I have a 91 RS with a 305 and this spring im planning on upgrading to a 350. I am going to keep the TBI, but i want to upgrade it to a holly 670cfm because the stock tbi would only be good up to like 250-275 from what i've heard. Im also going to slap the edelbrock performer RPM manifold for the TBI because the bores are larger and they flow significantly better than the stock manifold so i could get quite a bit more power. My other options are bored out 305/350 TBIs or a TBI off of a 454.

Has anybody had any experience with the holley tbi? If so let me know what you think or any suggestions would be welcome. Also Let me know what would be the best TBI setup to use.

 

I ahve one. Its ok but you have to use high fuel pressures to get the advertised flow out of the injectors. Another problem is that holley sort of intended these to be used in replacing carbs so the linkages arnt set up like a standard tbi. Theres no place to hook up the cruise control and the throttle hookes up to the wrong side. The modifications arnt too hard but if you can try to get a 454 tbi unit. Itll bolt up easier. If not the holley unit will work fine with a few minor mods.

 

Ah, knew I had this picture here somewhere.

The biggest thing I had to do was to rig up the throttle cable. I used the stock cable housing but used a lokar universal throttle cable. Drilled out the stock mount for the throttle cable and mounted the ball joint for the lokar on the right side and ran the cable. In the pic you can see there is a hole where the cruise control should go but no mount for it.

Youll also have to do some soldering as the injectors use different connectors and the tps uses the old style flat connector. Make sure you use shrinkwrap to insulate all the solder joints. I used electrical tape to bundle the wires together but that didnt last long in the engine compartment. The shrinkwrap insulation is holding up well, however.

 

<---- had the same problem with the Holley TB only I took the lazy way by just side loading the throttle shaft. Big mistake. After 3 years it now sticks open because of my rushing to get things done. Lesson learned.... sell car before 3 years after taking a short cut .
Seriously though, I'm going to be doing something similar to dim when I'm done rebuilding my Holley TBI.

 

I'm going to be using a Holley 670cfm TBI myself, but am not sure which model to get. There's one that says it's a direct bolt on replacement for a 5.0 and a different one for a 5.7, they have different part numbers too. Anyone know what the difference is in the 2?

 

Its the injector sizes. Came up in another thread and the 502-6 has the 60 something PPH injectors. JP verified them as flowing 65 pph at the stock fuel pressure. Theyll work with a 305 but youd need to change the base pulse width constant and EGR base pulse witdth constant along with scaling all the accel enrich stuff. There are other tweaks that youll have to do but that stuff will probably be manditory if the motor is near stock. The 502-6 is the one you will want if your doing mods. If you get the 502-5 or whatever it is youll have to spend $160 or so for the larger injectors down the road when you change your setup but that one will be more of a bolt on. All in all, though, you really wont need it if you have a 305.

Edit: too many abreviations...

 

Well, I guess the 502-6 is what I'll need. I plan on changing to WP Torquer 305 heads with thinner gasket for a slight compression increase, comp cam, edelbrock performer, holley 670 and custom chip. as for those egr and other adjustments, I haven't the slightest clue what you mean, is there a tech article or post you can link me to that sheds a bit more light on the subject?