Think my motor is hurt

[JLM]

Did some more work on my bird this weekend (painted the inside of fenders and hood to prepare to be hung).

Anyway I pushed the car out of the garage and proceeded to start her up to to keep all the oil from settling in the pan and causing dry starts.

The engine is pretty cold blooded and usually won't start on the first crank. The engine fired on the second crank and sounded like it backfired a little. The engien idled down and idles fine but now it will not run while under load (in drive). It sputters and stalls intself out.

It's also now making a knocking sound that is coming from the exhaust. You can't hear the knocking through the block but there is a definite knock coming from the exhaust pipes that wasn't there last weekend.

The absolute only difference from the car being run this past weekend and the weekend prior was the air cleaner was on the carb this weekend. Otherwise no changes had been made.

What do you guys think? Does it sound like I hurt something or could it just be in poor tune?

[Matt@RFR]

Check your power valves.

[JLM]

Check your power valves.



There is an Edelbrock carb topping the motor, so it can't be a power valve blow out.

[wick]

Might be a stuck valve or a plug not firing. I've seen a few engines stick a valve if they have sat awhile.

[JLM]

It sat for quite a while up until about 3 months ago but has been fired a minimum of once a week since that time.

I'm going to swap the carb on it this week for a carter unit I have and see if I don't have something wrong with the carb. If that fails it looks like I'll have to start digging deeper .

[streetk14]

Sounds like you have some kind of misfire. The funny thing is that you didn't do anything to the engine. Did you check all of the vaccum plugs & connectins on the carb? You said that it popped back on start-up. I've seen PCV hose fly off when an engine backfires throught the intake. If so, you have a good sized air leak. If you have an extra carb, give it a shot. Maybe something got into the carb when you had the air cleaner off. Let us know how it goes,
Andy

[JLM]

Sounds like you have some kind of misfire. The funny thing is that you didn't do anything to the engine. Did you check all of the vaccum plugs & connectins on the carb? You said that it popped back on start-up. I've seen PCV hose fly off when an engine backfires throught the intake. If so, you have a good sized air leak. If you have an extra carb, give it a shot. Maybe something got into the carb when you had the air cleaner off. Let us know how it goes,
Andy

It didn't backfire through the intake. It kind of poped but the sound came from the exhaust pipes. I'm thinking, and hoping it's a carb issue. If it runs okay with the different carb then I know what the problem is. If no luck there I'm going to pull the valve covers and check the valve train as wick suggested. Since I've never touched the timing on the thing I'm probably going to check that as well.

[wick]

Before you pull those valve covers off, check to see if you have a dead miss. It's kind off backyard but with the motor running pull off one plug wire off at a time and listen for a change in the sound of the motor. No change and you found your dead cylinder.