Rabitz

I was wondering what injector sizes everyone is using.

been doing a lot of research and just get more lost the more I read.

I have a 347, and have read everything from the stock 19# injectors work well, to the 30# are not enough, so go to 42#

I was hoping to get some ideas of what people are running here.

My donor car is a 94 mustang GT, with a BBC CAI that I am not sure if I will be able to use or not...because of space and all that.

This is another reason I am interested in converting to a Carburetor.

My settlement has finally gone through, so I am no longer in the planning phase(if that is possible), and am systematically buying parts.

V8MiataMike

You will need to have it tuned to make that 347 work properly (if using a stock Ford EEC of some kind). Now might be a good time to locate a reputable tuner and simply go over the specs you will end up with and get a recommended injector size from them. I would have to think that 24lbs would do fine, 30lb for sure. Be sure to have a good fuel pump to support them as well.

Rabitz

A) Does the tune adjust the MAF, or do I need to get one to match the injectors?

B) Is anyone from Portland/Seattle are that can recommend?

Can anyone tell me if they have swapped out their fuel pumps for a higher flow rate also? I'm sure my 94 is stock, so it can probably use a new one anyway.

...hmm maybe carb...hmmm. seems like I'm still undecided. Ugh.

These are what one might call good problems

V8MiataMike

I think that attempting to keep the components "matched" is helpful but mainly if you are trying to avoid a proper tune. But once you start changing things, the stock computer will not be able to overcome/adapt completely. It may run well but after investing in all the modifications, it is somewhat of a waste without a proper tune.

The tuner will watch/adjust air fuel ratios, timing curves, among other things to get the most out of the package. Well worth it.

I would also highly recommend getting a tune with a carb as well. Again, via the dyno they can adjust air/fuel (jetting) and timing curve (distributor mechanical advance springs/weights) to get the most out of it that way as well.

Rabitz

Wiw, really good information. I had no idea you could dyno a car bed engine like that. I guess I never thought of it that way. I will definitely be doing that either way I go.

Any advice on aftermarket ECUs? I'm only familiar with megasquirt because they were so readily available with the miata.

engineer

Hi,


Your correct 347 injector size is aligned to your power goals. I am assuming that your 347 will be somewhere between 350-450hp. I can assure you that the 19#s are well under spec for a 347, the 24# will max out at around 200 rwkw (along with pegging the std maf I am assuming).


My advice to you here is to run a lightning 90mm MAF paired with 39-42lb injectors running at 43psi with a walbro 255 lph pump and a new fuel filter. This will ensure that your injector duty cycle and fuel pressure will fall into a good zone for long term safety and also provide good tuneability and expansion later if required.


The cost is only marginally higher for the larger injectors...its good insurance. There are many options out there for injector suppliers...Don't skimp here...and EFI is much better day to day than a carby..I have owned and tuned both for many years..EFI for me every time...


Cheers

Rabitz

well, that is exactly what I was looking for, Engineer.

The stock ECU will be fine after bringing it in to get a tune? or should I look in to after market ECUs such as MegaSquirt etc...

thank you for the info. I needed that

Rabitz

when I order the fuel pump, do I get it for a miata, or a mustang? I am unsure whether they fit a specific tank, or if they are a universal fit.

I saw this on summit :
http://www.summitracing.com/parts/vp...41bx/overview/

universal 255lph...

engineer

The EECIV is a very good ECU and very very tuneable. A good tuner with the right software can get that ECU to run an engine very nicely. No need for aftermarket ECU...EEC flash tuning capabilities have come along way in recent years...


As far as the fuel pump goes...the Walbro GSS 342 kit is the one for the Miata...Ebay have them for sale or summit/jegs etc. It is a universal pump but they are pretty easy to fit.


Just pull out the old pump and it will be obvious how to do it...just do NOT overtighten the rubber hose fittings..snug it up...but don't destroy the rubber with to much muscle.


Cheers

Casey

I'm using this 190 lph Miata pump kit with my close-to-stock 5.0L: Walbro 190LPH-HP Miata Fuel Pump NA8

Rabitz

thanks again, Engineer!