1971: replacing valve seals

[Greg F.]

All,

I'm pretty sure I need my valve seals replaced on my original small block and I'm looking for any advice before I have this done. Also, I'm wondering if my carb is involved with this as well. The car has 62,000 original miles and VERY unmolested. No engine rebuild, original carb, etc.

I'll give the current symptons:

When I start the car after sitting for a few days or so, it will blow blue/white smoke from the drivers side tail pipe. During these cold starts, I have to pump the pedal a good amount. The passenger side doesn't blow as much. It's not an extreme amount but enough to draw attention. Also one side seems to blow the exhaust harder than the other.

After it warms up and while I'm driving it; the smoke goes away. When I do "warm starts" it blows a small puff once started but that's it. The car is not burning any oil.

Does this seem like valve seals or could it be the carb since I have to pump the gas a good amount to get it started originally (could the smoke be coming from the gas in the carb and it's just burning off)?

Any advice or direction is appreciated.

Thanks,

Greg

[Joe L.]

Re: 1971: replacing valve seals

Greg-----

It's likely valve seals or valve guides. With the relatively low mileage you have, the seals are the best bet as the source of the problem.

You can replace them with the heads on the engine if you purchase a lever type valve spring compressor tool and air fitting for the spark plug.

You can replace with stock-type o-ring seals. When you remove the old ones, you will find that they are worn and quite brittle. You can also replace with positive-type seals. Usually, these are only necessary on the intake valves. Use Viton type seals if you go this route.

[Joe L.]

Re: 1971: replacing valve seals

Greg-----

It's likely valve seals or valve guides. With the relatively low mileage you have, the seals are the best bet as the source of the problem.

You can replace them with the heads on the engine if you purchase a lever type valve spring compressor tool and air fitting for the spark plug.

You can replace with stock-type o-ring seals. When you remove the old ones, you will find that they are worn and quite brittle. You can also replace with positive-type seals. Usually, these are only necessary on the intake valves. Use Viton type seals if you go this route.

[Jack H.]

Re: 1971: replacing valve seals

If engine is stock, on cold start you should EXPECT the RH exhaust flow to be weaker than the LH side because the heat riser valve hasn't warmed and opened up yet.

Blue/white smoke could be from valves not fully closing, but it could also be the result of your carb's choke not being setup properly (wrong cold engine idle mixture).

Before tearing into the engine, I'd get a competent mechanic's opinion. Remember, on some things (like piston ring wear + valve operation) you don't have to guess! A compression check can be done to spot/isolate weak cylinders then followed by a leak-down test to fault isolate (is it piston rings not sealing, intake valve operation, exhaust valve operation?)....

[Jack H.]

Re: 1971: replacing valve seals

If engine is stock, on cold start you should EXPECT the RH exhaust flow to be weaker than the LH side because the heat riser valve hasn't warmed and opened up yet.

Blue/white smoke could be from valves not fully closing, but it could also be the result of your carb's choke not being setup properly (wrong cold engine idle mixture).

Before tearing into the engine, I'd get a competent mechanic's opinion. Remember, on some things (like piston ring wear + valve operation) you don't have to guess! A compression check can be done to spot/isolate weak cylinders then followed by a leak-down test to fault isolate (is it piston rings not sealing, intake valve operation, exhaust valve operation?)....

[Jim T.]

Re: 1971: replacing valve seals

Greg your original carb your 71 may need some attention if you have to do all the pumping you mentioned just to start your car after a few days. Q-jets have a known history of leaking fuel. The fuel bowl leakes the carbs stored fuel and requires a refill when you attempt to start the car. This problem can be repaired, however removal of your Q-Jet is required to seal the well plugs. It is not a highly technical repair. You will additionally need need a rebuild kit so you will have new gaskets and with a new accelerator pump from the kit your Q-Jet should contribute to quick start-ups even after a few days of sitting. For the best epoxy to use on sealing the well plugs, someone may offer the information. You can also check the archives.

[Jim T.]

Re: 1971: replacing valve seals

Greg your original carb your 71 may need some attention if you have to do all the pumping you mentioned just to start your car after a few days. Q-jets have a known history of leaking fuel. The fuel bowl leakes the carbs stored fuel and requires a refill when you attempt to start the car. This problem can be repaired, however removal of your Q-Jet is required to seal the well plugs. It is not a highly technical repair. You will additionally need need a rebuild kit so you will have new gaskets and with a new accelerator pump from the kit your Q-Jet should contribute to quick start-ups even after a few days of sitting. For the best epoxy to use on sealing the well plugs, someone may offer the information. You can also check the archives.

[Greg F.]

Thanks everyone!!! *NM*

[Greg F.]

Thanks everyone!!! *NM*