Carb Question

[Jmonty]

What kind of saw/saw blade/hole cutter/tool thingy works to make that big of a hole? I have a dremel so grinding isn't a problem. Same deal with the belt sander.

You can use a hole saw that you can get at any DIY type store. They are primarily for wood but if you get a set that says it is "bimetal" it will cut through the cast iron easily enough. Just go slow using lower RPMs and let the tool do the work. Attempting to force it thru will just get the thing super hot & ruin the teeth on the cutter. Cast iron makes a lot of fine chips similar to dust so you'll have to keep the shop vac working at the same time.

Use a Dremel or other die grinder with either a carbide burr type bit or a med grit grinding stone to smooth the edges. Just use a sharpie and draw your outline then stay inside the lines. Think of it is the adult version of a coloring book

Good luck!

 

[burnoutstang]

Great! That was the info I needed. After doing a little research and shopping I came across this.

http://cgi.ebay.com/ebaymotors/GM-TBI-T ... enameZWDVW

Returning to the earlier conversation about fuel delivery needs does anyone think that a piece like this could be used and boost referenced/ programmed to provide the extra fuel under boost? That way a smaller injector could be used (ie a chevy 350 tbi) and this plate? Thoughts?

 

[350kmileford]

Yea, the right regulators, along with megasquirt, can take care of that stuff pretty darn well.

 

[Jmonty]

Great! That was the info I needed. After doing a little research and shopping I came across this.

http://cgi.ebay.com/ebaymotors/GM-TBI-T ... enameZWDVW

Returning to the earlier conversation about fuel delivery needs does anyone think that a piece like this could be used and boost referenced/ programmed to provide the extra fuel under boost? That way a smaller injector could be used (ie a chevy 350 tbi) and this plate? Thoughts?

The megasquirt can fire 2 banks of injectors but they have to be the same impedance (high or low) because of how the length of time they are open is controlled. I don't believe that you can have different "on" times between injector banks but you could just have injectors in the aux block sized about the same as the TBI injector(s).

Something similar to that item will work to supply extra fuel & you might be able to wire it up so that the injectors get the current through a pressure switch so that they only come online when you have X amount of boost but you don't need to... just get injectors that supply close to the same amount as the one(s) in the TBI and you tune it. The need is for injectors that will be able to supply the necessary amount of fuel at max engine output. In the power range of these engines, even boosted, you shouldn't have an issue with injectors so big that they can't be tuned to give decent idle & cruise.

Keep in mind that (based on my research) TBIs like a fuel pump to put out about 30psi & the onboard pressure regulator handles that well enough, while MPFI injectors as shown on the unit listed require mid to high 40s in PSI. If you did a TBI with aux injectors you might need to run 2 fuel pressure regulators. Not a big deal but something to watch for. The Tempo FI conversion sticky mentions that an MPFI pump was used at first then had to be changed out for one with a lower output due to overfueling.


Whichever way you decide to go, if I were you I'd consider doing it in stages. Get the FI working and tuned up, then possibly the ECU controlling spark (eliminating the vac & mech advances on the distibutor) then adding boost. Or as Addo suggested ECU controlling spark then fuel then boost. I tend to think it may be easier to do the fuel first rather than modding a dizzy or fabbing up a crank trigger to drive those sexy on plug coils

Good luck!