I am having block girdles made for the Buick 350!

I am having a run of girdles made for the Buick 350! The more people who get in on this the lower the cost. The Buick 350 is very strong however a block girdle is cheep insurance to keep them long lasting when we are abusing them. :idea2:

As you can see by this picture the Buick 350 has a nice deep skirted bottom end. Many other engines have the mains hanging out of the block while the Buick 350 does not.

The idea is for a girdle that will work with minimal machine work to keep costs down. I am going to put together a hardware package to go with the girdle as well.

I will not know the cost until I know how many people are interested.



Please PM me if you are interested, thanks. Sean :TU:

 

I think the 340 uses the same layout, and maybe the 300 as well don't they? If you can confirm that it might increase the number of people who are interested.

JB

 

This would be great to know.

 

I think i have a 350 pan I can try on my 300 block, BUT I believe the 300 has smaller main caps with narrower main bolt spacing.

I would be interested if you could offer some with the 300's main bolt spacing...

How thick and what materials are we talking here Sean?

 

You know I'm in for this! any worth wild for custom billit caps? Overkill but can't hurt to ask..But. With this we will only have to worry about crank flex if its even a problem with the sbb...

 

'65 300 and '70 350 - same oil pan gasket part#

 

yea but 71 to 81? 350 is different gasket..


so the best thing to do to be absoluty sure if to check a 68-70 350 vs 71+ 350 then 300 and 340

i'm sure theyre all the same though but might as well have someone confirm first hand!

 

I am 100% sure the oil pan and mains are the same on the 68-80 engines. Not sure why a different number for the gasket but nothing to worry about. :TU:

 

Makes a difference, along with the precision of location and sizing of bolt holes. Any holes drilled "oversize" to ease fitment issues voids the whole concept.

"Halo" girdles are great for adding useless weight to the engine.

 

Sean, one of the important functions of the TA big block girdle is to tie in the surfaces between the newly machined main caps and the oil pan rail with an interference fit, causing compression on the main caps themselves when the girdle is torqued down to the rail (which is why the align hone/bore has to be done with the girdle installed). Have you considered finding a way to do this with your small block version?

If not, I'm thinking that without additional preload on the main caps, it'll behave like a typical halo whether it's tied to the oil pan rail or not.

Is there a known failure mode on or near the mains that's been seen with some of the big hp numbers some folks have been pushing with forced induction?

Devon

 

I assume this will be like the V6 girdle. You'll need to mill the tops of the caps flat, then you can set preload with shims.

On one V6 girdle, I set the block in a mill, machined the entire pan rail so that it was flat and square to the main registers, and then milled the caps so that they were "proud" by the recommended preload. Then you don't need shims.

Edit: I'm in for a girdle, assuming reasonable cost.

 

looks and sounds good brother!

 

I will not be able to get to my shop for a few days to measure a 350. I was able to take some measurements off the girdle template that you sent me from your 340.

These are with a tape measure so not 100% accurate. Should be close enough to find out if the 340 and 350 are the same though.

The 340 measurement between the main bolts center to center is 4"

Can anyone verify if the 350 and 300 are the same?

The distance between the #1 and #2 mains is about 4 3/4" center to center

The distance between the #2 and #3 mains is about 4 1/4" center to center

The distance between the # 3 and #4 mains is about 4 1/4" center to center

The distance between the #4 and #5 mains is about 4 3/4" center to center

 

sean : so what do ya think the strength/flex dif would be between the pictured 340 girdle and a "full across the mains" style ? thickness would seemingly make up some of that i'd guess .

 

Thanks for chiming in Devon, I appreciate your input.

Because we will not have to mill the caps or anything else I feel the girdle would still support the mains and the whole block even without any pre-load on the mains. We will be using shims to provide a tight fit between the girdle and the main caps. Because of the height of the mains compared to the oil pan surface I see no reason to mill the caps at all. Anytime where the caps are machined I feel that the pre-load is mandatory.

I am going to have a girdle made, provide the studs, nuts and washers, and the person who installs the girdle can decide whether they want to add just enough shim height to remove any gap OR they can add an extra 10 thou. and then have the mains align honed.

My goal is to provide a girdle and the user can decide if they want an interference fit or not.

Below is a pic of Jim B's light duty engine girdle that shows the shape that ours will be. Ours will be 1/2" steel however and will feature studs with recessed nuts to secure the girdle to the block around the oil pan surface. I will provide a spacer to lower the oil pickup screen into the pan back to the proper height.

Bill Mah found some bearing scuffing on the edges due to some block flex at the 800-1000 HP level using a procharger on his 350 Buick. He added a halo girdle but the block eventually cracked at the main webbing when running 8s in the quarter. So they need a new block to re-build and a girdle like the one I am having made.

Sonny Seal had a similar situation, he cracked the main webbing on a block with HUGE compression while racing and then went to a full girdle like the one I am having made. He used 10 thou compression on the main caps and then never had a problem. The difference with the one Sonny used is that he milled the heads flat and had the girdle cover over the whole cap.

Thanks for the input Kendall, it will be priced reasonably.

Have a look at the pic below and you will see how our SBB girdle will be different than the V6 version.

