Smitty275

The straps may not make the block stronger, but they do eliminate "cap walk". I'm still not sold on the step ladder girdles that are offered for sale for Olds blocks. If your twisting it enough to break the block with stock caps or caps & straps I just can't see a piece of 1/2" plate with a rather thin crossection making much difference. Now if they were fully hardened and ground that would be a different story. But as far as I know none of them are hardened and ground. You can flex those available a few thousandths by hand. But each has their own theory on what's best. So go with what ever you think fits for your application.

Steve O

I just dont see how bolting what amounts to a glorified washer over the cap could make it stronger or stop the caps from moving... I always thought it was an old Mondello make work campaign, especially the part about machining the main cap down LOL The studs can only do so much Id think... You can add extras as has been done for years, that at least makes sense to me...

My 482 has the Pro-gram girdle that bolts together.... That with every other trick in the book and it still showed signs of cap walk.... They are time and $$$ bombs....

Id do a SBO if I was still into trying to go really fast with an Olds.... It just costs way too much these days to be any fun anymore...

Steve O

Hey J, I doubt Id ever go back to Ill-Annoy but you never know

507OLDS

That was one thing that was not done to my caps.They were not milled for the caps. We used longer Pontiac studs. Still not gonna save the world like that.

cutlassefi

Yes one of the strap manufacturers mentions milling the caps .400, why?
We take less than .200 off and the stock length ARP studs work fine. There's a thread or two left over, that's all you need.

But again all this is just a band aid for a block that was never made to make this kind of power at the rpms guys are running them at, plain and simple.

Smitty275

Better to bandaid before, than to wish you had after.

coppercutlass

Now what about main cap design in it's self ? I know that all main caps are arched on the inside but wouldn't it be stronger if you had a more rounded cap vs flat on top? All I usually see is most aftermarket main caps with a little round bump on the top but would it make a difference in the clamping force if you kept a more rounded shape or does the square exterior act like a strut ? Im thinking if you have a flat top main cap would that make the arch want to push outwards when a downward force is applied vs a rounded design with bolt bossed closer to the edge . Now I now when you measure the main bore it's always wider at the sides so that acutally answers one part but wouldn't a more rounder design work better to keep things more round or true and possibly more clamping force .

Smitty275

As long as there is adequate cross section it doesn't matter if it's flat or rounded. The forces are not straight down anyhow. they are actually more towards the end of the bolts. Kind of 45* off to each side more or less.

67 Cutlass Freak

Mark I did a bad job of explaining the theory of the steel strap early on in this thread. I had a hard time understanding the theory behind it myself. I still have the instructions from my straps. They say machine 1/2" off the main caps when using the windage tray. I talked to Joe Mondello about them after my short block was assembled. Think about replacing that 1/2" with stronger less flexable steel. I'm not sure if the strap actually will do anything, but the theory is to reinforce the cap across the top, to even out the clamping force.

Boldsmobile

This

I bought one - not the eBay one. Was not happy with the hole location and tolerances and the finish. I posted my observations with photos and i took some crap for being truthful and presenting the facts.

I haven't convinced myself of straps over a halo.

So I designed my own halo in CAD to EXACT dimensions. Did somewhere around 6 mock ups for test fit and than had one built. Ive since acquired a bridgeport and would machine it myself next time. I did it because I wanted to prove to myself I could.

I had a full write up on ROP before the crash.

For sure the studs aren't moving

image_zpsea523e15.jpg

botmbulb

I will pass along MY experience (and conclusions) from MY engines. I didn't have any issues until I stepped up to a roller cam to pick up enough ET (from 11.00 to 10.70) to run Super Street.

1st engine: 455 block +.030, filled, straps, N crank, Arias pistons, Eagle rods, BHJ balancer, externally balanced, iron heads to start and switched to Edelbrocks after about 1500-1600 runs, hydraulic flat tappet cam to start and switched to roller after about 2800 runs. After this engine had about 2800 runs, it was freshened for the first time (used the same block, crank, rods, and pistons), and that's when the cam was changed. It then went between 400-500 runs and broke the crank into 2 pieces at #4 main, and broke #4 main bulkhead. When the engine was freshened there was very little evidence of cap walk, but after the crank broke it was noticeable. The bearings and plugs showed no signs of detonation.

