Cam Degree & Pushrod Length Measuring Questions Placeholder
04-15-2019, 06:21 PM
#41
Melting Slicks
Thread Starter
1. Probably not. The difference in lift is split by 2 so whatever it is it isn't much
2. As mentioned earlier just shim the heads with whatever. Baseball cards whatever.....
3. With a tape measure. Off the shelf push rods are in .100 or .050 length. You'll be rounding up or down. .05" = 1.27mm. Any tape measure can measure this....
4. Until the slack is gone
5. Measure them then add subtract the difference. You should be able to look up your lifter height and order a solid match.
2. As mentioned earlier just shim the heads with whatever. Baseball cards whatever.....
3. With a tape measure. Off the shelf push rods are in .100 or .050 length. You'll be rounding up or down. .05" = 1.27mm. Any tape measure can measure this....
4. Until the slack is gone
5. Measure them then add subtract the difference. You should be able to look up your lifter height and order a solid match.
Thanks Jim!
#4 is what makes me the most nervous; I hate all the subjective "do-it-by-feel"-type operations because I have no reference for how it's supposed to be. (That's why I really like the Straub / Foxwell method.)
I think I'm good to go now. I should be able to finish this up tomorrow evening and I'll post my final measurement back here, then just in case it sounds crazy.
Adam
04-15-2019, 10:25 PM
#42
Team Owner
Member Since: Oct 2004
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St. Jude Donor '05
Id there a poster near him that can go be an extra set of eyes for him?
Easy to overthink this stuff if its your first go round.
Easy to overthink this stuff if its your first go round.
04-19-2019, 01:35 PM
#45
Race Director
I was thinking.... Use a piece of wire to make a angle/template. Go vertical up the valve and make a 90 degree bend at the center line of the rocker tip. There's you 90 degree angle going back towards the stud. From there simply loosen or tighten the nut until the pivot center line is aligned with the bent wire.
04-19-2019, 06:13 PM
#46
Melting Slicks
Thread Starter
The guideplates just weren't aligned correctly.
I have to push the intake push rod as far over as it can get without hitting the intake port; the exhaust pushrod needs to be somewhat centered within it's pushrod hole.
These guideplates will work.
Adam
I have to push the intake push rod as far over as it can get without hitting the intake port; the exhaust pushrod needs to be somewhat centered within it's pushrod hole.
These guideplates will work.
Adam
04-19-2019, 06:40 PM
#47
Melting Slicks
Thread Starter
I was thinking.... Use a piece of wire to make a angle/template. Go vertical up the valve and make a 90 degree bend at the center line of the rocker tip. There's you 90 degree angle going back towards the stud. From there simply loosen or tighten the nut until the pivot center line is aligned with the bent wire.
Adam
04-22-2019, 08:58 AM
#48
Melting Slicks
Thread Starter
Well... I measured and it was not as straight-forward as I expected.
I actually installed the head gasket and measured:
When I used the Straub / Foxwell method, I had to unscrew the pushrod length checker all the way open, which is 7.8" and honestly it needed a tiny bit more to have the line drawn between the rocker trunion and the roller tip bearing be perfectly parallel with the top of the valve / retainer. The rocker's nut had maybe 1 or 2 sets of threads holding it on -this was obviously before I lowered it 0.300" (6 turns of the nut) so that it was parallel at 1/2 the lift.
Then when I rotated the engine over 3 times and checked the witness mark the witness mark was too far towards the exhaust, which made sense just looking at it; If I used the same length on my exhaust valves it would be slightly worse as the lift is less on the exhaust lobe.
I continued to shorten the pushrod length checker until I got a nice, short sweep pattern in the center of the valve tip. Then I took the checker tool off of the intake and checked the exhaust and it was pretty good, too.
Having the two methods not "agree with each other" isn't what I expected or wanted to see and I'm not sure why but with the Comp Ultra Magnums with a 1.6 ratio on a 7/16" stud and 0.600" lobe lift, the Straub / Foxwell method made for a VERY long pushrod and a sweep that was moved out towards the exhaust.
I'm going to measure what I have and probably run with it. I think these super long comp rocker nuts would probably hit my baffles if I went with the super long pushrods anyway.
Adam
I actually installed the head gasket and measured:
When I used the Straub / Foxwell method, I had to unscrew the pushrod length checker all the way open, which is 7.8" and honestly it needed a tiny bit more to have the line drawn between the rocker trunion and the roller tip bearing be perfectly parallel with the top of the valve / retainer. The rocker's nut had maybe 1 or 2 sets of threads holding it on -this was obviously before I lowered it 0.300" (6 turns of the nut) so that it was parallel at 1/2 the lift.
Then when I rotated the engine over 3 times and checked the witness mark the witness mark was too far towards the exhaust, which made sense just looking at it; If I used the same length on my exhaust valves it would be slightly worse as the lift is less on the exhaust lobe.
I continued to shorten the pushrod length checker until I got a nice, short sweep pattern in the center of the valve tip. Then I took the checker tool off of the intake and checked the exhaust and it was pretty good, too.
Having the two methods not "agree with each other" isn't what I expected or wanted to see and I'm not sure why but with the Comp Ultra Magnums with a 1.6 ratio on a 7/16" stud and 0.600" lobe lift, the Straub / Foxwell method made for a VERY long pushrod and a sweep that was moved out towards the exhaust.
I'm going to measure what I have and probably run with it. I think these super long comp rocker nuts would probably hit my baffles if I went with the super long pushrods anyway.
