I got my 1970 Rallye 350 back from the engine builder in May of last year (2010) and it has 1,200 miles on the rebuild. I had to add 2 quarts of oil before the first oil change at 500 miles, and have added 4 quarts since the oil change (700 miles). Is there something obviously wrong in this build? It is not leaking anywhere, and smokes “a little” when driving, but not bad. I just need some ideas to have the builder check. The car has good power, and throttle response. Any ideas are very much appreciated.

From the engine builder: The bore is fitted to a .030 piston and rings with a nominal bored of 4.087. The rings are not a file fit and have a proper end gap of .019-.024. The crank was a replacement as yours was damaged by the rod hammer and lack of oil pressure, the grind is .010M/.010R undersized,new clevitte bearings were installed on the mains and rods as well as the camshaft housing. The stock #6 cylinder heads were cleaned and crack checked,guides were knurled/reamed to factory spec (.343), given a competition valve job(3 angle ) and milled (.012) to straighten the deck surface. New springs and valve stem seals were installed also. After a run and tune, I drove the car for the first 160 miles. checking fluids and tune.

• CAMSHAFT: Performer-Plus Olds 350
• CATALOG #3712
• ENGINE: Oldsmobile 307/330/350/403 c.i.d. V8
• RPM RANGE: idle-5500
• CAUTION: Use only recommended Edelbrock Sure Seat
Valve Springs #5812 or original equipment equivalent.
Duration at .006” Lift: Intake 280° Exhaust 290°
Duration at .050” Lift: Intake 204° Exhaust 214°
Lift at cam: Intake .280" Exhaust .295"
Lift at valve: Intake .448" Exhaust .472"
Timing at .050 Lift:
Open Close
Intake 4° ATDC 28° ABDC
Exhaust 49° BBDC 15° BTDC
• CENTERLINES
Lobe Separation angle: 114°
Intake Centerline: 106°

Block - Oldsmobile 1976 350 Long Block
Master Rebuild kit RVCO350
Compression Ratio 9.4:1
Crankshaft #556607 w/ Pilot hole
Crank Oil Slinger “Used”
Transmission – Muncie M20 Wide Ratio 4 speed
Rear End – Stock 3.23:1 Single (SE)
Harland Sharp Roller Rockers S50026A 1.6:1, 5/16
8.400 long 1 piece chrome moly, Comp Cams .080 Pushrods
Crane Cams XR-i Points Conversion Ignition Kit #750-1720
AC Spark Plugs R45-S
Stock 1970 Manifold and Carburetor – Quadrajet 7040250 Rebuilt
Fuel Pump – AC Delco 41566
Stock exhaust manifolds w/ 2 Ό” straight pipes No Mufflers
Valvoline conventional 30 wt. Oil 4 Ύ qts.+ 8oz. Lucas Engine Break-In Oil Additive TB Zinc Plus
Fuel - 92 Octane Super Unleaded

 

My first guess is a poor seal between intake and head, allowing oil to be sucked out of the lifter valley and in thru the intake ports and valves. What type intake gasket are you using?

What oil pump was installed and what valve covers do you have? If a high-volume pump was installed without restrictors, it's possible it's pumping enough oil into the rocker area that the PCV is sucking it into the engine and burning, especially if the valve covers do not have proper baffles at the breather and PCV valve areas.

Finally, what material are the rings and was the bore finished for that material? How do the plugs look?

I went thru much the same scenario with a 455 and turned out to be the intake to head seal. I used an old Offy Dual Port that in hindsight should have been milled. I'm thinking a cast iron intake shouldn't be that much off true though.

 

Improper cylinder preperation can cause the oil rings not to seal. I`ve lived it. My cylinders were improperly honed in a car I owned, a long long time ago..