377 SBC- Pushrod Problem? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 07-11-2012, 08:55 PM
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377 SBC- Pushrod Problem?

I ran in a fresh 400/377 motor and experienced some overheating so I did not run in the cam for the full 20 minutes, more like 12 minutes. I pulled the heads and found the over heating issue was apparently caused by plugged steam holes. I fitted correct head gaskets and reinstalled the Procomp aluminum heads. After adjusting the valves, i noticed that when they are closed, they are very loose on the pushrod. I went back and re adjusted them ( 1 full turn past zero lash). Still loose. This engine was built a year or so ago, and it sat till i had a project, and I recall that i checked the pushrod length with a pair of adjustable push rods, and all seemed well.
So, I'm wondering...
1) Was the cam damaged during the running in. It does have a rough idle, but is advertised as such. it is 270/270, 224/224 duration and 470/470 lift. Comp cams #12-211-2

2) Are the pushrods simply to short, and the cam OK. Or?
Any thoughts?
Thanks

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Old 07-12-2012, 05:12 PM
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It could be that your push rods are too short but I doubt it , it sounds like you are running a hyd. cam if it sat up for a year then they are probably bleeding down from having tension on them for that period of time hyd. lifters are designed with a spring and a check valve in them and you have too prime them before installation, I soak them for a day or so before I install hyd. lifters just my preferance.
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Old 07-12-2012, 06:41 PM
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Finish your breakin on your camshaft then pull the valve covers and readjust the valves. They may indeed need to be pumped up. Did you use the same head gasket? A thicker head gasket would change your adjustment.
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Old 07-13-2012, 03:05 PM
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check your pushrod length.... If I remember correct those heads take + .150 longer pushrods... BUT you need to check... every engine can and most likely will be different at times depending on machine work done...
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Old 07-13-2012, 03:34 PM
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Pushrod length will have nothing to do with valve adjustment on a SBC. It has to do with centering the rocker tip on the valve stem. Since you can adjust the rocker arm to take all the slack out, how would the length make it loose again?
If you properly adjust the valve lash, and it then gets loose, either the lifter is collapsing, the the rocker stud is coming out of the head, or you're valve is not completely closed when you adjusted the rocker.
Pro Comp uses screw in rockers as far as I know, so check to see that the studs are not unscrewing. Make sure you're adjusting the rockers correctly also, so the lifters are on the low point of the cam, and valve is closed. If this is not done the lifter gets loose as it reaches it's lowest point, and any adjustment prior to that is futile.
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