I am beginning to research my next project '94 LT1 M6, stroker 383. My question is about the crank choice. Is an internally balanced crankshaft superior to an externally balanced crank. I am planning to go for low end and midrange torque limiting to 5800 max rpm. Will a cast crank be reliable up to 450hp. at flywheel? I would like to achieve excellant driveability using a shorter duration cam approx. 220deg@.050 int / 228exh w/ 114 lobe sep. and AFR heads with 195-200 cc int vol. Would 6" rods be best for this application? Any suggestions, cautions or advice is welcome as I begin my research and shopping list.

 

ALL one piece rear main seal type cranks were designed from the factory to be externally balanced. If you buy individual components and match them up, they will be hard to balance internally and hard means expensive. Your goal is a good one with realistic overtones. You will have good success staying with a cast crank and staying externally balanced. This will allow you put more money in other key areas that are expensive to get no matter what the performance level like tranny and rear end.

I highly suggest when you buy the internals, do it as a kit that is prebalanced. I like 6" rods and have them in my 383. Some here argue against them but the reasons they use are not valid if tuned properly. The benefits of longer rods far outway the consequences. Oliver rods are just simply the best money can buy. I must admit however, I have never seen Carrillo rods.

Be careful of assembled short blocks or complete engines. My son's buddy got a 383 complete from Jasper and had loose rod bolts when fired up. My point here is anyone at any time can make a mistake. The more that is left up to others only invites the possibility for more mistakes.

Also don't make the high volumn oil pump mistake. More people than not will tell you it only serves to heat up the oil more than a std volumn pump by putting more oil up top where it heats up. Unless you are spinning at very high rpms, you don't need high volumn. Stick with the std volumn.

To change the 3 center mains to 4 bolts is easy. It will then need to be align bored. Care should be taken not to drill too deep and chance going into the water jackets. Not much in the way of cost for good sound peace of mind. The part that is missed however in a stroker is adequate clearance for the rods. Mine had to have the oil pan rails clearanced and the bottom of the cylinders clearanced. If at all possible, do this before you have the cylinders bored and honed. That way if you get any scratches in the cylinders, it won't matter. Pay the extra money for the cork hone job at the end. Puts an excellent finish on the cylinders.

lastly, wash, wash, wash the block clean as a whistle. Get a set of cleaning taps and run them in every threaded hole in the block before you wash it. Get a set of cleaning brushes from your favorite performance parts place. Hot soapy water and go to town. Rinse it good, wipe out every cylinder with clean paper towels and have compressed air handy to blow it dry quckly and then spray the whole thing down with something like WD-40. Be sure to blow out every hole on the block.

New cam bearings, a good set of brass freeze plugs and your set. Measure for the bearings on the mains and rods carefully and use a good lube that will stay in place while you finish the job. STP mixed with motor oil works well. Don't forget to get the right bearings for cranks that have radiused (did i spell that right?) journals.

Oh yeah, one last thing. You will have a hard time finding cams that use the old style distributor drive so you will more than likely have to switch to the newer drive. Meaning you will need the new style timing cover and the seals to go with it. The vent system is critical for the success of this new style distributor so grab the hoses and restrictor from the JY. The Trick Flow gasket set is complete from soup to nuts and is worth the cost IMHO.

Dave

 

Ya know... I haven't found that it's too hard to internally balance a 1 piece seal stroker crank.

A Internal Balanced crank is the better way to go period.

Bret

 

Uh oh... two experts with opposite opinions.... WHOS RIGHT?! Lol.

 

I'm no expert by any means, but the guy that built my 383 insisted that it be internally ballanced. The downside for me was that I had to buy a brand new B&M SFI flex plate and have the weight removed from it since I couldn't find anyone that made one for an LT1 that was for internally ballanced engines.

 

I am about to be running a solid roller 383 with a 300 shot on top of it. My engine shop and head porter (jordon musser) both said to get the motor internally balanced. So that is what they did.

 

Thanks to all for your input!!
A couple more questions. My car has a manual trans. if I end up with internal balanced crank will I need a new neutral balance flywheel? If I go external balance will I need a special flywheel? I assume the answer is yes to both questions. Who sells the flywheels or do they typically come with a kit? Any experiance with who provides the best kit?
Craig

 

i got mine internaly ballanced and u will need a neutral ballanced flywheel, IE: Spec Lightweight Billet flywheel. Something that doesn't have couterweights on it, unlike stock flywheel...

 

ATI makes one for internal balanced LT1s. A little pricey but nice.

Dean

 

Yeah I was just goint to say the ATI one.

 

also internally balanced here with a neutral sfi balancer and mcleod neutral flywheel that came with my street twin.

 

Sorry about that, I should have noted my setup.

Internally balanced LT4 383 with:
Callies Dragonslayer Crank
neutral balanced ATI Superdampener
neutral balanced B&M SFI Flexplate