Any valvetrain experts out there... HELP!
05-08-2012, 10:37 PM
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Car: have a 92 camaro rs...in pieces
Engine: none now...probably 383 stroker
Transmission: none yet
Axle/Gears: none
Any valvetrain experts out there... HELP!
So here's the 411. Working on a 383. In process of measuring for pushrods and am hitting a wall and not sure what to think or do next. This is my first build and I'm in need of help. Here's what I've done so far....
1) Checked the lobe lift on the cam and it comes out to what the cam is supposed to be. In this case, .353 lobe lift. So I know the cam card and cam are correct as far as specs.
2) Mocked up check springs and used a comp cams adjustable pushrod. I used the solid lifters that were included with the degree kit... At the time of using these lifters I did not check to see lift at the valve, I was just checking to see what witness mark I ended up with... I was getting something like 7.950" for length. Mistake on my part... The solid check lifter and the hydraulic roller lifter I have are different sizes (length wise)
3) So I decided to use the hydro lifter I got, along with the check springs... Now it's more like it... Getting a length of between 7.300 - 7.350... So I'm thinking I'm good. Witness mark looked good but also noticed the lifter bleeding down when I had a dial indicator on the valve retainer...
4) It just so happens there were 2 7.350 pushrod's laying around the shop. Installed them and checked the witness mark.. It looked relatively good, but still somewhat biased towards the exhaust side of the valve tip.
5) Put a dial indicator on the retainer and proceeded to check what the geometry looked like at mid lift... but before checking mid lift I decided to check max lift... and now here's where I'm stuck.
I have 1.6 rockers and 7.350 pushrods... I am supposed to have a .565 lift with these rockers... Yet once I achieved max lift as per the indicator it only registered .395!
WHAT?! What am I doing wrong here?
So I figured the difference from what it should be, .565 and what the indicator said, .395... THat's .170 less....I can't see the loss would be on the valve side... So I calculate backwards... .170 divided by 1.6 is .106...
SO I'm not sure if the lifter is preloaded .106 or it's a combination of lifter preload and pushrod length making me lose .170 lift?
I'd like to hear opinions.
1) Checked the lobe lift on the cam and it comes out to what the cam is supposed to be. In this case, .353 lobe lift. So I know the cam card and cam are correct as far as specs.
2) Mocked up check springs and used a comp cams adjustable pushrod. I used the solid lifters that were included with the degree kit... At the time of using these lifters I did not check to see lift at the valve, I was just checking to see what witness mark I ended up with... I was getting something like 7.950" for length. Mistake on my part... The solid check lifter and the hydraulic roller lifter I have are different sizes (length wise)
3) So I decided to use the hydro lifter I got, along with the check springs... Now it's more like it... Getting a length of between 7.300 - 7.350... So I'm thinking I'm good. Witness mark looked good but also noticed the lifter bleeding down when I had a dial indicator on the valve retainer...
4) It just so happens there were 2 7.350 pushrod's laying around the shop. Installed them and checked the witness mark.. It looked relatively good, but still somewhat biased towards the exhaust side of the valve tip.
5) Put a dial indicator on the retainer and proceeded to check what the geometry looked like at mid lift... but before checking mid lift I decided to check max lift... and now here's where I'm stuck.
I have 1.6 rockers and 7.350 pushrods... I am supposed to have a .565 lift with these rockers... Yet once I achieved max lift as per the indicator it only registered .395!
WHAT?! What am I doing wrong here?
So I figured the difference from what it should be, .565 and what the indicator said, .395... THat's .170 less....I can't see the loss would be on the valve side... So I calculate backwards... .170 divided by 1.6 is .106...
SO I'm not sure if the lifter is preloaded .106 or it's a combination of lifter preload and pushrod length making me lose .170 lift?
I'd like to hear opinions.
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