Hey guys, well my brothers chevelle wouldnt start. We got the timing all right, and the motor shows 0 compression on all 8 cylinders. I pulled the rockers off, and the number 1 exhaust pushrod was SUPER BENT!! Some others also showed some bending, but very minor. The car was running great and all of a sudden it shut off and wouldnt start. The car has a gear drive, but I think it may have jumped some teeth. I hooked up the air compressor to each individual cylinder, and they all held the air, without it escaping through the valves. Any ideas?

 

Number one reason for bent pushrods is piston to valve contact or something got into the cylinder and got between the piston and valve. Normally clearance during a cycle is no less than .100" so even a tiny screw dropped down the intake can cause damage.

Pull the spark plug and see if it's damaged.

If timing gears have jumped a tooth then there's some major failure inside the engine since there's no way for a gear drive to jump teeth.

 

there is no damage to the plug. I too thought the valve's had to be bad, but they both hold air without escaping, so they cant be bent.

 

Kinda far fetched but mayve the heads are cracked?

You have a cooling system pressure tester? Thats what i would try next,sounds wierd.

 

At first I thought the cam had went flat, but the valves are moving. But perhaps the piston wacked a valve and split the piston, and the air is escaping throught the bottom end instead of the valves. I dont know. Im gonna start by pulling the timing cover and go from their. Keeping the fingers crossed..

 

update, piston's are not cracked. No air is escaping. How in the world are the cylinders holding pressure, yet there is no compression? It had to have jumped timing, causing the bent pushrod, correct? Also, this all happened after someone adjusted the floats, could this have been a result of hydro-lock?

 

Yes. I've had some o-rings fail in the needle and seat and the carb floods the engine. My BBC uses 3/8" pushrods so it's hard but not impossible to bend them. It doesn't take much with a 5/16" SBC pushrod. Every now end then when I do hydraulic my engine, I pull the plugs, especially the back 4 and see if the engine cranks over. Normally that's all it takes. Blows all the fuel out the cylinders. At least I can crank my engine over without the ignition turned on or you risk igniting the fuel from a spark.

It's common to bend a pushrod from a hydraulic'd engine after pulling an injector from a Ford Powerstroke diesel. If you don't drain the high pressure oil gallery first, when you pull the injector, all the oil will fill the cylinder. Drop a new injector in and crank it over and it will bend a pushrod.

 

well I pulled the front cover off, and the gear drive had fell apart. Only has 500 miles on it. Pete Jackson! What crap! Luckily no teeth broke off.

 

Ouch. I wonder what caused it to fail? Did it fail first or did something else cause it to fail? Sometimes playing detective to locate the original failure can be hard.

I have a set of Summit noisy gears in mine. I talked to a tech at Pete Jackson. The gears are not the same. Summit has a different pitch to the teeth so they're not interchangable with Pete Jackson gears. I was after a different idler in my last engine because it had been line honed too many times. The idlers wouldn't fit between the gears. I ended up using a shorter Cloyes chain in that block. When I built this new engine, I put the gear set back in. Backlash and endplay are within spec but I haven't fired the engine up yet.

I guess the easiest way to have checked the gears would have been to pull the distributor cap off and crank the engine over. If the rotor doesn't spin around, there's a timing chain/drive problem. Either that or the roll pin for the distributor gear is sheared off which I've seen a few times.

One trick to make sure the timing set is well lubed is to drill a 1/16" hole in the gallery plugs behind the cam gear. Since the only other way for the timing set to be lubed is from pan oil sloshing to the front, this gallery spray hole makes sure there's lots of oil up front.

 

the distributor was moving. What happened was since this geardrive has a free floating idler, with two gears, the metalbrackets holding both gears in place fell apart. Its just a faulty gear drive. Thank God none of the valves got bent, nor did any teeth come off the gear drive. I filed a claim with pete jackson, and they are going to be covering everything.