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Author Topic:   rough running
posted April 23, 2004 05:01 PM
We can't adjust the valves on my 350 chevy, bored .030 howards .410 cam hydraulic cam, rotchester two barrel with 71 jets. When we try to adjust the valves it dies and runs rough. When we back off the valves it will smooth out, but the rockers are real loose. So far suggestions have been that we have solid lifters, over carburated and last bad distributor(HEI). Any thoughts?

posted April 23, 2004 06:54 PM
Setting them cold after priming engine per FLATLANDER will get you as close as you need to be. Setting them hot like that is ok but you must turn slowly and not too far and let them run loose until you break her in.

posted April 24, 2004 10:34 PM
Try idleing engine up and turning nuts slow.

posted April 27, 2004 10:04 PM
I had a similar problem. We have a max cranking compression rule at our track. I had swapped on a set of "good used heads ready to bolt on" so I was trying different head gasket thickness's to get most compression without going over the max. Anyway, when tightened the adjusters 1/2 turn past zero lash and then ran a compression test several cylinders had no compression. Back off the adjustment so there was some valve lash and compression was normal. It turned out the springs were so weak they would not preload the lifters. Instead they would open the valves. replacing the springs solved my problem and I think will solve yours also. Check the spring pressure at the installed height and open height. With that small cam you may be able to shim them to get enough seat pressure but if they are weak valve float will also be a problem. New valve springs are a lot cheaper repairing the damage to motor caused a broken valve sping or valve

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