Dohc Efi To Carb Conversion

[Guest malcolmc]

Is it possible to convert a DOHC engine from EFi to ordinary carbs ? Is it simply a matter of replacing the inlet manifold or does the cylinder head need to be changed as well ?

[Guest julien]

Is it possible to convert a DOHC engine from EFi to ordinary carbs ? Is it simply a matter of replacing the inlet manifold or does the cylinder head need to be changed as well ?

...the dohc did come with a carb also..electric pump and a 2v tld weber

[Redspec]

You will need to change the head OR blank off the holes for the injectors, sort out the sparks - megajolt?,

Change the fuel pump or use a low pressure regulator. The standard carb set up is about 20-25 BHP down on the EFI system and a well set up EFI system will be more reliable / easier to live with.

 

Can I ask why you want to change?

 

Steve

[Guest julien]

You will need to change the head OR blank off the holes for the injectors, sort out the sparks - megajolt?,

Change the fuel pump or use a low pressure regulator. The standard carb set up is about 20-25 BHP down on the EFI system and a well set up EFI system will be more reliable / easier to live with.

 

Can I ask why you want to change?

 

Steve

..steve are the injectors not fitted to the manifold.? .

[Guest julien]

..steve are the injectors not fitted to the manifold.? .

...also if the standard carb was used .spark would still be ok wouldnt it.and couldnt he use the standard fuel pump already used..? but agreeing with u if i had efi i wouldnt dump it for carbs..

[Redspec]

...also if the standard carb was used .spark would still be ok wouldnt it.and couldnt he use the standard fuel pump already used..? but agreeing with u if i had efi i wouldnt dump it for carbs..

 

I did not sat the injectors were in the manifold, you a right they go into the head thats why he needs to get rid of the holes that they would leave.

The spark on the efi system is controlled by the ecu and I don't think this will work as a stand alone ignition system, but I stand to be corrected but I have never seen this done.

The injector fuel pump runs at 3 Bar so you would have to change the pump OR fit a low pressure regulator like I said before and return excess flow to the tank or swirl pot.

Another point is, the inlet manifold is part the coolant system so you can't stick any manifold on, it has to be engineered to do the job,

 

Steve

[Guest julien]

I did not sat the injectors were in the manifold, you a right they go into the head thats why he needs to get rid of the holes that they would leave.

The spark on the efi system is controlled by the ecu and I don't think this will work as a stand alone ignition system, but I stand to be corrected but I have never seen this done.

The injector fuel pump runs at 3 Bar so you would have to change the pump OR fit a low pressure regulator like I said before and return excess flow to the tank or swirl pot.

Another point is, the inlet manifold is part the coolant system so you can't stick any manifold on, it has to be engineered to do the job,

 

Steve

u def know ur stuff steve.just a quick question for u not related to this,sorry.ive brought an unfinished 2b ,prob like many others. how would i go about gettin a chassis number once stripped and rebuilt,with not having the original bill of sale from robin hood as i beleve they give the first 3 letters.i heard people say dvla give u 1,also ive heard u just make 1 up.also heard with sva it was 13 letters,numbers. and with iva its now 17 .any info would be gratfull ...thanks...

[speedtripledan]

i broke a dohc carb sierra a while ago and still have the ecu and loom if that helps. yours if you want it

 

Getting rid of EFI from my pinto was the best thing i ever did to it !! bike carbs run so much better at all points in the rev range and a shed load more power sure the same would apply to the dohc if set up right.

 

Dan

[ZeroKnowledge]

iam doin a dohc with fazer 1000 carbs+ megajolt for ignition in a zero, i bought the car part built with most bits included. i have read that the carbs

are best when respaced and the new alloy manifold has the thermostat housing built in. the megajolt wasnt too bad to setup once all the wiring was sorted.

the engine runs ok but when the build is finished a rolling road session is essential.

i can post some pics if needed

 

cheers Paul

[Guest malcolmc]

You will need to change the head OR blank off the holes for the injectors, sort out the sparks - megajolt?,

Change the fuel pump or use a low pressure regulator. The standard carb set up is about 20-25 BHP down on the EFI system and a well set up EFI system will be more reliable / easier to live with.

 

Can I ask why you want to change?

 

Steve

 

I just wondered that if it was a simple conversion then I would be left with a system that is a lot less complicated than the fuel injection version, particularly with regard to the electrics and the fuel pump. On balance it seems that it is not worth the trouble but I am concerned that all the various sensors that appear to be set up to regulate the EFi system will end up being a headache

[Guest Vindi_andy]

I just wondered that if it was a simple conversion then I would be left with a system that is a lot less complicated than the fuel injection version, particularly with regard to the electrics and the fuel pump. On balance it seems that it is not worth the trouble but I am concerned that all the various sensors that appear to be set up to regulate the EFi system will end up being a headache

 

I was worried about the EFI sensor setting up etc but in the end I just connected all the wires turned the key and it fired first time.

 

Just need to keep the ICSV on the air intake and it sets itself up. If the battery has been disconnected for a period of time the ecu "learns" the settings it needs.

[Knock-on]

iam doin a dohc with fazer 1000 carbs+ megajolt for ignition in a zero, i bought the car part built with most bits included. i have read that the carbs

are best when respaced and the new alloy manifold has the thermostat housing built in. the megajolt wasnt too bad to setup once all the wiring was sorted.

the engine runs ok but when the build is finished a rolling road session is essential.

i can post some pics if needed

 

cheers Paul

 

I'm thinking of doing the same with my Zetec. Can you post a couple of pictures please?

 

Also, are you using the 37mm carbs or 40mm R1 ones?

 

It would be interesting to get some feedback as to which would be best. 37mm or 40mm.

 

Any ideas people?

[ZeroKnowledge]

here are some pics of Fazer 1000 carbs on DOHC

they are 37mm

[ZeroKnowledge]

also pics of thermostat housing

[Knock-on]

Thanks for that mate. very useful.