604 grenade......ideas on the how???

[dukesracin]

Duke,
Ego is right on with the balancer. BTW, that Chinese balancer is pretty much junk, I have spun them up on a Hines and they are 30-40g off on their own ( supposed to be neutral ).

Since we are allowed to balance ASA 604's and they allow a smaller balancer I have seen 10+ ASA engines blow up shortly after the small diameter balancer was installed ( without re-balance ). I have purchased 3-4 of these engines and the reduction in mass on the damper increased the valvetrain harmonics that are pretty bad in these engines about 5200-5300rpms. Valves end up hitting pistons and either a valve head goes missing in the engine or the retainers pop off and lets the valves go flying.

I also followed this up with a similar test on the RCR spintron and the results were pretty wicked just changing from the stock 604 balance to the smaller 6 1/4" GM balancer.

You can reduce some of the harmonics with weight matching on the valvetrain parts. You can also get the valve seats trued up, flat and round and eliminate about 25% of the noise. If you run a little interference on the seat in the head and the valve seat this will also help a lot.

Finding and testing valve springs on a valve spring dyno is a final step and can reduce your valve train noise almost to zero.

Thanks, that makes a lot of sense......i should know better to buy that chinses stuff anyway....it always bites me in the rearend.