Max spring pressure on early SBFs before pressed studs tend to pull out?

[NXBOY]

221 dur@.050 .550 lift with 1.7 rockers and max of 6,000 rpms, more like 5,500 . Dual plane 302, 10 to one TFS 1 cam. Rather not pin them in case a stud breaks. I know its best to drill all the way through, but if doing that much work i'd be better off putting screw in studs. Was hoping 120# closed 300 # open might hold. Ready to put head together, time to decide when to stop throwing money on this beater engine. Can always do later if start to lift if i'm wrong. Too bad my friend with his TnS 2000xl guide and seat machine doesn't have the milling tooling with it or I would mill for guide plates and tap at same time. Not looking forward to tapping by hand. I think Whip Lash just imaging it. I'm at the time I wish I picked a different hobby

[turbo2256b]

Stock pressure has pulled press in studs. pin or screw in a must for those pressures

[In-Tech]

I am assuming you have a rail type 1.7 rocker. At your spring pressures and RPM I doubt you will have a problem unless you sit on valve float a lot, bad things happen when a valvetrain is out of control.

If you have enough room under the valve covers, a stud girdle will end your worries about studs pulling but, again, if you ride on the limit of the valvetrain, something WILL let go. PBM/Erson has inexpensive kits, Jomar makes the bars for them, not sure on the adjusters.

[mag2555]

Your walking a tightrope here with no balance pole on a windy day!

Your adding 12% more stud pulling leverage by means of the increased rocker ratio and at least 60 more psi of open spring pressure and then to top all that off due to the increased ratio you Appling that increased spring pressure faster!!!

If your concerned about studs snapping off you should be running a Girdle , no question about it!!!
Or place two tac welds 180 across from each other at the stud boss.

[turbo2256b]

1.7 rockers are not standard on a 302 if the cam specs are based on std 1.6 rockers duration and lift will be a bit different. some cases .550 lift or more could cause issues with piston clearance.
so is this a roller cam with what heads and block

[DaveMcLain]

If the heads have never been baked to clean them or severely over heated which would loosen the press fit I think the studs will stay in place. I ran into this about a year ago with a 289 on the dyno. After cam break in/one hour of run time I had a few loose rockers but the lobes were fine. One of the heads had a few loose studs that I could pull out with a Vise Grips! I took the heads back off and converted them to screw in studs but what was interesting was how on one of the heads they were tight as heck, the other head screwed up! That was with a flat tappet hydraulic cam with lower loads than you are using but I have run a hydraulic roller with press in studs and similar loads with no problems.

[NXBOY]

Yes roller tip 1.7, comes close to .550 lift on exhaust. 70 351w heads cut .040 . Spacers to make studs adjustable, Flow around 230 cfm. 1.94 valves. I was thinking about a stud girdle, but won't fit the 5/16 stepped down stud. Was afraid tack welding might weaken studs, but with a mild build I think that will work. Thanks

[BigBlocksOnTop2]

Yes roller tip 1.7, comes close to .550 lift on exhaust. 70 351w heads cut .040 . Spacers to make studs adjustable, Flow around 230 cfm. 1.94 valves. I was thinking about a stud girdle, but won't fit the 5/16 stepped down stud. Was afraid tack welding might weaken studs, but with a mild build I think that will work. Thanks

Tack welding the stud to the head? No, no, no! The cast iron is pretty well oil soaked/ graphite composition and most likely the weld deposit will not fuse. The heat effected zone on the stud is a sure fire way to cause it to fail also not to mention that it will bend from weld heat/ pull....don't do it. Get the screw in studs, scrap the 1.7 rockers on the exhaust side. Have a piece of mind, seriously.

[PackardV8]

As alluded to above, the answer of safe spring pressures is unknowable; too many variables. Back in the bad old days, I helped on a no-bucks round track Fairlane and it ran a whole season with stock studs. He worked all winter on porting another set of heads and half of the studs pulled the first race.

