I'm taking the head off a engine I acquired some time ago. The head has 7 Bolts and 8 studs.
The bolts are mostly on the passenger side and the Studs on the drivers side.
Why would someone use both?
Is there an advantage to using studs if the threads in the block are not so good?
Your thoughts, my friends are appreciated.
Without meditating on the question to figure out more possibilities, I see two possible reasons the studs are there.
1 Somebody was short of bolts and had studs handy;
2 The holes had crud in the bottom so the bolts wouldn't seat, and they used studs instead of cleaning out the holes.
Maybe others can think of more theories.
I'll tag in on Daves' questions with my own. Aren't the threads on the nut end of the stud finer than the ones that go into block? If so, what effect, if any, does this have on torque requirements?
Or, maybe some of the head bolt holes in the block are stripped, so someone installed studs with loctite in those holes in the hope that they would hold.
Won't studs make it pretty much impossible to remove the head once the engine is installed in the car?
If the car is a stock Model T, yes. You have to move the head forward to get it out.
There is less wear on the threads in the block when using studs and they also have finer threads on the nuts. Both types will rust out and break when they get wet.
The original equipment was bolts. The Model A had studs.
It is easier to remove the head with bolts for two reasons. You don't need to pull so hard on the head to remove after the bolts are out. The studs can sometimes be tight in the head even though not threaded, it is just dirt and rust causing it to stick. The other reason the studs are harder is the firewall is over the back part of the head and you cannot raise the head high enough to clear the studs unless you either slide the engine forward, or remove the firewall or slide the body back.
I've come across a few, used as a thread fix in the block, many years ago you could buy studs with over size threads ranging up in a couple of sizes.
Years ago our late friend Ralph Ricks made a post that he blew out a head gasket about once a year on his Fronty. I had just been in my shop working on a racer and late that night was looking at the Fronty and a Model A engine...I noticed the 2 front water neck studs on the A looked just about right for the Fronty head and took a measurment, the match looked good so I ordered enough to put the Fronty on the T block with studs. I posted to Ralph about this and he got right on it.
Ralph of course took that to the next level and made many posts with torque specks on the course thread and fine thread top nuts for the overhead. He was at my house and brought it up again that he had never again blown a head gasket out as he had more control of torque with studs and didn't have to worry about stripping out the T block.
I use studs on overheads and if I was installing a high compression head would also use studs. You can use studs on a standard head no differently than bolts...just double nut the top, drop them in the head and position it on the block and run them down. Remove the top nut and torque it. To remove double nut the stud and remove it like a bolt (never run studs down with vice grips..it will chew up the stud and make it rust and stick in the head). You will have to use studs long enough for a double nut on top or there is a possible bad situation...ask us guys who work on tractors about broken studs or stuck heads because you can only take the nut off and not remove the stud. A double nutted stud is no different than a head bolt.
On a stock motor I would use head bolts and have never stripped one but I clean the holes first, run them in to 45lbs, run the motor to warm it up, re torque it to 50 and do it again and again until 55lbs. I also spray the head gasket with copper coat both sides. I always worry about stripping out the threads in a block and it will eventually happen, too many guys before me with more force than brains.
Studs are fine if you follow my directions and use them like bolts, you can get a more confident seal on the head gasket but of course this won't correct a bad block deck or head surface.