Bent Valves, AGAIN?

General Engine Discussion

Moderator: John_Heard

Message
Author
User avatar
wikd69
Posts: 2077
Joined: Sat Feb 23, 2008 12:42 pm
Location: Rocklin, CA
Contact:

Re: Bent Valves, AGAIN?

#16 Post by wikd69 » Mon Aug 01, 2011 1:09 pm

Hopefully this will be of help...

I just went through this procedure during original build and then again in the car after recently advancing the cam. It's pretty simple if you have the right tools. Here is the valve spring tool (SUM-906784) from Summit needed to swap valve springs - image below was from original bench build but you can do this with the heads installed - make sure the piston is at TDC so as to not run the chance of dropping the valve into the cylinder during the spring swap.

Image

You'll also want to get a set of light checking springs. You could maybe do this without swapping springs but it'd be a bitch to do, especially if you're running really stout springs in your race motor. Here's a set of Comp springs (CCA-4758-2) from Summit (there are others avail as well). You'll want to be sure to get a set of springs which will fit over your installed valve seals. Note the use of these in the images below. You'll also need a dial indicator with either a clamp-on or magnetic base. You'll note in the pix below I fabbed up a light piece of strap which I bolt down using the valve cover bolt holes - this serves as a handly platform for this sort of activity. In the two pix below you can see me checking valve to piston clearence both on the stand and in the car. I am using a degree wheel here but you can do the same thing using your installed damper, assuming it's degree marked appropriately.

Dial indicator w/trainer springs - on engine stand

Image

Dial indicator w/trainer springs - motor in car

Image

Checking Piston to Valve Clearance

It is recommend at least .080" clearance for intake valves and at least .100" for exhaust valves.

Add .030" to these figures if you have aluminum rods.

The easiest way of checking piston to valve clearance in an engine with the cylinder heads installed is to use a pair of light checking springs in place of the normal valve springs on #1 cylinder. These light springs will allow you to depress (open) the valve easily at any time during engine rotation to measure the piston to valve clearance.

After the checking springs are in place on #1 cylinder install the rocker arms and adjust valve lash to zero on that cylinder. As a general rule, the closest point of piston to valve clearance during the rotation of an engine is between 15 degrees and 5 degrees before top dead center overlap for the exhaust valve and between 5 degrees and 15 degrees after top dead center overlap for the intake valve. This sequence takes place during the overlap cycle when both valves are open, 360 degrees from the top dead center compression stroke.

Note: The actual position of closest piston to valve clearance will depend on how far advanced or retarded your cam is. Remember, as you advance your cam you will lose intake piston to valve clearance and as you retard your cam you will lose exhaust piston to valve clearance.

Exhaust Valves: With the exhaust valve on #1 cylinder adjusted to zero lash turn the engine in its normal direction of rotation until you come to 15 degrees before TDC on the overlap stroke. Set the tip of the dial indicator on the exhaust valve spring retainer, in line with the movement of the valve. Preload and zero the dial indicator to about the mid-point of travel. Depress the valve with your finger by pressing on the valve end of the rocker arm until the exhaust valve contacts the piston, making note of the reading on the dial indicator. Repeat this procedure every 2 degrees until you reach 5 degrees after TDC. Remember that the piston and valve will both be moving relative to each other – either reset the dial indicator to zero before each clearance check or subtract the difference in relative positions.

Intake Valves: With the intake valve on #1 cylinder adjusted to zero lash turn the engine in its normal direction of rotation until you come to 5 degrees before TDC on the overlap stroke. Set the tip of the dial indicator on the intake valve spring retainer, in line with the movement of the valve. Preload and zero the dial indicator to about the mid-point of travel. Depress the valve with your finger by pressing on the valve end of the rocker arm until the intake valve contacts the piston making note of the reading on the dial indicator. Repeat this procedure every 2 degrees until you reach 15 degrees after TDC. Remember that the piston and valve will both be moving relative to each other – either reset the dial indicator to zero before each clearance check or subtract the difference in relative positions.

Notes:

Hydraulic lifters - do NOT preload the lifter when setting 'zero lash'. When setting zero lash, tighten the rocker until you get a light drag while spinning the push rod.

Fly cutting - if you do not have adequate piston to valve clearance you can flycut the pistons in place (in the block) by buying a valve relief flycutter and an old head. You can find any number of articles on the net describing this. Not something I'd want to try in the motor, but people do it.
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm

DOTracer
Posts: 466
Joined: Tue May 24, 2005 11:12 pm
Location: Westminster, MD

Re: Bent Valves, AGAIN?

#17 Post by DOTracer » Mon Aug 01, 2011 1:29 pm

wikd69 wrote:Hopefully this will be of help...

