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620KC on 720 bare frame build


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Hi guys, I'm new to this site but have been posting my build on the 510Realm. I'm doing a resto-mod using a 75 620KC  that I'm grafting onto an 85 720 reg. cab long bed, benefits are: power steering, front disc brakes, non-kingpin steering knuckles, bigger gas tank, and bigger/more functional wiring harness.

 

I started my build a couple years ago and after stripping down both trucks to verify frame differences, I needed to relocate the forward 2 box mounts to account for the longer KC/shorter box, plus nip off some excess rear frame length, otherwise the frames are the essentially same. I believe the D21 Hardbody is also the same frame but not confirmed. Modified frame was completely stripped to bare metal and checked over for any cracks etc. before going any further. At this point I have a full rolling chassis done, I fabricated new brake/fuel lines and mounts for them, new PS lines, and have replaced or refurbished pretty much every mechanical piece in the process.

 

I'm about to begin the engine teardown and the current plan is to use the 2.4 Naps-Z that came in the 720 then later I'll swap in something more powerful. I'm probably going to stick within the Nissan family, but if I bastardize it then I might do an LS swap ( I'm not a bow-tie fan).

 

The body was reasonable with rust in the usual areas, I've sourced replacement front fenders and tailgate. I'll have to make or hopefully find replacement rockers. One thing I'm yet undecided on is what to do with the hole in the roof as the truck had a sunroof installed. I could fill it in but I like a sunroof. 

 

I'll post some pics once I figure out how to insert them on this board. Or see my post on 510Realm.

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I swapped a '78 King Cab onto an '82 720 Long Box frame. I relocated the two front most box mounts but really you could just cut them off.

 

The Z24 has lots of torque for pulling a truck. If you must get a KA24E or DE and transmission. It will bolt up to the Z24 5 speed but the KA's are much stronger.

 

 

I'll never have a sunroof again. Hardly ever used it for a vent and warm humid cabin air condenses and drips on you when driving.

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Next time I'm out in BC I'll have to touch base and see your 620, you probably know Byron.

 

One idea I've been mulling over is to graft in the factory sunroof from something like the Honda CRX which is the "spoiler" type, meaning it opens out not by retracting into the roof. Once the weather permits I'll go scour local wreckers and see what I find.

 

Here's where my build is presently at:

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  • 2 months later...

Well I haven't been on this site too much lately, mostly post on 510Realm with many more pics but a quick update on my progress:

 

Frame is essentially complete after sorting out issue with L park brake cable (had to modify one that was too long), and have been busy building the Z24 motor. It is now ported & polished, balanced & blueprinted, bored +.050, and all cleaned up. I'll soon have it ready to re-install into the frame.

 

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  • 2 weeks later...

Carb is rebuilt and been sorting out the vacuum lines/EGR delete etc. Now to refresh the trans/clean it up & mate it up to the motor.

Should have that step done next week then into the frame.

Beginning of illusions of having it together and on the road this fall.🤪

 

If interested, I have posted some wheels/parts in the classifieds, will add some more extra parts soon.

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  • 2 weeks later...

DUH moment happened, seems that I forgot during the engine teardown that this dizzy cap screw had twisted the head off, and now it really doesn't want to come out.

 

I've soaked it with penetrating oil and even with some vise-grips on the shaft it won't budge. I'm thinking I'll have to try to drill it out from the underside as there is I think just enough recess for the bit to center correctly. Not sure if I should try heating the dizzy body as I don't want to risk any warping.

 

Time to cross my fingers and head out into the garage

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Got the dizzy fixed, and of course the remaining stub of screw shaft broke off. According to Murphy the drill press chuck was too big to get past the housing so I had to downsize the tools, ended up using my Dremel and even that just squeaked past the housing. Good thing I had a selection of tiny bits and small bore collets or I'd've been screwed.

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  • 4 weeks later...

