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Old 05-08-2012, 10:56 PM
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Checking pushrod length... help needed.

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 the .106/ .170 lift.

I'd like to hear opinions.

Thanks.

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Old 05-08-2012, 11:06 PM
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Quote:
Originally Posted by weaz4200
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 the .106/ .170 lift.

I'd like to hear opinions.

Thanks.
It could be a combination of pushrod flex and the hydraulic lifter bleeding down.
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Old 05-08-2012, 11:09 PM
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It could be a combination of pushrod flex and the hydraulic lifter bleeding down.
Okay.... So then what should I do next?
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Old 05-08-2012, 11:38 PM
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Quote:
Originally Posted by weaz4200
Okay.... So then what should I do next?
It sounds to me like you're trying to re-engineer it. If the cam is new and you've checked the cam with the cam card, install the correct springs for that lift of cam and it sounds like you have already checked the pushrod lengths and found a good length. I would buy 3/8" diameter chrome moly pushrods instead of 5/16", buy a new set of lifters and install it, follow the correct break-in procedure and be happy.
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Old 05-09-2012, 12:23 AM
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The guide plates are for 5/16 pushrods and the lifters are new... So your saying I should just forget about the lift I'm losing and call it a day?
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Old 05-09-2012, 03:28 AM
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Quote:
Originally Posted by weaz4200
The guide plates are for 5/16 pushrods and the lifters are new... So your saying I should just forget about the lift I'm losing and call it a day?
The lifter needs to be solid. You can stack washers inside the lifter to make it solid then put it back when you're done checking. I have also used heavy grease but there can theoretically be some slight compression over time if the lifter is left w/full spring pressure on it.

BTW, just checking the lobe lift or valve lift doesn't mean the cam or timing set, etc. are accurate. You should degree the cam using a degree wheel and your dial indicator if possible. If you choose not to degree the cam, don't bother to advance or retard the cam (install it straight up) because IMO w/o knowing where you are at to begin with, there's no point in arbitrarily changing the phasing.

Here is a list of valve train points to check.
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Old 05-09-2012, 11:12 PM
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Quote:
The lifter needs to be solid. You can stack washers inside the lifter to make it solid then put it back when you're done checking.
I think I might just try that...

Quote:
You should degree the cam using a degree wheel and your dial indicator if possible.
Just a quick FYI.. I purchased the short block assembled.. Minus the cam and timing set. Had the shop install the cam and chain/gear... That being said... Even though they installed it I still took it upon myself to see where it was installed.

I checked where it was installed, dial indicator and all... Cam is installed 2 degrees advanced.
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Old 05-15-2012, 01:37 AM
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Opinions welcome. Here's a few pics of the geometry and sweep mark...

Sweep


Valve/ geometry closed


Valve/geometry at mid lift


Valve/geometry at max lift
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Old 05-15-2012, 03:22 AM
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hmmm

your install height looks wrong by what i can tell from the pics but might be bad camera angle. you just can't throw any cam in a motor or you may get coil bind and wipe out everything. have you taken into consideration for head gasket thickness?
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Old 05-15-2012, 06:14 AM
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Quote:
Originally Posted by weaz4200
Opinions welcome. Here's a few pics of the geometry and sweep mark...
The width is acceptable. Obviously the placement could be better. I hesitate to say "run it!", though, unless you have used an adjustable p-rod and have seen that's the best the parts you have can give you. So if you haven't yet used an adjustable p-rod, I think you should.

If you have used an adjustable p-rod and have determined that this is the best you can get, then it is what it is and I see no reason not to run it as-is. An argument could be made that valve guide life won't be as good that if you had a centered but wider swept area. But there's a reasonable counter-argument to be made that the valve stem-to-guide load/wear caused by an off center but narrow swept area is less harmful than a wide, centered swept area. I will have to leave that up to you to decide.

Bottom line for me: Run it- if that's the best you can get w/an adjustable p-rod and the parts you are using. But that's MY opinion. There are others here that are expert engine builders and hopefully there will be other opinions- even if they differ from mine- for you to consider before you pull the trigger.
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Old 05-15-2012, 12:31 PM
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your install height looks wrong by what i can tell from the pics but might be bad camera angle. you just can't throw any cam in a motor or you may get coil bind and wipe out everything. have you taken into consideration for head gasket thickness?
I will attach some hopefully better pics. The head were ordered with spring good up to .600 lift. The cam was picked by the engine shop I got the short block from. I just told them I want to assemble the top end myself. I chose the head gasket thickness that I believe works the best. It's .039" thick.

Quote:
If you have used an adjustable p-rod and have determined that this is the best you can get, then it is what it is and I see no reason not to run it as-is. An argument could be made that valve guide life won't be as good that if you had a centered but wider swept area. But there's a reasonable counter-argument to be made that the valve stem-to-guide load/wear caused by an off center but narrow swept area is less harmful than a wide, centered swept area. I will have to leave that up to you to decide.
Yes, I used an adjustable Pushrod in conjunction with 2 dial indicators... 1 indicator placed on the retainer to register lift and the other mounted on the actual retainer that measured the sweep of the roller tip. This is the best sweep I could get. Turned out to be .028" sweep closed to mid and a hair less at .026" sweep from mid to max. Then the same on the closing side of the ramp. With my current setup unless I went with an offset trunion I believe that to be the best... Now it's more so about deciding whether to run it like the pictures show with the narrowest sweep and exhaust biased or jeopardize the sweep to try to center the mark a bit more...I'm leaning towards leaving it where it is myself.

Here are more pics as promised.

Intake closed



Intake Mid



Intake Max

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Old 05-16-2012, 12:01 AM
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geometry looks ok. personally i've never checked for max lift. i check piston to head clearance and piston to valve clearance. but i have a spare head gasket and always put it on when i check.

two things i notice are
you are slightly back on the roller to valve tip.
lash caps will help that

the other is your dial indicator must be in exact alignment with the valve stem. yours is not
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Old 05-16-2012, 12:34 AM
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Quote:
you are slightly back on the roller to valve tip.
I'm uncertain on what that means. Can you elaborate please?
Quote:
the other is your dial indicator must be in exact alignment with the valve stem. yours is not
I assume you mean the indicator that's vertical measuring lift? How much could the reading be off?
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Old 05-16-2012, 06:21 PM
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It's way off. Look at those sideways pics closely. The tip of the roller is about to roll off of the edge of the valve. You need shorter pushrods to get it in a better spot.

You have to understand that if you use a shorter pushrod, the entire rocker arm HAS to install a little lower onto the stud. Look at the angle of the stud versus the angle of the valve. As you go from the top of the rocker stud down to the base of the stud the distance to the valve stem gets greater. You need the rocker back further.
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Old 05-16-2012, 06:28 PM
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Your pictures are very fuzzy but this is close to what you have:




^^^^ that is horrible!




Here's an IDEAL pattern:




Make it like this:


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