Alright everyone, I plan on running a set of vortec heads, with my LT4 hotcam, through the holley 670 and RPM air gap manifold with adapter. Well, I have the cam and was about to order the heads, but I was curious if even with a custom chip and 85# injectors ifl I'll have enough fuel. My stock heads and cam seem to run lean with my current 65# injectors. Of course, these are old used caprice injectors...so they probably aren't flowing quite up to full potential. But anyways, I just would like to know if I'd have enough fuel to make full potential out of this combo with 85# injectors with upped fuel pressure.

 

the 85's should be more than enough.My 55 pph's are enough for my 350. Youll probably have problems idleing with that much fuel, though, expecially with that LT4 cam. It would also be wise to invest in a new fuel pump. The old fuel pump is much more likely to cause your lean condition then the caprice injectors. The injectors themselves seldom fail.

 

oh as for those vortecs, make sure you take all the proper steps to set them up for that cam. Like machining the guides, enlarging the spring pockets for decent springs, etc.

 

Oh I know all that. Is it possible that my fuel pump could be causing my lean condition??? I am currently getting around 14 psi...so I didn't think it would be a problem. Oh, I am running rich at idle currently, but lean up high. I think I just need a custom chip. The vortecs I'm getting are from SDPC and come with the upgraded springs. Why would I need to upgrade the guides??? Any info would be appreciated.

 

Yes. You may have 14 psi at idle and when it's not under load, but it could be dropping when under load. The 65pph injectors you're using now should be more than enough with your current set-up.
Go with a Walbro 255. I am very happy with mine AND I can get all the pressure in the world (well 90psi). As far as the injectors go, I for one believe Holley underates their delphi injectors. I have 85pph injectors w/ my 383 and am currently running them at 22psi. I have plenty of fuel. You WILL run out of air before you do fuel. Yup. You will really need one after you do the mods you're looking to do. Springs alone will not do it. The max lift of the vortecs is only .480", springs or no springs, and your hot cam has plenty more lift then that. The vortecs will need machining and upgraided guides for the extra lift.
You could always go with Pro Topline's vortec heads. More bang for the same price and can handle .550" lift from the box I believe. I'm using them, very happy with them, and they saved me money....by the time I would have had the machine work done to gm's votecs, the gm vortecs would have cost more.

 

Well, that sounds good to me then...I just didn't want to do the fuel pump because I've heard it's a true PITA. My exhaust runs under the gas tank...so I'd have to drop my exhaust and drop the fuel tank....but oh well. I guess to get my car running right it will be worth it. Thanks.