4AGE questions

[Sprinter Freak]

ok so im nearing doing my 4age conversion and theres a few things im a bit iffy about, the engine i bought didnt have any injectors or dizzy, so i bought a set of small port injectors and a dizzy, with out thinking if they would work with the big port head, and am now not sure if i can use them or not

firstly, can you use small port injectors on a big port head?

secondly, how can you tell whether a dizzy is small port or big port and can you use a smallport dizzy on a big port head

lastly, scince the motor came with no dixxy, how do i go about putting the dizzy in, is there anything i nedd to do to the engine before i install it? (e.g. rotate the engine to top dead centre?)


any help is much appreciated guys

[Skylar]

Q1: yes on physical fit. Will need smallport ecu to match

Q2: a) Take cap off and look for toothed wheels, bigport has a 24 tooth wheel and a 4 tooth wheel. Smallport has a 24tooth wheel and a wonky round thing with a blip in it.

Q2: b) yes, interchangeable

Q3) top dead centre, look through oil filler hole find the indent on inlet cam. If indent isn't there, spin the engine 360 degree and it should be there, otherwise, something's wrong with cam timing/timing belt. Line up the dot on dizzy gear to dizzy body and stab. Look in the manual in the tech articles or something for a more detailed way.

[slide86]

you will need the bigport fuel rail with the injectors.......the smallport one wont work.

[mrbigport]

dizzy signals and plugs are different so it depends on what loom and computer your running. small port runs a 4 wire setup and bigport runs a 3 wire setup
if your working with all bigport gear i have a spare bp dizzy here, if you want it pm me an offer and we can sort something out

[Sprinter Freak]

ok so should run big port injectors then instead? because i have a big port ecu. ok thanks for the advice

yea i have one, so they should fit and run ok? or are they faster flowing?

so when you say the signals will be different do you mean there will be less voltage going to the spark plugs? i'm guessing its a big port one because the head is big port but i'm not sure ill check. i'm running a big port ECU.


also does anyone know whether 4kc distributor bolts will work to hold a 4age distributor on a big port head because mine didn't come with any

[mrbigport]

the bigport dizzy will run 24 pulses for the cam angle sensor and 4 home signals for the crank angle sensor
the small port dizzy runs 28 pulses for the cam angle sensor and 1 falling edge pulse for the crank angle home signal (which fyi is the same as the signals used by the gze cas if anyone wanted to wire up a gze but didnt have a cas they can use a small port dizzy for the pulses - im running one on mine)

the cas/dizzy has no bearing as to the voltage going to the spark plugs, that is controlled by your igniter and coil. your igniter does however require the correct pulse signal from the computer in order to fire the coil at the right times

the computer needs the correct pulses from your crank angle sensor, if it is a bigport computer then you'll need a bigport dizzy. yes you can swap to a small port dizzy and computer and it will run, but they still need to be a matched pair or your ignition just wont happen.

[Andy San]

If they are the same as the GZE CAS then they are 24 teeth as well on the smallport dizzy with a single cam home

[mrbigport]

sorry my bad 24-4 for bp and 24-1 for sp, and gze