Jump to content
Kingcab

Chevy 4.3 into my 720

Recommended Posts

So I'm getting this 4.3 motor from a 92 chevey s10 for free also getting the wire harnes driveline and rear end. I was wondering what it would take to swap it into my 720. I've been doing a little bit of research but cant find out exactly what I would need and how it fits. Any info helps

Share this post


Link to post

There were mounts available for this at one time. Other than that if you can't find a documented swap you are kind of on your own. Hope you are good at welding. Getting the exhuast routed should fun. Adapting power steering and oilpan clearance will make this a large project.

Share this post


Link to post

Do some cautious measuring. When in place will the starter hit the frame or cross member? Oil pan fit? Sometimes free just isn't.

Share this post


Link to post

I have never been a fan of the 4.3L V6, unless it's the vortec. Too heavy and vibrates like a buck board. That said, they do make sense,if you're looking for cheap, easy power. Though the TBI only makes a measly 150 hp. The Vortec 4.3L made a ton more HP and was smoother running for some reason. A Nissan KA24E swap would make more sense, and more power too.

 

Are you going to keep the fuel injection or swap it over to carb? What about trans? manual or auto?

 

Is your 720 a 4x4?

Share this post


Link to post

Is there an oil pan I could bolt on for better clearance? Also would I need to mod the driveline?

Share this post


Link to post

You'll have to tell us. Not a lot of 4.3 swaps into 720s. Drive line will likely need a different spline on the front and lengthened or shortened. You sure you don't want to run a KA?

Share this post


Link to post

I have had 3 vortec 4.3s. 2 in astro vans that had no major issues in 200k miles. The third was in a 3/4 cargo van, burned a valve in the 120k mark but the consensus was to much van not enough engine and I concur. With the aluminum pan you will have some fun. not insurmountable with cash but the KA is cheaper and well documented. Still plan 2k plus for that. 

Share this post


Link to post

I would much rather a ka but this motor and parts are free to me. And it doesn't seem to hard to swap into 720 until I find a ka 

Share this post


Link to post
On 11/16/2018 at 5:56 AM, datzenmike said:

 Sometimes free just isn't.

 

11 hours ago, Kingcab said:

I would much rather a ka but this motor and parts are free to me. And it doesn't seem to hard to swap into 720 until I find a ka 

 

If your end game is a KA don't bother with the 4.3. By the time you get the 4.3 in you won't want to do this all over again for a KA. Putting a 4.3 in will not 'soften the 720 up' and make a KA swap any easier. The only advantage will be the high pressure fuel pump already in.

Share this post


Link to post

Well if your heart is set on the 4.3, there are a couple areas you will need to be careful.

 

- steering shaft clearance at the exhaust manifold

- oil pan clearance at the crossmember and steering tie rod (which you are already aware of)

- possible valve cover clearance issues with brake booster (just speculating)

- radiator to fan clearance

 

The V6 should theoretically be shorter than the 4 cylinder you're taking out, but the GM 4.3 has a very long accessory drive stickout. It's not very compact up there. Exhaust manifolds came in different configurations, so likely you will find what you need in cast manifolds, but you can also get cheap shorty headers that can be modified to fit in a pinch. Depending on what transmission you end up with, you need to be aware that a lot of GM transmissions use mechanical linkage. Best to find a late model T5 trans out of an S10 or S15 pickup. This will have a hydraulic slave cylinder that can easily be adapted to e used with your existing Nissan master cylinder. Motor mounts willneed to be fabbed, throttle linkage (for carburetor or TBI), new larger radiator, fan shroud and hoses, heater hoses, exhaust system, transmission crossmember, shifter hole in trans tunnel, remote electric fuel pump, power steering hoses (if you want to run power steering) and possible distributor to firewall interference (late model distributor is smaller than "HEI" style distributor). These are all things you will need to find solutions for.

 

Yes, you will need to have a custom drivehsaft made, but any driveline shop can build this for around $200. If you can't find the right oil pan, you can always modify the stock steel oil pan.

 

I have no idea how it will fit in the engine bay, but get it as far back and as low as possible. A comprehensive mock-up will be the best way to find out how it looks in the engine bay. And it's probably best to get the trans you want to run ahead of time so you can mock it up with that in place too.

 

Again, I'd rather have a strong KA over a 4.3, but free is free.

Share this post


Link to post

I swapped a vortec 4.3 into my truck. Now, keep in mind, my frame, steering box and body is all that is stock on my truck.  SAS on tons, 4L60e, 241/205 doubler. Your stock 4.3 manifolds will be a tight fit. I actually had to use a TBI manifold on the driver's side to clear the steering shaft because I set the engine slightly to that side of the engine bay. Oil pan and hood clearance will probably be your biggest issues. I made my own power steering pressure hose. I was a lil concerned about a DIY hose but it's holding up very well. 

 

Sure, you can get a carb intake for it but they are $200-300 unless ya can somehow find a used one. Then finding a carb suited for a v6. Converting your fuel system to fuel injection will be cheaper but like Mike said, a free engine is rarely free. Just about the only exception would be a free identical engine. 

 

If you're dead set on a v6 swap then get after it. It can be done but it will not be cheap. There are motor mounts for this swap but again, that's more money outta pocket. If you have the tooling, skills and a retarded amount of money, great, but if you're like the rest of us, show the Z motor some love. 

 

I love my 720s, as well all do. Currently have a clean 84 in the garage being rebuilt right now and even with all the builds I've done, I'm still fighting the urge to go crazy on this one even though I know better. 

Share this post


Link to post

I had a 4.3 from that one year FWD Cadillac. Came with 4bbl Quadrajet. The problem was it was a feedback carb just like the 720 had. An earlier 4bbl would likely fit it though. '85 GM and GMC Astro and Safari 'mini vans' had the same engine as an option. I don't know when they eventually had to EFI them. I drove one to Montreal from Toronto and back and it fuckin' A goes!!! It had that early torque converter lock that kept jumping in and out on hills. Antone remember those?

  • Like 1

Share this post


Link to post

Yep, the famous shift hunting problem.

 

The best 4.3 I ever drove was a Vortec 4.3. It actually made a bit of power. All others I have ever driven were compete letdowns. I've done three 4.3 TBI swaps in Toyota trucks, and I never liked any of them.

Share this post


Link to post

It was a Chevy Astro van. Short wheelbase like an S-10 and light as fuck. It would rubber a van length into 2nd.

Share this post


Link to post

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.

Guest
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.

Loading...

×
×
  • Create New...

Important Information

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