Adam
04-22-2019, 09:02 AM
#49
Melting Slicks
Thread Starter
Comp also recommends the sweep pattern method in their instructions with the Hi-Tech pushrod length checkers and to answer a question earlier in the thread:
Each rotation of the Comp Hi-Tech pushrod length checker elongates the pushrod by 0.050", they advertise this as a benefit as you don't need giant calipers to determine pushrod length. (I'm going to check it both ways.)
I also find it interesting that the Comp Hi-Tech pushrod length checker and a 7/16" -20 rocker stud both move 0.050" per turn.
Each rotation of the Comp Hi-Tech pushrod length checker elongates the pushrod by 0.050", they advertise this as a benefit as you don't need giant calipers to determine pushrod length. (I'm going to check it both ways.)
I also find it interesting that the Comp Hi-Tech pushrod length checker and a 7/16" -20 rocker stud both move 0.050" per turn.
- Easy to Read
- Eliminates the Need for Expensive Calipers
- Each Complete Revolution is Equal to .050"
- The Best Tool to Measure Pushrod Length
04-22-2019, 09:45 AM
#50
Le Mans Master
Member Since: Sep 2001
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Comp also recommends the sweep pattern method in their instructions with the Hi-Tech pushrod length checkers and to answer a question earlier in the thread:
Each rotation of the Comp Hi-Tech pushrod length checker elongates the pushrod by 0.050", they advertise this as a benefit as you don't need giant calipers to determine pushrod length. (I'm going to check it both ways.)
I also find it interesting that the Comp Hi-Tech pushrod length checker and a 7/16" -20 rocker stud both move 0.050" per turn.
Each rotation of the Comp Hi-Tech pushrod length checker elongates the pushrod by 0.050", they advertise this as a benefit as you don't need giant calipers to determine pushrod length. (I'm going to check it both ways.)
I also find it interesting that the Comp Hi-Tech pushrod length checker and a 7/16" -20 rocker stud both move 0.050" per turn.
- Easy to Read
- Eliminates the Need for Expensive Calipers
- Each Complete Revolution is Equal to .050"
- The Best Tool to Measure Pushrod Length
In usa ... thread pitch TPI is Xnumber of threads per ONE inch
take 1 and divide it by number of threads per inch = distance between threads = same distance it moves per One turn... thread pitch TPI 16 is 0.0625 per turn
04-22-2019, 10:10 AM
#51
Melting Slicks
Thread Starter
makes no difference if a PR checker, a stud or a bicycle bolt ... 20 TPI pitch will always be 0.050" per turn ... if thread pitch were 40, it'll be 0.025" per turn ... if thread pitch were 28, it'll be 0.0357" per turn.
In usa ... thread pitch TPI is Xnumber of threads per ONE inch
take 1 and divide it by number of threads per inch = distance between threads = same distance it moves per One turn... thread pitch TPI 16 is 0.0625 per turn
In usa ... thread pitch TPI is Xnumber of threads per ONE inch
take 1 and divide it by number of threads per inch = distance between threads = same distance it moves per One turn... thread pitch TPI 16 is 0.0625 per turn
Adam
04-24-2019, 02:33 PM
#52
Melting Slicks
Thread Starter
I ordered a set of CompCams Hi-Tech 5/16", 0.105" wall thickness, pushrods, 7.7" long.
Pushrod length checker measured 7.65" long but comp doesn't sell that length in the 0.105" wall thickness. <-This was the length I arrived at by centering the valve sweep pattern on the valve. The Straub / Foxwell method wanted a slightly longer pushrod so I just rounded up to the next available size.
Seattle recently banned drinking straws so I decided I should go with the 0.105" wall thickness to not run afoul of the ban... ;-)
Adam
Pushrod length checker measured 7.65" long but comp doesn't sell that length in the 0.105" wall thickness. <-This was the length I arrived at by centering the valve sweep pattern on the valve. The Straub / Foxwell method wanted a slightly longer pushrod so I just rounded up to the next available size.
Seattle recently banned drinking straws so I decided I should go with the 0.105" wall thickness to not run afoul of the ban... ;-)
Adam
Last edited by NewbVetteGuy; 04-24-2019 at 02:43 PM.
04-24-2019, 05:07 PM
#53
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
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I ordered a set of CompCams Hi-Tech 5/16", 0.105" wall thickness, pushrods, 7.7" long.
Pushrod length checker measured 7.65" long but comp doesn't sell that length in the 0.105" wall thickness. <-This was the length I arrived at by centering the valve sweep pattern on the valve. The Straub / Foxwell method wanted a slightly longer pushrod so I just rounded up to the next available size.
Seattle recently banned drinking straws so I decided I should go with the 0.105" wall thickness to not run afoul of the ban... ;-)
Adam
Pushrod length checker measured 7.65" long but comp doesn't sell that length in the 0.105" wall thickness. <-This was the length I arrived at by centering the valve sweep pattern on the valve. The Straub / Foxwell method wanted a slightly longer pushrod so I just rounded up to the next available size.
Seattle recently banned drinking straws so I decided I should go with the 0.105" wall thickness to not run afoul of the ban... ;-)
Adam
04-25-2019, 11:12 AM
#54
Melting Slicks
Thread Starter
So partly I needed a thicker wall pushrod and partly $50 of “stupid tax” ordering a set of 12 and thinking it was 16..
My cams intake has only 227 degrees duration @ 0.050” but opens to 0.600” with 1.6 rockers still it’s an aggressive action and floppy noodle pushrods seem like a bad idea. (Mike Jones is a maniac.)
Adam
Last edited by NewbVetteGuy; 04-25-2019 at 11:17 AM.