Chalk one up for experience...
Elder User
Joined: Mar 2002
Posts: 609
Likes: 0
From: Watauga TEXAS
Chalk one up for experience...
[updated:LAST EDITED ON 26-Mar-02 AT 09:58 PM (EST)]I decided to check the length of my pushrods as I began to feel that the valvetrain was running a little tight. I've been having bad fuel mileage and lack of power in my rebuilt 360 with only 6000 miles on it. It's been running great but I felt it could do better. Ignition and carburetion was right on the money and so was the timing chain.
Compression was the first thing I checked. 90's across the left bank. I thought that was too low for a fresh engine. So I tried to check valve lash. I said "tried". The lifters would not bleed off so I assumed they were all too tight. Mistake #1- Never assume!!!!
So I proceded to istall shorter pushrods. I snugged the rocker rail down by getting all the bolts hand tight and then turning them 1/4 turn working my way back and forth until I had the rail snug to the head. I then proceded to torque the rail down in 10 ft/lb increments until I reached 40 ft/lbs, then went another 5 ft/lbs. All should be ok, right?
WRONG!!!!
Fired the bad boy up, rocked and rolled for a while, then I shut her down to check my clearances one more time. EVERY PUSHROD WAS BENT, EVERY LAST ONE OF THEM!
After a brief cussing session, I decided to pull my head out, open my eyes, and look to see what the problem was. The hydraulic lifters were not bleeding down as I tightend down the rocker rail. I tried pushing them in with a long skinny punch and they still wouldn't bleed off. Finally, what I had to do was fish the lifters out one by one using a magnet and take them apart to drain off the oil inside so they would compress down. Then I was able to check my valve lash and install the correct pushrods.
Now- do ya'll wanna know something? My hunch was correct. I went from compression in the 90's to between 105 & 110 lbs. Ya reckon I ought to try for more?????
Let me know what ya'll think!
Compression was the first thing I checked. 90's across the left bank. I thought that was too low for a fresh engine. So I tried to check valve lash. I said "tried". The lifters would not bleed off so I assumed they were all too tight. Mistake #1- Never assume!!!!
So I proceded to istall shorter pushrods. I snugged the rocker rail down by getting all the bolts hand tight and then turning them 1/4 turn working my way back and forth until I had the rail snug to the head. I then proceded to torque the rail down in 10 ft/lb increments until I reached 40 ft/lbs, then went another 5 ft/lbs. All should be ok, right?
WRONG!!!!
Fired the bad boy up, rocked and rolled for a while, then I shut her down to check my clearances one more time. EVERY PUSHROD WAS BENT, EVERY LAST ONE OF THEM!
After a brief cussing session, I decided to pull my head out, open my eyes, and look to see what the problem was. The hydraulic lifters were not bleeding down as I tightend down the rocker rail. I tried pushing them in with a long skinny punch and they still wouldn't bleed off. Finally, what I had to do was fish the lifters out one by one using a magnet and take them apart to drain off the oil inside so they would compress down. Then I was able to check my valve lash and install the correct pushrods.
Now- do ya'll wanna know something? My hunch was correct. I went from compression in the 90's to between 105 & 110 lbs. Ya reckon I ought to try for more?????
Let me know what ya'll think!
Senior User
Joined: Jul 2001
Posts: 298
Likes: 0
From: Oztralia
Chalk one up for experience...
[updated:LAST EDITED ON 26-Mar-02 AT 09:49 PM (EST)]So you had to use even shorter pushrods ?
How did the pushrods bend ?
What immovable obstical did the rocker or valve touch to cause the pushrod to bend?
Where the push rods seated in the lifter and rocker correctly ?
The difference in push rod length from original to current is about 0.250 inch ?, why?
Did you machine that much off head and block ?
Lifters that wont bleed down - sounds dangerous - dont ever float the valves.
How did the pushrods bend ?
What immovable obstical did the rocker or valve touch to cause the pushrod to bend?
Where the push rods seated in the lifter and rocker correctly ?
The difference in push rod length from original to current is about 0.250 inch ?, why?
Did you machine that much off head and block ?
Lifters that wont bleed down - sounds dangerous - dont ever float the valves.