I truly have no preference. We were gonna bore it to 440 mains just for crankshaft availability and selection. But molnar offers the crank I want and I have king bearings already on shelf so no sense in doing it
Ending the season early with a broken crankshaft
- Thread starter 71Demon528
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Bobzilla
Well-Known Member
Easy call for you. No need to spend more on the machine work for the larger mains if you don't need to.
What launch RPM and finish line RPM was thing running? Also, off topic, can you say what rocker arms you run on those heads?
Absolutely. No secrets here. They are jesel 1.6 individual pair rockers with an Indy R-3 cam solid roller.
Launch rpm was 4,000
Shift 1-2 at 7200
2-3 at 7300
Trap rpm on 1/8 mile was 7200
1/4 mile it was a screamer, 7800+ in decent air
Bobzilla
Well-Known Member
Very nice setup. Definitely not going easy on those parts. Thanks for all the details. I really appreciate it.
The biggest heart breaker is if you still have the receipt from buying that Eagle crank. Probably double the cost at least now.
Oh ya, you ain’t kidding. I truly have no clue what it costed back then but I’m sure it was half the price as it is now.
In a 400 block I should have said.
Ya I know when it comes to the stock blocks, the 400 is preferred over the 440 to do a stroker setup.
Thanks, but buying a house and having a kid next April are going to slow things down on fixing this for sure. But hey that’s life.
Thanks!
Do you have a mega block?
Negative,
Indy aluminum Maxx block
Indy aluminum Maxx block
Oh, nice. That's an eventually purchase for me too. Then there's a lot of meat on the main webs for expanding the diameter.
It is certainly nice having that block over a stock block.
Congratulations on both!
Thank you! Much appreciated.
Well finally got it apart. Don’t have pics of every piece of damage but here is so far what we gathered.
Bent two valves
Bent two rods
Pin bores on 4 pistons are damaged
#4 main is scarred up and can’t be fixed with an align hone. So will be getting it bored to accept 440 mains as we don’t really have a choice.
At least 3 main studs are bent
It broke right behind the #3, thrust, main. Can’t see any cracks in the block so we think we got lucky with that.
Going to be getting all new pistons with different ring pack but sticking with the 528 combo. As I’ve said before Molnar 4.15 stroke crank with molnar 6.76 rods and same custom diamond piston as I ran just with different rings.
Bent two valves
Bent two rods
Pin bores on 4 pistons are damaged
#4 main is scarred up and can’t be fixed with an align hone. So will be getting it bored to accept 440 mains as we don’t really have a choice.
At least 3 main studs are bent
It broke right behind the #3, thrust, main. Can’t see any cracks in the block so we think we got lucky with that.
Going to be getting all new pistons with different ring pack but sticking with the 528 combo. As I’ve said before Molnar 4.15 stroke crank with molnar 6.76 rods and same custom diamond piston as I ran just with different rings.
It’s a shame about all the damage but like we say in the racing business it could always be worse.
Yes sir. Always can be worse. I figured it was at least going to need crank rods and align hone plus a balance. So needing pistons sucks but oh well, gives us a chance to play more games. And the block needing taken to 440 mains is what it is. There’s a silver lining in everything.
Soooooo many different different thoughts on what to do. Ultimately it’s a bracket car and I was happy with it. So just fix it and get it back on the track.
Soooooo many different different thoughts on what to do. Ultimately it’s a bracket car and I was happy with it. So just fix it and get it back on the track.
ValiantS
Well-Known Member
Bummer that's it's broken. You were making good power but, I wouldn't think you were outside the strength boundaries of the crank. IDK Since you're having to buy a bunch of new parts I would consider the 4.25 stroke and 6.535 rod "540" which should bring the necessary speed down a tad.
Like all things there’s a trade off. I Have considered doing this many times but always decided against it. I really don’t want the extra rod angle with the shorter rod. We have spoke about pulling it off with the 6.760 rod opposed go the 6.535 rod. My pistons are custom built so we would have to have another custom set built with shorten compression height to pull that off. Still don’t think we will play that game because it was a very happy 528 til this happened. Car seemed happy too with this setup.
I’ve considered goin to 540 so many times just like I’ve considered glide, alky, etc. still racks my brain daily hahah
I’ve considered goin to 540 so many times just like I’ve considered glide, alky, etc. still racks my brain daily hahah
ValiantS
Well-Known Member
Couple of my friends have a 604" 9.8" deck BBC, the rods in that are 6.385". It made 1320HP on one carb. I may have misread your posts but it appears you need pistons rods and a crank? Or were you just going to buy the odd number of pistons and rods you'd need, reusing what's good of the old stuff? I have good respect for your engine builder and I'm not sure if this goes against the grain of what he's advising or is it from you? I know you can get some if not all 4.25" cranks to balance after you cut the counterweights for a 6.535 rod on a typical 1.3 c/h piston WITHOUT adding mallory. Now if you had a stock block, I like the longer rod for the reason you stated.
Oh we are certainly aware of the amount of BBC out there with short decks, short rods, and make big power. No disputing that. The rods I will be changing because they are chevy journal and chrysler width. So my option there is to buy another crankshaft that is chrysler journal and chrysler width, then have the crank cut down to 2.2 journal to use 6 of these rods and replace 2 bent ones. Since my choice for a replacement crankshaft and rods is molnar, their cranks come in chevy journal and chevy width. They don't offer one as chevy/chrysler. It is either chrysler/chrysler or chevy/chevy. Pistons, I may replace the 4 that need replaced, I may buy a whole new set. That is up in the air right now. My builder and I looked into shortening the CH on my piston in order to swing the 4.25 stroke and keep the 6.76 rod. It is possible, but may be a game we just don't want to play. Even if I shortened the rod, to pull off 4.250 stroke, my piston would still not work. My compression height is 1.125 and you are right, I would need 1.300 compression height with the 6.535 rod and 4.250 stroke. Although there are tons out there who do it and are successful with it, it is just not something I am interested in. If I went to a 540, it would be with a shorter CH piston (1.125 CH currently down to a 1.075 CH), and maintaining the 6.760 rod. That would do a couple things, first I would add compression to the engine going from 14.6:1 to 15:1 keeping the same Dome we currently run. Second, I would go with .9mm,.9mm,3mm ring pack over my current .043,.043,3/16 ring set. Third, it would lighten the piston even more running less CH. Would it make more power? I am sure it would. Is it worth the effort? That I am unsure about. The longer rod definitely has an advantage as you are aware. Shortening the rod and adding compression height to the piston would not only make the rod angle worse, but also add weight to the piston, so at this point just something I am going to stay away from. Even in my aftermarket Indy block, I prefer the longest rod possible.
For the sake of keeping it simple, I am leaning toward just staying with the 528 combo.
Sorry for not answering the question clearly. What you said is correct, my builder is advising against the shorter rod for the reasons listed above.
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