Here are some of the benefits to strengthening the lifter valley in 400-430-455 Buick engines:
1. Strengthens the block: The Buick lifter valley is an open web design which is very weak and contributes quite a bit to block flex under load. By sealing and reinforcing the lifter valley, flex is greatly reduced and the block is noticeably more solid. This will significantly reinforce the lifter bores which will help prevent damage when using a big roller cam.
2. Reduce oil aeration: The open web design allows all of the oil from the top end to be drained directly over the cam and crak which are spinning (hopefully) at a high rpm. This whips the oil into a froth even before it is returned to the pan where the spinning crank continues to beat the hell out of it. After this it is picked up and returned through the block with a lot of air mixed in. By sealing the lifter valley and draining the oil externally to the pan, a good bit of this monkey motion is eliminated and aeration is kept to a minimum.
3. Frees up HP: As oil drains back over the cam and crank, the oil creates drag and draws quite a bit of HP. Bob Gilleland, Performance Concepts, claims he has verified a 32 hp increase on a Stg 3 7500 rpm engine. In my application, my Stg 1 that shifts at 6200 rpm, the ET slips say I picked up a solid 20 hp.
Here is what you need to make the modification:
Make a trip to Grainger's (industrial supply house) and pick up 3 lbs of a new epoxy from Devcon called titanium (Ti) putty and 1 lb of Devcon flowable steel-filled epoxy. The Ti putty is extremely strong and has the same coefficient of thermal expansion as cast iron. It will set you back about $50 per pound. The flowable epoxy is used to provide a nice finish for oil drainback and will cost you about $25.
Go to the hardware store and buy a short (about 30") length of 1.5" PVC drainpipe and about 3 feet of 1/2" PVC water pipe.
From Summit or Jeg's, order four 6 x 1/4" mpt straight fittings, two 6 staight hose ends, two 6 90 degree hose endsand a 3 foot lenght of braided hose.
Here is how to make the modification:
Block needs to be bare, unmachined, clean and minus the cam bearings.
1. Prep the lifter valley: Strength is only as good as the bond between the cast iron and the putty which depends on the prep work. The lifter valley has a gray/black "crust" that must be removed with a die grinder and 36 grit sand paper rools. I also found that 3M "Rolock discs" which are small grinding discs made to fit a die grinder work well. Prep every square inch of the lifter valley as though you were prepping a body panel for filler.
2. Install the PVC forms: Slide the length of 1.5" PVC through the camshaft journals. It will just fit. Cut a few pieces of cardboard to fit over the drainback holes from the inside of the block. Apply grease to the side of them that will be facing the lifter valley and use the 1.5" to hold them in place. This will keep the epoxy from getting through the drainback holes. Now, cut 16 small pieces of 1/2" PVC water pipe. These will fit tightly into the lifter bores and keep the epoxy from running into them. Grease them and tap them into place with at least 1" sticking out.
3. Level the block" Self-explanatory. Also, I should mention that the fumes from the putty are highly toxic so this job is best done outdoors.
4. Pour the lifter valley: Begin with the Ti putty. This comes in two equal parts that must be mixed together to make one pound of material that has the consistency of peanut butter. After mixing, you have about 10 minutes of working time. Use three pounds, mixed one at a time, and fill the entire valley from front to back. Finally , use one pound of Devcon steel-filled flowable epoxy to finish the job. This is self-leveling and will leave a nice smooth finish. Let dry for at least one day.
5. Drill vent holes and install stand pipes: Drill 3/8" vent holes (one front, one center, one rear) throught the now solid lifter valley (don't drill through the casting) to allow for crankcase ventilation. Install short standpipes in the holes. I like to use 3/8" aluminum tubing for this, threaded into the valley.
6. Install drainback lines: Drill and tap 2 holes at the back of the block at the top of the pour and install two of the 6 fittings in them. At the bottom of the block, on either side of the rear main, you will find a location suitable to install the remaining fittings. Drill (slight angle required), tap and install the remaining fittings. Now, make up 2 short lengths of 6 braided hose to connect the lifter valley to the sump, using 2 90 degree hose ends as the top and straight hose ends at the bottom. The whole deal fits nicely behind the flywheel. If you like, instead of drilling through the bottom of the block, you can install a pair of fittings in the oil pan directly above the sump. This is a tight fit though and can be prone to leaks.