IAC on carb to throttle body conversion

[Orange65]

I am really new to FI - and I am cheap. I have had a MS1 version 3.0 sitting on a shelf for a couple of years now and am considering putting it on my BBC. It is currently a stock 454, but will become a 550 HP 489 in the next year or so. In the mean time, I want to set up FI on the engine. As for the throttle body, I have read a couple of places where people took old Holly carbs and made throttle bodies out of them. I have not seen what happens to the IAC on these. Do you need the IAC? If so, what do you do to mount it and how does it work? Also, is there a junk yard or low cost source for injectors that will work for my application? I plan on using a 4 barrel intake and modifying it for the injectors.

I am ordering a book or two tomorrow on FI. Any help you can give me will be greatly appreciated.

[dieselgeek]

IAC is not necessary, more of a "nice to have" that you might fit to your TB after everything else is tuned. You can mount a remote IAC later on, and feed a vacuum hose to any port on the manifold - that way you don't need a specific TB that cna handle an IAC. You will want a throttle position sensor, but you can use a string pot if you are going to use a carb as a TB - they're cheap and simple as well.

Someone else will chime in about the injectors, hopefully, I think there are probably some OEM ones that you can use.

For ignition, go with a simple ANY distributor that has a reluctor inside, then run a MSD-6a or equivalent (not digital, and no rev limiters or extra features are needed, all that is in your megasquirt). Should be good to go.

[Orange65]

Thanks! Do you have a source for a string pot? My search so far has turned up some pricey versions from Edelbrock.

[Beagle]

snag one off a junkyard Ford, they're pretty easy to adapt, or maybe take a look at how any of the throttle body injection stuff is mounted, like a GM truck maybe or Cougar / Tbirds. New TPS sensors shouldn't be more than about 20.00 ...

[dieselgeek]

Might try Digikey for the string pot, but as Beagle pointed out - it's probably cheapest to find a Ford TPS out of the junkyard and rig up a remote linkage of some type.

[BKBridges]

A little fabrication and all is well. Heres another idea...
Two junkyard Dodge 5.9 Ram throttle bodys (IAC, TPS, MAP already on board) and a cheap dual quad manifold. Each Dodge TB flows about 580CFM, and they run about 25.00 at the yards. They also take a 5" dia air cleaner. Youd need to fab a mounting plate adapter for the 4bbl to Dodge pattern...Injectors from a later big LS motor would work at 60+ PSI, I think, but you dont usually find 550hp V8s in the JunkYard...Maybe 2 sets of Turbo 4cyl injectors?
BKB

[Orange65]

I have done a little research and found that I can get throttle bodies for 4.3 L Vortec engines cheap ($30 from ebay). I am looking at making an adapter to fit two of these on a single 4 barrel intake. Like you say, BKB, a stock throttle body has all the sensors already on board. I will look at the Dodge throttle bodies as well.

The injectors are a sticking point right now. I am looking around. Still waiting on my EFI book to get here.

Do all injectors fit the same injector bung or is there a difference in the diameters of some?

[Beagle]

bung should be similar if not exact - check for ther 39# Mustang terminator injectors or 42# lightning injectors on Craigslist, local boards, etc. A lot of folks move up when they put big blowers on them. Our own BBR did a writeup on 460ford.com you may want to look at:

http://www.460ford.com/forum/showthread.php?t=102034

The trick will be Ev1 / ev6 connectors I think - at some point you have to become an injector connector inspector (sorry, had to.)

Also, depending on how you plan to drive the injectors, you want to know if they are high or low impedance. The MS probably will handle either, but find out for sure before buying.

Holley has a pretty good reference here that you may want to look at as well:

http://www.holley.com/data/Products/Technical/199R10263.pdf

[TheSilverBuick]

I've been thinking about this one as I'm going to be in the same boat here at some point.

What I was thinking of doing on my Centurion is hollowing out a Q-jet and using it as a throttle body and leaving the stock choke in place (preferrably electric, but may be a exhaust cross over spring) and just remove the upper butterfly but letting the high idle steps do it's job. It'll mean it won't automatically idle down if I start it and walk away from it, but if I'm driving it it'll idle itself down like a normal carb. In theory anyways....

[BBR]

Innovate has tps' for Holley carbs. They are $70, but would probably be worth it in my opinion.

http://www.innovatemotorsports.com/xcart/product.php?productid=16284&cat=265&page=3

[SpiderGearsMan]

ha , IAC is SOOO 80s , we don't run them any more
throttle actuated control , they are all good except toyota

[BKBridges]

Carbs can work as throttle bodys. but there are some problems, mainly with wear. Carbs have aluminum journal bearings for the shaft, lubricated with gasoline. When you run the carb dry, the journal bearings wear rapidly. Just lube em regularly and all should be fine. The electric choke will control the air bleed volume with the fast idle cam so thats cool! 70 bucks sounds pretty cheap as a cut rate TPS (new) is around 25.00. Im wondering what EFI junk yard motor has the same cylinder spacing as the BBC to cob fuel rails from...Most injectors fit into a .540 dia bung.
BKB

[milner351]

$70 is cheaper than a dual quad manifold and a pair of throttle bodies - even from the junkyard.

[BBR]

Ford EFI 460 would be a possible rail source.

[BKBridges]

$70 is cheaper than a dual quad manifold and a pair of throttle bodies - even from the junkyard.

Not near as cool though...If someone wanted to do it Id throw them the throttlebodies for free...Ive got a lot of them lying around. I like mulitiple throttle bodies.
BKB