I want to replace my old fuel injection with some carbs. I just dont know if i want the 40mm idf webers or the smaller 34mm ict weber carbs and i was wondering if you guys could help me decide what would work best. I have a completely stock 1972 1.7L motor. I live in colorado so the extra air would help i just dont know how well the 40mm will work well on a stock motor. I have read that i should have no problem with running the bigger carbs but on other websites the 34mm where recommended over the 40mm. I deffinentally want more horespower and i dont plan of keeping the motor stock forever and i plan on doing 2.0L exhaust and ignition before i put the carbs on. What do you guys think i should get??
Thanks alot,
James

I know nothing about carbs, but send your FI to me when you take it off.

If you really must go with carbs, the 40 IDFs will support more power later. The ICTs will start to choke the engine fairly early. Really, the right choice is aftermarket fuel injection, though. Leave the D-Jet on there until you actually do something that requires you change it. Then, go with Kit Carlson if it's available, or SDS if it's not, or Megasquirt it if you have the DIY skills.

QUOTE (jporsche914 @ Dec 30 2004, 06:47 PM)

I deffinentally want more horespower

unless you're planning on splitting the case and adding a more agressive CAM switching to carbs will *not* give you any HP increase.
on the other hand, your gas milage *will* go down for sure ...


if you're not in a hurry, i plan on selling my 40 webers in about 2 month.
Andy

im not gonna debate the "carbs vers F.I" but if you choose carbs go with IDFs.

Well my fuel injection is not doing to well right now it idles high(2000 rpm) runs rich and has barley any power below 3500 and i get about 13 miles per gallon. So i think my gas milage might go up with carbs and i am hoping it would make it run better. The fuel injection is reliable right know but the car is my is my daily driver and i would like it to be reliable no matter what and you never know when 32 year old fuel injection is going to crap out. I now carbs are not as good as fi but Carbs would be better than the fi that is on my car right now.

Heck, I'd go with a 44IDF and vent it down... This way when you upgrade you can go clear to a 2500cc engine and not need new carbs, just new vents!

The 34ICTs are a waste-

Fix the FI!

Why go backwards to carbs especially since you live in the mts.
First check the timing- should be 27 degrees before TDC at 3500rpms
Adjust the valves!
Check to see if the advance is working as it could be stuck inside the dizzy so you have no advance.

High Idle- AAR valve is stuck open- squirt some PB Blaster into is repeatedly until it frees up. or check the vacuum hoses for mega leaks! Change out the crappy worn out hoses for a few bucks with new stuff froma local VW auto parts place or order a set from Pelican parts or AA.

No power below 3500 and rich running- damn could be you have a blown out MPS- Check MPS witha vacuum tester to see if it holds a 15lbs vacuum for 5 minutes. If it doesnt then get a good used one from the classifieds. Forget the rebuilds as the ones I have seen were junk!

You should be gettting about 30mpg atleast with that 1.7l car so fix it or install carbs and get about 15mpg.

Maybe get a local to look at the FI for you as its pretty easy to fix and save $750 installing carbs.

Geoff

fixing FI = cheaper, more power, more reliability.

Well here we go agian. The carb vs FI question.

First, you most likely have a vacuum leak (idles at 2000rpm). Will also cause loss of power and gas mileage

Second, your valves, dwell and timing probably need to be set as well (no power below 3500 rpm). Will also cause loss of power and gas mileage

Third, carbs will not increase your horsepower.

Fourth, a set of new dual 40 Webers will cost as much or more than to fix the FI.

There are lots of folks here who can help you with the FI.

Thanks alot for the advise guys i guess i will try to figure out whats wrong with the fuel injection and go from there.

people get frustrated with the FI because they don't go through it methodically. once your valves are adjusted, your ignition is sorted, and your engine is timed, you have to:

test each component
validate that it is working correctly
ensure there are no vacuum leaks.

that's it.

it's half a saturday's work with some carb cleaner, vacuum pressure tester, fuel pressure gauge, multimeter, vacuum hose, and hand tools.

Go to this site and read on how to fix your Djet.
http://members.rennlist.com/pbanders/

I am no fan of the stock FI system... Now add a itCarlson EMS unit and thats a different story.

At altitude, carbs do suck...

