main stud girdle
 

I will be building a 408w using my stock block. Is a stud girdle necessary for a 4 inch stroke? Car is not raced, primarily used on the street.

No. The girdle helps to stabilize the caps at high rpm's. On the street you just don't need it.

I dont think you really need it but I installed one on my 408. I guess I didnt need the "H" beam rods or a forged steel crank either. I figure that a few extra bucks now may save some problems down the road... I did have some clearance problems between the support and my oil pump. I ended up maching a little material from the support. No big deal, but it did not bolt right up. Good luck with your build

One nationally know engine builder told me when I bought a stud girdle from him that all it would do is keep all the pieces together if/when the bottom of the engine blew up.........he sells them, but rarely uses them in engines he builds.............

On the other side of the equation,Ive been running a 351-W in a 65 Fastback since 1994. The engine came out of a 1972 LTD, which I rebuilt;stock crankshaft, reground; stock rods,ARP rod bolts; stock cast replacement flat top pistons, makes about 350hp. Has at least 100 quarter miles drag stip passes, shifting at 6000rpms and probably close to 2,000 miles on road courses,running from 3000 to 6000 rpms for 15 to 20 minute sessions and 22,000+ street miles, she's still purring like a kitten and runs as good as ever.... Stock/factory components are pretty tuff and can take a lot of abuse....

The engine I took out of the LTD had just over 100,000 miles on it, so the block,crank,rods,and heads had seen a lot of use before I rebuilt the engine.....

I thought it would have blown up a long time ago with the way I use it, as I had planned to build an aluminum headed 331 stroker for it's replacement, but so far, it still cranks right up the first time you turn the key and runs just as good as when I rebuilt it years ago.....

David

Necessary....no. Nice to have....sure. If you go to the trouble of building a nice stroked small block, might as well add a little extra insurance. I always put main studs in my blocks anyway, and the blocks should always be checked if not align honed, so it just makes sense to spend an extra $100 and strengthen the bottom end a little. The way I see it, it has to help reduce cap walk.

At the very least, make sure your rotating assembly is very well balanced and throw a good set of ARP studs in the mains.

Brent;

I agree with everything you stated, except the least expensive main girdle I've seen for a 351-W block is in the $300.00 range and up to $450.00 depending on the brand and hardware.... and you may have to have the main caps machined down for the girdle to fit, I know I did on my 302 factory block. total with machining and girdle and studs was somewhere in the area of 475 bucks.....

Still not bad when considering how much $$$$ some spend on an engine.......

David

Our builder said no,and we went with Billet mains instead...WB3

David, there are some affordable ones around. When I built my 425W, I paid about $200 for mine, including the ARP studs. It was 1/2" steel, all CNC cut. I think I got it from Coast High Performance. The caps didn't have to be clearanced as the girdle sat on washers/spacers. It was a nice piece.

If you opt to pay close to $100 for good main studs, the girdle isn't really that much more since they usually come with the fasteners.

But yes, I agree, in the overall scheme of things, $200-300 isn't much when looking at a $10k engine.

CHP sells one. I may purchase one, they are inexpensive and will add a little extra insurance. It seems that stock blocks are limited to the 4.000 stroke. If you go to the 4.1 or the 4.170 to get to the magical 427w, most guys suggest to go with the Dart or World block. I don't think there will be a huge HP difference between a 408w and 427w, using the same basic components.

You'll gain some torque with the longer stroke. My 425W was a 4.060" bore and a 4.100" stroke. It was very easy to make power down low. Nothing special was required. I had an Eagle forged crank, forged H-beam rods, girdle, etc. Just took a little clearancing of the cylinder skirts. That was on a D9 production block....again, nothing special.

Nothing's wrong with adding cubes...

Went with billet mains and a Canton main cap girdle. They had to machine the billet caps to fit the girdle. Over kill yes, peace of mind well worth it.