MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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Airwreckc
Eric Cumming
RTP, North Carolina
(253 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 340 upgrade
Posted by: Airwreckc
Date: March 07, 2024 01:34PM

Jim, that's great--thanks. I was dreading having to consider something like Megasquirt and thought the Rover ECU might not have enough upside for my obviously much larger and better flowing engine. Plus I like going to get something at the junkyard. I do plan on using a TB with a throttle cable as I think it'll be easier to set up with the standard pedal and one less thing to have to figure out. Does the 411 ECM come in different versions by year? I would assume throttle cable bodies are just older vintage?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6496 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 340 upgrade
Posted by: BlownMGB-V8
Date: March 07, 2024 02:29PM

Look at the connectors. They all have a red one but blue or green for the other one denotes the type of throttle. (check the gas pedal and throttle linkage) I THINK blue is cable but double check. Also you don't have to run an airflow meter as you can run speed density instead with no real issues. 4bbl throttle bodies are common and run around $100-150 and are considerably shorter than a carb leaving plenty of room for an air cleaner.

This is if you are using port injection. Do you have a suitable intake with injector bosses? You will probably need injectors in about the 30-35 lb range, I think the 3.5L Rover used 19's. There will be a significant amount of wiring, I have posted important details here and on MGE. I like the Deutsch connectors and DelCity is a good source for the butt splices. You will need a fair handful of the smaller clear ones, hard to find them anywhere else.

I used the Gen IV LS sensors including the trigger wheel and pickup, just welded the trigger wheel to the back of the damper. I used the internal trigger wheel but there are some with regularly spaced teeth that apparently also work just fine. For the sensors use a shielded pair and ground the shield at the ECM end only.

I found the easiest way to do the cam sensor is to modify a distributor body and shaft but Buick did use one on the V6. They are not very common. You'd need to find a Regal, GN or Olds of the right year. On ebay they sometimes show up but asking price is usually about $250. For that money I could make my own but If I happened across one in the junkyard I'd sure snag it. Pretty obvious what it is, just the bottom of a distributor with a knob on top with a sensor.

Jim



Edited 1 time(s). Last edit at 03/07/2024 02:32PM by BlownMGB-V8.


Airwreckc
Eric Cumming
RTP, North Carolina
(253 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 340 upgrade
Posted by: Airwreckc
Date: March 07, 2024 04:06PM

Thanks Jim,

I am using the Rover EFI manifold, which I will modify to have a much larger plenum and wider/shorter trumpets. I know some have swapped out the Rover injectors, so that is definitely something I can do.

Appreciate the insight on the rest of the components--sounds very doable.

Best,
Eric
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