NEED ENGINE HELP!-UPDATED AGAIN

[bordin34]

I think I have a valve sticking on my 400. The engine sounds like there is air being compressed and it backfires. When I remove the spark plug wire from that cylinder it quiets down. Could I have a valve sticking and is there an easy way to help solve this. The cylinder is the second one from the front on the passenger side.

[Todd Wilson]

I'd pull the valve cover and see if thats the case. Maybe move the rocker back and forth to try and free it up some. If you can get the thing to work some then I would run some marvel mystery oil thru the car. A jug in the gas tank and possibly one in the oil and then plan for an oil change in a day or so. Or run it for an hour and change the oil. If that seems to take care of it I'd run some mystery oil in a tank or 2 of gas.


Todd

[bordin34]

Threw the oil fill hole I can see the one closest to the hole moving. Would a stuck valve quiet down when there is no spark to that cylinder.

[jwc]

Try a compression check on that whole side and see if the readings are all the same.

[firefighter3931]

When I remove the spark plug wire from that cylinder it quiets down.

That's usually a good indicator that something is wrong. A compression test and leakdown test is in order. 


Ron

[bordin34]

I removed the valve cover and everything appears to be moving normally. However I noticed that one of those clear fuel bowl sight plugs was falling apart and as soon as I got it out it broke. I got all I could out of the hole but some may have fallen into the bowl. Is there any skill or new gaskets needed if I take off the bowl to clean it out. I also bought new spark plugs and will see what those do.

[bordin34]

I also found out I have 452 heads.

A short vid of it cranking look toward the bottom left and you can see both intake and exhaust moving.

[dukeboy_318]

id say somethings messed up, do a compression test like firefighter3931 said and see what the readings are.  sounds like you might have to pull the head though

[firefighter3931]

You could have a burnt valve or bent valvestem....either of which can cause the issues you are describing. Get the compression tester on it and see what you've got. 


Ron

[bordin34]

Ok thanks, now I gotta borrow a compression gauge from somebody.

[dukeboy_318]

jegs, summit or jcwhitney have em

[bordin34]

I changed the distributor cap with one I had and I unplugged all the wires from the old one so I forget where the number 1 wire goes and can't put the rest of the wires on unless I know where the number one is. Any help. I still can't start it to see if that is the problem, waiting on fuel bowl sight plugs.

[caddman]

bump the starter till the timing mark is at the zero line, the rotor will be pointing at the number one spot on the cap (might want to mark the cap).  the symptoms that you described are the exact same thing that i had with my 318 (just this week even), with mine it was a dead lifter that beat the lobe off the cam.  I watched your video but couldn't really see much to say if they were moving.  good luck to ya.

caddman

[dukeboy_318]

I changed the distributor cap with one I had and I unplugged all the wires from the old one so I forget where the number 1 wire goes and can't put the rest of the wires on unless I know where the number one is. Any help. I still can't start it to see if that is the problem, waiting on fuel bowl sight plugs.

number on should be marked on the cap, after that use the firing order to determine which ones go where

[bordin34]

There is no number one on the cap.

[dukeboy_318]

then remove the spark plug from the number on cylinder and bump the starter till it brings the piston to top dead center, rotor should point to number one location, then put cap on and place the wires in the proper firing order.  This only works if the distributor hasnt been removed.

[firefighter3931]

then remove the spark plug from the number on cylinder and bump the starter till it brings the piston to top dead center, rotor should point to number one location, then put cap on and place the wires in the proper firing order.  This only works if the distributor hasnt been removed.

To further expand on this ; make sure the timing mark on your balancer is lined up at Zero on the timing cover tab. You can stick a small piece of wire into the spark plug hole to make sure the piston is indeed at top dead center and not bottom dead center. Once you've determined that it is in the firing position (piston top of bore) look to see where the rotor is pointing on your distributor cap....this will be #1 cylinder.

On a big block the distributor rotates counterclockwise and you simply follow the firing order and route the plug wires. Firing order is : 1-8-4-3-6-5-7-2



Ron

[dukeboy_318]

of couse if you forget to write this down, its shown on the intake manifold if its the stock intake.

[bordin34]

I did just the finger over the hole with the number 1 and my number 4 is in the same location it was in before so I guess I found my number one.

[bordin34]

A different cap didn't solve my original problem. I swapped spark plugs from a know good cylinder to the number 4 which has the problem and that didn't fix the problem. I swapped the stock coil with a blaster and that didn't fix the problem. Could new wires or electronic ignition box solve the problem?

[Charger-Bodie]

before you throw alot of $ in parts at it do a compression test!

[caddman]

by the symptoms you described, I would just about put money on it that you are facing a mechanical problem.  the carb back fire is being cased by the exhaust not escaping the cylinder.  that is unless you have some plug wires flipped then you have 2 plugs firing at the wrong time.

[bordin34]

I haven't spent a dime in spare parts, they all came with the car when I bought it. I am just trying to do some troubleshooting until I can get a compression gauge.

[dukeboy_318]

id say youve got a stuck valve for sure

[Charger-Bodie]

id say youve got a stuck valve for sure

or burnt...or bent