I asked this in Engine Mods and didn't get much response.

I'm putting my BBC together and I have a question on at what point stud girdles are actually needed. I was under the impression that for high lift cams it's a good idea so I bought one. What I'm building is a 496 with a hydraulic roller . It has .629 lift in/exh and the open spring pressure is just over 400lbs with new 7/16 studs. I will eventually see very limited 1/4 mile time and was thinking maybe around 6500 rpm's. This setup may runout long before 6500 with my ported oval ports so this my never be an issue. The reason I ask is because I bought the GMPP valve covers with the breathers already on them and the underside nut on one side hits the stud and are very close to the girdle on both sides. I can fix this easy enough but is it worth modifying the girdle to fit if I don't need it. I've also read that you can break studs if the girdle doesn't fit perfect. Whats everybodies take on this.

 

What brand of girdle?I have the crane's on my BB in the boat,and run tall valve covers.I'd use them,cause you bought them,but they probably arn't needed for your application.They will tighten everything up up top.Mine were machined some to clear the valve cover bolts,but I would take as little off them as possible.I'm getting ready to drop this engine in a vett,and wondering if my tall valve covers is going to hit my brake booster,or am I going to have to run the org.non-PB setup?????

 

I have understood that 6000rpm is safe with all type of setups and over 6000 you start getting a bit risky. I had 6500 redline in my old 396 and it never had any failure and my shift point was like 6200-6400.

 

What determines if you need stud girdles is: If you assemble everything and place a dial indicator on the side of the rocker lock nut and it deflects over .003 when you rotate the motor over. You need a stud girdle

I don't think that mild modding of the girdle if you don't weaken it much is a big deal.

You have to remember that those big rocker studs are threaded into an aluminum head. I never leave home without one.

 

A stud girdle is always good insurance with a decent or better cam and springs. The biggest area of concern is putting the girdle on at exactly the right height, so that it doesn't deflect the studs from just tightening it into place. With the BBC's tilted rocker studs, there is one and only one place where the girdle can go without causing stud deflection. Take the time to determine where that is on YOUR particular setup. I spent hours testing/checking installation locations for stud deflection on my 540. Once I determined the ONE CORRECT LOCATION, I made some locating blocks just that height. Now I can set the blocks on the heads, drop the girdles on and tighten. Finally, a quick, no brainer deal.

 

I did notice the stud deflection when it was too low. That you have to be careful of.

 

I just sent a PM

 

You don't have enough spring pressure to have any need for a
girdle. The winner in 2005 engine masters challenge 509
cubes 844hp, 74O lb ft torque, cam 258/260 duration at .050
LSA 108 intake rocker ratio 1.8 exhaust 1.7, .828 valve lift
intake, exhaust .782, there is a picture of the engine with him
adjusting the rockers looser to try and creat some more low end torque,
it has aluminum rockers with no stud girdle. he used an 850 hp
double pumper holley all the others proffesional engine builders showed up with 1050 to 115O dominator they all left as loosers.

 

You wont need one unless you go supercharged.

 

I have spoke to an engine shop that has entered the engine masters competition. What they don't tell you about them is: out of 60 entrants 33% or 20 of the 60 motors blow up on the series of dyno runs. None of the winning motors are even made to run for very long. The rotating parts look like swiss cheese. holes in the rods and piston skirts. small diameter rod and main journals. spring weights just on the verge of valve float. like running big dual springs without the inner or damper removed. Loose timing chains. 5 or 10 weight oil with oil pumps that barely making enough oil pressure to keep them running

Just like an top fuel dragster motor. They are only made to last for the race.

so in the bigger scheme of things. you can cut corners. You can also save money by never buying new spark plugs

 

They are trying to use 12.5 comp., pump gas, detonationation problems gets a lot of them, very long strokes small bores because they are limited to how much rpm they can run and its a competition for the highest score in best overall torque and horsepower, if it were not
rpm limited you would see bigger bores. trying to run that much
comp on pump gas they have every type of coating on the chambers
pistons you could think up, but when you read about any failures
its still detonation thats putting them out. I think there limited to
6800 RPM, 509 cubes so most of the winners ive seen use a very long stroke
smalll 4.250 bore to get as high a score on torque as they can. there is
no doubt they use every trick in the book for power there not trying to really
make it all last, but if they were not limited on rpms you would see higher
HP and top torque numbers. the competition has always used limited rpms
to make things at least look like what a street engine would be. but back
to the original posters question of using a girdle. this engine builder is using a
solid roller and you can bet way more then any 400 lbs open spring pressure
and if there were any flexing going on he would use a girdle in a heart beat
to make sure he was getting every ounce of power.

 

I did a post a few years ago on stud girdles and the problems I ran into while installing.
I found the stud girdle would actually bend some of the rocker studs over when tightening. I modified the girdle to prevent this.
I believe in the stud girdle tying everything together. I use to run 420 pound open springs but this cam uses about 550.