Hey guys,
I'm new to this forum. I am working on a 63 Impala with the 340HP 409 ( rochester 4 barrel). Everything is stock as far as I know. This car was my Dad's, and has always had overheating issues since he rebuilt it in the early 80's. I know this is common on the 409's, but I decided to tackle the issue recently to see if I could find anything.
At the moment, it will get up to 210-220 F on an 80 degree day just sitting in the driveway idling. This is without running the front mount electric fan, which takes a few degrees off but the car still idles hot even with it on. I'm running Shell 93, highest I can get. No AC.
So far:
- Radiator boiled & flushed (it had a leak, which is what prompted this investigation). It's a 4 row Harrison
- I have the SBC fan shroud that goes 2-3 inches past the 7 blade fan. Plan to cut this down next time I have to pull the radiator, but as you will see further down, this is now a smaller concern
- New 160 deg F thermostat and new fan clutch.
-Newer Sun temperature gauge.
On cold start, engine warms up to 160 and then you can hear water flow and radiator gets hot very quickly. I haven't pulled the water pump, but it seems like the cooling system is working fine. The car comes back down to 190-200 at cruising speed.
Exhaust heat riser moves freely.
I went after the tuning next. I found that the vacuum advance and mechanical advance are working, but vacuum advance was not in effect at idle because I only had 5-6 inches vacuum. I sprayed around the carb and intake gaskets with WD40 but was unable to identify any leaks.
Then I found the PCV line was hooked up with no PCV valve. The air moving through that was noisier than the air going in the carb. If you pinched the PCV hose, the engine would stall. I put a new PCV valve in, readjusted the carburetor and my manifold vacuum is up to 8-10 inches. Still not very good.
I did a compression test. I have a range of 125 PSI to 150 PSI. Most are 130-140.
I'm planning to check valve lash next in the hopes I can get my compression evened out.
What would you advise? Is it time to get rebuild plans rolling?
Thanks!
Stephen
I'm new to this forum. I am working on a 63 Impala with the 340HP 409 ( rochester 4 barrel). Everything is stock as far as I know. This car was my Dad's, and has always had overheating issues since he rebuilt it in the early 80's. I know this is common on the 409's, but I decided to tackle the issue recently to see if I could find anything.
At the moment, it will get up to 210-220 F on an 80 degree day just sitting in the driveway idling. This is without running the front mount electric fan, which takes a few degrees off but the car still idles hot even with it on. I'm running Shell 93, highest I can get. No AC.
So far:
- Radiator boiled & flushed (it had a leak, which is what prompted this investigation). It's a 4 row Harrison
- I have the SBC fan shroud that goes 2-3 inches past the 7 blade fan. Plan to cut this down next time I have to pull the radiator, but as you will see further down, this is now a smaller concern
- New 160 deg F thermostat and new fan clutch.
-Newer Sun temperature gauge.
On cold start, engine warms up to 160 and then you can hear water flow and radiator gets hot very quickly. I haven't pulled the water pump, but it seems like the cooling system is working fine. The car comes back down to 190-200 at cruising speed.
Exhaust heat riser moves freely.
I went after the tuning next. I found that the vacuum advance and mechanical advance are working, but vacuum advance was not in effect at idle because I only had 5-6 inches vacuum. I sprayed around the carb and intake gaskets with WD40 but was unable to identify any leaks.
Then I found the PCV line was hooked up with no PCV valve. The air moving through that was noisier than the air going in the carb. If you pinched the PCV hose, the engine would stall. I put a new PCV valve in, readjusted the carburetor and my manifold vacuum is up to 8-10 inches. Still not very good.
I did a compression test. I have a range of 125 PSI to 150 PSI. Most are 130-140.
I'm planning to check valve lash next in the hopes I can get my compression evened out.
What would you advise? Is it time to get rebuild plans rolling?
Thanks!
Stephen