Your technique of milling the block and mains sounds very accurate. For this girdle I am not going to that extent however you could always go to that extreme if you wanted to.

**The pic is just the shape of what we are doing, the girdle will be 1/2" thick steel with studs holding it to the block all around the oil pan perimeter. The nuts will be recessed and then the oil pan will go on top then more nuts to hold the pan on.**

I will see what we can do, please measure the distance between the bolts on your 300 so we can see if it is different and go from there.

In my opinion a 1/2" plate of steel should be plenty stiff to keep the mains secure to the rest of the block with the style pictured above. This is likely overkill anyways but I am okay with that.

The mains are pretty secure in these engines anyway, so this is extra insurance instead of a band-aid like other blocks require to handle over 550 HP. I plan to shoot a 100 shot of nitrous and 15 PSI of boost from the turbos and I should be plenty safe.

Plus there is the fact that there is no need for a 3" step up like other engine designs require gives us a huge advantage in stability.

 

If you guys will recall, the part in the photo was primarily used to space down the pan 1/4", but also tied in the ends of the studs to help control stud flex and cap walk. As best I recall the main caps protrude above the pan face of the block about 3/8-1/2" so a girdle could be made 3/4-1" thick with machined reliefs for cap clearance and would not require align boring to use. It could be fitted with one or two 3/8" fine thread setscrews above (below) the cap for adjustable preload if desired. We discussed a 1" thick girdle for this purpose. Or a 3/4" thick girdle should be thick enough to compensate for the material removed by machining the caps off.

What Sean is proposing does not allow preload but also does not require the engine to be torn down and re-machined to install. Yet it does secure the free end of the caps and studs and you may be quite sure that these parts do move under enough load, so it is a good intermediate enhancement. Once it is done it is fairly simple to produce the 3/4 and 1" girdles with full cross straps for maximum performance applications. In the meantime the 1/2" girdle is certainly much better than what we have now. And bear in mind that if the girdle is fitted so that when clamped to the caps it sits proud of the pan flange, it will indeed apply a load to the caps at the studs, and with about a .010" gap and a half inch thick clamp that load will be substantial.

By the way, the notion of a precisely laid out girdle fitting better or more closely than a hand fitted one is erroneous. Bear in mind that cast iron is an amorphous solid. It's structure is very much like glass that way, and we all know about how very old window glass becomes thinner at the top and thicker at the bottom because the glass's appearance of being solid is in reality only a very extreme thickening of its liquid form. In fact it is still liquid and it continues to flow downward over time from gravity. Cast iron is the same structure and over time and with many many heat/cold cycles it deforms and changes shape. So those precisely laid out holes are not in exactly the same place they once were. And that's assuming they were where they were supposed to be to start with. Production gang drills will wander just as the bit in your drill press will, even more so once they begin to loose their edge. That is why we have clearances in the pan holes, the main cap holes, and other places. So for a genuine close fit even the most precisely laid out holes in the girdle are still going to have to be hand fitted. For the most precise fit they would be drilled undersized and enlarged to the correct position, which is the way I fitted up my lightweight girdle.

But it should be very close. Holes with minimum clearance will slightly flex a few of the studs and that shouldn't affect the bearings. I think Sean is on the right track here. Make the lower cost alternative first, and then if there is enough demand move on to the more expensive pieces, by which time most of the hidden costs should have surfaced.

JB

 

Jim, thanks for the input.

At this point it was either build the 1/2" girdle or not use any girdle at all so I choose to go this route.

 

One more thing. You see the casting line across the main caps in that top photo? That is about where your surface is going to be once you mill the main caps. Don't think for a minute that you will get back the strength lost by removing that metal by simply laying a 1/2" preloaded strap across it. It's not quite that easy. Consider that you are removing the arch of a bridgework. That removed section contributes more strength to the structure than every bit of what is left after it is removed. Now you are trying to replace it with an arch of similar cross section but loosely connected and unsupported until it reaches the studs which are at double the width. Plus the material is less rigid and more mallable. The fact is that even at a 3/4" thickness any increase in strength is questionable and the only true advantage is that the opposing sides of the block are somewhat rigidly tied together to prevent spreading. For this type of girdle to really be effective you would pin it to the pan rails with multiple fairly substantial dowel pins, dowel the mains to the block, and dowel the mains to the girdle. A 1" thick full girdle relieved for the caps with twin preload screws is stronger than a flat 1" girdle with cut down caps, because the bridge structure of the existing main caps is not removed and does not have to be replaced by a heavier but more poorly designed structure.

JB

 

I agree JB,

I want to leave the caps alone on my mains and secure the tops of the main studs to the block. :TU:

 

I want a girdle that goes across the main caps, requiring milling and pre-loading of the caps. Seems to work for Turbo v6 guys running in the low 9's on stock blocks and milled main caps.

I will be using billet v6 caps for the 300 race engine in conjunction with a girdle, once it gets to that point. Perhaps I will try dowel pinning or vacuum brazing as Jim suggested here and on the britishv8 forum.

Looking at the 350 picture again, the 300 caps are definitely narrower. I will try to measure the 300 today. I wish I still had those two 215 blocks.. could have killed several birds with one measuring stick.