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Noah Fernandez

78 620 truck Eng. Swap

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Hi guys

Have a 78 620 and i would like to do an engine swap to a smog legal fuel injection. I would like for any one to give me and Idea of what engine I could use or if there is a kit that I could buy some place. Thank you for reading this and in advance thank you for your help.

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You're in California... right? Before you get a hard on over some trick engine swap you better see the DMV about engine swaps on post '74 vehicles. Be a shame to spend upwards of $6,000 on a swap and get pulled off the road. This is definitely a case for asking permission first rather than asking forgiveness later. 

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Best bet is to check your local laws and get to know your local smog ref before starting. This will let you know what motors you can and cannot use far better than we could as well as get your a guy on your side once it is time for inspection. 

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This is one of those situations where if you have to ask, you probably shouldn’t. Engine swaps are not for the feint of heart. Budgets are not small for whatever you choose, especially paying someone else to do the work for you. 

Best bet is to either buy an already swapped rig or find something closer to what you want. 

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I do tons of engine swaps here in my shop, and if you've got to pass emissions, the best way to have all the parts required is to buy a complete donor vehicle. The easiest swap would be a D21 Hardbody KA24E. Buy a whole truck for $1500 and use the entire EVAP system, fuel system (including fuel tank, and click type fuel cap), etc. You may find it easier to use the D21 wiring harness and adapt it to fit the 620. That way, you know it will work with the engine and all the emissions equipment.

 

One area of major concern is the exhaust. The ref is very strict on CAT placement and tubing size.

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The D21 is very similar to the later 620's .

 

Pulled one from a 1990 with the in tank pump. Looks like it might even bolt in for the 620 frame, but hobo hasn't test fit yet. 

 

 

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Why you gotta call me out like that? It at least made it to the shop, come on over and offer it up to a frame. Got two with no tanks already, 79 and 73

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Because your the one that took that junk :)

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If your in Napa, CA, whatever swap you choose must have ALL the emission equipment that was required from the year of the donor. My suggestion would be a pre 95’ since those are OBDI and simpler. You could also look for something pre OBD, like say a Z22 setup from a S11. As others have said, best to just get a donor vehicle and swap all the emission system to the 620 to be legit and get a BAR tag. May be easier to just drop your 620 body on a D21 chassis.

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23 hours ago, ]2eDeYe said:

The D21 is very similar to the later 620's .

 

Pulled one from a 1990 with the in tank pump. Looks like it might even bolt in for the 620 frame, but hobo hasn't test fit yet. 

 

 

Thank you I will check all options that I can fine.

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2 hours ago, datsunrides said:

If your in Napa, CA, whatever swap you choose must have ALL the emission equipment that was required from the year of the donor. My suggestion would be a pre 95’ since those are OBDI and simpler. You could also look for something pre OBD, like say a Z22 setup from a S11. As others have said, best to just get a donor vehicle and swap all the emission system to the 620 to be legit and get a BAR tag. May be easier to just drop your 620 body on a D21 chassis.

Yes I know

That is why I want to swamp because I  can not find the air injection pipes for it. So If im going to spend money on it. Mines well do a legit swap. Thank you Ill start Looking.

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You're choosing a multi thousand dollar swap over finding a '78-'80 L20B exhaust manifold?????????? How does this make any sense? All '75-'77 square port would also work.

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On 1/24/2019 at 1:14 PM, ]2eDeYe said:

The D21 is very similar to the later 620's .

 

Pulled one from a 1990 with the in tank pump. Looks like it might even bolt in for the 620 frame, but hobo hasn't test fit yet. 

 

 

 

On 1/24/2019 at 5:00 PM, hobospyder said:

Why you gotta call me out like that? It at least made it to the shop, come on over and offer it up to a frame. Got two with no tanks already, 79 and 73

 

 

HOLY CRAP!!

That would be badass if it fits!

 

https://www.rockauto.com/en/moreinfo.php?pk=7677792&cc=1210958&jsn=378

 

....

