efi to carbies

[shift47]

hi every one im converting my 4age from efi to twin 40mm carbs. I have plugged the holes in the head where the injectors go in taken the tvis off and i was wondering if i can use the alternator that came with the motor or do i need to get one that suits a carby motor and the same with the distributer can i use the stock one or do i need one that suits carby. And does any one know if i can use an alternator and distributer from a 4ac. Any help would be great, its for a track car so nothing has to be road worthy.

[oldcorollas]

err... alternator has nothing to do with EFI.. unless it is too small to power things.
it will be fine

dizzy.. that depends if you want to have ignition advance or not. the 4AG one will have no advance at all.

at worst, you could just swap the guts of a carby dizzy into the 4AG one..

tho it has to be asked why you want less power and drivability for a track car???

[shift47]

i am converting it to carbies coz the motor has been built to N2 spec and a motor sounds a lot better with twin carbs hanging off the side of it sucking hard.

[jfallen]

Dude, if you've got an N2 motor, run ITB's and injection. also if it is actually built to N2 specs, you'll want 45mm DCOE's or DHLA's

Anyway, since like me you've got your heart set on a twin carbie 4AG, you can either fiddle around with Dizzy's (which are rubbish) or look at using an ignition only computer (as I have.) The "MegaJolt Lt." requires old ford Escort parts (like all do-it-yourself kits) the EDIS ignition parts in particular. These units also came on the locally delivered "Ford Mondeo." Basically it's a crank mounted trigger wheel that is used to fire Twin coils in a wasted spark type ignition system. A good source of twin coils is mid 90's Hyundai Exel's.

Mine not up and running yet but the Ignition computer is built (I'm using the MAP sensor version) and have had a fiddle with it on the computer and it looks like a great easy to use system.

Cheers
jordan

[oldcorollas]

hmm...

put on carbs, remove chokes, leave injectors,,,, run carbs as ITB's and still haev electronic control over fuel and spark... and have the sound... and NOT have the restriction of having chokes that are much less than the 40mm butterflies of the carbs?

[Ben Wilson]

Like oldcorollas said, TBs are the go. Either gutted carbs, or GSX-R 750 TBs if you're up for a bit of fabrication, or a T3 manifold and 20v TBs if you want to go the easy way.

[shift47]

Thanx heaps fella's but the induction side of things has been taken care of i need to know about the distributer i dont want to use any thing that needs a computer the reason for changing to carbs is coz they are so simple AIR, FUEL, SPARK and bang the motor is running Im no good with computers or electronics so if some thing goes wrong at the track i want to be able to fix it my self i dont want to have to plug a computer in to whats wrong. Im old school what can i say...

[o_man_ra23]

Umm... Stop being afraid, crawl out from under your bed and look at the monster you are afraid of. EFI is EASIER to make changes at the track!! You going to carry an assortment of jets with you if you get a lean spot?? Are you going to know if you get a lean spot BEFORE the motor cooks?? EFI can tell you a lot about how your engine is running, and modern EFI programs are really easy to use. I like old school too... but if your going to race, use everything you have at your disposal. Carbies are gone, they no longer outrank EFI in any way, and are only good in racing when your not allowed to run EFI due to class restrictions.

It truly is easier to work with EFI than Carbies. If something goes wrong, you know what it is, they take the guesswork out of fault finding. Also, most systems should give you fault codes with a blinking light. These codes will tell you what sensor is having problems, from there you can find out what it is without plugging in a computer. What is scary about them?? They work on all the same principles, except instead of relying on fluid dynamics (which change with pressure and temperature) they use electronic control... and do it much more accurately so you can get more torque through the entire rev range.

EDIT: carbs arent simple at all. The reason people perceive they are simple is because they only allow you 2 (generally) adjustments. Mix and idle opening. The fact is they are extremely complex and although I have worked out EFI completely self taught, I have put just as much research time into carbies, and still only know a tenth of what is involved with them. Most mechanics wont touch carbies anymore, because they are so complex. One bloke at work got stung $700 for a mechanic to find out what was wrong with his carby that his 390ci T-Bird wouldnt do a burnout from planting the foot. Then there was parts and fitting on top, they had to order the part and it took a week from take it in to have it fixed. That would end your race day. EFI detects a problem, you find out what sensor is having issues by looking at the fault codes, and if you dont have a spare, and can prove the sensor is faulty (if it reads cold air temp on a summer day thats a good indicator, or it reads boiling hot coolant after running for 20 seconds) then you can tell it to ignore that sensor, and you can finish the day with almost no loss of power.

