TBI to Carb swap

[Jarrett Melvin]

I have 350 TBI, it's registered as an 86 but I was told it was an 89, the TBI been giving all kinds of trouble and the PO had said he picked with it and stuff.

So I have an 83 with a 350 also with a carb. So my intention was to swap the intake and carb onto the TBI and make it all mechanical.

I have a new fuel tank with a mechanical sending unit, mechanical fuel pump, intake and the carb. I'm aware that if the crank don't have a lobe on it for the push rod pump and I may have to use an inline electric. Im gunna use a manual choke.

Questions I have, will the intakes change over?

The TBI has a distributor with a 9th wire on it going to he top of the intake, not sure what its for and will I need to swap the distributor aswell?

Is there any wiring or harness issues to deal with?

Thanks

 

[SirRobyn0]

I will preface this by saying I have not done the conversion you are talking about, but I have worked on both systems extensively.

I would strongly encourage you to troubleshoot and repair the TBI system if at all possible. These TBI systems, while sometimes misunderstood, are actually a very solid and simple system and are a step up from the carb, in terms of reliability, drivability and mileage. If whatever the problem is with the TBI motor is not related to the TBI system then it will still be there after the conversion ie., if the engine actually has low compression or a wiped cam lobe, clogged exhaust, stuck heat riser, slipped timing chain ect, ect. There are plenty of us that will help you troubleshoot the EFI system if needed. Of course if the PO has butchered it badly enough then maybe the carb swap is a good idea.

If you move forward, I would strongly suggest that you make sure this engine is good shape and able to run properly. To answer your main question, you will need to at least change the module in the distributor, and you will probably have to change how the distributor gets power. If I recall correctly "I think" but don't remember for sure, I think the distributor is powered from the ECM.

 

[Jarrett Melvin]

I will preface this by saying I have not done the conversion you are talking about, but I have worked on both systems extensively.

I would strongly encourage you to troubleshoot and repair the TBI system if at all possible. These TBI systems, while sometimes misunderstood, are actually a very solid and simple system and are a step up from the carb, in terms of reliability, drivability and mileage. If whatever the problem is with the TBI motor is not related to the TBI system then it will still be there after the conversion ie., if the engine actually has low compression or a wiped cam lobe, clogged exhaust, stuck heat riser, slipped timing chain ect, ect. There are plenty of us that will help you troubleshoot the EFI system if needed. Of course if the PO has butchered it badly enough then maybe the carb swap is a good idea.

If you move forward, I would strongly suggest that you make sure this engine is good shape and able to run properly. To answer your main question, you will need to at least change the module in the distributor, and you will probably have to change how the distributor gets power. If I recall correctly "I think" but don't remember for sure, I think the distributor is powered from the ECM.

Another question I have, once I remove the TBI and swap the distributor. What else is controlled by the ECM or do I even need it?

 

[45acp]

I agree with Sirrobyno,the tbi is a much better system. That being said I'm going off of memory ( that's a little spooky because I'm getting old) but it seems there was something about the intake manifold to head bolt angle that didn't match. I would at least check it before you get to far into this project.

 

[Taylorb27]

If you swap to a pre 87 manifold to a motor with tbi heads you will need to drill out or slot the middle 4 bolt holes on the intake. Tbi heads have a different bolt angle. I agree with diagnosing and keeping the tbi.

 

[eric 87]

If you swap to a pre 87 manifold to a motor with tbi heads you will need to drill out or slot the middle 4 bolt holes on the intake. Tbi heads have a different bolt angle. I agree with diagnosing and keeping the tbi.

isn't there new aftermarket intakes for this though? I am doing the swap but with all new aftermarket parts. I would keep it but if you look at the issues I am having and what has been done. The engine is too strong running for me to continue with the TBI. And it is NOT reliable to drive now. It is in the garage for a week now. 550 in parts later and it is still having issues.