1968 327 in a 75 stepside

[qwas37]

Great read. Could OP need to double check push rod length? If cam timing is off, would more than one piston show valve kiss or rods bent?

Perhaps I should check the pushrod length while I’m here. All of the Pistons on the passenger side have valve kiss but no push rods are bent. I checked them by rolling them on a flat steel surface.

 

[qwas37]

You'll probably find a lot more 193s than 083s or 601s but despite all the bad mouthing people give 193s they are a great work truck dd head.better mpg and lowend torque. That's what they were designed for, the swirl atomizes the fuel so it burns better,so you use less ignition timing to light it off. The reduced timing means the piston isn't fighting ignition as long on the upstroke. It's minimum best timing. MBT. Everyone attributes the power and mpg of the the tbi trucks to the tbi,nope it's the tbi heads.

This is good to know as it will help broaden my search.

 

[Craig Nedrow]

Reread, and did not see if there was a cam change. Also not aware that gen 1 engines use different length pushrods. My book says exhaust should have min .080, Intake .050 minimum clearance. It looks like the intake only is hitting, but not sure. Could you confirm? Is the engine still in the truck? Reason I ask, I would be checking the timing chain/gears. The 68 327 was the last year of production, and shares the same crank journals as the 350. Kinda a valuable engine, and as an ol' coggie, had lots of seat time in cars with 327's.

 

[bucket]

Reread, and did not see if there was a cam change. Also not aware that gen 1 engines use different length pushrods. My book says exhaust should have min .080, Intake .050 minimum clearance. It looks like the intake only is hitting, but not sure. Could you confirm? Is the engine still in the truck? Reason I ask, I would be checking the timing chain/gears. The 68 327 was the last year of production, and shares the same crank journals as the 350. Kinda a valuable engine, and as an ol' coggie, had lots of seat time in cars with 327's.

You are correct about the pushrods, they should be the same length.

The 327 was still offered in '69 though.

 

[Ricko1966]

I buy blank pushrods and cut them to length on many performance builds so I can get my rocker geometry where I want it. Compensate for milled heads and more valve lift. Just because they'll adjust doesn't mean the geometry is correct.

 

[Turbo4whl]

Okay, the valves could have been bent with a cam gear failure. For awhile GM had cam gears with nylon teeth, to keep engine noise down. When the gear failed, and they did, the engine would still be rotating, but the cam not as fast, before it shut down. Since the engine (slang) "is not freewheeling" all the valves get bent just a little.

Many times you could replace the timing chain and gears and restart the engine, it still runs. The nylon gear teeth end up in the oil pan for years.

 

[bucket]

Okay, the valves could have been bent with a cam gear failure. For awhile GM had cam gears with nylon teeth, to keep engine noise down. When the gear failed, and they did, the engine would still be rotating, but the cam not as fast, before it shut down. Since the engine (slang) "is not freewheeling" all the valves get bent just a little.

Many times you could replace the timing chain and gears and restart the engine, it still runs. The nylon gear teeth end up in the oil pan for years.

Yeah, that's definitely no fun when that happens.

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In my case, it started to sound a little more "lopey" at idle, then later that day, the ugliness reared it's ugly head. No bent valves though, all the exhaust pushrods took the bullet.

 

[Turbo4whl]

Yeah, that's definitely no fun when that happens.

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In my case, it started to sound a little more "lopey" at idle, then later that day, the ugliness reared it's ugly head. No bent valves though, all the exhaust pushrods took the bullet.

Like you, I've been there. I guess that's how we learn. Called, "school of hard knocks"

I believe the bent valves happen when the gear fails completely at a higher RPM. Engine spins a bit before it stops, but the cam has already stopped.