Angelini

I'm building a 350 Vortec TPI for my Camaro. I have a 99 088 cast 350 roller block out of a Silverado. I have matching brand new 906 Vortec heads that are stock so far. I want to run something higher than the .414/.428 lift that comes stock with these engines. I was hoping for something closer to .500 lift, or whatever can provide me with the best power gain over stock. Gas mileage doesn't really matter, but I would like to be able to get around 15 if I puppy dog it, which shouldn't be a problem. I've been looking at LT4 hotcams and stuff but I just do not know what to do. I bought .015" thick 4.1" diameter head gaskets for a 305 that I was going to build but then lost in the flooding here in Pennsylvania, so with those head gaskets on the 350 it will put me at 9.7:1 CR.

I found on ebay a guy selling brand new LS6 springs, lock, and retainers that I was thinking about getting because I've been reading a lot that the best upgrade to valvetrain that you can do is get LS6 or comparable springs.

I'm looking for around 350hp but I don't care so much to hit it if I can get a better driving, more powerful feeling car in the end instead of something not so streetable.

Also, my other vehicle is a 2001 Silverado LS with a 4.8L Gen III engine, and I really like the way it runs. I get great power down low (1500-2500) with a pretty good mid range and if I want I can open it up to get going pretty quick (4500-5500).

Now I know that the intake and everything is completely different on the LR4 in my truck than say a L98, but I am going to be using TPI for my build, and I don't need a cam that makes all its power around 6000 because the TPI runs out of air around 4500-5500, and thats great because thats actually where I would want max power to come in at, and I'll probably get my transmission build for maximum upshifts at those engine speeds.

Also, with the 906 heads, would I be safe just upgrading the springs to accept more lift, or do I have to get any machine work done, or modify anything else to make it work?

Any suggestions? I already have pushrods and that stuff, I'm going to run full roller valvetrain with 1.5:1 roller tip rockers. I want to start putting this thing together in a month or so. Thanks for the help guys!

Angelini

Also, tuning isnt an issue, I know that I will have to tune and I can get it done. And I also have #24 injectors to use for this engine, and would like to take advantage of them, and not use them to dump excess fuel into the engine for no reason/performance gain.

Orr89RocZ

iTrader: (20)

cant use the retainers/locks I dont think due to LS6 having 8mm valve stems. I think you'd need new retainers for 11/32" valve stems that come on most SBC motors.

It may be easier to just buy the Beehive comp 981 or pack 1218 spring kit for this application since they make matching retainers/locks.

If you cant have the heads machined to accept greater than .500" lift then beehives may give you clearance to run a .500" cam. I have read this on this forum but I have never used vortec heads and dont know what clearances are.

You'd have to take the springs out and leave valves in with retainer on the stem with locks, and measure how much valve lift you can get before the retainer/locks hits the valve stem guide boss on the head. Then subtract .050" or so for safety clearance.

I have seen most people report that .470" is max you can run before valve guideboss becomes a clearance problem. This can vary depending on the castings. Measuring is the only way to tell for sure.

The other way you can gain more clearance is to buy offset locks, +.050" and get about the same thickness of shims under the spring seat. This will raise the entire spring assembly .050" higher and give .050" more clearance. So that .470 may become .520" which is plenty for a 1.5 rocker on the LT4 hotcam which does work. Great little cam. Very driveable and cheap.

Angelini

So if I buy the Beehive springs or the kit and offset locks, I can run the lift that I need to get without machining? I would like to try and avoid machine work because all the machine shops around here do really poor work from what I hear, I can't find any good ones. I'm really at a loss when it comes to the details of the valvetrain system of an engine. I just know that the 3.1L that was in my car had valvetrain problems, my 4.3L Blazer had valvetrain problems, and I want to avoid it at all costs on this build.

Orr89RocZ

iTrader: (20)

Its possible. I'd still pull the springs and check to see how much clearance you have. You'd likely need a dial indicator to do so. Can get them from summit for fairly cheap.

Angelini

So after I check my clearances, this kit is what I should use, with offset locks.

http://www.ebay.com/itm/SBC-Conical-...sories&vxp=mtr

Orr89RocZ

iTrader: (20)

I got a typo..... the beehives I was refering to from Comp cams was 918, not 981. 918 is short for 26918 and thats the beehive.

You may beable to run those springs with hotcam and 1.5 rockers for total lift of .492" without having to use offset locks/shims. Beehives need to be installed at the specified install heights, as do most springs but the beehives seem abit more picky about install height.
You can measure that install height with a valvespring micrometer from Summit/Jegs for 45 bucks.

Angelini

http://www.ebay.com/itm/COMP-CAMS-LT...sories&vxp=mtr


So this is what I need?

Orr89RocZ

iTrader: (20)

That should work, but you'd still need to measure to make sure it clears. Just make sure they send the right parts. That ad is confusing. It says LT1-LT4 kit but in general its suppose to be good for all SBC type setups using 11/32" valves. The description/detail says GM LS beehive kit so thats not what you want since those use 8mm stems. Just make sure.

Angelini

I hate doing this, haha I just want to have the parts to be able to build it, I get so confused with this stuff because its the part of the engine that I know the least about. Anyways, I found this kit on Summit, it says it will work for 92-97 LT-based engines so does that mean that it is incompatible with the Vortecs?

http://www.summitracing.com/parts/NA...n/?prefilter=1

And yes I know, I still need to check my clearances...