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Discussion Starter · #1 ·
So, some may have seen my other thread about a smaller ID balancer needed.
Short summary, my crank snout is undersized, slightly out of round and tapered.
No luck with custom balancer due to the taper and roundness issues.
I'm trying to figure out what I want to do to resolve this.

Engine details in sig, just a general summer cruiser, commuter....maybe some day get back on a road coarse.
Rarely rev it above 5500 rpm when winding it out.

I have 2 immediate thoughts.

Option 1: Pull crank, have the snout turned and get balancer made to fit (Innovators West can do this).
Do I need to worry about additional stress with the smaller diameter and the blower pulley/belt?
If I go this route, do I worry about anything around the journals or bearings or do I just pull crank, have the snout fixed and drop it back in?
I'm guessing the answer will be it depends on what it looks like and measurements.

Option 2: New replacement crank. I think I'd need to have it checked/balanced (?) before installing. If so, do I fully disassemble, maybe a quick hone and get it all fresh and new rings/bearings...etc? Or, skip the hone and just get a balance done.

Any thoughts?

Oh, I did find a local fresh rebuild long block for sale for $2500 with questionable history....the old, I'm selling for my brother who moved out of state story.
But, I could actually look at the engine in person.
306, TFS Heads and intake, e-cam. Also, has pan, timing cover, water pump.
Unknown who did machining or the compression ratio.

I could sell off my long block or part it out (heads, intake, cam and shortblock) and get back $1000-1500.
This is tempting because I could be back on the road in a weekend.
 
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What’s the deal on the engine you have now? Stock rotating assembly?
 

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Discussion Starter · #3 ·
Yeah, stock block, crank and rods.
Just a 0.020" overbore.
 

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I'd do a new crank but that far down might as well upgrade a few things while you're there.
 

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If you have the balance data from the last time it was done, you can just call the shop that's gonna do the balancing with your data and tell em you need another crank with those bobweight values. But if you don't have that data, yep you are gonna be better off taking the crank out and starting over.

With the blower I wouldn't suggest reducing the snout diameter if at all possible. And-to add more to that, by grinding the snout down and then ordering a balancer to fit, that balancer will only fit that crankshaft unless it's honed/machined again later on. So if for some reason you break a crankshaft or spin a bearing, that's one more machining operation that needs to be done in addition to what's already got to be done. Or buy another balancer. Additional $$$.
 

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A cast crank and the sideload from a blower is a recipe for trouble....but carry on, you'll do it right eventually.
 

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A cast crank and the sideload from a blower is a recipe for trouble....but carry on, you'll do it right eventually.
I never had an issues with the cast crank I got from y’all (CHP)with my Vortech. Hell I used it in two 347 builds and around 70k miles, it’s still going too in someone else’s car now.
 

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Discussion Starter · #11 ·
Thanks for the input gents.

I did talk to a local shop and they also recommended I don't grind the current crank.

I don't have any balance data for the engine.....and I question if it was even balanced.
I have some paperwork showing the block and crank were "checked" by a shop before assembly and the assembly was completed by a fellow 'stanger.'
And, by checked I mean I have bore measurements (.020" overbore) and crank journals (.020" mains and rods).
The build sheet lists bearing clearances, thrust clearances and ring gaps. i.e. a very DIY assembly. This was almost 15 years ago.

Question: If I were to go down the route of a new/used crank, can balancing be done with the pistons/rods/rings still assembled or does that all have to come apart to get the correct rotating and reciprocating masses?
 

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They have to come apart to weigh the big end of the rods, the pin ends of the rods, the ring weight, the pin weight and piston weight. You run a very real risk of cracking a piston when pressing out the piston pin.
 

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Discussion Starter · #13 ·
Roger that.
So, you're saying it would be best to let the shop press the pin out rather than me in my garage.

One more question, any reason I can't reuse the rings? Last compression test was in the 150psi range (last summer I think) and all cylinders were similar.
 

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It doesnt matter who presses them out. If they are not pressed precisely, it will crack the pin tower. Its a very real possibility. Its totally opposite when assembling them. The pin end is heated up red hot and the pin slides in, no pressing. The opposite poses a problem. While, of course its been done successfully, dont be shocked if a piston cracks.

You can reuse them if you like.
 

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You should be able to get the crank matched balanced.
If you have a late model 5.0 crank, the one I offered you is likely a direct swap.
 

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ndmp40 has a good thought on match balancing a crank - there's a shop here in Illinois that has match balanced flexplates for me when I switched between C4 transmissions & then to powerglide but I never have asked them about crankshafts...
 

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Discussion Starter · #17 ·
Thanks for all the input. At this point, I'm going to run the engine without the blower until winter storage and think about next steps this winter. Id rather enjoy it this summer and fix during winter downtime.

Engine is smoothish, but I feel like it could be better.

I highly doubt it was balanced when it was rebuilt (with .020" over pistons), so match balancing might not work out the best. I'd be better off getting it balanced correctly with a new crank.
 

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That sounds like the best plan. Leave it as is and start planning your next engine done right to the extent of your long term HP plans.
 
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