As for making more power- I don't see it happening with the 100% stock FI system- I have never experienced it. BUT I have experienced failed engines directly related to an FI issue.

Yes, and I have seen pistons melted from mis-setup dual carb setups. If you are going to do anything, do it right!

Carbs work ok, I have actually driven one 914 that ran nice with duals.
FI works great, I have driven many 914's that run well with the stock FI even a brand new one years ago.

Geoff

The problem with carbs is that most guys never get them set up really sweet.... I like carbs for downright simplicity, since they clean up the engine bay.

The other nice thing is that seldom will a carb totally strand you. I have had to patch up carbs on the side of the road many times with little of nothing for tools or resources.

I grew up with cars that had points and carbs, and while they may both be totally out of date these days, they do their job and they are simple- Simple is the key.

The thing about a carb is if its lean, its lean and it won't lean out at just one RPM like the stock FI can do and thats what melts things.

Save the Djet. My car runs great. Has sat 15yrs 6with me (lack of Cash) now daily runner again. But in the years it sat with me in Fl and the hurricanes no carport and 90% humidity the normal it always started I had the oilbath off and the throdle bodie filled with water frooze it up the TPS frozen water into #3cyl and got it running again. It later dropped a valve cracked spring did it. Only did valve job 80k orig mi #3 cyl looked fine still had hone marks. Running 2months now not driping or burning oil I love this car. Any way the Djet FI system I never have bought one part for it. I did alot of reading and followed alot of procedures on this form eg FI harness and grounds and all the Ohm testing all simple but tedeious..... There is alot of help here just ask. Start with the basics as process of elemination New points or even better point eleminator system (mine still on points and the mark jumps around when timing). Set dwell first then timing then adj the valves. Then change fuel filter and check its pressure for a start. For the fast Idle thing check for vaccume leaks, make sure MPS sensor can hold vacuume and same for the vac advance on the Dist. Test the Aux air regulator may be stuck......JAKE!..... Ive seen small custom blower setups on all kinds of motorcycles big Vs and 4cyl rice burners. Ive seen turbos on 914's way too much plumbing. How about an FI system, injectors and intake tubes mounted the same. Intake tubes sealed into custom made alum housing with small belt driven blower on it with air volume throdle bodie on top of it not a carb. Your probley laughing your ass off right now but it was just a thought.

I have supercharged many Type IV engines, but I didn't use stock FI.

I have never had the FI strand me in the 914. Now the accel cable has broken in rush hour, the Pertronix has crapped out twice in rush hour etc...but the FI has always worked for the 9 years I have had the car.
I re-installed the FI after two years of fighting the dual dells.

Geoff

I'm a newbie and the FI that is in mine is questionable at best. At times it runs like a champ, at others it just dies. I am taking in this thread and have come to the conclusion that I'm gonna have to get my hands real dirty, and "methodically" attack it.

The car is a 1.9L with stock FI. I sometimes think its the throttle valve, but instead of guessing I'm off to buy the necessary diagnostic stuff and start elliminating the possibilities.

Thanks gents for the sound advice. One thing for sure though one of those refurbished FI wire system from that guy B something might just be the biggest item on my ticket.

again - thanks and Happy New Year.

Read Brad's pages first before spending money! After understanding how basic Djet is then you can test it out. As you say, a good FI wiring harness is very important along with everything else is good working order.

Geoff

Thanks Geoff - I'm gonna read his article and hopefully it won't challenge me too much.

Are there any other good sites about the d-jet fuel injection.

not that I know of....Brad's is the bible on Djet as he has done all the homework figuring it out with help from others.

Geoff

I too like the advantages of FI over carbs, so much so that when I bought my 308 I purposely bought the least desirable of the lot: Fuel injected.

So far I have $2100 into my '76 914 in mostly new parts (NEW throttle body, injectors, pressure regulator, trigger points, CHT, dist breaker plate etc) and 2 rebuilt MPS, all new vacume hoses and I'm sure that it will run someday.....(my issues are ignition related I'm sure, and should be resolved this weekend.....)

My only concern with our D-jet is, there are no new ECU's and no new AAR's available, so no matter how much we are willing to spend, these critical parts will always be 30 years old, and stock FI is a break down waiting to happen.