[wagonist]

The other advantage of EFI is, that when the ECU detects there is a problem, it'll put the computer into a failsafe mode, which will not only tell you there's something wrong (because you've suddenly got half the grunt), but it'll stop you melting the engine completely costing you big bikkies.

I'm like o_man_ra23, self taught on EFI, know nothing about carbies at all.
Once an EFI engine is actually running properly for the first time, the only real things that can go wrong are sensors stuffing up, circuits becoming open (ie wire breaking, or plugs not contacting), some computers have certain issues (which a quick google search will point out), or injectors clogging.
Everything else is the same any motor. ie spark plugs, leads, oil, etc.

[shift47]

Thanx again fella"s you all have given me a lot to think about I still have the complete RWD efi set up for the motor so if Im not happy with the carbs I can all ways put it back to efi. And just for the record Im not hidding under the bed Im in the laundry cupboard computers are very scary but I will have to to learn about them sooner or later. Thanx again every one.

[wagonist]

Computers aren't scary. Just think of this way.
Someone else has already gone to the effort of programming it.
It uses inputs from many different places:
crank angle & camshaft angle to knock when to fire injectors & spark plugs;
air temp & air volume (air flow meter or MAP sensor) & throttle position sensor to know how much to open the injectors;
oxygen sensor & knock sensor to allow it to run at peak efficiency;
water temp, oil pressure to keep it safe.

Just because then engine now has 60 wires running off is no biggie, each sensor & injector has at least 2 coming off it.

I'm more worry about carbies (or even the mechanical pump on my diesel ) that use only some of these inputs mechanically (or vacuum lines) to operate all this.

[o_man_ra23]

Carbies are scary as. So many variables will make them run like poo, and they have nothing to compensate for it. EFI uses all those inputs to compensate for changes in environmental conditions. Even if you get a carby to run perfectly on a dyno (perfect air fuel mix all the way through the load range), you get a hotter day, or a humid day, or a dry day, or a freezing farking cold day, and the whole lot will run incorrectly. EFI will account for all those changes, and still run a peak efficiency.

Please note that peak efficiency = max output, minimum risk.

[shift47]

Well my mind is made up coz this is my first ever build of some thing like this {AE-86 race car} it is a full bare shell re-build i will run the carbs to start with untill I get use to the handling of it and the restricted power of the carbs and when I am confident behind the wheel I will definatly be running efi with after market ecu and quad throttle bodies. A lot of money has gone in to the handling and motor but funds have run dry now thats the other reason for running carbs, cheap set up. Thanx again everyone very usefull info.

[brett_celicacoupe]

carbys are definately simpler then EFI and im a big EFI fan.

once a carby is setup correctly then it should last for ever basically. the only real point of failure is if the main jet gets blocked. shouldnt happen if you got a good filter though.

they're basically tuned in the beginning for the worst case scenario, probably equivelent to 10:1 AFRs (not far off toyota AFRs really )

if you look at it from a probability point of view then a carby is always going to be more reliable. a main jet might fail once per year, on the other side, a EFI car may blow 1 fuse per year, or 2 sensors may fail once per year. there is at least 100wires on a common EFI engine so in a sense you have 100 more points of failure. a carby is essentially a couple jets and a float valve(s)


if your chasing that last 10-15% of power out of your engine then go EFI, otherwise, whack the carbys on and your on the road. if you got your motor in there without a intake then it might take 2 hours to bolt the carbys on and get it driveable. maybe another 2 hours to get it running pretty well. efi will most likely take a lot longer, especially learning and understanding what you need to do to make it work.


my suggestion, whack the carbs on and get it running. in the meantime research enough to understand how to put the efi on your engine and wire it up etc. then XX months down the track youll say now i know what im doing ill put the EFI on.

[Norbie]

While you say EFI has many points of failure, the fact is not much can go wrong with lengths of wire and solid-state electronics. In the 8 years I've been driving EFI-equipped cars I've never had an EFI-related failure, not even a blown fuse!