Read the "cranks" section of this:

http://www.enginebuildermag.com/Article/2562/rebuilding_the_chevrolet_lt1_engine.aspx

CRANKS

350 - The crank for the LT1 looks just like the one in the late 350 and has the same casting number 14088526, but it's balanced for the lightweight pistons that were installed in the LT1. Be sure to keep these cranks separate so they don't end up in a regular 350, and don't ever use a regular 350 crank in a LT1. In fact, if you are short of LT1 cranks and don't have a balancing machine in your shop, you would be better off using a crank from a 305 instead of a 350 because it's actually closer to the balance specs for the LT1 crank.

265 - The 265 has it's own unique crank with a 3.00" stroke. That's the same stroke the original 265 had back in 1955; it's funny how things go around and come back full circle. It's a 10168568 casting.

 

So is he in trouble? What can go wrong?

Thanks Fred

 

He has the Hyper ..... pistons from speed pro, all were weighed by the machine shop and the guy said it would be fine. What balancer should he use?

 

The LT1 is neutral balanced on the front (only a damper, not a balancer) and externally balanced on the back with a weight on the flywheel or flexplate.

How was the rotating assembly balanced? They had to either do internal or external, and if they did external, they had to know where they planned to but the balance weight. If the system was correctly balanced, the LT1 crank is fine. The "rebuild" article just cautions about trying to interchange parts without balancing....e.g. stock rebuild.

Because the LT1 is neutral balanced on the front, the damper alignment is not critical, so to save a huge amount of money, even though the LT1 crank has a keyway for the damper, GM used a damper hub with no keyway, and saved a nickel per engine by not using a key......... On really high HP applications, the stock damper hub may shift on the crank, and if you add a blower, its a good idea to cut a key in the damper hub and use a key. My ATI SuperDamper has a keyway. We added a timing pointer to allow external verification of timing.

 

Nothing was balanced. The guy at the machine shop weighed the stock LT1 rod with piston then weighed the LT1 rod by itself to determine the weight of the pistons he needed to order. After ordering the speed pro hyperut.... pistons, the piston was assembled with the rod and compared to the stock weight of the stock LT1 piston and rod. The machinist said the weight was the same. As far as the back of the engine, the flywheel is stock for the 89 regular 350 and it does have a weight. A friend had a ATI fluid damper that he is not using and said we can use it. It is for the older 350, pre 86. Will this work? Where did you put the timing indicator on your engine and where are you looking for the timing mark to line up? The older 350 is in the 2 o'clock position for the pointer, on yours is it in the same place?
He is using a key for the balancer. Also we have the stock damper hub, damper, and flywheel from the fleetwood, should those be used instead? The issue with that is, there is no timing mark and how would we know if it is in time?
Thanks for your help on this Fred.

 

If he replicated the weight of the LT1 parts he should be OK. With regard to the balance, I thought the pre LT1 SBC's had a large balance weight on the damper/balancer. I'm not an engine builder, so you have to trust someone who knows more than I do.

When assembling my engine, the shop used the ATI SuperDamper hub with keyway, and keyed it to the keyway in the Callies crank. Then they put #1 at TDC and put the pointer next to the "0" on the damper (it is marked a full 360*). Without taking a look, I think the pointer is at about 2:00 o'clock. FluiDampr is not made by ATI. FluiDampr went bankrupt about 10 or 12 years ago, and the damper line was purchased by another manufacturer, and I don't know the name.

I really wanted to work side by side with the shop, and they had no problem with that, but while they were waiting for Callies to make a run on one-piece seal cranks (it took 3 months for them to make a batch) my employer sent me to Italy to work for 6 months, and I only got to come home once a month, or less. So I would go to the shop and look over the progress, and ask a lot of questions.