Head stud question
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Member
Joined: May 2015
Posts: 22
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From: Arizona
Head stud question
On a 5.0L (302 old style) Has anyone drilled out the heads and drilled/tapped the block to use the bigger 1/2" 351 W head studs?
If so is the block hard or does it thread well? Thanks.
If so is the block hard or does it thread well? Thanks.
Member
Joined: Jul 2019
Posts: 43
Likes: 2
From: SouthEast
Miz,
Are you trying to salvage a damaged block? If so it can be done but also requires drilling the heads out unless you are using an aftermarket head with a 1/2” hole. If you are trying to put a cylinder head with a 1/2 bolt hole on a stock block the normal procedure is to use a specialty stepped washer from ARP. If you are going to get after the power and need more clamping pressure it can be done but I would, if you are using a stock block, have it sonic checked to make sure there is sufficient material to support the larger stud. It would be rather annoying to invest in the correct size drills, bottom tap and anything else you may have to buy and then have a stud pull because of a thin wall on the stud/head bolt hole. If you are after more power why not invest in an aftermarket block with the 1/2” stud option?
Are you trying to salvage a damaged block? If so it can be done but also requires drilling the heads out unless you are using an aftermarket head with a 1/2” hole. If you are trying to put a cylinder head with a 1/2 bolt hole on a stock block the normal procedure is to use a specialty stepped washer from ARP. If you are going to get after the power and need more clamping pressure it can be done but I would, if you are using a stock block, have it sonic checked to make sure there is sufficient material to support the larger stud. It would be rather annoying to invest in the correct size drills, bottom tap and anything else you may have to buy and then have a stud pull because of a thin wall on the stud/head bolt hole. If you are after more power why not invest in an aftermarket block with the 1/2” stud option?
Thread Starter
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Member
Joined: May 2015
Posts: 22
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From: Arizona
block question
I am doing a twin turbo build, so....a 4 bolt head gasket is my concern. Just a little matter of $1,800 USD and I would be happy to buy a Dart block.
The block has been mostly prepped. Bored, honed and the bores have been o-ringed for .040" wire. All holes tapped and cleaned. I had just wondered if anyone had done this? I own a small machineshop and the tools. I even have a mag base mill, so the drilling would be easy. The external head bolts are through into the water jacket and would be easiest to thread. There must be some reason they went to 1/2" thread size on the 351W engine.
Or just install 7/16" ARP studs and move on with life. Thanks!
The block has been mostly prepped. Bored, honed and the bores have been o-ringed for .040" wire. All holes tapped and cleaned. I had just wondered if anyone had done this? I own a small machineshop and the tools. I even have a mag base mill, so the drilling would be easy. The external head bolts are through into the water jacket and would be easiest to thread. There must be some reason they went to 1/2" thread size on the 351W engine.
Or just install 7/16" ARP studs and move on with life. Thanks!
Member
Joined: Jul 2019
Posts: 43
Likes: 2
From: SouthEast
miz,
You are definitely on the correct path upgrading the studs to 1/2" since you now can go to a 110# torque from 80. Is there anyone that can sonic check the block? Damn, it would be a disgrace to push a head gasket and ruin that block. If there is a thin spot in the bolt hole casting that would make you question the integrity at 1/2" at least then you will not be blaming yourself if you have a failure at 7/16". You did what you had to do. In the early days when we were depending on bore for power we were taking small displacement, 265 & 283, Chevy SBs to the limit and we would always sonic check the blocks to make sure that we did not end up with a thin spot after the bore job. You will not be the first person to upgrade a stock block to 1/2" so I wish you the best of luck if you decide to just jump in and start drilling and tapping. When 400 SBCs were a dime a dozen the street racers loved to use that block with filled cavities. They would put a ton of money in the rotating assembly and heads, throw a ton of squeeze on it and then wonder why the crank hit the ground. We refused to use 400 blocks as a starting point because failure was inevitable. You could end up in that same situation with 1/2" studs if you are not 100% sure of block integrity.
Randy
P.S. just playing devil's advocate because the old adage always holds true: Fast, cheap or good. You only get to choose two.
You are definitely on the correct path upgrading the studs to 1/2" since you now can go to a 110# torque from 80. Is there anyone that can sonic check the block? Damn, it would be a disgrace to push a head gasket and ruin that block. If there is a thin spot in the bolt hole casting that would make you question the integrity at 1/2" at least then you will not be blaming yourself if you have a failure at 7/16". You did what you had to do. In the early days when we were depending on bore for power we were taking small displacement, 265 & 283, Chevy SBs to the limit and we would always sonic check the blocks to make sure that we did not end up with a thin spot after the bore job. You will not be the first person to upgrade a stock block to 1/2" so I wish you the best of luck if you decide to just jump in and start drilling and tapping. When 400 SBCs were a dime a dozen the street racers loved to use that block with filled cavities. They would put a ton of money in the rotating assembly and heads, throw a ton of squeeze on it and then wonder why the crank hit the ground. We refused to use 400 blocks as a starting point because failure was inevitable. You could end up in that same situation with 1/2" studs if you are not 100% sure of block integrity.
Randy
P.S. just playing devil's advocate because the old adage always holds true: Fast, cheap or good. You only get to choose two.