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The continuing saga of my '69 Chevy C10 continues. While a very helpful TC member was improving my Q-Jet's idle characteristics, I replaced the stock intake with an ebay special Edelbrock Performer QJET RPM which cost me less than half the price of a new one. The engine in the truck is very mild (stock with a small cam) and needs to remain on "truck duty" to haul the Chevelle and other trucky tasks, so I was worried a much larger intake would hurt the low end grunt.
Anyway, for review, here are the specs on the engine:
-SB400 with a .040 overbore
-cast pisons good for around 9:1 static compression
-5.7 inch rods
-stock rams horn exhaust manifolds (dual exhaust with a cross over)
-stock Q-Jet on a stock cast iron intake (now Performer QJET RPM)
-1.72 valve heads, rough edges sanded down, but basically as cast
-Crower Baja Beast (#03015, 278HDP) cam:
-112 degree centerline
-Intake/exhaust duration: 283/286
-Intake/exhaust duration @ .050: 204/214
-Intake/exhaust lift: .422/.444
It also has a TH350 with a shift improver kit installed as the towing/RV version and 3.73 gears in a posi axle.
My only real complaint prior to the recent changes was that idle quality was poor. I had to have the idle set at 800-900 just to get it to idle in gear without stumbling or struggling. Anything beyond idle and it ran just great.
The results are in and after the slight modifications made to the carb it now idles smooth and slow and has plenty enough breath to idle in gear as it should. Another side benefit to the slower idle setting is that it shuts down better with no dieseling like it did sometimes previously.
Once I got the timing set and the choke properly adjusted I have finally gotten to drive it a little. The off-idle response is slightly softer (probably due to the much larger intake) but it definitely has more power in all RPM ranges. While getting on the interstate this morning I was very impressed how this engine moved 2 tons of brick-shaped truck from 30 to nearly 80 while only dipping into the secondaries for a few moments. If this thing had bigger heads it would be a heck of a hot rod.
I always thought the 1.72 valves were the real limiting factor as this engine was done at about 4500 (don't know for sure, the truck doesn't have a tach), but it obviously it was the intake too as it now has somewhat more top end than it used to, not that I'll use it much in a truck but it's fun to play with when I'm just tooling around. I really did not expect that changing only the intake manifold, especially on such a mild combo, would provide such a noticeable change.
I did end up having to chase down an oil leak at the oil pressure sending fittings but that was an easy fix. Along the way I found one of my exhaust manifolds has a huge crack in it so I'm not done tinkering with it yet I guess.
Would a nice set of 1-5/8 inch headers hurt low end torque.....?
Anyway, for review, here are the specs on the engine:
-SB400 with a .040 overbore
-cast pisons good for around 9:1 static compression
-5.7 inch rods
-stock rams horn exhaust manifolds (dual exhaust with a cross over)
-stock Q-Jet on a stock cast iron intake (now Performer QJET RPM)
-1.72 valve heads, rough edges sanded down, but basically as cast
-Crower Baja Beast (#03015, 278HDP) cam:
-112 degree centerline
-Intake/exhaust duration: 283/286
-Intake/exhaust duration @ .050: 204/214
-Intake/exhaust lift: .422/.444
It also has a TH350 with a shift improver kit installed as the towing/RV version and 3.73 gears in a posi axle.
My only real complaint prior to the recent changes was that idle quality was poor. I had to have the idle set at 800-900 just to get it to idle in gear without stumbling or struggling. Anything beyond idle and it ran just great.
The results are in and after the slight modifications made to the carb it now idles smooth and slow and has plenty enough breath to idle in gear as it should. Another side benefit to the slower idle setting is that it shuts down better with no dieseling like it did sometimes previously.
Once I got the timing set and the choke properly adjusted I have finally gotten to drive it a little. The off-idle response is slightly softer (probably due to the much larger intake) but it definitely has more power in all RPM ranges. While getting on the interstate this morning I was very impressed how this engine moved 2 tons of brick-shaped truck from 30 to nearly 80 while only dipping into the secondaries for a few moments. If this thing had bigger heads it would be a heck of a hot rod.
I always thought the 1.72 valves were the real limiting factor as this engine was done at about 4500 (don't know for sure, the truck doesn't have a tach), but it obviously it was the intake too as it now has somewhat more top end than it used to, not that I'll use it much in a truck but it's fun to play with when I'm just tooling around. I really did not expect that changing only the intake manifold, especially on such a mild combo, would provide such a noticeable change.
I did end up having to chase down an oil leak at the oil pressure sending fittings but that was an easy fix. Along the way I found one of my exhaust manifolds has a huge crack in it so I'm not done tinkering with it yet I guess.
Would a nice set of 1-5/8 inch headers hurt low end torque.....?
