I am helping a friend with his newly purchased 69 Cutlass wagon. I'm a Chevy guy with no Olds experience. We are puttng an Edelbrock intake a Q-Jet on it to replace the stock 2 barrel. Its a stock 350 engine. We plan to replace the thermostat because we are there. I have always used 180 deg Robert Shaw thermostats. What is the recommendation for the Olds 350?

Thanks
Tom

 

180 Robertshaw will work fine. Factory spec is 190-195 but that was for emissions.

Olds was still using flapper style Dole thermostats in 1969. They worked great long as they were installed correctly. Mid 1971 they switched to the Robertshaw design, and put out a dealer tech bulletin noting the change and recommending installation of RS design for all earlier cars when the car came in for cooling system service.

 

Thanks. I guess there is a special gasket for the thermostat? Looks like there is some kind of bypass built into the manifold?

Tom

 

That's right. Olds t-stat housing incorporates a J shaped bypass tube that goes to the water pump. It uses a short length of heater hose to connect the two. If you're familiar w/ big block Chevy, it serves same purpose as the hose that goes from intake coolant crossover passage to the water pump.

The Olds thermostat housing gasket should be available. If you have to order it get a couple extras for down the road.

Hope you have the factory cast iron housing. The aftermarket chrome ones are notorious leakers and require the long obsolete 65-67 style bypass hose.

 

Thanks. Yes it has the stock housing.

Tom

 

The cast iron pieces are durable, but if you have a piece of plate glass, put a piece of 240 grit sandpaper on it and run the housing a few passes over it. That will true up the gasket surface and leave enough "tooth" for the gasket and sealer to work. Also use a soft-setting sealer on the t-stat housing bolts as the threads are open to coolant. They'll corrode bad enough with an iron intake but throw dissimilar metals together and you can get a real mess.

 

I did the same to my stock thermostat housing when i installed a new 180° thermostat, because it had some rust dents/holes.

I just put some sandpaper on a machined piece of steel and sanded the housing down to a smooth surface. A mirror or some other glass works also well.

I reinstalled both with a new Fel-pro gasket and put a thin coat of RTV on both sides of the gasket and torqued the bolts to spec. Never had any sealing issues. Just make sure, that the thermostat is installed the right direction (spring facing to the manifold, "arch" to radiator)

 

Thanks for the suggestions! I keep a piece of leftover granite countertop to "plane" surfaces like that. Didn't think about doing the housing though was unaware the bolt holes went into coolant passage.
:thumbs:
Tom

 

I thought on the Edelbrock intake the holes were sealed from the coolant passage. Been a while since I worked on mine, so I may be remembering incorrectly.

 

on all my edelbrock intakes, the bolt holes are closed to the water passage too.