Hello, I am freshening up a 98 vortec 5.7 engine , will use a performer vortec intake with an adapter plate, and external EGR plate setup, starting out with a modded stock bore TBI. Need to know if I can use a LT4 cam and maybe use 1.5 rockers to knock some lift off of it to make the idle a little better, The LT4 cam is $80.00 cheaper than the LT1 cam at GMparts. Will be using the 93 GM truck computer system and 4L60E, Hooker 1 5/8 full length with custom Y pipe tig welded by me. From factory-no AIR system. I plan on getting the prom burning set up for this and a Second Gen EFI project but would like to get a cam for this that will run OK to start off with then tune with chip mods. I found that Tunercat does support my PCM. Thanks for any help and suggestions , Dave

 

The LT4 cam will idle just like the stock vettes. Plenty of vacuum. I'd keep the 1.6 rockers.

The LT4 Hot Cam will idle with less vacuum and will probably run quite rich until you start prom burning.

 

Idles with 18 vac. You can use more cam if you want to with no problem in my opinion. Good luck!

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91 RS L31 350..... Vortec heads..... Holley 670..... Edel. intake .... Lt4 cam 1.6 rollers ..... Edel. TES headers .. 3" exhaust ..... 5spd 3.08

 

Why doesnt TunerCat support your 93 computer? It supports the 93 computer in my dad's truck.

My LT4 HOT cam gives my TPI car about 16-17" of vacuum at idle. I dont know what that would be in a TBI engine.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Kevin , I said that they do support my PCM and I think it takes 27c512 chips, so i hope there is a flach chip that i can use . have you programmed a 93 PCM? Thanks , Dave

 

Oops, I misread it.

Yes, my dad has done proms for his truck, and for a friend's 94 truck. I dont know about flash chips, he is using a 27C512.