2nd engine: 455 block + .030, filled, billet main caps (2 bolt), N crank, SRP pistons, Eagle rods, ATI balancer, externally balanced, same heads, same cam. Because of the noticeable cap walk, we went with the billet main caps. We went with the ATI balancer in an effort to dampen harmonics better. This one lasted about 725-750 runs and broke the crank into 5 pieces, and broke #2,3 and 4 main bulkhead. In fact, each piece of crank still had a main cap/bulkhead still attached and torqued. The bearings and plugs again showed no signs of detonation. The caps still showed signs of cap walk.

3rd engine: 455 block + .030, filled, M&J bed plate, Eagle 4.500 crank, custom JE pistons, Eagle 7.100 rods, ATI balancer, internally balanced, same heads, same cam. The reasoning this time was to tie the main caps to the pan rail to take load off of the bulkheads. We were going to go with a 4 bolt main, but I was pretty fed up at the time and the bed plate seemed like the best thing available. Between 675-690 runs, the oil pressure dropped and I pulled the engine. The crank was bent .020 and was cracked through #3 main journal. I had the block magnafluxed and no cracks were found. I got another Eagle crank, had it balanced and put all back together, and have 290 runs on it right now. My plan is to put 260 runs (310 max) this year and get another crank. I may go with a billet crank.

What I have learned: While the block is weak, the crank is the biggest problem. The crank with straps broke into only 2 pieces, while the crank with billet main caps broke into 5 pieces. After going to the bed plate, the crank still failed, but I was able to see it as a problem on the oil pressure gauge before it broke. Also, the crack was on #3, not #4, indicating the load shifted to the middle. All this tells me that the block is no longer moving, but the crank still is. An offset ground 455 steel crank may hold up better, but at this point I'm not about to try and go past 600 runs with anything besides a 4340 forged crank (if one were to be produced) or a billet crank.

67 Cutlass Freak

botmbulb, thanks for your post. This is exactly the type of testing and results I was hoping to see. You sure have put in a lot of runs. Can you give us any more details about your car and the engine? Specifically: what horsepower level were you at for each of the builds? Are you running a trans brake? How heavy is your car? Do you have any photos of the carnage, or are they too painful for you to look at? How 'bout a photo of your car? If you were going to go with a billet crank, would you order one with the extra counter balance?
Thanks again for your contribution in this thread.

botmbulb

It's a 73 Omega, footbrake car, weighs 3450 lbs. with me in it, TH400 with a 2.75 low gear, 3.89 gear, Select Performance 9½" 4200 stall converter, 30x9 radial slicks, 900 cfm Holley ProJection, 1¾" Hedman headers, Offy Port-O-Sonic intake, 11.8 cr, shift @ 5400, through the traps @ 6000, best ET 10.49 @ 124 with a 1.35 60 ft.

The first engine with the iron heads went 11.21, then with the Edelbrocks went 10.96. This was with a Comp Cams XE284H hydraulic cam and Performer intake, shifting @ 5200 and crossing @ 5600 with 3.73 gears. Then I switched to the custom hydraulic roller cam (with similar specs to the flat tappet) using solid roller lifters, switched to 3.89 gears, and ran 10.68.

The second engine ran the same, but during it's duration I switched to the 2.75 low gear in the trans and ran 10.59.

I would estimate the current horsepower to be 530-540 and the torque to be 615-630. As far as the billet crank, I've thought about getting one from Ro-Dy (which is considerably less than a Bryant), but I keep going back to Bryant because I can get it with center counterweights. If I'm going to spend money, I might as well spend enough to get what I really want.

I'll try to dig out what carnage I kept and take a few pictures. Here's a pic of the car.