I just went through this procedure during original build and then again in the car after recently advancing the cam. It's pretty simple if you have the right tools. Here is the valve spring tool (SUM-906784) from Summit needed to swap valve springs - image below was from original bench build but you can do this with the heads installed - make sure the piston is at TDC so as to not run the chance of dropping the valve into the cylinder during the spring swap.

Image

You'll also want to get a set of light checking springs. You could maybe do this without swapping springs but it'd be a bitch to do, especially if you're running really stout springs in your race motor. Here's a set of Comp springs (CCA-4758-2) from Summit (there are others avail as well). You'll want to be sure to get a set of springs which will fit over your installed valve seals. Note the use of these in the images below. You'll also need a dial indicator with either a clamp-on or magnetic base. You'll note in the pix below I fabbed up a light piece of strap which I bolt down using the valve cover bolt holes - this serves as a handly platform for this sort of activity. In the two pix below you can see me checking valve to piston clearence both on the stand and in the car. I am using a degree wheel here but you can do the same thing using your installed damper, assuming it's degree marked appropriately.

Dial indicator w/trainer springs - on engine stand

Image

Dial indicator w/trainer springs - motor in car

Image

Checking Piston to Valve Clearance

It is recommend at least .080" clearance for intake valves and at least .100" for exhaust valves.

Add .030" to these figures if you have aluminum rods.

The easiest way of checking piston to valve clearance in an engine with the cylinder heads installed is to use a pair of light checking springs in place of the normal valve springs on #1 cylinder. These light springs will allow you to depress (open) the valve easily at any time during engine rotation to measure the piston to valve clearance.

After the checking springs are in place on #1 cylinder install the rocker arms and adjust valve lash to zero on that cylinder. As a general rule, the closest point of piston to valve clearance during the rotation of an engine is between 15 degrees and 5 degrees before top dead center overlap for the exhaust valve and between 5 degrees and 15 degrees after top dead center overlap for the intake valve. This sequence takes place during the overlap cycle when both valves are open, 360 degrees from the top dead center compression stroke.

Note: The actual position of closest piston to valve clearance will depend on how far advanced or retarded your cam is. Remember, as you advance your cam you will lose intake piston to valve clearance and as you retard your cam you will lose exhaust piston to valve clearance.

Exhaust Valves: With the exhaust valve on #1 cylinder adjusted to zero lash turn the engine in its normal direction of rotation until you come to 15 degrees before TDC on the overlap stroke. Set the tip of the dial indicator on the exhaust valve spring retainer, in line with the movement of the valve. Preload and zero the dial indicator to about the mid-point of travel. Depress the valve with your finger by pressing on the valve end of the rocker arm until the exhaust valve contacts the piston, making note of the reading on the dial indicator. Repeat this procedure every 2 degrees until you reach 5 degrees after TDC. Remember that the piston and valve will both be moving relative to each other – either reset the dial indicator to zero before each clearance check or subtract the difference in relative positions.

Intake Valves: With the intake valve on #1 cylinder adjusted to zero lash turn the engine in its normal direction of rotation until you come to 5 degrees before TDC on the overlap stroke. Set the tip of the dial indicator on the intake valve spring retainer, in line with the movement of the valve. Preload and zero the dial indicator to about the mid-point of travel. Depress the valve with your finger by pressing on the valve end of the rocker arm until the intake valve contacts the piston making note of the reading on the dial indicator. Repeat this procedure every 2 degrees until you reach 15 degrees after TDC. Remember that the piston and valve will both be moving relative to each other – either reset the dial indicator to zero before each clearance check or subtract the difference in relative positions.

Notes:

Hydraulic lifters - do NOT preload the lifter when setting 'zero lash'. When setting zero lash, tighten the rocker until you get a light drag while spinning the push rod.

Fly cutting - if you do not have adequate piston to valve clearance you can flycut the pistons in place (in the block) by buying a valve relief flycutter and an old head. You can find any number of articles on the net describing this. Not something I'd want to try in the motor, but people do it.
Although not simple, this is one of the best methods with one exception. This method using checking springs does not take into account deflection of the valvetrain. When I checked mine using checker springs I had .023 or .026" as I recall. When I installed the actual valve springs, I had in excess of .070" clearance.

My point being, if you have .060" or more using checker springs, you have plenty of clearance. If your on the tight side like mine was, you need to do some other secondary checks to take deflection into account.