Well it's been too long since I posted about my build and things have been in progress. Engine build completed, transmission serviced & mated up. On the weekend my son & I got the engine mounted up into the frame, another milestone achieved.

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Now I'm sorting out the exhaust routing, took my drawings into the exhaust shop this morning and should have my custom bits ready on Friday.

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When I bought the new tubing the brake shop had these vinyl coated steel lines - decided that not only would they coating further keep rust at bay but it would dress them up for the same price. I regret not going with the nickel-copper tubing a little as the 3/8 (green fuel supply line) was much harder to get nice bends than the smaller stuff. Once the body is on, no-one will see much of that anyway, just the bit that shows in the engine bay.

 

Muffler shop got my bits ready this morning so I have the exhaust set up now, just need 1 more clamp & that's done.

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Precious little clearance beside the header

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1 hour ago, EDM620 said:

Muffler shop got my bits ready this morning so I have the exhaust set up now, just need 1 more clamp & that's done.

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Precious little clearance beside the header

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Pretty awesome. Assuming you bought the pipe from the muffler shop as well, how much did the whole setup cost you from headerback (in Canadian)?

I was planning to do the same thing for my KA24 swap when I get to it, but was thinking about buying a 2.25" or 2.5" mild steel exhaust kit from amazon for ~$200cdn that could maybe make a good 3 or 4 full systems - then use what I need and sell the rest to recoup the cost or something. Unless its cheaper to have a shop chop and bend some pipe for me one time.

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Thanks for the comment. The whole thing cost me just over $300 CDN. I bought the muffler & pipe sections from CDN Tire so I could cobble up my intended layout and get measurements, drew that up on Word (I don't have CAD) and gave the muffler shop my drawings of each section - downpipe, mid-pipe, and tailpipe. I was very careful with the measurements making sure that I was using center-to-center for everything, and the muffler shop was able to make the sections no problem. I kept the muffler but returned all the pipe sections. Pipe & bending was $250 from the muffler shop.

 

I suspect that you live much closer to the border than I do, have you used the warehouse services in Sweet Grass? You can save a bunch of shipping (& duty but can tell you more on that) by making a run across the border to pick up your parts.

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@EDM620 -- Thats pretty damn clever, and something to consider. Is that 2.25 or 2.5" pipe? Looks to be about as close to the frame as you can get it - assuming itll be lowered.

 

Im actually just down in Calgary - my brother had some friends do some border crossing warehouse runs in the past but Im not too schooled on it. Theres a ton of things that I'd love to grab but shipping completely kills the deal (wheels come to mind). Smaller items I end up shipping to family over in Washington but the lockdown has kinda screwed me a bit... Ive got some parts held hostage until we can freely cross lol.

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Engines with torque need lots of wiggle room for the exhaust, but also secure mounting. I use OEM style rubber mounting with isolators from Pypes - https://www.summitracing.com/parts/pye-tphv6

 

Exhaust systems also grow with heat. If you measure the end of the tailpipe, you'd be surprised how much length they gain after they get hot, so account for this too.

 

Systems that are mounted too rigid will have excessive vibration or resonance and will eventually tear the tubing, the mount or both.

 

Here is a system I build a lot. An LS3 conversion on a Toyota Land Cruiser makes lots of torque and requires a good amount of movement, both fore/aft and side/side. The metal rods are 3/8 stainless that I bend here in the shop, but you can buy them.

 

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Edited by Stoffregen Motorsports
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Stoffregen, that is a nice clean system, I like how you've got that hangar tucked up inside the factory bracket. I still have to put my hangars on so will definitely allow for expansion.

 

klam07, there is a warehouse service there in Sweetgrass (Montana Shipping) that will receive & hold freight for up to 6 months I think, pretty reasonable fee based on size/weight. Considering how much cheaper freight is to locations within the lower 48 (sometimes free) it is well worth it. And I've found a few times that something won't ship to Canada but will to the US, so that has saved me as well (new rubber body mounts from Thailand was one). And save even more cash, any part for a vehicle 25+ years or older is Duty Exempt.207522603_CBSAD10-15-20.thumb.JPG.d2c033a3c12c435f090c4b235d86a0ae.JPG

 

And yes that tubing is 2.25", optimal size for the exhaust flow. I will be lowering the truck only a little as it is being built to be driven & roads here have so many frost heaves and potholes I gotta have some clearance.