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There's a bit more to it than that Mike. First off, EFI...need I say more.

 

Secondly, some people just want the challenge and reward of doing an engine swap.

 

Third, the KA24E has 40 more HP than the late model L20B. That's not nothing.

 

I'm all for an engine swap. But please finish what you start. Nothing worse than another classic Datsun biting the dust because of an unfinished hack job of a swap.

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Well then, I would expect the first excuse should be EFI, then reward/satisfaction, then power, and no mention of "also the air injection tubes are no good." Above all, as mentioned, the smog laws rule and have the final say. This is a > $50 fix vs. $4K < (likely up to 50% more with lots of legal hoops to jump through) 

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On 1/23/2019 at 7:20 AM, Ben_upde said:

This is one of those situations where if you have to ask, you probably shouldn’t. Engine swaps are not for the feint of heart. Budgets are not small for whatever you choose, especially paying someone else to do the work for you. 

Best bet is to either buy an already swapped rig or find something closer to what you want. 

I can do the work no problem. I jest never done it before and like to hear  opinion from you guys that have done it. Thank you

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On 1/25/2019 at 6:52 PM, datzenmike said:

You're choosing a multi thousand dollar swap over finding a '78-'80 L20B exhaust manifold?????????? How does this make any sense? All '75-'77 square port would also work.

Yes I know but. I being all over and close by i have not being able to find the a good air injection pipe or manifold with the pipe in ok working conditions. All i find its missing part of the AIP eating away by rust. IF you know any body that have in ok condition exhaust manifold with the AIP. Ill would love to buy it. Thank you

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On 1/27/2019 at 9:19 AM, Stoffregen Motorsports said:

There's a bit more to it than that Mike. First off, EFI...need I say more.

 

Secondly, some people just want the challenge and reward of doing an engine swap.

 

Third, the KA24E has 40 more HP than the late model L20B. That's not nothing.

 

I'm all for an engine swap. But please finish what you start. Nothing worse than another classic Datsun biting the dust because of an unfinished hack job of a swap.

Yes Im with you. Job must be 100% done.

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On 1/23/2019 at 7:16 PM, Stoffregen Motorsports said:

I do tons of engine swaps here in my shop, and if you've got to pass emissions, the best way to have all the parts required is to buy a complete donor vehicle. The easiest swap would be a D21 Hardbody KA24E. Buy a whole truck for $1500 and use the entire EVAP system, fuel system (including fuel tank, and click type fuel cap), etc. You may find it easier to use the D21 wiring harness and adapt it to fit the 620. That way, you know it will work with the engine and all the emissions equipment.

 

One area of major concern is the exhaust. The ref is very strict on CAT placement and tubing size.

Thank you so mush for you advice.  Where are located.

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Ah crap...I just threw away the complete exhaust manifold assembly from my 1975 620 (California truck). All the air injection pipes were in great shape. I figured I'd never use it again and nobody would ever want it. Sorry.  

 

I also recently sold a complete engine assembly with one, so they're out there. Even if you did have to buy a complete engine, it would be a whole lot easier than a swap.

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The '75-'77 exhausts are bolted to the intake. Not to mention the ports are square and the '78-'80 L20Bs have round exhaust ports.

 

 

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I may have at least 1 manifold with the air injection pipes. Doing my 78 with Hooker header & Offenhauser manifold & Weber carb.

Will see if i can find it.

Chopper Jim

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Found the exhaust manifold with the air injection pipes.Also the intake.

Datzenmike, when did they change from bolted to the intake? 

 

Chopper Jim

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ALL '75 through '77 used them with the U67 heads. From '78 through '80 they were separate and used the round exhaust W58 heads. You can use the '75-'77 exhaust with a later separate intake by using the bolts to clamp the cover on the hole in the intake.

 

intake-plate-1024x768.jpg

 

This plate is sandwiched between intake and exhaust but could just as well fit on the exhaust and be bolted down to seal the hole.

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