If I were to try and find a used 4.3TBI what engine/Car should I be looking for? This will be to bolt up to a 3.1?

When I look up junkyard parts I see the 4.3 TBI listed for Astro Vans, Blazers and S10's. They also list 6A4, not sure what that means?

TIA

Matt

<small>[ February 06, 2003, 07:09 PM: Message edited by: MattGold ]</small>

If I were to try and find a used 4.3TBI what engine/Car should I be looking for? This will be to bolt up to a 3.1?

I hate to burst yer bubble Matt, but 4.3's dont bolt up; 3.4's do... What you want is a Firechicken or craparo(I think thats how its spelled, hehehe) donor motor. Remember that you have to drill and tap the new block to keep the starter in the proper place. I hear thats easy though...

Joel,

I think what I am trying to figure out is if you can set the 3.4 intake manifold on the 3.1 Block? I am not sure if this is even possible...If so it it would give me the option for the 4.3TBI?

I am not sure that this is even possible? Otherwise I would jsut go with the roller rocker arms and try to get the 3.1 heads polished and ported

Matt

Matt-

You want the 4.3 TBI, not the manifold. I believe that you will have to modify the 3.1 intake manifold to match the bores on the 4.3 TBI, but other than that it is supposed to be pretty straight forward. You will need to use your 3.1 injectors in the new TBI, or there will be too much fuel. Was the description not in Sean's article?

Search for a post from last year from Joel (I can't remember his screen name, but he is from the Seattle area (now in the Vancouver area)).

I am sure the v6 dudes will pipe up soon.

Michael

Oops sorry Matt, I guess I should read things twice from now on <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" /> IIRC the 4.3 tb bore is bigger so you have to do a bit of grinding to the intake to make this swap worthwhile, but seems very worth it... nice to see youre bitten by the mod bug too! Hows the oilpan holding up? Did you replace it or just repair it better???

I haven't done this yet, so take it FWIW. From what I've read, you should see a decent gain in HP from doing this conversion. A 4.3 TBI, a tbi spacer or power tower and a bored to match intake manifold would be the complete way to go. With that, you may/should be able to get away with using the 4.3 injectors (someone please correct me if I'm wrong) Once again from what I've read, you can get away with not boring the intake, but it will leave you with a "flat spot" in the RPM band.

Matt

<small>[ February 07, 2003, 09:02 AM: Message edited by: unirevolt ]</small>

I read Sean's article and mostly it discusses the 2.8. I assumed that the 3.1 would be close enough that this should work. I thought that I would try to bore the intake off the 3.1 so that I could fit the 4.3TBI and the spacer.

What I am curious about is what vehicle I might find one of these on? I think that Matt at Indy4x has spacers that should work for the 3.1 manifold. Otherwise I was wondering if you had to try to fit a 3.4 manifold to the engine.

When I get the 3.1 from Joe I will be able to take the top end apart and experiment.

Still leaves me looking for the TBI though.

matt

I have a 4.3 TBI mounted on my 2.8. I didn't bore the manifold, which would really make a difference. I'll do it when I get a 3.4 installed.

As for what vehicle to take the TBI from, any of the ones you listed will work (as far as I know). The differences lie in some of the finer details. Mine came off of an S10 (I think). It doesn't have the holes to mount the throttle cable bracket. I still made it work, and you can always have it drilled and tapped for the bracket.

I would just get the cheapest one you can find that isn't totally gummed up. Mine took at least 5 hours to clean, used a whole bottle of degreaser, a package of Q tips, and a dremel. It was pretty nasty. Get a rebuild kit for it. It will have all the gaskets you need.

As was said earlier, use your injectors from your 3.1. This comes up every time the topic is raised.
The idea is to add more air, not more fuel.

I've read that when using the 4.3 tbi on a 2.8/3.1 to use your stock injectors. But what about when you swap to a 3.4? I have read that you should use the 4.3 injectors for the 3.4. I dunno for sure, maybe someone could shed some light....

thanks

Paul

Hmm, not sure about all the numerical confusion, but maybe this will help. Do NOT use the 3.4 intake. It is set up for the MPI system on those cars. You use your 2.8 intake (and have it bore matched to the 4.3tbi). I have not heard concerns w/ using 2.8 injectors in the larger tbi, but at least w/ the 3.4 I would not do that.

Again, if you have another $1400 just get the Fageol scharger and forget all the dollars you toss away on $50 and $100 minor upgrades. Bite the blower bullet and just awe the rest of us. Can you say 260 spanking horses?

s
<img border="0" alt="[Rat]" title="" src="graemlins/rodent.gif" />