did anybody ever think of modifying a 425 with an electronic fuel injection? i was dealing with many chevy sb tbi engines this year, so i wonder if this could be an idea for that thirsty 425 of mine. the tbi unit could be easily adapted, harness and metering as well. and if there is an chevy 454 tbi unit to exist, this could be the way to go. (but i do not know this, since i have never had seen one jet) any experiences on this?
TBI Injection on a nailhead would be easier than pie! All you would need is an O2 reading, map sensor, etc and since most kits anymore include this (like the throttle position built in) it would really easy. I have thought about it myself. Mike
This months HotRod did a full spread on bolt on EFI for "any car" as long as it is a Chevy or Ford. Seriously they did have a few universal kits that look like they will work on any make. They did make some great MPG #'s compared to the carbs.
The easiest way to do it is to use a 4 barrell unit like holleys pro jection..... run the intake ''wet'' and ,I think, with the manifold heat to make sure the fuel vaporizes.... the more complex way is to braze bungs into a cast iron manifold or an alluminum performance manifold and go with the multi port type.... then it is a matter of getting all the sensors in to the system .... you would have to create your own wireing harness and have a programable brain box..... Personally I have STRONGLY considered doing this to a nail..... it would make a strong running engine,,, i actually did it on a jeep engine and it ran strong..... [inline six] but..... you have to have a fuel map that is compatable with the cam that is in the engine.... i ran into that with the Jeep and after several years with a high speed miss that I could not tune out ,,, I finally took it to a holley 4 bbl.....I could not find anybody that could recalibrate the brain box for me, at the time..... You will have to get the harmonic balancer or the flywheel set up for a crank position sensor.....so the brain box will know when to fire the injectors....
a tbi unit does not use a crank sensor - just some metering sensors that could easily be mounted somewhere, and map/throttle ect thats already mounted in the tbi unit... and wiring harness is easy to adapt, i did that several times (even built a tbi 305sb in my 70s f-100 ford) i was just wondering which tbi unit i should use, i have never been able to get my hands on a bb unit - if that exists. sb units are easy to get... maybe they can be adapted? cfm would not the big nailhead problem, the amount of fuel is.
The early TUNED PORT systems used a DISTRIBUTOR...so making one sequential port would be easy, those early systems fired the injectors one bank at a time, leaving the vapor in suspension for a fraction of a second before vale opening. Since Carmen in New York modifies chevy hei distributors into nailhead distributors, all you'd have to find is an early 305- or 350 tuned port setup, and modify your intake for injectors, and go PS I've been thinking about this for a long time:TU:
There you go... you might have to play with injector size, i'd use the turbo tomco greenstripe to stat with, then go from there The only problem you might have is if you need a VS ( vehicle speed) sensor input, if thats the case, then use agear sending unit out of a 4t80, which is basically a turbo 400 with overdrive let us know how you make out:beer
exactly. The MORE fuel isn't a problem. Just need bigger injectors. Doc~ Did you do your own system MPI? When we modified a 400 pontiac with coil on plug (THE WORKS!!) it was really easy to adjust the fuel map and the ignition map,etc. All of the aftermarket companies I've looked at (not megasquirt yet) have that adjustability. Mike PS> getting closer to finishing my 364. Maybe in the spring we can try your 3bbl?
Yep, it was a mpi ...... basicly I took the stock set up from a 89 jeep and made it work with my 81 engine.... so I had to set up a crank sensor and then dismantle the wiring harness and rewire it to work for my application.... Holley made a 4bbl tbi unit for a while that flowed 950 cfms.....But I havent been able to justify the cost.....I guess I am just cheap....:laugh: :laugh:
The biggest obstical to running a factory EFI system on a nailhead is the firing order. If you start swaping cylinders bank to bank you will confuse the computer and the O2 sensors will be looking at the wrong bank and you'll get a misfire code on most of them. The solution for using a factory system would be to get something with only 1 O2 sensor so it has no idea which bank is going on and everything is cool then just cross the injector and plug wires to match the Nailhead firing order. However about all I can think of for factory EFI systems using 1 O2 are ancient TPI and TBI systems
or buy a megasquirt that would control it for 350 bucks and set it up to run it for about the same as a custom tune
I have been pondering this same thing after reading that Hotrod article. The only thing is all the universal sytems seem like their TBI. If I am going to the trouble of FI I would like to have an MPI system but that is probably cost prohibitive. I liked the one company they had that does the dual TB unit for 2x4's but they are $3000+. In reference to RB25's quest. You could get a TBI from a 454 Chevy pickup that might flow enough. Of course you could get an aftermarket one that is modified as well to play with.
well basically i figured it up with junkyard parts and a megasquirt you could do a mpfi system for about a grand
A couple of years ago there was some pics here on the board of a Buick nailhead that some one had adapted the mpi from an lt1 or what ever that chebby thing is... and it looked factory,,,, the guy did a 1st. class job....
That would be Marty and his '40 Chev hot rod. Intake is an Edelbrock which adapts nicely to a fuel rail since the runners are at the same height. Most of the components are Accel. Cost was around 3k a dozen years ago. He's putting another setup together for his Nailhead-powered Regal. Said it's gonna cost even more this time. Yes, Marty does excellent work!:TU:
