How do you find the journal bearing clearance?
For these reasons, bearing clearances are specified as “vertical clearance” and must be measured at 90 degrees to the split line. The best method of measurement is with a dial bore gage that measures the bearing inside iameter when the bearings are installed at the specified torque without the shaft in place.
What is the rod journal size on a small-block Chevy?
All small-blocks except the 264 and 400 use 5.7-inch-long (center-to-center measurement) con rods. However, there are two different rod journal sizes to match the two different crank journal sizes available.
How much play should a crankshaft have?
Provided it’s within manufacturers’ specs, some crankshaft movement is necessary and normal, but either insufficient or excessive movement outside the normal range can eventually damage other parts. On a traditional small-block Chevy, the endplay should be 0.0020. 006 inch.
What is the clearance of crankshaft main bearing?
The commonly accepted rule that most crankshaft manufacturers prefer for street and performance engines is 0.0010-inch for every 1-inch of journal diameter. So for a 2.45-inch small-block main journal, the bearing clearance would be 0.0024-inch.
What tool is used to measure crankshaft bearing journals?
micrometer
First, the crank main bearing journals are measured using a micrometer. The micrometer is then installed in a vise so that a dial bore gauge can be installed and zeroed to the crank journal’s diameter.
What are the torque specs for a 350 Chevy?
Low-End Torque Specs Main-cap torque specification on the typical Chevrolet 350 two-bolt-main engine is 70 ft. -lbs. Specifications for the four-bolt-main are 70 ft. -lbs for the inner bolts, 65 ft.
What is the stroke of a 350 Chevy?
3.48-inch
Like the 302, it was based on the 327 block, but the 350 had an all-new crankshaft with a 3.48-inch stroke.
What is end float on a shaft?
end float in Automotive Engineering End float is the amount by which a shaft can move lengthwise. The right amount of end float is important so that your axle does not overload the opposite hub bearing by feeding axle loads from one side of the car to the opposite bearing.
How much main bearing clearance is too much?
It’s less of a concern in a dedicated racing engine, but for an engine that’s driven daily, it can increase wear and make it easier to spin a bearing, which will totally ruin your day. As a rule of thumb, main bearing clearance should be targeted between 0.0025- and 0.0020-inch for most street and street/strip engines.
How much bearing clearance do I need for a crankshaft?
The old rule of thumb is to provide .0007? to .001? of bearing clearance for every inch of shaft diameter in a stock engine. Consequently, if the crankshaft has two-inch diameter journals, the rod and main bearings should be assembled with about .0015? to .002? of clearance.
What are the bearing clearances for NASCAR engines?
In a NASCAR engine, rules limit the minimum diameters of the rod and main journals on the crankshaft. The rods are 1.850? in diameter while the mains are 1.999?. Most of these engines are running rod and main bearing clearances of .001? or less, and they are doing it with low viscosity racing oils such as 0W5, 0W30 and 0W50.
What should the bearing clearance be on a high revving engine?
This, in turn, deforms the bearings and reduces bearing clearances on the lower rod bearing while increasing it on the upper rod bearing. For high revving performance engines, some bearing manufacturers recommend rod bearing clearances of .002? to .003?, with an absolute minimum clearance of no less than .0015?.
What kind of bearing is best for cast iron cranks?
Aluminum bearings are often recommended for cast iron cranks because they have a polishing effect on the journal surface. What’s more, according to some bearing manufacturers, a high silicon alloy aluminum bi-metal bearing will actually resist seizure longer than a tri-metal bearing if the protective oil film goes away.