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4.3 vortec swap


defrag010

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I had everything set out and planned for a nice little mild 200-ish hp L28 turbo motor with rebuilt 4n71B auto tranny in my 1980 280ZX.... until I magged my block today and found a bigass crack right down the middle of it.

 

This will put me way over budget finding a new block, and frankly I don't want to hunt down a new L28 block local or have to deal with shipping and start over again.

 

I got offered a 1995 low mileage vortec CPI 4.3L / 4L60E pullout complete with wiring harness, ecu, radiator, and basically anything I need from the donor for 500$.

 

I'm selling my freshly rebuilt P90 with zero miles, std/std L28 crank, and a few other misc. things so that I can recoup some of the cost of this 4.3 pullout and still come out ahead.

 

My questions is this:

 

I've been researching for days about this swap on here. I couldn't really find a definite answer on mounting. Everyone says that the JTR mount kit will work, but it sits the motor 4-5" too far forward, others say it will sit the motor back where it should. I read that someone said the 280ZX firewall is closer to the front of the car than in a Z, so that means the 4.3 would sit back farther.. but that doesn't make sense because the firewall would go through the back of the stock L28.

 

Instead of hassling with what might work, I figured I would go ahead and buy a Universal SBC engine crossmember (from s ummitracing), and just mount the engine where I want to.

 

Is there anything else I need to get/do to complete this swap? I heard someone say I need the Astro van oil pan. Is that true? I do not want to read a bunch of replies asking me why I'm going 4.3, and telling me that a SBC would be better because I'm just working with what I have and on a super budget.

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Something similar to the JTR setback plates should work. Measure the distance from the rear of the block to the rearmost mounting hole for the motor mount. Compare this dimension with a 350 block (17" from the center on the rear motor mount hole to the rear of block). The difference between the two is the amount that will need to be added to the setback plates to put your engine in the same setback as an SBC. This would make the setback plates very long potentially. Longer plates would be more prone to getting twisted up by engine torque, so keeping it at a moderate torque level would be a consideration. For durability, I'd say go with the crossmember style motor mount. The oil pan shouldn't be much to worry about as it will be almost a full foot or more behind the factory front cross member. As long as you install the new motor mount cross member in such a way to clear the pan, it shouldn't be an issue. Hope this helps,

 

Mike

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The 4.3 Vortec is basically the same as the 5.7 with two fewer cylinders. It has the same mounts but I "think" they're a bit farther back to compensate for balance.

 

I had everything set out and planned for a nice little mild 200-ish hp L28 turbo motor with rebuilt 4n71B auto tranny in my 1980 280ZX.... until I magged my block today and found a bigass crack right down the middle of it.

 

This will put me way over budget finding a new block, and frankly I don't want to hunt down a new L28 block local or have to deal with shipping and start over again.

 

I got offered a 1995 low mileage vortec CPI 4.3L / 4L60E pullout complete with wiring harness, ecu, radiator, and basically anything I need from the donor for 500$.

 

I'm selling my freshly rebuilt P90 with zero miles, std/std L28 crank, and a few other misc. things so that I can recoup some of the cost of this 4.3 pullout and still come out ahead.

 

My questions is this:

 

I've been researching for days about this swap on here. I couldn't really find a definite answer on mounting. Everyone says that the JTR mount kit will work, but it sits the motor 4-5" too far forward, others say it will sit the motor back where it should. I read that someone said the 280ZX firewall is closer to the front of the car than in a Z, so that means the 4.3 would sit back farther.. but that doesn't make sense because the firewall would go through the back of the stock L28.

 

Instead of hassling with what might work, I figured I would go ahead and buy a Universal SBC engine crossmember (from s ummitracing), and just mount the engine where I want to.

 

Is there anything else I need to get/do to complete this swap? I heard someone say I need the Astro van oil pan. Is that true? I do not want to read a bunch of replies asking me why I'm going 4.3, and telling me that a SBC would be better because I'm just working with what I have and on a super budget.

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The V6 and V8 share many commonalities. The engineering drawings show the motor mounts identical and located equally from the front of both blocks. The V6 can be installed in the V8 location and the transmission mount will need to be moved forward as well as a longer driveshaft. The better choice would be to relocate it back about 5" (the approximate difference in block length between the V6 and V8). That would provide better balance but require some creative front mounts or brackets. I would fab plates to relocate the actual motor mounts forward to the V8 position. This would allow the use of any existing V8 conversion kit. I've run an OBDII '96 4.3 for about 8 years in my '71 land rover. Bonestock it produces 200hp and 250lb/ft. That is strong motivation for an early Z. As my latest land rover will sport a LS1 I am giving strong consideration to planting that V6 in my '71 240Z in the future.

