350 sbc coolant drain plugs
 

Having a problem getting the drain plugs out. The engine is in the car. The block is a 3970010 casting. If I break them or some other bad news, I'm thinking my only option would be to drill them out and try to tap the hole to a bigger size. Are there other options?

My goal is to change the coolant but I don't want to create a disaster to accomplish that.

Those are tapred pipe plugs, 1/4"-NPT. If you can get heat to them and a lttle wax, they'll usually come right out. Make the plug "glow" (NOT the block around it). 9/16" six-point socket...

Jim

If the block hasn't been hot tanked before, don't be surprised if you manage to get them out and little or no coolant comes out- they are sometimes clogged up w/scale and rust. Take a length of coat hangar and poke around up in the hole and you'll loosen some of the crud enough to get some drainage out of them. Once you get some flow, flushing w/a garden hose and poking w/the wire will loosen/remove more crap until you get a good flow.

Sounds good, thanks fellas.

While I've got your attention - is a sintered bronze fuel filter at the carb sufficient (Summit brand replaceable) or should I add a paper or stainless or sintered bronze before the mechanical pump? Street car with 350 H.P. max.

Many guys don't like the sintered elements. I personally don't mind them as long as the particle size matches the application and it has enough area and flow.

I see Summit has a couple different sintered elements. The one that looks like a small top hat doesn't seem to have a micron rating so I'll guess it's fairly coarse. It is smaller than I'd want to see. But the longer cone-shaped sintered element (35 micron) looks OK.

A mechanical pump is pretty forgiving to crud in the fuel. In many/most cases the factory didn't bother to use a filter before the mechanical pump, most vehicles had only the sock in the tank until the filter right at the carb. That said, a 100 micron filter before the pump couldn't hurt as long as it has sufficient area/flow.

A finer filter can be used after the pump, like a 40 micron. Same thing with enough area/flow.

That was good information cobalt327, thanks.