But no, don't try to run with the setup you described.

[pamotorman]

when i pinned chevy rocker studs i just went into the stud about .062 and drilled and tapped the boss for a allen set screw to hold them. never drilled clear thru the stud to weaken it

[turdwilly]

I ran an old Speed-Pro solid flat tappet in 2 different cars back in the early 80s, a 1969 Cougar, then a 1967 Cougar after I totaled the '69. Both were my daily driver (my sole means of transportation) 351W with C9 heads, just over .500" gross lift, factory 1.6 rail rockers, somewhere around 250* duration @ .050". Springs were around 135# seat (force not pressure! ) & around 300# open. I replaced the factory shouldered nuts with 5/16" Ramco lock nuts on the bottle-neck studs so I could adjust the lash using the little points-style feeler gauges. Drove those cars for several years across several states, bracket raced on the weekends. The engine quit making good power before 6000 rpm but I was young & stupid so I turned it well above that on a regular basis, even higher when I missed a shift with the ragged-ass toploader 4-speed. I didn't pin shit, I didn't weld shit, & I didn't convert to screw in studs. But maybe I'm just a lucky mf??

[BirdMan]

If you have the longer valves that come in 351W heads or I used .100 long Chevy valves (close to same length) then pull the studs, bolt the heads together opposite directions then they sit level on drill press. Insert the 7/16-nc tap in the drill press or mill after bolting heads down and tap all stud holes Without milling. You do not need to mill the stud bosses. The rockers will come close to stud nut but even using the large radius ones I didn't have a problem with Crane Gold rockers. Maybe some cheaper / bulkier ones would rub???

[turbo2256b]

Yes roller tip 1.7, comes close to .550 lift on exhaust. 70 351w heads cut .040 . Spacers to make studs adjustable, Flow around 230 cfm. 1.94 valves. I was thinking about a stud girdle, but won't fit the 5/16 stepped down stud. Was afraid tack welding might weaken studs, but with a mild build I think that will work. Thanks

eNDS UP ABOUT .540/.550

2 weeks after purchasing a shelby 350 GT. I pulled the heads , ported them, drilled and tapped by hand for studs 7/16 3/8 reused the rail rockers, a hyd version of the 289 hipo cam. Later installed a tight lash solid cam still using rail rockers no guide plates.

hAVE you actually measured spring installed ht and open pressures

[NXBOY]

Yes , Thats my problem, ran too many 292 cams and seen other 351w as well with .550 lift not pull back in the day (18) when wanst sure what 390 GT FE springs pressure was at when installed at 1.80 lol. I've seen a ton of Chevys have to get beat back down and pinned. My buddies has two seat and guide machines and hardware. Surely he has something or something simple I can get to use a tap on the boss. Not afraid of doing extra work, But unfortunatly neck pain and sleep DON"t mix and don't want to worry about getting one off a bit. I've done the guides and seats and most likely will the milling. I like that 069 cutter with a 35 top angle I guess I'll hang in there untill I find a good solution to tapping bosses. He has yet to buy a good drill press/mill, but can bore blocks and alot more. As you guys know it takes time$$. He does really good with the head department since having a 50 hr a week job too. This is first time I've been around a machine shop inside the workings, he might be able to borrow a chuck from one of his friends, . Its a nice thing when a friend helps out not only with his equipment but tries to get someones spirit up . I'm pretty sure I can buy a tool to cut the bosses down and use in his machine, who knows he might have more then I know, he just said he's going to buy stuff for milling on his seat and guide machine. If they made a jig like for Chevy this be alot easier to do by hand and a LONG T handle.

[NXBOY]

when i pinned chevy rocker studs i just went into the stud about .062 and drilled and tapped the boss for a allen set screw to hold them. never drilled clear thru the stud to weaken it

Thats a good Idea, drilling the head is the easy part and set screws are easy to remove if need be. Thanks guys, I got alot of good advice. Just getting inpatient in my old Age I guess.