I was wondering what type of balancing the L98 crank uses? Internal or external balancing? I've been looking at 383 stroker rotating assemblies and see both listed.


Thanks, Went

 

Internal

^^^This was an error, I meant to say external.

 

Late ones with 1 piece rear seal external with counter weight on flywheel.

 

So is my 1989 L98 considered "late"? I believe my L98 has the one piece rear crank shaft seal.

Thanks

 

I would say yes as we did the Callaway cars then and all got balanced and don't remember seeing any production cars that did not have a counter weight on either the flexplate or the flywheel for a stick. There were over 400 so hard to forget LOL. The counter weight takes the place of the off center wing on the 2 piece seal factory crank.

 

'86 and newer = 1 pc rear main (counter weighted FW). Big year for the SBC.

 

The answer is really neither. The 1986 and latter engines have an externally balanced flywheel or flexplate and a neutral balanced front balancer. The pre 1985 engines all except the 400 CID SBC used a neutral balanced balancer and a neutral balanced flywheel. The 400 CID used a externally balanced flywheel and externally balanced front balancer. These are the parts that were used a 383 kits and they needed to be externally balanced both front and rear. Latter the aftermarket came up with kits that could be internally balanced which means you could use a neutral balancer and a neutral balanced flywheel. What you need to know before you buy the kit is? Is the crankshaft a one piece to two piece real seal design (You need a one piece design). You also want to know is the new 383 designed to be internally balanced and use a neutral balanced front balancer and rear flywheel or is it designed as a externally balanced engine to be used with the stock 1989 components which are neutral front balancer and 1986 and latter externally balanced flywheel? Just make sure you ask the correct questions and get the correct parts ordered. Many people purchase the incorrect parts.

FYI, I assume you want to use your stock 1989 parts so you want the one piece rear crank seal 383 kit that uses the stock front neutral balancer and the stock externally balanced flywheel.

 

Does anyone build one of the 383 engines out of a 400 block and a 350 crank using the 5.7 length rod ?? Or are these engines built with the 350 block the 400 crank and the 5.5 inch 400 rod ?? Or is there some combination totally different ??

 

Most combos are built using a 350 block, .030 over and a "400 crank". Quotes, b/c now days they're using kits that are effectively a 3.75", 350 crank. Meaning 350 sized journals, balancing, etc. as bjankuski said, in virtually whatever combo you need for your block of choice.

Every once in a while, we get a guy who wants to de-stroke a 400, w/a 350 crank (making a 377, I believe), so they can "rev it to the moon!"

Regardless of the crank/block combo, I don't think many are using a 5.5" rod anymore.


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Ok.
That's pretty much what I was thinking. I'm going to make a new thread about the general consensus on these engines. I mean are the folks using them generally happy with the end results ? Or is everyone just sort of ho hum about it thinking to themselves "i needed a new crank anyway" ....

 

"FYI, I assume you want to use your stock 1989 parts so you want the one piece rear crank seal 383 kit that uses the stock front neutral balancer and the stock externally balanced flywheel."

You assume correctly...I do want to use my stock block. I have a new cam, roller rockers, ASM runners, high flow manifold and other parts. I am "negotiating" with my wife on a set of AFR heads to top it off. Still need to order the header system.


Thanks, Went

 

Sounds like adding in the vacation someplace warm with white sand needs to go in the budget to close the deal LOL

 

I don't know if the "primary choices" have changed in recent years. When I went to pick, the main (reasonably-priced) options were a cast Eagle vs Scat9000.

The later requires 1-pc mallory on the nose (for external balancing). IIRC, the Eagle was internal balance...which would accept your stock balancer. Since you are building a long-tube stroker, the Eagle might be your best choice.

One thing I learned when researching the topic is: forged ("better") cranks are great options when you're looking for higher-rpm builds. That's where harmonics/imbalance can "flex" the crank, hurt the bearings, and destroy your build.

For the lower rpms of a torque-monster, a cast Eagle is strong enough...and, again, no imbalance on the nose. In my city, only the best builder really wants to deal with heavy metal for balancing. Plus, that "extra" adds to the cost.

Wouldn't hurt to select a builder...and consult with him before selecting your rotating assembly components. For one thing, it would be good to have your block bored/checked before picking pistons/rings.


Oh yeah...as pointed out, the back-end of the crankshaft requires external balancing for a 1-pc RMS block (like you have).

 

Is the GM crank available that they use in their 383?

 

We just went to Puerto Vallarta Mexico for a week....