Help needed for a 1977 K5 BLAZER 305 ENGINE HELP thank you?

(2010-05-30 16:12:52)

1. Midnighter1 Says: I have a 1977 chevy K5 blazer with a 305 engine with 35 inch tires . My problem is that it will purrrr like a kitten all day as long as I keep it under 50mph, but if I go over 50mph for longer then 5 minutes it begins to tick tick tick tick tick really fast but then when i slow down the tick goes away. I asked a few people and have gotten mixed answers like a flat spot on the camshaft, a sticking rocker, a bad rod bearing a oil pump going out or clogged . Any advice or opinions on this type of problem would be appreciated Thank you all for your time and answers.

2. bad attitude Says: It sounds like you have an oil pressure problem. If you don't have a guage go to a parts place and get one for about $10 15.00 and hook it up. Oil pressure should go up the higher rpms you have but if you have an oil pump going out it will lose pressure at higher revs. I have never heard of a cam having a flat spot and not causing the engine to miss.If it were a rod bearing it would knock at all speeds. same with a sticking lifter. Hope this helps and good luck.

3. Pilsner Man Says: Could be a lifter or rocker.

Try a can of seafoam in the crankcase, follow the directions.

4. Jared Says: Your camshaft probably has got a flat spot. Common with older small block Chevy's motors. Your cam bearings are getting some wear also. Time for a rebuild, I had an 85 305 and changed the oil pump
to a high volume one, it helped until I got another one ready to go. You can take you valve covers off and rotate your engine and check your valve springs and push rod lift. You will make a mess if you start it but you will know if your getting oil pressure.