I am swapping in what seems to be a fairly souped up 400 sbc. It idles at about 1000-1200 rpms, and when it was running fairly crappy before I tore it down, would pull up to about 6500 rpm. I just bought it, so I had the valves ground, and with some other general maintenance, including a good tuning on the Holley once I get it running again, it appears that it will run fine.

The 400 currently has the stock externally balanced balancer on it. Somebody recommended going with a Professional Products solid stell 6.75" balancer instead of the stock piece. Is this necessary? If so, why? Is this a good balancer to use for my application? I'm also wondering if I will run into problems with crank pulley alignment and timing pointer alignment. If anybody has used one of these, will it function as a stock replacement, or will I need to modify other things? I don't want this "cheap" $60 upgrade to turn into anything more than that. I also wasn't sure if changing the balancer means to have to match it to the flywheel as well. If somebody can offer me some guidance, I would really appreciate it.

Thanks,
Eric

 

An aftermarket balancer is more for higher rpms to keep the rotating assembly from causing major vibrations which will inturn effect the whole rotationg assembly along with valves and such. In my own opinion, i think its a safe cheap insurance for your motor. I'm not familiar on your setup, so i couldn't tell you exactly, but i would just ditch the stock balancer. Hopefully someone else can chime in here and answer the rest of your questions.

 

Balancers don't last forever. The rubber that joins the 2 pieces together deteriorates and can allow the outer ring to slip out of place.

Considering GM hasn't produced a 400 since 1979, I'd say it's time for a new balancer. Price out a factory replacement from your local parts store or GM dealer. You don't need a high end SFI certified balancer but a new one should be used. You can even pick up a nice non SFI balancer from your local speed shop.

Here's one from Summit for less than $100

http://store.summitracing.com/defaul...5&autoview=sku

Although the timing mark on the balancer should always be inline with the keyway, even when using a non stock balancer and/or timing chain cover, you should always use an adjustable timing pointer. Using a degree wheel and a piston stop, find out exactly when the piston is at TDC and adjust the point to the timing mark on the balancer. Even a stock setup can be out a few degrees. I had an engine once that was out 8*.

Spending a little more money for an SFI balancer is just insurance against failure at high rpm. Personally, anything that spins higher than 5500 should have an SFI balancer. At the drag strip, anything running quicker than 10.99 in the 1/4 mile must have an SFI balancer.