I am looking at doing a 4.3 TBI on a chevy 250 that is a conversion in a 67 Landrover NADA. As far as the manifold goes, is it possible to make an adapter to go straight from the throttle body to the original 1 bbl intake instead of buying a new offy or clifford intake?

You would probably have better results in using a TBI unit off of a 2.5L engine than a V8 or V6. Since the 2.5L is a single barrel configuration, it still may be somewhat restrictive but much less than trying to funnel the twin barrel style into a small single orifice.

The air restriction is one thing I was worried about, as was the propensity for the 4.3 TB to be basically shooting right against the walls of the taper from 2 barrels to 1. I imagine that it would be doing some wonky things with the pressure drop as well, but was hoping that somebody else had done it.

Looks like I will continue looking for the new intake.

Thanks.

Question 2. Any reason why I cannot post a wanted add in the swap meet?

The 1 BBL GM TBI would be a good compromise and still add some benefits of modern tech to your combo. Posting in the Swap Meet is by permission only. You can contact the Administrator for that.

As for a good intake, they are available in endless supply on ebay anytime you want one.

I found a clifford that I put in an offer on. I would like to get a 4.3 TB as I eventually would like to try to squeeze a little more power out of the engine when the Transmission is replaced. Kind of limited with how much power can be ran with the stock tranny.

That and we already have a 4.3 donor truck.

Thanks for the help!

Seth

Probably wouldn't be a problem. The 4.3 TBI has the injectors above the throttle blades which means the injectors are spraying against a mostly closed throttle blade 99% of the time. This actually causes better fuel atomization than the newer TBI's with the injectors below the throttle blades because the fuel sorta puddles up on the blade opening and the air has to pick up the fuel as it goes by. As long as the adapter is tapered I doubt it'd be any more of a problem than the abrupt 90º turn the air/fuel makes going from a carb/TBI to the runners.

I managed to find a Clifford 6=8 intake. Curious as to what kind of headers will work for this thing. It is very apparent that the original exhaust manifold will not work. Are there any workarounds for this?

I welded an old manifold close

So you just welded the flanges out and then welded the top port closed off with a piece of steel?

What controller are you going to use to run the TBI?

Yeah just a 1/8th in plate on top and knocked the flap out plugged holes

efi-diy - I was planning on using the stock GM ecu. Would you recommend something different?

lowboygmc - Do you by chance have a picture of your setup? What did you do for the flange holes on the clifford. It seems like there is not much of an ear to bolt through with the other half of the flange from the exhaust manifold.

I would suggest running a megasquirt 2 - no need to find someone to burn eproms for the GM ECM.

Install a wideband O2 - and let the MS2 tune itself.

On another forum I just recommended a guy go for a Microsquirt (MSII based) and harness for $369.

https://www.diyautotune.com/product/microsquirt-engine-management-system-w-8-39-wiring-harness/

I bought me a microsquirt a couple weeks ago. Unless you are running sequential fuel injection they are the ticket. I am thinking about tbi, can you blow through turbo them? Are they pretty well sealed up?

Is there any plus side to the microsquirt with the exception of size and being a sealed unit (Which is a huge selling point for me)? How hard are these too tune?

I really don't have any interest in tuning the engine for performance. Once I get past 175 hp or so, I seriously have to consider replacing the tranny for fear of blowing the stock one apart.

For me I like how tunable the microsquirt is. No burning chips or anything like that. Plus it has other I/O for controlling other stuff like 2-step launch, methanol injection, etc. But that stuff won't apply to you if you don't need or want it. Plus if you have an HEI distributor it can control timing as well. And you can download the software for free and play with it to start learning. But you can pay, I think $50, for the upgraded version that has self-tuning capabilities.

It runs identical to the MS2. It's just smaller and uses an external MAP sensor. It's not water proof unless you take steps to water proof it, but it is certainly more sealed than the normal assembled Megasquirt. The other I/O's can be used for shift lights, vehicle speed sensing, radiator fans, torque converter lockup or simply datalogging things like oil pressure. There is no better bang for the buck EFI controller than the microsquirt.

With purchase of the licensed Tunerstudio you get the Auto-tune feature, which works well but still requires some hands on setting up. I personally prefer tuning manually and with the O2 closed loop turned off. But I have used both the auto-tune and closed loop to get the satisfaction of driving a newly put together engine without spending an hour or two getting the tune in shape enough to drive.

See my response under electrical re: TBI injectors

Guys

The TBI injectors are low impedance peak and hold. Microsquirt cannot drive this type of injector. Megasquirt 2 can.

As far as sealing - its no different from the '747 GM controller - both need to reside inside the passenger compartment. Nether are sealed.

Tuning is easy - install a wideband O2 sensor and after you have the engine idling - run autotune.

Once autotune is finished - go to a chassis dyno and do the WOT settings.