LS1/SBC valve train results ?

[604rail_king]

For those that have used the LS1 or SBC 1.94 - 2.00 & 1.55 - 1.60 stainless steel valves + springs, would you say the time/effort and relatively "low cost" to replace the stock jeep valve train is worth it or have noticeable results?

my head is going to be sent off to my machine shop shortly and if the new valves will help improve flow id likely end up going this route. theres also plans to do minor p&P on the head.

im not looking to squeeze every last hp from my planned 4.6 stoker build however just have a well balanced reliable setup.

my setup will be using a stock 96+ cam with kb 944 pistons with a 7120 head. ideally im aiming in the neighborhood of 9.5 SCR, 8 DCR, .43-.53 quench. if i can get away with 87 oct great, but it wont bother me if i have to use up to 91 oct.


thx

[SilverXJ]

The only real gain to be had is cheaper valve spring setup. If the stock valve guides need to be replaced, that might be another incentive. The larger valves show no gain and the extra weight certainly doesn't help anything.

If you are interested in SS valves take a look at the Mopar Magnum V8 aftermarket valves. Some decent prices and they are near drop in and about the same size as stock. And a lot cheaper than the 4.0L specific SS valves.

[gonridnu]

The valve size relative to port cross section of the stock 4.0 is adequate, so unless you slightly enlarge the ports it is not going to do much of anything except maybe drop some bottom end. If you do some port work and a bowl blend for the larger size valves it will help. It's convenient to remember the per cylinder displacement of a stroker engine is larger than a 350 Chevy so if you get the head to work there is a lot of power available.

On the other hand I replace all the valves on all the engines I build (especially exhausts) and the stock LS-1's were cheaper than 4.0 valves and allowed me to use new stock springs and shim into a suitable spring pressure.

My LS-1 valves were actually lighter than the stock valves due to the tulip design of the LS-1's vs. the flat face design of the stockers. I remember weighing them but don't remember by how much. Prob just a few grams.

I also CC'd the heads with both and with the LS-1s the combustion chamber cc'd a little larger maybe 1 or 2 cc's but every little bit helps if you are on the ragged edge.

[6TIME]

I've been running LS springs/retainers/valves for 26k with great results. I weighed my valves and retainers and they came in surprisingly lighter than the stock 4.0 pieces. With less total weight at the valve, I could keep my spring pressures conservative with the Lunati cam. I had the 2.00 Intakes turned down to 1.95" and kept the stock 1.55" exhaust valves. The swap works great and it's a cheap alternative. I spent about 60 bucks for the valves, retainers, locks and springs on Ebay....

[amcinstaller]

sorry to hijack but sixpak id be interested to know maybe part numbers or an application that your valve train pieces came from. i ended up with a comp 68-239-4 cam for my stroker (yes, i finally bought parts ) and im trying to figure out which valve setup to use that wont wipe out my cam or give me nasty valve float. also, if itll save me a couple bucks on parts and fit under the valve cover (cast, not stamped) then im winning all around

[Antifreeze2]

My head is in the process of being cut for new valves and springs. I picked up magnum valves from Engine Builder on Ebay. My machinist told me they are actually 5/16th and not 8mm. The only hard part has been sourcing 7* locks, since I am trying to fit Comp 26125 Beehive springs with 701 retainers. I'm waiting to see if it works before posting the details, but why not let the cat out of the bag.

"SPECS: 2.020" intake, 1.620" exhaust, 8mm stem size (.3115") , BEADLOCK style keeper groove, stock length @ 4.92" exhaust and 4.906" intake, 21-4N premium Stainless Steel, ONE Piece fully forged. These are high pressure rolled out not just in the fillet area but over the entire piece, CNC polished, heat treated single keeper groove even encompasses the keeper groove, making these massively strong.. NO lash cap required, fully hard chrome plated."

$109 for a set of 16
Part number on the valve:
2.02 Intake valve - 10716EPN
1.62 Exhaust valve - 10715EPN

[gonridnu]

I used LS-1 valves in my build along with stock retainers, LS-1 keepers, and a new set of stock springs. I believe there is a disparity of one degree between the locks and the retainer but I’ve checked a couple of them and they seem to be fine.

The stock spring shimmed to 90 lbs on the seat and 210-220 lbs. open has a maximum valve lift of .450” with a remaining .055”-.060” to coil bind. If you take the shim out to accommodate more lift the resulting spring pressures will be insufficient for a performance cam of that type and if you run it with significantly less clearance to coil bind you will likely have eminent catastrophic failure.

There was only a small difference in valve stem diameters but I put in new bronze guide liners and adjusted stem clearance accordingly. I used the stock LS-1 valve head diameters and a carbide bowl blending cutter to open the bowl up under the seats. You should also install hard seat inserts on the exhaust. Machining to open them up that big often cuts through the flame hardened portion of the factory seat resulting in a future sunken exhaust valve. A little hand porting and the obligatory valve job will finish it off.