I'm pretty sure that's a production Olds big block with one piece Jeff Smith girdle on the 2-3-4 caps tied to pan rail, but I could be remembering that wrong.

 

Yes it's a '65 425 block that's filled. Billet main caps and a Jeff Smith girdle that ties into the pan rails. Don't waste your time with a halo. Either do this or just run studs and straps and cross your fingers.

 

Thanks for showing us. I also notice your freeze plugs are square as well, I guess that comes with good machine work.

 

Couple of questions, straps do the caps get milled just enough to be flat? What studs are used? And in regards to the halo isn’t the halo just a tied to gather strap system in a sense?

 

 

Nice!!
This build is in another league. Max HP & TQ build that required a well thought out bottom end support.
When I think of the halo, or straps its in the 500 HP max entry level HP build.

 

I am working on my 403 build. If I have a mild cam, 9.0 compression with 7a heads, and cast pistons, I think I am looking at 325hp ish at 5200. Do I need to do any bottom end mods at this power or RPM on a 403? When do you need a girdle? 6000? 7000? I know these are heavy pistons. Would there be any benefit from balancing the reciprocating assembly? I previously had it done on a 350, and the engine builder said it wouldn't hurt anything but not necessary unless I was going 6500+.

 

 

 

 

Depends on who you ask- some say it does absolutely nothing and some say it helps keep the caps from walking around.
I have one, and the caps showed signs of walking, so maybe it does nothing.

 

What it should do by connecting all the mains together is it make a more stable assembly. Kind of like boxing a frame.

 

Except you are not boxing the frame! You are boxing the main caps. The weak spots are the webs. It can help somewhat but what difference does it make when the webs are not being reinforced. The only good solution is to be tied to the block like chadmans girdle.

 

That is exactly what I was trying to do. I installed my hallo without milling caps 1 thru 4. I can't see that it doesn't help. This is not a 600 ho + build. So I think it will help and certainly won't hurt. If I was to build a motor such as chadman's, I would certainly use a girdle. A girdle is the only option for high HP/TQ. The HP/ TQ in my build does not warrant a girdle and the cost of one.

 

I have been think about a girdle like Chadmans. Unless you are making more than 500 hp at the flywheel I see no need. Reason my 468 is around 480 and no cap walk. I have no halo . When I refreshed it I could have re -used the bearings but I bought new. Jmo

 

I did this to a customers engine only because he had already bought the parts. It’s a stock type build so I just cut the caps enough to install the halo under the straps. Didn’t have to clearance the pan either.

in the end it would have been less to get four billet caps ..either way it’s getting line honed and labour

 

 

BTR makes a very similar girdle.

 

Jeff Smith is no longer around. He passed away a few years back. BTR stopped making his girdle as well due to the new RR block being available. If you are looking to make serious power the RR block is by far the best option. By the time you have a full girdle made and pay to have it installed correctly you are a good ways toward the purchase price of a RR block.

 

Hey Chad,
On your full girdle, what do you use to check the oil level with or do you just keep a tab on how much you put in ? Do you have a fix to get around the girdle ?

Thanks
Glen

 

I find this interesting as a tool and die maker of 40 years, my 2 cents...
If you need to stop parts from movement, parts need to be keyed or doweled together, bolts/nuts alone will not do this, (why the caps are keyed to the block) most all industrial tooling, stamping dies and molds, all components are doweled, keyed or pocketed, the rule we use in tool, die and mold work is bolts are for clamping, (bolt holes have clearance for the bolt) dowels/keys are for locating, (no clearance), movement of .001 or 2 can spell disaster for a die or mold, it's just not done that way. Chads girdle thing looks ok but can't tell if its doweled/keyed or not, looks like girdle traps caps, well done if it's a precision fit! looks like some extra holes around the block though, dowels to block Chad? the halo things might work well as long as each cap is doweled/keyed to the halo, a simple operation that would have to be done prior to line bore, drill and ream for 5/16-3/8 dowels, press fit through the halo and slip fit in the cap, as far as material for the girdle, a pre hardend 4142 alloy is great for this application, were you are removing most of the material, stays stable while you remove most of it structure, bars | McMaster-Carr.
A way to check the girdle/halo for movement is to check for fretting under the nuts/bolt heads, of course this would have to be done after use.
IMHO the girdles/halo's I'm seeing are marketed and sold because they can be installed easily with little or no machine work? (bolt on) is this the case?
I'm not an Olds engine builder, but this is basic structural machine work.

 

In this case it's best to use something like a Canton pan that has a separate dipstick opening directly in the pan.


The halo girdles are a cheap and easy addition that might do something but probably don't hurt anything. Everyone agrees that they don't do much, so they're only considered good for adding maybe 100HP capacity to the block, whereas a full girdle can add 300HP+ capacity. A halo won't make the caps fully rigid, but they will add some resistance to movement. Not much, but at least a little. The physics we're worried about are pretty intricate. We don't, necessarily, need the bottom end to be completely rigid. The movement needs to be controlled well enough that the bearings don't loose the oil film - so we've got 2thou to 4thou to play with - and the forces distributed well enough that the webbing doesn't break. A halo will help a tiny bit with this, but a full girdle will do much better.
I'm saying this as someone that added a halo girdle to a 403. It dynoed at 450HP/460ftlb and hasn't destroyed bearings or broken the block, so the halo must work!!

 

no girdle or halo for the Olds is Key’d or dowel’d that I know of. it’s not perfect but some of them do help with main cap stability.

the ones that tie into the oil pan bolts on the #2 #3 and #4 are the best of what’s available

 

Trying to learn here,
The caps are located in the block, laterally precisely, correct? how are they moving? is it from crank imbalance or cranks that are not straight or a combination of, within .001 over the length I would guess would be the max if you are running high rpm
Yes, realize they are not keyed/doweled, that would be out of the wheel house for most auto machine shops, more in line for a T&D shop/ machine shop, once doweled to caps the only movement you would have would be in the flex of the halo's web, I'm thinking that that would improve them substantially if they were doweled, not a bad job once on the mill.

 

Not to get off subject but is anyone making the .018" thick 403 head MLS gaskets he used to sell?

 

Call Cometic. They will make you what ever you want. They made my custom gaskets with a 1 week turnaround.

 

Cometic does a .027 403 gasket. Not sure what they can do custom.

 

I have a customer who wants one. are they ready yet? ill let him know.

 

Tyler Jensen of J&S Machine still makes these. He purchased the machine shop from Jim.
His PH: 605-228-5001

 

thanks…I’ve been trying to get an answer from Mark about his Halo for a few years. I would rather support a board member …

it’s been over four years since he said they would be available. I guess I’ll have to go elsewhere

 

I have that 4 main but I assume you want a 5 main Halo? I also have a Speedmaster flywheel. I would like both gone. I will sell them cheap. PM me if interested.