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#18 Post by Ls7camaro » Mon Aug 01, 2011 8:49 pm

The only valve that is bent is the Exhaust valve on the #8 cylinder. My dad took the heads to PA to a machine shop his friend uses. They are going to pull everything apart and check, the rocker arm had dings on both sides where the pushrod goes up in. Everything looks good so far. Now, I took a 6" ruler and laid across the cylinder and rotated the engine, the #8 cylinder actually comes up and touches slightly, the other cylinders do not, so I know there is a tool to get that and check. I didn't get a chance to do much as this is month end close and I worked way late.

Guys, thanks all for the help, I have actually printed out what you have typed so I can review it at lunch time, I need to buy some tools so I think I am going to order that stuff at lunch, dial indicator, magnetic base and the piece that bridges across the cylinder to see if maybe that piston is coming out meaning the block is not square.

This 400 is my dad's motor, and its just been a mess since he got it from the machine shop. 1357 cylinders look good, right now its just #8.
I can't wait for race season, this has got to be the year.

User avatar
wikd69
Posts: 2077
Joined: Sat Feb 23, 2008 12:42 pm
Location: Rocklin, CA
Contact:

Re: Bent Valves, AGAIN?

#19 Post by wikd69 » Tue Aug 02, 2011 2:07 am

Ls7camaro wrote:The only valve that is bent is the Exhaust valve on the #8 cylinder. My dad took the heads to PA to a machine shop his friend uses. They are going to pull everything apart and check, the rocker arm had dings on both sides where the pushrod goes up in. Everything looks good so far. Now, I took a 6" ruler and laid across the cylinder and rotated the engine, the #8 cylinder actually comes up and touches slightly, the other cylinders do not, so I know there is a tool to get that and check. I didn't get a chance to do much as this is month end close and I worked way late.

Guys, thanks all for the help, I have actually printed out what you have typed so I can review it at lunch time, I need to buy some tools so I think I am going to order that stuff at lunch, dial indicator, magnetic base and the piece that bridges across the cylinder to see if maybe that piston is coming out meaning the block is not square.

This 400 is my dad's motor, and its just been a mess since he got it from the machine shop. 1357 cylinders look good, right now its just #8.
So #8 actually sits higher at TDC then the other pistons ? Do you think maybe the builder swapped out a piston or mixed some parts up ? Maybe the wrong rod length ? This sounds bizarre, be sure to clue us into what you find.
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#20 Post by Ls7camaro » Thu Aug 04, 2011 11:46 am

Guys, sorry for the delay, I have a lot going on, my tools should be here today, dial indicator/base/calipers/cam checking gauge.

I need to pull the water pump off and front cover to make sure the cam is straight up. I don't have the heads back yet.

I talked to the engine builder and everything is vague, keeps telling me the cam is wiped out, if thats the case, the valve should be very low right?

I have a couple pics to put up,
Attachments
head.JPG
I can't wait for race season, this has got to be the year.

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#21 Post by Ls7camaro » Thu Aug 04, 2011 11:52 am

This is the engine side
Attachments
photo.JPG
I can't wait for race season, this has got to be the year.

User avatar
wikd69
Posts: 2077
Joined: Sat Feb 23, 2008 12:42 pm
Location: Rocklin, CA
Contact:

Re: Bent Valves, AGAIN?

#22 Post by wikd69 » Thu Aug 04, 2011 12:06 pm

Ls7camaro wrote:This is the engine side
Double *ouch*....

I'm wondering what your rod bearings are like for that cylinder... That thing really got hammered...
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#23 Post by Ls7camaro » Thu Aug 04, 2011 1:05 pm

Wikd69, I didn't even think of that. I was thinking I just needed to check the Piston to valve clearance and put the top end back together and go from there.

Do you think there is damage to the cam, I wiped the piston off there are no grooves or anything, but still would have hit pretty good to bend the valve like that.
I can't wait for race season, this has got to be the year.

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#24 Post by Ls7camaro » Thu Aug 04, 2011 8:07 pm

Ok, got to get some work tonight, I got the front end off, when I looked the cam looks like its advanced 2degrees. top the dot is straight down and the bottom says A2, I am thinking that, it would be good to run the cam straight up? Would there be any extra issue running the cam advanced like that?
I can't wait for race season, this has got to be the year.

User avatar
Carolina Kid
Posts: 254
Joined: Sat Jul 26, 2008 10:56 am

Re: Bent Valves, AGAIN?

#25 Post by Carolina Kid » Thu Aug 04, 2011 8:36 pm

If it were me, I'd pull the motor & go thru the whole thing. :|

User avatar
chpcamaro
Posts: 773
Joined: Sun Nov 09, 2008 1:28 am
Location: socali

Re: Bent Valves, AGAIN?