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Well, I have a 72' Z at my step-Dad's property in Louisiana. We had installed a 4.3 V6 with the JTR mount plates and engine mounts. It sits about 4" inches forward of where a V8 would be. A benefit of this, the stock Z trans mount could work with minor mods. The trans is an S10 700R4.

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4.3? What are you thinking ;) Take advantage of the weight distribution, not the shortcut and JTR it. Best to fab up your own mounts. I used the Datsun pads with a front engine mount. Cross member idea good, probably stronger. I used Astro pan, since it was from an Astro, but they are pretty deep as I recall.

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John!!!!

 

I was hoping you'd join in this thread - how are you!!!! Haven't heard from you in such a while. It's good to hear from you buddy! Hope all is well. I like the 4.3 engine package. If you search you'll find some great info from John that he shared some time ago.

 

Ernie/RacerX

 

Doing fine, thanks for asking. Good to hear from you! Been V8 for so long now I tend to overlook the 4.3 V6 stuff. I'm sure more is now in archives than what I remember anyway. V6s are great in the Z.

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Cool, it will be fun to see the progress. If you get greedy with power, who doesn't, go to the Sy Ty sites for what works. I swore I would be happy with 10 psi. I'd probably still be driving it with the same belt if I stuck to it. Been talking to a few local Sy Ty guys and they all say at 10 second+ high altitude+ 3700#, the 4.3 gets real expensive. Especially when you want to make it last. No where near the durability and success of the GN V6s, but still a fun engine to play with.

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yeah.. this whole 280ZX project is more or less just a replacement daily driver project that will have a little kick. I have a 1991 rx7 that is getting a VH45DE and I'm going to use that for my all out powerhouse fun car.

 

I've been wondering if the engine I have is any different internally than a syty 4.3. I know the syty heads are older because they upgrade to vortec heads. I was thinking about buying a set of syty turbo exhaust manifolds because they will bolt on.

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Looks like a nice find. The 4.3's IMO are not as power savy as say a 350, but I think they make a really good daily driver combo in a Z. Also, they are somewhat cheap to boot. There are quite a few "street rod" guys that use the 4.3, and I am sure that "early" iron is heavier than our Z's. Anyway, good luck on your swap.

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I've got GMCs version of the Astro, the Safari with that engine tranny package in it. I really like it, has enough torque to propel the van down the road at 70-75 while pulling a full-size 14' pop-up tent trailer and still get decent milage. It now has 160,000 miles on it but runs and drives great. In fact the body of the van is showing the miles much more so than the drivetrain.

 

I think you'll have a nice Z once the transplant is done. Keep us informed and post lots of pictures.

 

Wheelman

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  • 3 months later...

well, I know a few people had said they looked forward to this swap, but I took the 4.3 heads into work and ported and rebuilt them real nice, and had a sy/ty guy come in the shop and offer me more than I paid for the whole 4.3 pullout for just my rebuilt L35 heads and resized rods!!!!! I had to take it. I sold the 4L60 for 300 dollars, so I actually made money.

 

I had a third gen camaro buddy give me his old L03 305 pullout for free, so I'm going to use the extra money I had saved up and the profit from the 4.3 sale to build this up. I'm going to sleeve it out to 4.00" bore for 335c.i. of high rpm doom! I found me another daily driver, so I want to hop this one up now.

 

motor parts I have so far:

-crower 3.335" Billet ultralite small journal crank w/ big block snout

-billet 4-bolt main cap conversion w/ 1pc main stud girdle

-6.125" carrillo H-beam rods

-4.00" bore wiseco proplite pistons, 1.2" comp height

-patriot "procomp" 195cc sbc "vortec" style alum. heads (260cfm@.600" intake)

-edelbrock air gap w/ injector bungs installed

-vortec 75mm TB w/ square bore adapter

-LS1 plastic gas tank w/ intank walbro 255

-65K HEI billet dizzy

 

Parts I need:

-fuel rails

-adjustable FPR

-megasquirt fuel ECU

-built 700R4 (ouch)

-R200 rearend w/ LSD

-zero balance big block damper

-cam

-gear drive/timing cover

 

 

Still have alot to go, but Im alot farther along than I anticpiated!!

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  • 2 years later...

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