I think it would be difficult to stick a 1/2" holio in such a short run (thats what she said...) 

 

.

[flatcat19]

If you're asking me how I know the things I posted...I am a fat guy that feeds 3 kids, a wife that doesn't work, and myself by working on cars at a dealership.

 

I also work in an area where a lot of "ethnical modifications" are performed. When these said mods turn on lights I get paid to shake my head and tell customer to return it to stock form or how to better modify/repair their blunders.

 

 

 

Have I seen exactly what you speak of? Yes.

[datzenmike]

I have heard of a few KA swaps that only ran well once the MAF was relocated farther away from the MAF The ones with the MAF closer simply may not have driven their cars in a manner that showed a problem. I know that SUs and snowmobile carbs will exhibit stand off at full throttle where a fog of fuel forms above the throttle. It actually spits gas out and sucks it back in. All caused by the strong pressure and vacuum pulses. 

 

Try it, and be ready to put it back the other (correct  :lol:  ) way if there are drive-ability problems later.

[Dolomite]

If you're asking me how I know the things I posted...I am a fat guy that feeds 3 kids, a wife that doesn't work, and myself by working on cars at a dealership.

I also work in an area where a lot of "ethnical modifications" are performed. When these said mods turn on lights I get paid to shake my head and tell customer to return it to stock form or how to better modify/repair their blunders.

Have I seen exactly what you speak of? Yes.

Ethnical modifications...I’m deffo going to use that one.

[flatcat19]

Lol. Jerk.

[Dolomite]

I'll credit you. I'll say underwritten by gatocorp llc each time.

[Bayou620]

Thanks Flatcat. I fed a kid once but haven’t done most of that other stuff haha real experience is exactly what I was looking for. I’ll probably do as Mike suggested and just try it out once the important stuff is done since it’s so easy. $15 silicone elbow, some fittings to reattach vacuum, and stretch some wires back out. It will be a good test for this community and I can let everyone know that I should have listened to Flatcat!!

Part of the reason I bought the truck was to have something simple to work on so I’ll probably be fixing some things that aren’t broken.

 

FrankRizzo your truck is what kept me interested these last 2 years. I was going to buy it before it was posted on BAT, but I was in the middle of relocating from Alaska to Louisiana and logistically couldn’t do it. I love what you’ve done with it since buying. I also have some Speedhuts on order (expected this week) and just installed some seatbeltplanet parts. Those people are great.

[Farmer]

Boatman on here has a 510 De with a short intake. Has all the power and fuel economy needed. You can always go megasquirt and delete the maf

[Bayou620]

I’ve only used Megasquirt once, on Shell Ecomarathon vehicles, and hope to never need it again!!