Anyone ever seen this happen to a CB performance crank?

[iswinkels]

I had a CB crank in my last 2332 turbo engine.

It didnt break, but when I had it all balanced I was told by the machine shop that it was out by 8 grams on the counterweight at the pully end.

Im using a revmaster crank this time.

[richie morena]

good point, was the crank assembley fully balanced with flywheel and clutch, if the engine was put together without this being done then the crank would be out and cause a small ammount of vibration, this could cause the crank to break.

[pocketrocket]

The center main on all the cheap china cranks over 78 mm are weak. Not enough over lap at the rods. They all should have been made with a 411 center main. You should have DPR make you a crank off a early 13,1500 german non crossdrilled core, with a 411 center main & don't go over 82mm. With some china parts you dont know if its made of a chevy block or a china wok. Rocky

[perrib]

No but I had one of their rods crack through the big end at a 45 degree angle to the h beam back in 1990. Since then I only use Scat , and some expensive welded strokers with Pauter or Carillo rods. Now my last engine a Mahle piston cracked from the bottom of the skirt to the oil ring land and the cam and lifters went flat in 100 miles. This was a first in twenty years. It seems the price of some parts have not gone up much in 10 years but the quality has disappeared.

[neil68]

A friend had a stock based crank break much in the same fashion, just flush with the bearing jornal.

Result of not getting your foot off of it during an unplanned jump, and landing in high gear with 9500rpms on the clock.....

Jan

I've also seen a few broken welded strokers made from OEM German crankshafts...some of the old OEM's are getting a bit brittle after 40+ years

Surprised to see a new forging break like that...maybe type 1 mains and chevy journals leave too little overlap strength?

[4agedub]

I've also had a Type 4 Scat 82 stroker break like that before. The engine still ran, just had a terrable knock when on power.