350 TBI to Carb with Manual Transmission NV3500

[skylark]

If you use 1.6 roller rockers you should be able to get more lift without machining but again search about this to be sure. I think you would want to go no smaller then a 600cfm carb.

1.6 rockers work fine at low lift but move the push rod further out towards the head as the lift increases. The stock push rods hole is about 7/16", when running over .500 lift, I like to drill the push rod holes to 1/2". The last thing that you need is for a push rod to flex a little at 4-5K rpm and hit the push rod hole. Also always check that the rocker is centered over the tip of the valve. The geometry may change enough that the push rods may have to be changed. For 1.6 rockers I like the scorpion, narrow body, 3/8", self aligning, full roller rockers. They are quiet unlike some other "popular" brands out there. The narrow body means that they will work under the stock valve covers. I have used a "popular" brand before that hit the under side of the valve cover with just a .480 lift cam (production LT4). Self aligning is required because the push rod hole is round rather than slotted, the rocker "cradles" the tip of the valve to keep it in alignment. I wont waste my money a cheap set of rockers or just roller tip rockers.

 

[skylark]

But it sounds like an L31 long block will work with a different balancer, timing cover, and the holes drilled in the thermostat. As well as required modifications to the valve guides and springs to accomodate the larger cam.

I did find a Intake manifold + Carb set on Summit for around $650.00. Square bore dual plane vortec intake, 750 CFM manual secondary 4barrel carb, Open air filter, and misc gaskets, bolts, & sealer. But might be able to find that stuff cheaper used. Who knows.

I'm not even sure where to start with the cam, I considered maybe a stock LT4 cam which they redline at 6,300 and removing the dowel on the front for the optispark. or maybe go with some more lump and get an LT4 Hot cam. I'm really not sure what I'm doing as far as Duration, lift, LSA, centerline, cylinder pressure with the cam, advancing, retarding, any of that stuff goes. It's a little over my head to be honest. So many variables to determine what cam is the right cam, and I definitely don't want to choose the wrong one.

You don't have to worry about valve guide issues until you get over .480 lift. Those issue are easily solved but using comp cams "beehive" valve springs and retainers. Using that set up you are good to .550 lift. 600-650 is plenty of cfm, 750 is a bit much. Cam is a big personal preference. Reading through your wants and intended application I would recommend the LT4 "hot cam". It has .525 lift with the recommended 1.6 ratio rockers and is a nice all around cam with a strong bottom end.

If I were doing what you are looking at. I would hit up one of those 80K vortecs that you mentioned. The have a roller cam already installed. I would drop in the LT4 hot cam, change the spings and retainers, up the fuel pressure, advance the timing 4 degrees, ditch your ENTIRE exhaust system and run a set of hooker long tube headers to the muffler of your choice and smile for a long time. There is no way that I would go back to a carburetor!

 

[5SPD350]

Thanks for all the info guys, I'm still going carb and not TBI but I can still apply all that info towards my build as well as other info I found.

I've compiled a parts list:

$500.00 Used Vortec Long Block
$220.00 LT4 Hotcam
$290.00 Scorpion narrow body 3/8" self aligning full roller rockers 1.6
$61.00 LS6 Valve Springs
$52.00 Comp Cams 787-16 retainers
$32.00 Sealed Power Dodge Daytona Turbo 4 cyl Valve Stem Seals
Free Drill pushrod hole out to 1/2"
$37.00 Screw in Studs 7/16"
$601 Vortec Dual Plane Carb intake/600 cfm Carb/Air Cleaner
$90.00 HEI Distributor
$102.00 Fuel Pressure Regulator
Free Timing Cover
$4.00 Timing Tab
$69.00 Double Roller Timing Chain
Free TBI Balancer
Free TBI Pulley
Free TBI Accessories
Free Drill Holes in Thermostat
Free TBI fan
Total: $2,058.

That's if I want to go all out and buy everything new for the most part but I'm going to try and find some lower cost used item as well where I can here and there.

This doesn't including any shop work I need done, or exhaust parts.

I think with that combination my goal of 300fwhp and an operating range of Idle-6,000 rpm while running 87 octane is within reach. I might be missing some things, but I think that's the bulk of it.

With the low mileage NV3500 I have waiting for it, a Centerforce Dual Friction clutch, and the 454ss 3.73 14 bolt rear end I have, long tube headers, 2.5" duals with an X pipe, and some Dynomax Bullets dumped, it should be a nice streetable setup.