1957 Blow-by

[Telluride T-bird]

Last summer I bought a '57 that's been sitting in a shed since 1989. I just got the stock 312 running am seeing a TON of exhaust gas coming out of the dip stick and valley pan cover vent. In fact, I don't see any exhaust coming out the exhaust headers at all. I poured some Miracle oil in the cylinders last summer, turned it over a bit and let it sit all winter before getting it running. I'm a poor person that has an addiction to old cars that don't run......it's a mental illness. Anyway, I can't afford to get this engine rebuilt right now, so what can I do? I have a feeling this engine is toast, but I don't want to overreact. Will I do any serious damage to this engine if I try running it for a longer period of time? I'v only let it idle for about 5 minutes so far.

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[knuckle47]

What comes to mind quickly is that if the vehicle has been sitting for so long, check the ports and exhaust for nests or mud that may have blocked them. The internal pressures need to be exhausted properly. If shear force from startup won’t do it, you should probe these lines There are several other things you’ll need to do but, it is running so that’s a start. I would not run it much until your sure it’s clean and fluids are new. After this check the compression on each cylinder

 

[Matt Moore]

Check the heat riser valve on the right exhaust header. It could be frozen in the closed position and block that side.

 

[Telluride T-bird]

I replaced the stock exhaust manifold for stainless headers but didn't check the exhaust ports. Will a dead cylinder add to all my blow-by exhaust issues? Will I do any serious damage to my motor if I run it? All fluids are changed. Engine oil is NOT detergent currently. Also, what is the vacuum hose that I have kinked off with a zip tie there in front of my carb? What does it do? I can live with the smoke if I know it isn't doing any damage to the engine. And maybe it will subside a little bit as it gets re-broken in?

 

[knuckle47]

That zip I see is the heater control… probably not needing it today on the east coast 😉

 

[Ward 57]

I replaced the stock exhaust manifold for stainless headers but didn't check the exhaust ports. Will a dead cylinder add to all my blow-by exhaust issues? Will I do any serious damage to my motor if I run it? All fluids are changed. Engine oil is NOT detergent currently. Also, what is the vacuum hose that I have kinked off with a zip tie there in front of my carb? What does it do? I can live with the smoke if I know it isn't doing any damage to the engine. And maybe it will subside a little bit as it gets re-broken in?

That zip tied hose goes to the heater control on the dash. Yah your mufflers could be full of critter nests.

 

[74 Harley]

You aren't going to hurt anything running it. That's what it really needs.

 

[Frankie the Fink]

A compression and leak down test will tell you the engine condition pretty quickly and doesn't take that much effort.

 

[doug7740]

The best way to check for a restricted exhaust is with a vacuum gauge. Connect the gauge to manifold vacuum, normal engine reading is 18 - 22 inches of vacuum with a steady needle. Increase the engine speed and if there is a restricted exhaust, the vacuum will slowly drop to zero when the engine speed is high.

If a lot of smoke coming from the down draft tube that would indicate the engines has worn bores/rings or some piston ring sticking is going on.

doug7740
1955 Thunderbird Blue