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@EDM620 That is some solid info. I actually do remember looking into Sweetgrass at one point, I remember their website. It'd definitely save me a ton of money, like for the ka24 mounts from Redeye, shipping to Canada is a pretty big additional cost. Would I just call or email to get a quote?

The 25+ year rule is game changing! But I wonder, how would you prove that its for X car? Like wheels for example, a universal'ish item, how would I prove that its for the Datsun (or another car).

 

4 hours ago, EDM620 said:

And yes that tubing is 2.25", optimal size for the exhaust flow. I will be lowering the truck only a little as it is being built to be driven & roads here have so many frost heaves and potholes I gotta have some clearance.

Yeah, its been a while since I went up to Edmonton but I can attest to having some pretty crap roads down here too. My trucks lowered maybe 3" all around, no issues with ground clearance but Im on new air shocks & 720 leafs in the rear and monroe reflex front shocks - it feels good, 'like a car' with 195/60 tires. But even though Im normally used to a stiff and bumpy ride I still prefer to drive my 'slammed' honda over the truck most times. Its just somehow more comfortable for me - honestly probably the lack of power with the l20.

 

Pic was before I lowered the rear. It got 2" blocks and is barely raked now

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23 hours ago, klam07 said:

Would I just call or email to get a quote?

Just shoot them an email, it's real simple. They register you & you get packages sent to their address with your name,  they let you know when something has arrived. The warehouse is literally 2 blocks in across the border, you can be in & out in a jiffy. Rates are fixed so you can estimate ahead.

 

The Duty-free exemption could be a bit difficult to prove but I've not even been asked so far. If your sales order identifies the part as being for your year of vehicle that seems to satisfy them. Honestly I've had more hassle going across from BC by US customs to pick up parts, not coming back. Getting a US shipper to put on the proper Tariff code (9966.00.00) is harder than it ought to be, so I make a point of putting that into my address as a separate line (limited success). Guidelines section #2 requires some "interpretation".

 

Nice looking ride!

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@EDM620 Thats really good stuff to know. Ill look into it a bit deeper when the time comes and when borders fully open again. Id likely just drive straight down to Sweetgrass, I bet that border agency gets these types of trips all the time, but I wonder if that'd make it easier or harder lol. Maybe Ill even try calling them just to know
Thanks for the tips!

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7 hours ago, klam07 said:

I wonder if that'd make it easier

In my experience, the Canada border guys are ok with you bringing in parts, when I've told them I'm bringing parts for an old vehicle they just say thanks & be on your way (had a trunkful). Even had my aunt make the trip once for me, no issues. She lives near the border & regularly crosses for groceries.

Give No BS, get no hassle.

 

The US border guys whole other story... got hassled just crossing to go across to pick up my parts, had to show the Craigslist ad for my used tailgate.

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  • 3 weeks later...

Time for an update. Today I set up to lift the cab onto the frame using my home built gantry. By the numbers I was going to be 2" shy of clearing directly over the motor so I changed how I was going to hook up - plus I looked at what was left of the cab mount holes and decided I'd best start with replacing those before going any further.

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I was lucky enough to find the balance point lifting the cab where I could balance it with one hand while hoisting with the other.

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Now with the cab sitting up at a comfortable working height, I can focus on the repair patches while my brother tackles the required straightening here & there.

I was also able to fit up the dash and will be going forward with the 720 dash. Next I have to determine if I can use the 720 heater/blower assembly as the squirrel cage blower is wider (& moves more air).

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Soon I'll be spending some quality time with my welder and grinder...

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