350/L31/LT4 hot cam/Vortec/TBI –my first build
I finally got around to get that motor build for my 92 camaro RS. It will be daily driver /weekend warrior car. It is going to be my first build and I need from you guys recommendation, advises and suggestion to put this motor in. This list is based on reading all threads regarding L31/vortec heads/hotcam/tbi
Here is the plan and part list I already have or plan to use:
Block L31/stock crank/stock pistons (will need rings and bearings recommendation)
Oil pump (will need recommendation)/k&N filter/ mobil 1 syntetic
Vortec heads with some machining/screw in studs/ fel-pro fel-1094 gasket
Lt4 hotcam/LS6 springs/787-16 retainers/648-16 locks/st 2015 seals/1.6 RR
Valves/lifters/pushrods (will need recommendation)
Clo-9-1157 timing set / (would like chrome cover?)
Gmpp vortec tbi intake (already have it) – should I bore it for bigger holes 46mm?
Stock TBI with ultimate mods (unless I drill intake then I guess will need new tbi unit)
350 injectors or ( will need recommendation) / fuel pump already upgraded to 255
MSD-6al - already have it/LO3 dizzy – already have it
Hooker 2460 headers with 3 in y-pipe/cat/ - already have it
350 esc module/ 350 knock sensor
Spark plugs (will need recommendation)
Let me know what you think about this build and thanks for any suggestions you may have to help me build my first SBC.
Will let you know about the progress as today L31 was disassembled, block looks good, heads looks good too. In next two weeks block and heads going to be cleaned by machine shop.

 

OK, I'll take a shot at this. Not far from my engine.
First of all I am not a fan of the LT4 hot cam. Older technology and not very aggressive ramp rates. I prefer the Comp Extreme Energy or XFI cams. Since you are going with stock dish pistons you may want to go one step smaller on cam. Also since you said it is a daily driver, if mileage is important, then one step smaller would be ideal.

On the other hand if mileage and driveability is not important then go with flat top pistons and consider one step larger cam.

And yes you probably should go with a larger throttle body and injectors.

Al

 

Thank Al,
All suggestions counts and thank you for it. This project idea started about four years ago when after reading "budget tbi build" by fast355 I started collecting parts. I am open to change direction in this build by getting more info about parts selection. Like I said some parts I already have and would like to use them. I would like to know what cam and pistons (parts number) you think may work better.
This car will be driven on weekends but would like to know what this combo will make in HP and what mileage I can get.

 

Well, for cam suggestion, look at my signature as a starting point. I used a Comp XR269HR-12 cam p/n 08-502-8. This cam has similar spec to the LT4 hot cam but has more aggressive lobes. For a cam of this size or larger, go with any good brand hypereutectic flat top pistons to raise the compression ratio to about 10:1. But keep in mined you are now in the range where premium fuel is required and mileage will suffer. I do not even bother to check mileage on mine (but it is not good) and mostly just cruises around town. Desktop Dyno says mine should be about 400hp.

On the other hand if you stay with stock pistons and go down to about a 264 cam you can probably get by with reg. or mid grade fuel and will have a much better chance of getting good highway mileage. I would guess this would put you in the 350 hp range.

 

I think around 350 hp and decent mileage driving around the town that is where I want to be.

 

You can also consider a D cup piston such as a KB-193.It provides a good quench area while still offering some volume to keep CR in ck.

 

The GMPP TBI Vortec intake is great for passing emissions and overall driveability, HORRIBLE for making power. I know a guy in Colorado that had a 330 HP 350 engine in his TBI pickup. I think it made about 250-260 RWHP (through a stalled 700r4 and transfer case IIRC) with a 2" bored GMPP intake and 454 throttle body and fell flat. It may or may not have had the Hotcam at that point, I don't remember honestly.

That being said I recently had a custom grind from comp made for the L31 in my Express van. It has a GM Goodwrench crate engine for a 1-ton with the forged crank, 4 bolt mains, and single roller timing chain.

270/276 @ .006, 215/220 @ .050, .501/.510" lift, 114* LSA and 4* advance built in for a 110* ICL/118* ECL. It is basically a Lingenfelter grind that I had ground with 4* advance built-in for more low-midrange grunt. Will be going in with a pair of Edelbrock Etec 170cc heads. I plan to pull the engine out and swap to forged flat top pistons and put a decent set of rods in it. Plan to zero deck the block and run a .038" compressed thick head gasket for good sealing. Looking for 10-10.5:1 compression on my build and feel it should be a torque MONSTER.

With the EBL I think it would be very TBI friendly. With a restricted intake engine like a TBI it is my opinon that the intake/exhaust duration/lift split need not be as great as with a carbureted engine with more induction flow.

 

So help me figure out what direction to go with this motor. I thought it will be straight easy swap but now I am more confused about parts selection. Thank you all for any input as I am trying to find a way to finally upgrade this motor. Should I go with LS instead. Lol

 

If your goal is 350fwhp cruiser that will be fun to drive, then your task will be fairly simple. A basic stock L31 (just rebuild the block with stock parts) with a cam and valve spring/retainer change, headers, and exhaust will get you there. Be prepared to diy tune. Possibly consider EBL from RBob, which should ease that process.

So it seems to me you were pretty well covered with your original list. The only items I had mentioned was my own preference for Comp Cams over the lt4 hotcam and that you would be marginal with the stock bore tbi.

Yes, an LS swap is nice but I think by the time you are done it will cost a lot more and be more work.

 

Comp XR264HR is another good cam to use with your setup.If you having machine work to the block,i'd have @ .010 taken off the deck so that you can still use the .028" GM gasket to achieve a good quench.Somewhere between .035 to .045.This will give you slight bump in CR over stock & help fight off detonation as well.It will also give you a more complete & efficient burn.