Questions on a 3a block into my 1.5l 78 rabbit...tried to search

[Vr6DubNY]

I Have searched but i am failing to understand a couple things. Partly due to the fact i am waiting for it to ship to me

Background...car has fuel injection...not a carb car...and engine is a fully assembled unit that was running in a mk1 rabbit before..p&p'd with i believe a 300ish cam..i know its big...correct oil pump, gaskets, and dizzy. However no injectors or fuel rail.

1. Seeing how this is a 78 with fuel injection...is there anything needed other than a knock box being wired in? To get it running correctly...taking into account timing and fueling is correct.

2. If i remember correctly there are different size air boxes...is the 1.5 box sufficient or do i need one from a 85-87 8v gti/gli..

3. Which injectors and fuel rail are needed? My 1.5 stuff can't possibly be the right stuff, can it?

4. I plan on going with the late style 8v knock box...any objections?

5. Is o2 sensor needed for this to run correctly?

Sorry for the questions...I did search...but everything i've seen just states you need a knock box its a direct swap...maybe it is and i just question things too much

[ps2375]

You seem to be confusing CIS and EFI. If you stick with your CIS, you may have to adjust the CO mixture, but that should be it. Was the 3A on CIS or some other system, you might have to change injector seats for the CIS injectors. As for spark, that will be up to what you and what will work, depends upon what you have and need. And as for the O2 sensor, if you don't have one now, no need for one and no way to add it to CIS basic anyway.

[Vr6DubNY]

Sorry for the confusion...i just mean its on cis...not a carburated car...

So the stock cis box is fine if adjusted properly, engine was on cis before...but currently lacks injectors and fuel rail.

[ps2375]

there is no fuel rail with CIS. The injectors on the current system should work just fine, if they are currently working now.

[Vr6DubNY]

The injectors are missing...just run the 1.5 ones?

[ps2375]

yes, for the most part, CIS injectors are CIS injectors.

[ziddey]

I'm assuming this car is CIS basic? I'm not sure what your options are in that case, and if you'd be able to switch over to a larger metering plate / funnel from a later distributor (assuming that one does have the small funnel).

I believe I read there is power to be had by upgrading. But the problem will be if you can maintain your current CIS basic setup easily. I'm assuming CIS-E/Motronic units are not easily able to be retrofitted for CIS basic use with the CPR? Maybe CIS-L is usable?

[Vr6DubNY]

That is my concern...that this car is too early to run such a motor with any success.

Would switching to a euro setup yield better results?

[ziddey]

It'll be successful. That's not the question.

[Glegor]

I Have searched but i am failing to understand a couple things. Partly due to the fact i am waiting for it to ship to me

Background...car has fuel injection...not a carb car...and engine is a fully assembled unit that was running in a mk1 rabbit before..p&p'd with i believe a 300ish cam..i know its big...correct oil pump, gaskets, and dizzy. However no injectors or fuel rail.

1. Seeing how this is a 78 with fuel injection...is there anything needed other than a knock box being wired in? To get it running correctly...taking into account timing and fueling is correct.

2. If i remember correctly there are different size air boxes...is the 1.5 box sufficient or do i need one from a 85-87 8v gti/gli..

3. Which injectors and fuel rail are needed? My 1.5 stuff can't possibly be the right stuff, can it?

4. I plan on going with the late style 8v knock box...any objections?

5. Is o2 sensor needed for this to run correctly?

Sorry for the questions...I did search...but everything i've seen just states you need a knock box its a direct swap...maybe it is and i just question things too much

1.) why do you want a knock sensing ignition system? its really only good if you want to run different grades of gas on a single tune.. myself personally, i like the vac advance ignition systems.. plus, thats what your car already has in it, so why not leave it there? vac advance with electronic ignition works great, plus you can tune it where you want, without the knock sensor pulling all your timing away..

2.) an air box is an air box.. just run your stock box. make the inlet to it bigger if you feel you need to. DO NOT swiss cheese it..

