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Low cost efi conversion of 350 v8

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My cousin has a carbed 350 in an old s2 XJ jag.

I intend to convert it, using a univeral wire in ecu (semi sequential ignition & injection internal map sense for load), likely keeping the existing wet manifold and standard heads with an injection throttle body. I would appreciate any feedback people have on holley footprint injection throttle bodies (prefer factory length/style cable throw) and crank trigger kits, also higher output alternator options?

Want to throw a turbo on so will be gapping rings out. Is it likely I will need stiffer valve springs if i push towards 1 bar with flex/AI to avoid valve float? How expensive are springs and cams, or do i just throw in springs and lifters? I'm happy to have a go at a rough port job on the standard heads and openning oil returns. Is a new harmonic balancer a good idea? Will have a T400 on the other end.

So you want to run a boosted small block chevy with some kind of stock/mild head and cam, and one of those throttlebody injection kits? You've got to keep in mind what those kits are designed for. They're designed to be drop in for simple all motor "vintage" builds where the owner doesn't want to deal with some of the carburetor hassles but doesn't have the desire or expertise to use higher feature engine management.

The big problem in your case is spark control. You are really at a disadvantage if you want to do a fuel-only system and then some kind of primitive locked distributor or a non integrated auxiliary ignition controller. And then of course there is boost control. And methanol injection control, and all the other stuff you might realize you want later.

So you can have a series of separate, non-connected solutions to engine management, or you can go with one engine management that can do everything you want. Considering this is an in-depth engine management community rather than a more casual one focused on vintage engines, the line here is going to be "one box to rule them all"

Therefore I'm going to recommend you either move up to a more sophisticated engine management that can handle spark, methanol injection, boost control, etc or consider an all motor build where a drop in throttlebody injection system with no spark control will work pretty well.

Well If i am not wrong you are talking about a jaguar with a chevy 350 v8 engine, if so its great because the ability of parts for that engine.

A good option for your proyect is an assembled Megasquirt 2 because those have a friendly cost and are tailored for the diy user also are good products

for that kind of proyect and there are a lot of help and information on their web site and forum .

And injection throttle bodie is also a good idea to keep your existing manifold for some intial simplicity , there are a lot of throttle bodies with injectors , from a

factory gm tpi with two injectors to aftermarkets with four or even eight injectors around the butterflys .

Here are some links that may help you because are similiar to your proyect.






The throttle bodies arent cheap parts but you have to consider that they came with sensors and injectors

And yes always is a good idea to upgrade the valve springs , there are many kits that came complete with camshaft, valve spring and lifters for a chevy V8 engine , price range goes from 150 to 400 us dollars for normal not exotic full race cams kits.

It depends on what you want to spend ,but yes is a good idea also with a reconditioned valve job. The new harmonic balancer is always worth the money on a

new engine build.

Excusme if I assume the Jaguar have Chevy V8 Engine swap , and maybe its not ,but the tittle appear to be that, and there are many with this swap.


Thanks for the input. Yes Jag with engine swap. It blows my mind a bit how cheap a kit with cams and springs is, I will go that way and do a balancer for sure if that is the case. That terminator with 4 80lb injectors should be enough for reasonable boost on 98 octane.

To be clear I have an adaptronic 440 ecu (but brand is irrelevant, it will run the engine fine semi sequential waste spark if it can run rotaries waste spark at 9000rpm, will run boost control and AI fine) I intend to run a high tooth count crank trigger, will have full ignition and fuel control, will run 8 IGN01A coils. It is the physical parts quality/fitment/limitations that I have no idea about.

Just some thoughts - If you could score a LT1 injection manifold it would be a cheap alternative . Also instead of multi coils you can still run a distributor as a cam sync in conjunction with a trigger wheel mounted on the damper . I have myself done a similar conversion on a old school 440 dodge motor running a Link G4+ atom . Semi sequential Injection with a distributor - twin turbos . I would recommend that you run batch fire ( link call it group ) as far as i can tell there is little advantage to performance and it can be set up with just a mag pick up type distributor - MSD or the like . Ill help more if i can .

Thanks if i csn grab an efi manifold for similar $ to a new throttle I would go that way for cold start & cruise benefits. Likewise I was thinking batch injection would be needed with thr common intake to maintain consistent mixture. Given the relative low cost of the 01As and yhe massive power they have I would want a very cheap dissy setup with powerful spark to convince me otherwise.

I am concerned about additional electrical loads and efi pump on the standard alternator, are there drop in higher output alternators?

Hi - There must be literally hundreds of alternators available for sbc - just do some googling. Also with the dizzy you can run a MSD ignition box ( as i do ) . It runs great . You did talk about budget so i thought id run that option by you .

Thanks. I will work out relative costs for ignition, it's just that I have seen so many people resolve issues going to fine wire irridium plugs and those coils and I would much prefer a crank trigger.

If you want go with a bathfire injection and wastepark route , you could use this part or something similar for rpm signal


And if you want something more simple and less parts for the ignition setup this distributor could help even it could be used

with sequential injection setup.


There are a lot of alternators and brackets kits for the small block chevy so you have to know your requiered amps load of all the car to choose one.

The same with the fuel pump , there is a lot of inline fuel injections pumps to choose you have to know your aproximate fuel flow demand and add a little more

for safety backup ,to choose one . If I am not wrong there is a webinar on how to choose fuel components .

Here is a nice article with good information , not the same setup as yours but it coul add some guidance for your proyect.


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