racers50

I am converting my 84 to a 383. Because the 400 crank uses the flywheel for balance, it is necessary to use a 400 flywheel. Problem is the 400 flywheel does not fit inside the 350 bellhousing. I know I am not the first person to do this so how did others resolve the problem?

Mojave

Rather than deal with an actual external balance 400 crank, lots and lots of companies (like Scat and Eagle) make internal balance SBC cranks with a 3.75" stroke. I would internally balance the rotating assembly and then neutral balance the flywheel and damper.

Daddybugs

I also did this...purchased complete forged rotating assy. (Eagle) all internally balanced...saved some extra headache...DDBS

bjankuski

You can buy 153 tooth externally balanced flywheels or you can buy a bolt on adapter that allows you to externally balance the 400 engine and still use your neutral balanced flywheel.

Daddybugs

I bought a neutral balance billet flywheel and attached it to my forged rotating assy. ...DDBS

rodj

Unless you have the crank real cheap , nobody goes to the trouble and $$$ of cutting a 400 crank down to fit in a 350 anymore and the associated balance problems

racers50

We finally sorted out all the problems and the car is unbelievable. If you are on the fence about just rebuilding the 350 or going 383, my vote is 383. That said, as you read in this post, go with an aftermarket crank. The 400 crank just has to many problems associated with it to make it a good deal. I had a 400 crank laying around and used it.....big mistake. The flywheel problem was fixed by getting a truck bell housing from the local bone yard. Problem there is the slave cylinder was on the wrong side. Ordering a new slave and hose for that truck solved that one. Also, the 400 uses a large Harmonic Balancer. This hits the frame when the engine is in place. Removing a piece of the frame and rewelding solved that one. I also had the Dana 36 rear and decided to convert the a 44 at this time. Thanks to this forum, that was less of a problem than anything else. The steps to take are well documented here and work very well. If I had it to do over, I would do the 383 conversion in a heartbeat. It is that good. But I would do it as advised in this post.......