My 74 has always burned a little oil, but nothing major. A couple days ago, it really started running rough. I pulled a couple plugs, and there was oil on a couple. Cylinder one and three to be specific. I checked the compression and all cylinders were between 120 and 130. Is this high enough for a 74 454. It has never bee rebuilt as it has 53,000 miles. I'm wondering if oil is getting past the valve guides or what. I also heard a clicking or tapping shortly before it started running so rough. Any help you guys have would be greatly appreciated. Thanks again.

I just went thru this many times in the last 6 months with my 79 L82. It had been sitting a lot during upgrading. 59,343 miles. Ran very well, then one day, I start it, it sputtered, coughed, and missed like hell. Kept on missing. Pulled all plugs, #3 & #8 had oily deposits. Others were same, but very light. Made app't. at Corvette Performance, 60 miles down expressway. Fifteen miles down the highway at 70+mph, it smoothed out like a new kitten. Stayed that way. It sat again for about 5 weeks, while working on it. Same thing all over again. Took it out, ran the hell out of it, and now running great. I have had good input from Kstyer, Sarge, and a couple of other members here, that is to keep driving it. I put dry gas in it just to take any condensation out of the tank. Now I drive it at least every other day. Running great. I did put new AC's in.
Boatman

I run gm's top end engine cleaner through the fuel system about half a bottle once in a while used to have problems like that. Also use it as an escuse to drive your car......hahaha

I do think that something in the valves needs to be corrected. I'm not sure if I have to replace guides, or just adjust something. There was so much oil on the number one plug that I can't believe it was firing whatsoever. And the car had not sat long before running it that day. I tried running some marvel's mystery oil and that seemed to do a lot more harm than good. Very significant loss in power. I don't know if that cleared out all the sludge in the guides so now oil is leaking through, or what. Any thoughts would be great. Thanks again.

There is a case where MMO can do a lot of good. Get the crud out of the engine. But you are correct in guessing that the crud can sometimes be the only thing sealing the engine. You may need new valve seals, but I would run a bit more cleaner, the change the plug and recheck results before doing major repairs.

It sounds like you have a bad valve seal on a couple of cylinders.

I had the same problem on my 68 vette, L-79.

Hunter

chevy engines of the 70's were known to wear out valve guides often. i can rember pulling the plugs out many times and cleaning them and reinstalling them. you can go to a hotter heat range plug. they will burn off the oil better

big blocks seem to use alot more oil than most, plus they sound noisy coming through the fiberglass, compression sounds good, no real low ones, with the low milage, it sounds like that 30yrs might have dried out the stem seals, like Ken said, try a new set of OEM plugs and make sure engine is in tune, see what happens, you might want to change the oil and filter, by the way, I run 20-50 GTX in my oven.

|UPDATED|7/6/2004 11:11:07 PM (AZT)|/UPDATED|