All that have done EFI conversions, a question?

[84convertablegt]

Im trying to line up a winter project and i think i want to go efi. anyway. i got a whole computer and intake etc. with injectors etc setup as a trade for an old carb. the stuff came out of a fox body stang, but i believe it was originally from a t-bird. at any rate, its a speed density system. what i want to know is if anyone has used a speed density setup vs. a maf setup which seems to be the norm and where all the focus on every website is. My engine is basically stock, heads, block, with the exception of headers. i know the speed density is basically not good for mods, but i dont really have any major mods. do you think it will work ok on my 65 289? and as a bonus, i believe the t-birds had a standard 5.0 firing order as opposed to the HO firing order which could work out well in the long run. any tips, thoughts or opinions???? if this wont work, ill just stay carb. im trying to keep a very tight budget here.

 

[ForceFed70]

I'm planning my conversion for this winter also. But I'm going about it differently. I'm going to use a megasquirt ECU.

From my research, the answer to your question is tricky. Speed density tends to be the better EFI system. BUT it does not handle changes to the engine well at all. I think you will have alot of troubles retrofitting this system into your car with a factory ECU. Mass air handles modifications alot better.

Your engine may not have alot of mods... but guaranteed it's alot different than the engine that it was built to run on.

If you want to keep the speed density system, I suggest you switch to a programmable Speed density based ECU like the megasquirt. This way you can program the ECU to work perfectly for your engine.

If you want to go with a factory ECU, then you'll have to use a Mass Air system.

 

[88 Fox GT]

You can use the factory Ford EEC-IV computer and the speed density. It will work fine. Speed density reads vacuum pressure from the intake manifold via the Manifold Absolute Pressure (MAP) sensor. Don't plan on doing any serious mods that change vacuum properties or you will need to tune it.

 

[Rollinns]

Speed density will work fine on a stock 302 with headers as the only mod. But I'm not sure how it will react to being on a 289 instead of a 302. I had full length headers on a stock 302 and everythings worked great I ran it for a year to work out the bugs then switched to mass air. The only bug I had was a bad alternator, which wasn't even EFI related. If you end up needing to chip it to get it to work with the smaller engine then just upgrade to mass air and skip the chip.