350 SBC Cam Selection Help

[Opas69]

Hi everyone! Fairly new to gearhead-efi and REALLY new to EFI. I am learning a great deal from this site. Thanks in advance for the help.
I do not know if this should have been posted here or in the EFI forum. First the background.....I bought a 69 Camaro in pieces from a friend of mine. In the end I want this as my daily driver. Doing body work now. Changed rear suspension to triangulated four link. Mini tubbed rear for 315's, narrowed a ford 9" (3.70 ratio) and added coilovers. 700R4 transmission with 2000 stall. Thinking ahead to the motor. I have in hand a complete TBI from a 1988 5.7 GMC Vandura, 7747 ecm added ZIF and chip from Moates. I am considering using the TBI intake as I read on a forum somewhere that it is a bit of a high rise???? The machine work had been done on the gen 1 350 block and the GM 441 heads when I got them. Block is bored .030, Align bored, cam bearings installed. Keith Black flat top hypereutectic pistons. The heads are 76cc GM 441's. (I think I will be at 9-9.2 comp ratio) They have hardened seats, 2.02/1.60 valves, three angle valve job and screw in studs......So I hate not to use them. I want to go retro hydraulic roller cam to maximize performance. (I know I will have to change the valve springs). I realize this will not be a high RPM motor. I would like to have the largest cam I can and still be able to tune the EFI myself. (I know gearhead-efi is the place for that) I called Comp cams, they suggested 12-466-8 camshaft, 268/276 dur 218/224 @ .050, .570/.565 lift, 113 degree LS. I thought this one a bit much with the RPM range a little high on both ends, especially the bottom.
Sorry for being sooooo long winded but I thought you would need all the info to help me.
I am sure I will be leaning on you all later when it is time to tune. Thanks again, Steve

[PJG1173]

that cam shouldn't be too much trouble to tune. I have found a WBO2 is almost a must with a bigger cam.

[dave w]

The 1227747 is a very popular ECM. I would use the 16197427 (aka '7427) TBI PCM used from 1993 to 1995 which has the red / blue connectors for an engine like your building. The '7427 PCM has two timing tables and two fuel tables, near idle / off idle. Tuning for near idle and off idle is a HUGE advantage the '7427 has over the '7747! The '7427 has fuel and spark table up to 6400 RPM's. The '7747 has fuel and spark table up to 3200 RPM's.

With some intermediate wiring skills, the '7747 computer connectors can be swapped over to the '7427 red / blue connectors.

dave w

[Opas69]

Thanks for the replies. I will find a '7427 pcm. Any thoughts on the cam and motor combination?

[dave w]

Thanks for the replies. I will find a '7427 pcm. Any thoughts on the cam and motor combination?

I'm slightly outdated on SBC cam choices. The last time I built a SBC was back in 2009 for my 1993 K1500 5.7 liter TBI. I did a budget build with 4x4 performance in mind. I built my K1500 engine using a factory 5.7 roller block (1998 Vortec 5.7), not the original 5.7 TBI block. I am using stock TBI heads, a modified stock TBI intake (see pics below), 670 CFM throttle body, shorty headers flowing into a 3 inch single exhaust / catalytic converter, stock 96 ~ 99 Vortec 5.7 liter roller camshaft, and 1.6 roller tip rocker arms. The compression ratio is about 8.7:1. My 93 K1500 has the '7427 PCM from the factory. I have a rebuilt factory stock 4L60E. My K1500 weighs about 5200 lbs. My 0 ~ 60 MPH time is about 7 seconds, and passes Washington State emission testing.

I think it would be OK to under-cam an engine, instead of over-caming an engine using TBI. If I were to build a "Street Car" TBI 5.7 liter I would strongly consider using the factory LT1 or LT4 roller camshaft with 1.6 roller tip rocker arms. I would strongly consider using the Edelbrock TBI intake manifold, which needs the center mounting holes elongated to fit the 411 heads. The Edelbrock TBI intake will need the throttle bores bored out to accept a 670 CFM throttle body.

For tuning the 5.7 liter TBI "Street Car", I would likely "Clone" the LT1 / LT4 timing tables into the '7427 timing tables and adjust the fuel tables as needed. I basically "Cloned" the factory roller 5.7 liter timing tables into my K1500 '7427 PCM. I would install a WBO2 along with the factory O2 sensor, and enable WBO2 data logging in the '7427 chip. See attached screen shot on using WBO2 for tuning a '7427, that's tuning with Microsoft Excel and data logs!

dave w