3.) use the injectors that are currently in your 1.5L engine.. they will work just fine. CIS does NOT have a fuel rail, like was already mentioned.. just beware, your 3A has a different head and intake than your 1.5 does.. the 3A has pear shaped intake ports, and the injectors mount in the intake manifold, not the head like the 1.5 does.. if i were you, i would get a head off an 85-88 GLI/GTI and install that on your 3A block.. you can use the intake manifold, and all the other stuff off your 1.5 tho.. but the 1.5 head wont fit on the 2.0 block, plus, the GTI/GLI heads have bigger valves

4.) again, WHY? the knock box ignition isnt really BETTER than the vac advance setup imho.. only way its better is if you like to switch fuel grades often.. my GTI started out life as a Golf, so it has vac/mechanical advance, and i like it BETTER than the knock setup.. its MUCH more simple, you dont have to bypass anything to time it, and it doesnt contain your rev limiter.. the knock box controls the rev limiter, so if you want anything higher than the 6250rpm rev limit from the factory, its ALOT HARDER to change it with a knock box, rather than just swapping your fuel pump relay like you would on a CIS-lambda, or CIS-basic car..

5.) pretty sure your car nevr had an o2 sensor, so it shouldnt need one once you install the 2.0.. but i imagine you will want to swap out your fuel distributor for a unit out of a later rabbit with the bigger sensor plate and stuff.. the early metering plate is TINY compared to the later units..

a knock box ignition system is FAR FROM PLUG AND PLAY in this car.. you will have to find a car with the WHOLE IGNITION SYSTEM still intact, and remove ALL OF IT.. like, unwrap the harness, and pull ALL OF THE ignition system wiring out of the harness.. you need the dizzy, the ignition module, the knock box, the knock sensor, and the wiring..

THEN you have to install all of it into your rabbit.. and it was never intended to have that style of ignition system, so its going to be ALOT MORE WORK than you originally thought..

your car should have vacuum/mechanical advance right now, with points ad a condenser, correct?

[ps2375]

I'm assuming this car is CIS basic? I'm not sure what your options are in that case, and if you'd be able to switch over to a larger metering plate / funnel from a later distributor (assuming that one does have the small funnel).

I believe I read there is power to be had by upgrading. But the problem will be if you can maintain your current CIS basic setup easily. I'm assuming CIS-E/Motronic units are not easily able to be retrofitted for CIS basic use with the CPR? Maybe CIS-L is usable?

More likely already has the larger metering plate, they were on the earlier cars then they got smaller and then bigger again. This swap is good for a few hp as it reduces some of the intake restriction and these plates are interchange-able, as they are the same size where they seal to the upper half of the airbox.
I did this swap on my '81 w/ CIS-L and my '80 with CIS basic already had it stock.

And for my MS build, I gutted a CIS-e metering frame and bolted that to the upper section of my '80's airbox. So, there will be no issues if the OP needs to swap them.

[Vr6DubNY]

Ok...so i'll just swap the engine in with my existing cis stuff. The engine already has a 1.8 head on it...sorry for not being clear. And the reason for wanting to run the knock box is that every post that talks about putting an aba or 3a in says that for it to run correctly you need to. However they must all be speaking of a different system than i have.

As for a cam...found out last night the 306 cam was pulled from the engine...more than likely a blessing as the 306 wouldn't kick in until god knows when...i'm thinking the 274/270 is going to be my best bet

[nairmac]

Knock box is not necessary at all, especially with CIS basic although you can add it on later as a stand alone unit if you like. I have a 3A with a 1.8 hydro head, CIS basic with parts from many vehicles, no knock box and driven daily for years now...

[Glegor]

Knock box is not necessary at all, especially with CIS basic although you can add it on later as a stand alone unit if you like. I have a 3A with a 1.8 hydro head, CIS basic with parts from many vehicles, no knock box and driven daily for years now...

that ^^

is exactly how i would build it...

knock box is NOT necessary if you can use a timing light, and your ears to listen for pinging..

just tune it good, and run it on PREMIUM..

use the 1.8 head thats on the block if its still there.. the 1.5 head WILL NOT WORK..

[Vr6DubNY]

Thanks guys...and sorry again for the confusion