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how to go from mpfi to carbed!!!!!

4K views 9 replies 6 participants last post by  hondalude86 
#1 ·
Hey all! I have a 89 civic hb with jdm sohc zc, ran by pr4 ecu! I have the indi. carbs but wondering what is needed to make it run. I have it running fine mpfi, but i ran across some nice carbs and want to use them on my civic! I am not an idiot and can complete this easy with some help! If you have ever done this mod from mpfi to carb i need your help! I have all the stuff i think but the thing is, can i do this without removing the computer or do i need it! can i just run old school and take out computer, run points system and carbs! if so how do i do that? what dizzy or is there a braket to make it points! sorry i have read lots of threads but yet to find anyreal step by step how to's! I just cant figure out how to get the spark, rest is easy! any help is much appreciated! Adam
 
#3 ·
Yeah I'm not sure why you'd do this, I'm assuming you got the dual sidedraft setup or something? You'd be better off staying MPFI and building a d.i.y. ITB setup for the same effect w/o killing your tuning ability.

Otherwise I don't see how you can defeat your ecu's fuel system and still maintain a good ignition map, you'd have to get the mechanical advance old school dizzy. There's a reason you haven't found any writeups going from injection reverting back to carbs, it makes more sense to go the other direction.
 
#4 ·
hahahaha, you guys are all kids practically.
dual weber dcoes on any honda motor, would be like ITB's which everyone knows that itbs are ideal for all-motor apps. thing bout the webers are, they are nearly half the price at most of the itbs setup. depending on what size carbs you use, it might cost you less than 500bucks for an all out itb setup, without depending on a stand alone or piggy back.

since i'm planning on this for my b16a with an obd0 computer, i figure you would run a map sensor stil, tps on the end of the carb shaft with some kind of adapter bracket, and you could still run your computer. may get a check engine light, not quite sure yet, not even sure if you need the tps or not. i figured with the tps you'd still get vtec engagement plus you dizzy would advance/retard like normal. obviously you would need a fuel pump thats low pressure for the carbs but even that i beleive you can still use the stock wiriing. i'm excited about it really! good luck! (btw, check over at honda-tech, old d series motors with webers is a pioneered area already...just a thought)
 
#5 ·
Yeah, we're all practically a bunch of ignorant kids. :rolleyes
Pretty sure you're going to get some CEL's running an MPFI ecu with no fuel injectors hooked up... The MAP is likely to always give you problems, any setup without a plenum will throw off the operating vacuum range. To even come close you will have to tap all the runners on the carb manifold into a vac manifold and run the MAP from that. I'm sure there are other issues.

Anyways d-i-y itbs have been done many times with bike throttle bodies for a fraction of the cost of prefab aftermarket setups using these same ideas.

Also, it's a great idea to make your first post on a forum one that insults other members and assumes they don't know anything.
 
#10 ·
The MAP is likely to always give you problems, any setup without a plenum will throw off the operating vacuum range. To even come close you will have to tap all the runners on the carb manifold into a vac manifold and run the MAP from that. I'm sure there are other issues.
you have to run all the runners to a vacuum canister... no big deal there really, was super easy, and even with a large cam now, very little pulsation withOUT the use of a plenum.

Anyways d-i-y itbs have been done many times with bike throttle bodies for a fraction of the cost of prefab aftermarket setups using these same ideas.
wouldn't you have to use the above technique as well with bike itbs? as well as a full stand alone? even a cheap one puts your close to a weber budget anyhow, and despite that, what do you think flows better, a carb that made for this type of application, or a stock intake manifold that gets cut up, and mated to a now modified for original setup motorcycle itbs all joined together with silly little silicon connectors? this would flow substantially better?
 
#7 ·
hmmm, how my about my 5th post more than 4 years later?



Thing that cracks me up about these forums is that everyone always assumes that the first post anyone has is there entry into the internet world and into automobile haven... Just funny how sensitive people were and even more so, still are...
 
#9 ·
huh, there are some other things missing here that were here before...

To be completely honest, the biggest reason some years ago i toyed with the idea of webering a b series in the first place was because i had a slow build happening with the car that you see before you... or at least the carbies... I'm running a MegaJolt ECU paired with a ford EDIS ignition system. It still is a work in progress, but with a bad head gasket and not making power over 5200rpm (on a motor that should make it to 7k at least), I still made close to 40whp over stock... this of course is on a motor that no one (or at least very few) would even consider modifying in a platform that isn't retro yet, and isn't desirable by most now.


with leaky headgasket



post headgasket, but with only a 6500rpm rev limit
 
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