[undy]

Here's my problem..

I'm getting high temp spikes shortly before my thermostat opens. It'll, for a very short time, go to 225/250 before the thermostat opens and then it'll drop back to 180 or below. My temp gauge is accurate. When the temps spike you can hear one or two cracks and pops of steam hammer in the motor before the stat opens up. Once she opens in warm weather it tends to be OK with no more temp swings. If it's cooler outside the temp spike scenario can play out 4 or 5 times once the t-sat cycles shut. I have plenty of cooling capacity in the system, at idle or speed, so that's not an issue.

Here's what I have ..

It's an aluminum block Pond KC built 482. I'm running the Mr. Gasket/Robertshaw hi-flow thermostat with three 1/8" holes drilled in the cone. I tried more/larger holes in another stat and I couldn’t build any engine temperature in cooler weather. The 3 - 1/8" holes seemed to be the best mix, at least in my application. I've done away and plugged my pump bypass line; hence the t-stat drilled holes. The rest of the cooling system's well up to the task.

Here are my thoughts...

Without the pump bypass in operation I'm not recirculating water through the block/heads. The three holes in the stat just aren't moving enough volume of water to get a good block/head circulation and "blending" of engine water temps. This lack of circulation is causing localized hot spots in the cooling system to develop (probably heads). This is why I'm getting the massive temp spikes and steam hammer before the stat finally opens. My concern is with the temp spikes come excessive momentary coolant system pressure spikes too. With the "fragile" FE intake gaskets this is not a good thing. I'm good thus far but don't want to continue tempting fate.

Here's where I ask for help..

Since lack of cooling capacity isn't an issue I'm inclined to reconnect the pump bypass, as the factory intended. This should restore proper engine coolant flow. Is my thought process sound? What would you guys do??

Dave