[IMG][/IMG]

J-(Chicago)

GREAT post. The cranks aren't that great. Especially the N cranks. If you run stock forged, they're still heavy as hell and 50 years old, which probably isnt any easier on the block. The CN cranks from the j headed motors I like better than the N cranks. If you notice on the journals, they have a pressure rolled fillet on the ends that I believe makes them stronger. Other than the fillets, they're the same old junk though.

One time I had an old junk 350 long block with an n crank in the back of my work van. It's only about a 30 inch drop from van door to the ground. I shoved it out of the back into the scrap pile, it landed on the balancer and broke the snout off flush with the timing cover. Looking into the broken casting, the steel was unimpressive. looked like someone spray painted a piece of styrofoam grayish black

Smitty275

250-300 passes in a year is a good bit. A lot of people say no way. But when your a regular at the track and go rounds its easy to do.
Just to share endurance stories. My reciprocating assembly went together in 2001 or 2002. Offset ground 425 crank, Manley aluminum rods, etc. and in a block with my 4 bolt main conversion installed. 12.2:1cr. It has over 3500 passes on it. I'm going to run it till it let's go. At this point it doesn't owe me a thing. The block was replaced a couple years ago for a crack in the deck that bit me in the 5th round at Norwalk one night. Best I can figure is that when I was injured at work I didn't drain the block that year and it froze. I pulled the lower hose off but that isn't enough to get the water out of the block. I normally pull the nose of the car over a bank in my side yard to drain the block. That year I only pulled the lower hose off into a pan in the trailer. Wasn't something I really had much control over at the time. But either way I think this demonstrates the durability of the 425 cranks. This combo has always ran mid 10s or better and is now in the 10.0s. Still dragging the same 3550# down the track.

Smitty275

Botmbulb, thanks for sharing your experience.

Smitty275

Well, I can't find any pics of the actual installation of a four bolt main while I was doing the machining. But I did find pics that show how and where the bolts go through, and next to the main webbing and with caps installed.
In this photo it's hard to see where the bolt holes have been drilled and tapped into the block. If you look at the center three main webs toward the bottom of the picture you will notice a slight scallop in the top of the main web. This is to make room for the bolt to go through as close to the main web as possible. Then look below the scallop and you can see where the bolt hole is drilled and tapped on the angle.
DSC01409-1.jpg
This next pic shows a cap in place. Notice the blue layout dye just out from the end of the cap. That is where I skinned the bottom of the block to be sure everything was flat and true. After that I did the same to the pads where the original caps seated. While doing this I make sure that the depth from pads to block bottom is the correct distance so I do not have to do extra work setting preload height on the outer ends of the caps. In this particular set up is where I am getting ready to drill and tap the splayed bolt holes. A guide slips into the bolt hole in the cap and keeps the drill centered where it needs to be as it gets started going into the angled area of the block. Without the guide it would be nearly impossible to put the holes in the proper position without a lot of extra work.
DSC01297.jpg
The following few pics are of the caps installed and also showing them with the splayed bolts installed.

DSC01436-1.jpg
DSC01435-1.jpg

Bernhard

If a halo is not 100% flat do you think it could have a negative effect and actually cause more harm than good?
I could see that straps would have a advantage over a halo in this area.
Dave smith used to sell straps in the early 80's and he new a thing or two about building hi- performance engines.
I could see a halo and straps helping with cap walk in mild performance builds.

67 Cutlass Freak

I'm sure some of you guys frequent Real Olds Power website, but some of you may not know about it. there's a thread over there about straps and other lower end support. You will have to sift through some BS, but there is some good information. Have a look-
http://realoldspower.prophpbb.com/topic4089.html

Smitty275

Only "some" BS? LOL

young olds

sorry if i missed it, i pretty much skimmed through looking only at the pictures. anyone here use smitty's 4 bolt caps on a big block?

69455

What is the highest HP or tork any one has dynode from a BB olds


With what lower end ?