Head currently has 3/8" pressed in studs. The hole left is the size needed for 7/16 studs. Can this be done with a hand tap? Or does it have to be done on a mill?
Not sure what engine you are using, however the stud boss will need to milled down the thickness of the hex on the new stud. The tapping/milling is usually done together on a mill.
You can do it by hand, of course, but it is easier to make everything straight and true if done on a mill.
My new valves are actually taller than the stock ones. The additional length is more than the thickness of the nut on the stud. So I was thinking I could just tap them, order longer pushrods and essentially "raise everything" up across the board.
If all the centerlines (valves, studs and pushrods) are parallel, that would seem to work.......but I think examinaton will show they are at different angles. If that is the case, the geometry of the valve train will change somewhat. Whether or not that is enough to matter, I don't know......but you might want to check into it. Ray
I believe they are: Valve stem, guide, pushrod - 12, 8, 8 degrees Valve stems are .16" longer than stock. Think it will be an issue?
The issue is the stud boss must be flat on top and square to the threaded hole for the new screw in stud to register properly and torque down correctly if using the racing type with the hex. If this is a standard replacement stud for press in repairs , You or have some machinist drill a piece of 1" stock with a slot(for adjustment) and a threaded hole(the guide) on the other, Adjust by slideing the slot on the next stud till tap is centered on repair hole and have at it . If the hole size needs to be bigger, machine the slot longer and drill another hole next to the tapped hole. New taps always work the best
Valve train geometry and clearances can be fussy. Many things affect it, including regrinding seats, longer valves, bigger springs and retainers, etc. The safest bet would be to have a machine shop that knows all the pitfalls do it for you. As mentioned, the hole must be tapped square and the top of the boss must be machined flat and square to the stud. The boss height can be critical as well, depending on your combination of parts. There will be a generous radius on the top side of the hex flange of the stud, be sure it doesn't interfere with the underside of your rocker. If you're using Chev style ball and cup rockers, be sure the slot in the rocker isn't contacting the stud at max or min lift. Do some homework on valve train geometry, the rocker should be at about 90 degrees to the stud just before mid lift, or you'll be putting too much side load on the valve, which will wear the guide quickly. Some builders ***emble one intake and one exhaust with a soft spring and adjustable push rod to check clearances and establish optimum push rod length.
Is this for a racing engine? If it is than the 7/16 stud is a good idea. If it's for a street, mild engine, the 3/8 stud that's there is strong enough. What I've done a few times is cross pin the pressed in studs with an 1/8 inch dia. dowel pin to make sure sure that they are not going to move up. Just a little insurance. The last one I did I used 1/8 roll pins instead of dowels. This eliminated reaming the dowel holes for a tight fit on the pins. Frank
I just thought it would be a good idea do swap them out. Opens up a lot more roller rocker choices. Cam is spec's at .480 lift for a 1.6 ratio. Going to a 1.7 chevy will take it 5.1. I thought that combined with some heavier springs might make screw ins a good idea.
I'll have my machinist do it. I am just trying to get a general idea of how much work is going to be involved to do all of this.
SBC? so you mean from 1.5 to 1.6 ratio? Yes, have the machine shop do it as they can knock the tops true flat, drill and tap all with a single setup - like for bbc they have different canted angle and you'd have to flop the head around quite a bit to get it done right but the sbc can all be done on the valve guide machine with different cutters. Piece of cake.
There are 2 types of studs for this. The first type is for heads without guide plates for the push rods. These do NOT require milling the tops of the bosses and do NOT require a milling machine, but DO require a inexpensive drilling fixture available most any where. These studs are 3/8" on top and 7/16"-14 on the head end. The same tool is used to pull the old studs. The second type of stud is for use with guide plates, and are easily distinquishable by having a nut machined into the shank betweeen the top and bottom threads. These do require a milling machine. The tops are available in both 3/8" and 7/16" fine, and the bottoms of both are the 7/16"-14 thread, TR
I would not recommend a 1.7 rocker on the SBC. Also when changing to a 1.6 ratio, you will have to check for pushrod clearance in the cylinder head and more than likely open the hole larger or better yet slot or elongate the holes. This can be done on most any well made drill press and again a inexpensive and readily available fixture/tool, TR
It is for a ford 300 six (240 head). It currently has slots for the pushrods that will have to be milled out for 3/8" pushrods negating the need for guideplates. Big Block Chevy Rockers are actually the closest off the shelf rollers that match the inline 1.6 rockers, so yes it is 1.7 on this application. I have plenty of room. I am definately going to look into the rocker studs that DON'T have the hex head, that may save me some bucks on machine work. If you have any links to them I would appreciate it.
This is correct, referring to the first type, studs with no hex, and easily done with the fixture from summit and a GOOD tap with a nice lead on it. Before tapping, put a little chamfer on the hole to be tapped. Use loc-***e on bottom of the stud and thread sealer at the top, as some of them go into the water jacket. Just take your time and don't rush.
Hey so i have a question along the lines of this, old thread i know, i didnt dig TOO hard for a more recent one, but this thread ***le was relevant.... Looking at my attatched image, how much does core shift affect decision to pin pressed studs or thread for new..? i have a sinker at work i can burn the old stud out with, so i dont have fears of it breaking the boss pulling it out, but how much “meat” do we need to then thread it for screw in studs..? Maybe its dependant on the length of the threads on the studs? this to me, looks, not really enough and a better candidate for pinning...? Cam will likely be comp 280magnum or isky 280mega.... I can post stud thread length and cam spring specs if need be..
Those slots are actually what acts like a guide for the current pushrod. If you drill them out you will have to install guide plates. Sounds like you need to hand this off to the machine shop.
This might help you to get started, and as @Ericnova72 said you can buy the tapping block if you want. https://www.jalopyjournal.com/forum...uds-for-screw-in-studs.1193749/#post-13580991
Ha! I remember that thread. I did pull all my studs out with my homemade puller using about 150$ in HF stuff and some fabbing, and did pick up studs like you show, but still contemplating having my bosses milled and using a different stud with the nut and roller rockers vs the stamped ones. Damned OT and night shifts delay things quite a bit
Oh, the item I got from summit is pretty close, but doesn’t (in my opinion) locate the tap as good as I like it. Plan is if I stay with the studs I have and not have to bosses milled, will be to sleeve the tool for a better fit.
I have always pulled studs using a couple of used rocker balls, some washers, 3/8-24 nuts and a ratchet or breaker bar. Cheap and effective. I even did a set once on a 350 in a ‘68 Corvette. The tapping block I made is sized to slip on a 3/8 stud and the 7/16 hole on the other side guides the tap accurately. Sounds like the block you bought has an oversized hole if you see a need to add a sleeve. What size is that hole?
Set the head on a surface that makes the old stud holes perpendicular. Get an extended tap handle and it will help you stay perpendicular and get a "starter" tap to initiate the threads start. Run a drill bit into the hole to clean it up and size it, then put a small chamfer at the top of the hole. Squirt WD 40 on the tap and align it visually using the long tap handle to help stay perpendicular. Cut some initial threads, back the tap out and change to a "plug" tap (which is what most people have). Tap till it bottoms out. If the stud doesn't screw all the way in, get a "bottom" tap to finish the treads all the way to the bottom of the hole. Its really pretty easy to do. https://www.zoro.com/irwin-hanson-t...bCAwEPNd7wNrH08enq4LBKJYajKsQC90aAh06EALw_wcB
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