Vortec plastic timing cover replacement
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*The plastic cover's bolts are shouldered to prevent over-tightening the cover | *The plastic cover's bolts are shouldered to prevent over-tightening the cover | ||
*The p/n for plastic cover '''w/sensor''' hole is: p/n 10244600 | *The p/n for plastic cover '''w/sensor''' hole is: p/n 10244600 | ||
| − | *The number for plastic '''w/o sensor''' hole is: p/n 12552557 | + | *The number for plastic '''w/o sensor''' hole is: p/n 12562818 (old p/n 12552557). This new design cover is used on all ZZ4 crate engines, and will bolt to any small-block Chevrolet engine from 1995 through current model except LT1/LT4 (Gen 2) and LSx engines. |
==Vortec block== | ==Vortec block== | ||
| − | A block using a steel cover uses dowel | + | [[File:Front 880 002.jpg|400px|right|thumb|Some blocks do not have all the timing cover holes; holes that may be missing are circled]] |
| + | A block using a steel cover uses dowel pins in the block, and has the locating holes in steel cover. | ||
| − | + | The Vortec block (right) does not use block mounted dowels to locate the cover. Instead, it has holes for the plastic cover's locating pins. The locating holes in the 880 block are >15/64" and <1/4", which is about right for a press-fit 1/4" dowel pin. That said, it's not presently known if the hole size is correct for a press fit solid steel dowel like used on the earlier blocks. As a precaution, the hole should be carefully measured before driving in a solid dowel to avoid cracking the casting. Another alternative is to use a 0.250" OD hollow roll pin to avoid stressing the casting. Also the timing cover flange is thicker - 5.7L cylinder blocks with the #880 casting will accept early and late timing covers. | |
| − | + | The 880 Vortec block shown has all the holes present and tapped. This is not always the case; some blocks (those used with the 1996-02 C/K truck and vans to 2002 with the exception of those used for marine or industrial applications) are missing two holes and will need to use a gasket as a template to drill and tap the missing holes. (These blocks with the 2 undrilled timing cover holes will also have the water pump bypass hole and its corresponding hole on the RH block deck undrilled. Drilling the hole for the water pump bypass requires the use of a water pump gasket as a template (RH water pump hole) and a pre-Vortec head gasket (the hole is drilled at an angle). Fuel pump mounting boss area is usually unmachined (as with the previous 638 or 727 castings where the fuel pump pushrod hole is undrilled even if a factory blockoff plate was used). The timing cover bolt thread size is 1/4-20 (1/4" coarse), the pilot hole can be drilled with a #7 bit. | |
==Gaskets and seals== | ==Gaskets and seals== | ||
| − | The last thing that needs checked is the type of front oil pan-to-cover seal is needed. | + | The last thing that needs checked is the type of front oil pan-to-cover seal is needed. To check what front seal is needed, put a straight edge across the front of the pan and measure down to the lowest part of where the seal rests. |
| − | + | *2-1/4" = thin (early 1955-'74) seal, 3/32" thick | |
| − | To check what front seal is needed, put a straight edge across the front of the pan and measure down to the lowest part of where the seal rests. | + | *2-3/8" = thick (later 1975-'85) seal, 9/64" thick |
| − | *2-1/4" = thin seal | + | |
| − | *2-3/8" = thick seal | + | |
==Dampers== | ==Dampers== | ||
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[[File:DAMPER COMPARO GEN I to 1-PC RMS2.jpg]] | [[File:DAMPER COMPARO GEN I to 1-PC RMS2.jpg]] | ||
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| + | ===Vortec Reluctor Wheels=== | ||
| + | The Vortec reluctor wheels are either 4x (L31 or L29) or 24x (L21) signal type that measure 4.00" in diameter with an overall thickness (height) of 0.410" and have a flange thickness of 0.100" for the small block and 0.200 for the big block. The flange thickness needs to be considered when adding or removing the reluctor as it will change the crank pulley position. | ||
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