At least Jim's stainless 3/16" (open center) girdle plate doesn't require milling and weakening the main caps. The Mopar style caps are one piece, new, cross bolted thru block sidewall. Kind of reminds me of 4 bolt splayed mains. and probably only need the three center caps for support...
That Mildon Mopar setup does look VERY strong and appears to add a lot of rigidity to the block as well. Not sure it would work in a 350 due to the potential problems Sean points out. Jim's sandwich looks very neat and since it's made of stainless it isn't likely to warp so much as crack if it's over torqued or twisted. The 350 block itself (factory) seems to be quite rigid and I wonder when(RPM?) these kind of extreme measures become necessary?
I would say gsjohnny is taking this block to the limits no one else spins this thing to 7500 plus so we wait his results.
I ran that plate on the 340 only in 1/4" mild steel but without the scraper. The nut surfaces on all but the rear main cap are flush but spacers are needed on the last two studs. Unlike a girdle, if it is added after the mains are align honed it doesn't affect the bearing crush and alignment. The main intent is to stabilize the loose end of the studs so the caps can't walk. Stainless is a tough, springy material compared to mild steel. I'm expecting this engine to see 7k but not every time it is taken out like Johnny's. It also will have the blower but at a reduced pressure. And the CR is 10.5:1, and it is a street engine with a relatively mild cam. It's going in a 2700lb car. Jim
I've always wanted to make a grill out of an engine block. I've seen a SBC that was completely gutted with burners installed. The valley and cylinders were torched out of it. One head was on a hinge and it opened right up. It was pretty cool.
That Mildon Mopar setup does look VERY strong and appears to add a lot of rigidity to the block as well. Not sure it would work in a 350 due to the potential problems Sean points out. there in lies understanding what happens to metal when disturbed. case in point r&d/exp background when machining inconel(4% machineability) is drilling or milling (grinding is real tricky) incorrectly leads to a 'white layer'. white layer is spot hardening in the material under a microscope which leads to microscopic cracks. the front big fan hub on a jet fighter is inconel. small white layer cracks lead to big cracks which lead to engine failure. no truck stop in skies to fix. so with that explanation, proper tooling, feeds and speeds and finishing should alleviate any future issues. did i answer your worry? an apology is in order from me. i did not finish what the finish should. ok. aside from heat treating or hard spots on the part/hole, all finishes inside the hole and enter/exit should be smooth and polished. like water, cracks will find its own level. depending on what the contents of the cast iron, it is possible to get hard spots just like brake drums/rotors.
If you machine very much stainless, you will notice that unless your tools are sharp and you apply enough force (as in drilling) the metal can work harden at the point of attack. So contrary to conventional practice with mild steel where you can ease into it, with stainless you really shouldn't and instead approach the beginning of the cut aggressively to penetrate and begin chip formation. Then continue at a feed rate that forms a good substantial chip. Less than that and you burn up tools and work harden the piece. Of course a waterjet doesn't have this problem. Jim
Actually I wasn't worried about that part ;~) I am not 100% sure about the alignment of the bearing caps with regard to the machined fittings for the oil pan. This could complicate or prevent the cross drilling? Also the casting of the 350 in my memory is not as flat as that mopar on the inside? Don't have one laying in the garage to look at, so just going from my distant memory.
I like Jim’s design with the crank scraper built in, it’s far less expensive and obtrusive vs doing a side (cross) bolted main with custom caps. agree that his design helps secure the tops of the caps from walking front to back on the block. At most power levels that is likely more than adequate. When Bill Mah was doing his 1021 HP 350 they looked into cross bolting the mains with custom caps however they determined there was not enough meat in the block to make this work. They were looking into doing a girdle like mine, thier only hang up was the oil pump mount location and how that interferes with the girdle. When sonny seal was running his stroker 350 in the low 11s NA he busted a block right apart on one of his first runs. The mains were pushed right out of the bottom of the block and the crank was bouncing around within the block that had the mains busted out. With the same combo and a girdle similar to mine he never had any future issues. Garry Paine is friends with Sonny and we were thankful to have him create a 7/8” girdle similar to what Sonny ran. I know they had to start over on the design so lots of R&D it’s an amazing piece! Gary also helped get his machine shop to finish my short block once the girdle was designed and applied to my block. There is no issue with clearances changing, this is a 7/8” thick support number to tie the machined oil pan rail to the mains to hold them secure with 10 thou pre-load. It’s align bored and honed and then it’s good. Machining material off the tops of the caps is not an issue as the caps are now supported by the 7/8” thick girdle that has 16 studs holding it secure to the newly machined oil pan rail surface. The material removed from the the cap is more than adequately replaced by the girdle holding them in place and handling any excess vectors of force on the caps in that direction. Also I remember Sonny explaining that the girdle really helped keep all of his cylinders from flexing, it adds rigidity and strength to the entire block.
It's a fine piece for the higher HP and RPM builds. My engine is not likely to ever see anything much north of 500hp and that's just fine with me That would be past 6lb/hp and my car has always been a daily driver so it would be a smidgen excessive for most anyone. Also, vertical real estate is a concern. I prefer to be able to see over the scoop. So basically use Sean's girdle for the max effort and my design for more moderate builds. Jim
yes under 600 HP I wouldn’t do a thing other than ARP studs and internal balance. Jim’s setup would be extra insurance in the 500-600 HP range.. Yes there is no vertical issue in my Skylark Chassis the custom alum pan clears no issue. In your application there is limited room in every single direction. Good work with everything including those custom headers.
sonny broke his block. was it sonic checked, x-rayed and a bunch of other metal tests before and after machining. if not, don't blame the block. and sandwiching part on top of part just becomes a big yucky mess. you never get the correct feel for torque. we could discuss material issues all day. don't matter to this old school machinist.
There is nothing yucky about my girdle setup, it’s the best setup available. Maybe Gary will have his machinist chime in on this? Yes Sony was completing sonic testing etc on his blocks, I know this for a fact as he told me it took a bunch of tries to find a good block. I would magniflux a block to look for cracks but that’s the only test I can see being applicable to checking the block main strength. Sonic testing is only applicable to the bores.
Yes Johnny I will ensure I don’t build any jet engines LOL. Why don’t you enlighten us on the metallurgic testing required to determine the strength of the blocks mains?
Well I know that Ultrasonic Testing can be completed, I don’t know anyone who does this but it’s an option. Johnny should enlighten us instead of making snide comments.
