Originally Posted by Hogg
I also find this "Verrrrry interrrrresting" lol
Let me see if I have this straight. You drill through the upper part of the oil galley, through the oil galley, and then continue drilling into the bottom surface of the oil galley?
Then you fab up a stud which threads through the upper surface, and into the lower surface. The stud area of the stud which is exposed to the oil galley is machined smaller(assuming no threads) so that oil flow is NOT impeded?
This would contrast simply drilling through the upper surface of the oil galley, tapping the same hole, then installing a stud into that hole?
Do I have this straight?
I guess it all comes down to cost. Do the 400 SBC with roller cam/reluctor wheel mods, OR use the Vortec 350 block and do an offest ground crank and overbore to make a 391-396 SBC.
I see that Speed-o-Motive offers these stroker kits but I have heard "stories" about their quality.
You have me straight I've done Gen I non roller blocks two ways.
1) Plan A
- Drill, after locating where to drill, into the center oil passage casting using a 17/64ths bit if you have one if not 1/4qtr is close enough.
- Then tap the hole for a 5/16ths by 18 threads. The casting is actually pretty thick in this area, almost as thick as a 5/16th's nut so it probably has enough strength to hold the spider as it doesn't see much operational load. Probably the greatest risk of damage to the hold down fasteners is clumsy installation and removal of these parts.
- Anyway, cut 5/16ths by 18 threaded rod for 3 pieces of 1-1/4 to 1-1/2 inch lengths. Saw what will be screw driver slot into one end which will become the top of the stud. Dress the ends with a file so they thread into a female threads smoothly having no burrs.
- Clean then dry the cut threads on the oil passage, the studs and 3 of what will be locking/locating nuts very thoroughly to be sure no oily residue is on these parts where assembly needs to take place.
- Apply Locktite to the threads of the holes in the oil passage and on the studs you made. Screw the studs into the holes to where they just meet the inside diameter of the oil passage.
- Apply Locktite to the stud from about 5/16ths above the oil passage casting. Thread a 5/16ths nut down the stud till it lightly contacts the casting. Do this for each stud.
- Torque the nut, to do this do not let the stud turn, this is what the screw driver slot is for. Hold the stud from rotating with a screw driver while torquing the nut to 10 foot pounds. Probably will need a crow food open end in whatever drive size your torque wrench uses.
- Walk away for 8 to 10 hours to let the Locktite cure. The Locktite keeps the parts from vibrating apart and prevents oil seepage past the stud threads in the oil galley casting.
- Final assembly is accomplished by dropping a 5/16ths fender washer (large diameter compared to a standard washer) onto each stud. Drop on the spider then a standard 5/16th washer with a nut. Again you do not want the stud to turn, so restrain it with a screw driver or if you can snake an open end under the spider grab the nut beneath to keep it from rotating, then torque the upper nut to 10 foot pounds, you may use Locktite or a self locking nylock nut to ensure long term security of the fastening.
2) My plan B on these things where I felt better retention of the stud or bolt if you choose that direction (though I think the stud makes this simpler) is to do everything in section 1 except I continue the drill into the oil passage that goes to the cam and finally the main bearings for these 3 in the center. You will see that the already factory drilled oil from the main to the cam bearings continues into the main oil galley hole happens to be right under where you need to drill for the spider studs.
- When I'm nervous about the anchorage of the spider retention studs I've continued the tapping through the upper hole drilled into the top of the oil passage casting and continued for about a half inch into the passage to the cam bearing.
- I add this additional length to the studs when cutting them off.
- I measure for that part of the stud that is exposed inside the main oil passage to where it bottoms in the feed passage to the bearings.
- From the point of entry into the oil passage I cut into the stud 4 grooves that emulate the width of the grooves in a tap, this leaves 4 threaded ridges on the lower part of the stud. This provides oil flow past the stud to feed the cam and main bearings.
- I then measure for the area the stud occupies as it passes through the main oil galley. Then dress the threads off that portion of the stud to provide flow around the stud for oil moving up the main oil galley.
- I'm careful not to put Locktite on the lower portion of the stud where it penetrates into the oil passages as the structural strength of the stud has been compromised in favor of oil flow to a point where trying to back it out against the forces of Locktite in the bottom threads might cause the stud to break in its reduced diameter area which happens to be inside the oil passage. If that were to happen removing the spider will now become removing the engine to get at the broken studs.
- I always combined this method with the installation of a high volume, high pressure oil pump to be sure adequate lubrication to the center cam and main bearings is maintained with the reduced flow area of the modified studs.
What applies in all of these methods is cleanliness. You must be sure that chips are thoroughly washed out and oily residue is eliminated from surfaces where Locktite has to be used. Further you must be careful that reassembly doesn't create chips which means you need to carefully deburr your work. This is the best assurance against trapped, unseen chips is to do this work with cam bearings knocked out.
The YouTube that was attached by "icsamerica" is interesting in that he talks about but does not show a method of putting a bar into the oil passage that is drilled and tapped for the studs and is shaped or drilled for oil passages. I can envision at least a couple ways of doing that but have never used that method myself.