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TNCHEVYMAN 12-13-2012 08:36 PM

timing cover
 
I have a 97 roller cam sbc 4 bolt motor, i will soon start building, it nas the plastic cover on the timing chain. it says on it to replace it if removed. why is this. should i get the oe unit or should i go aftermarket? what cover should i use? THANKS

Greg T 12-13-2012 11:01 PM

Quote:

Originally Posted by TNCHEVYMAN (Post 1622552)
I have a 97 roller cam sbc 4 bolt motor, i will soon start building, it nas the plastic cover on the timing chain. it says on it to replace it if removed. why is this. should i get the oe unit or should i go aftermarket? what cover should i use? THANKS

It says to replace it because it's a piece of crap. I would get a two piece so changing cams is much easier.

cobalt327 12-14-2012 01:29 AM

Quote:

Originally Posted by TNCHEVYMAN (Post 1622552)
I have a 97 roller cam sbc 4 bolt motor, i will soon start building, it nas the plastic cover on the timing chain. it says on it to replace it if removed. why is this. should i get the oe unit or should i go aftermarket? what cover should i use? THANKS

I think it is supposed to be replaced because the front crankshaft seal is non replaceable. If the cover wasn't leaking from the front seal I see no reason to not reuse it.

Below is a side-by-side shot of a plastic cover from a 1997 Vortec engine and to the right of it is a '80s non-roller steel timing cover for comparison.

http://www.hotrodders.com/forum/atta...chmentid=38269

Some differences are:
  • The plastic cover has more room around the crank gear. This cover was equipped with a crank sensor, so the additional room may be to make room for the crank position sensor rotor.
  • The steel cover is deeper, from inside the front to the sealing surface.
  • Generally, there seems to be more room around the inside of the steel cover, even though the photos don't look that way due to how the covers are shaped. This is except for the area around the crank gear.
  • The plastic cover has fewer bolt holes at the top.
  • The plastic cover has male pins or dowels to locate the cover onto the face of the block; the steel cover has holes in the same position for the dowels that are used in the older blocks.
  • The plastic cover's bolts are shouldered to prevent over-tightening the cover.

The older block uses dowel pins (male pins in block, holes in tin cover), while the Vortec block (below) has the holes for the plastic cover's pins.

This 880 block has all the holes present and tapped. As said the dowels are absent, instead there are holes. The dowel holes in the 880 block are >15/64" and <1/4" (right for a press-fit 1/4" dowel pin, I'd guess).

http://www.hotrodders.com/forum/atta...chmentid=39001

The p/n for plastic cover w/sensor hole is: p/n10244600.

The number for plastic w/o sensor hole is: p/n12552557.

The last thing that needs checked is the type of front oil pan-to-cover seal is needed. I would guess it would be the later, thicker seal- but I'd check it first if the older cover was going to be retrofitted to the Vortec block.

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 seal
2-3/8" = thick seal

I would think using a '87-up steel timing cover w/the 1-piece oil pan gasket would be the best bet, although any steel or aftermarket cover may well work as well.

Good luck.

cobalt327 12-14-2012 03:04 AM

The SBC damper has to be installed fully so it "sandwiches" the crank gear between the crank and the damper snout. The Vortec damper from a reluctor wheel-equipped engine is shorter by the thickness of the reluctor. So if a reluctor-equipped Vortec damper is used, a spacer made from the reluctor needs to be used if a steel timing cover is going to be used.

This is because the reluctor ring won't fit behind the steel cover. Without the spacer, the damper will go on too far and the pulleys won't line up, and the damper might even bottom out on the timing cover.

http://www.hotrodders.com/gallery/da...o_1-PC_RMS.jpg

cobalt327 12-14-2012 11:40 AM

Also be prepared to get the timing tab and damper TDC line sorted out. Most likely you'll want to verify TDC anyway. Just add a damper line to match whatever timing tab you use.

Find TDC
Differences in SBC timing tabs and damper TDC lines

TNCHEVYMAN 12-14-2012 06:28 PM

ok I see, thanks alot. this info is invaluable. with out it i would have been screwed, so like i said THANKS!

cobalt327 12-15-2012 11:26 AM

My pleasure, TN.

For future reference, the above info is condensed here.


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