#26 Post by chpcamaro » Thu Aug 04, 2011 9:51 pm

as wikd69 said i bet that bearing isn't very happy even more if this isn't the first time you might check the cam it could be ground wrong and that lobe could be off also check the crank incase it is offset ground so the piston comes out of the hole or the piston sits higher on the rod from not having the motor in are hands it all we can give you is things to look at. hopefully you find it easy and it is cheap to fix. keep us updated
best to date N/A 8.91@153
psca westcoast heads up racing open comp
67 Camaro RS/SS
BBC Powerglide 4800 stall 4.11 29.5x10.5W
http://www.chpdragracing.com

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#27 Post by Ls7camaro » Wed Aug 10, 2011 7:36 pm

OK, got some tools, I got a magnetic bridge piece, and put my dial indicator in it, this is what I got, I set the dial indicator to 0. Here is what I got

#4 was .342
#8 was .346
#1 was .334
#5 was .333

#8 was the problem cylinder. I talked to the guy that originally built the engine, said, he gave all paperwork to my dad, and since then we have had a fire at his business so that is gone. I pulled the cam out, its a COMP CAM Part # 12-609-5, not overly radical?

The engine builder did say the cam was advanced 2degrees, now, there are a bunch of keyways, so not sure about that, in my car, we just ran the timing gears dot to dot, how do I do that on this one? the other thing, how do i know which zero is correct? the one on the outer or inner circle?
I can't wait for race season, this has got to be the year.

User avatar
chpcamaro
Posts: 773
Joined: Sun Nov 09, 2008 1:28 am
Location: socali

Re: Bent Valves, AGAIN?

#28 Post by chpcamaro » Wed Aug 10, 2011 8:25 pm

post a picture of the gear set and we can tell you exactly what marks to line up
best to date N/A 8.91@153
psca westcoast heads up racing open comp
67 Camaro RS/SS
BBC Powerglide 4800 stall 4.11 29.5x10.5W
http://www.chpdragracing.com

User avatar
wikd69
Posts: 2077
Joined: Sat Feb 23, 2008 12:42 pm
Location: Rocklin, CA
Contact:

Re: Bent Valves, AGAIN?

#29 Post by wikd69 » Wed Aug 10, 2011 9:54 pm

Ls7camaro wrote:OK, got some tools, I got a magnetic bridge piece, and put my dial indicator in it, this is what I got, I set the dial indicator to 0. Here is what I got

#4 was .342
#8 was .346
#1 was .334
#5 was .333

#8 was the problem cylinder. I talked to the guy that originally built the engine, said, he gave all paperwork to my dad, and since then we have had a fire at his business so that is gone. I pulled the cam out, its a COMP CAM Part # 12-609-5, not overly radical?

The engine builder did say the cam was advanced 2degrees, now, there are a bunch of keyways, so not sure about that, in my car, we just ran the timing gears dot to dot, how do I do that on this one? the other thing, how do i know which zero is correct? the one on the outer or inner circle?
<red faced> I um, recently had some experience with this...

Start on the page below and read forward - I have some pix of my goof and the fix...

viewtopic.php?f=2&t=4098&start=135
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

http://www.marsh-racing.com/harrys_camaro-1.htm

Ls7camaro
Posts: 113
Joined: Tue Mar 25, 2008 11:31 am
Location: Medina, OH

Re: Bent Valves, AGAIN?

#30 Post by Ls7camaro » Tue Oct 11, 2011 11:54 am

Guys, thanks for all the input.

Here is what I found / did. First, Disassembled everything to the short block. Sent the heads back to PA with my dad to a machine shop his friends use. The Valve to Guide Clearance needed to be "Opened" up a bit on the exhaust valves. Once that was done, heads have been re-assembled, and then the shop checked the amount each valve was in proportion to each other in the heads. I re-assembled everything, but in doing so, used "Silly Putty" to measure the Piston to Valve Clearance, when I cut the putty and the lowest level it was .051 thick, so with the head gasket, .039 compressed, gave me .090 and then the valve lash was .028. So I am good there.

I just took the car to Dragway 42 on Sunday Oct 9, the car ran really good 11.66 @ 115mph, the car does pull to the drivers side and launches really well, right now there are drum brakes on the front and rear, and the sloppy steering, any suggestions on how to fix that would be GREAT. Now, if we put Disk brakes on the car, do you put them on the front or rear(bigger tires, more stopping power?) The car needs some tweaks and some prettying up, but with some fine tuning all the way around, I am thinking this car should be in the 11.30 to 11.40 range.

THANKS Everyone for all your Advice and Help.
I can't wait for race season, this has got to be the year.

Post Reply

Who is online

Users browsing this forum: No registered users and 16 guests