Pushrod Length Question
01-01-2017, 10:35 AM
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Pushrod Length Question Hey guys, trying to figure out where I might be messing up here.
Had some LS7 lifters, doing some general upgrades so I decided to go with Morel 5315s. Prior I had 7.400" pushrods and, from what I've read, the Morels are a little longer so they are supposed to have a shorter pushrod.
I put my pushrod checker in cylinder 2 with cylinder 3 at TDC (only passenger head is on right now so I used 3 as a reference for exact TDC). I started off with the pushrod checker at 10 rotations and adjusted 1 rotation per until I got zero lash, which I checked both by holding the rocker on the stand and tapping, and then by bolting the rocker bolt in but not torquing it and tapping. I also setup and checked via the EOIC method with the same result.
With both methods, at 11 rotations I still had a very very slight amount of lash as noted by a tapping, but at 12 I had none, so I assume that 12 is where I should be. (I should note, the lash I have at 11 is very very minute, but just enough that with tapping the rocker I can hear a very slight tap, but not enough to notice any actual movement)
Now, the question comes in in that, with it being 12 rotations, that would be putting the pushrod checker length at 7.400" (0.05*12+6.800"). Then, add in preload, which Morel recommends .045" - .050", that puts me at 7.445"-7.45", a larger pushrod than what I currently have.
Am I doing something wrong here, should I go with what the calculation shows, or....?
For what it is worth, TSP 228R cam, upgraded beehive springs, MLS head gasket.
Had some LS7 lifters, doing some general upgrades so I decided to go with Morel 5315s. Prior I had 7.400" pushrods and, from what I've read, the Morels are a little longer so they are supposed to have a shorter pushrod.
I put my pushrod checker in cylinder 2 with cylinder 3 at TDC (only passenger head is on right now so I used 3 as a reference for exact TDC). I started off with the pushrod checker at 10 rotations and adjusted 1 rotation per until I got zero lash, which I checked both by holding the rocker on the stand and tapping, and then by bolting the rocker bolt in but not torquing it and tapping. I also setup and checked via the EOIC method with the same result.
With both methods, at 11 rotations I still had a very very slight amount of lash as noted by a tapping, but at 12 I had none, so I assume that 12 is where I should be. (I should note, the lash I have at 11 is very very minute, but just enough that with tapping the rocker I can hear a very slight tap, but not enough to notice any actual movement)
Now, the question comes in in that, with it being 12 rotations, that would be putting the pushrod checker length at 7.400" (0.05*12+6.800"). Then, add in preload, which Morel recommends .045" - .050", that puts me at 7.445"-7.45", a larger pushrod than what I currently have.
Am I doing something wrong here, should I go with what the calculation shows, or....?
For what it is worth, TSP 228R cam, upgraded beehive springs, MLS head gasket.
Last edited by Shigun; 01-01-2017 at 12:47 PM.
01-01-2017, 08:38 PM
#2
When you are using the adjustable length push-rod are you sure that you are NOT pre-loading the lifter? Are you on the base circle of the cam?
If you are NOT pre-loading the lifter, and you ARE on the base circle of the cam, just maybe the cam was ground on a smaller profile than factory and needs the extra length.
I just went through this and my cam was ground on a LARGER profile than factory so I had to get shorter pushrods. 7.300" is what I ended up with (and they measured 7.315" in actuality).
Did you try the zero lash and then count the # of bolt turns until you reach 22 ft. lbs? It is far less scientific than using the adjustable push rod but it is another method to compare to what you are doing now. The more turns it takes the shorter the pushrod you need. When I tried the factory push rods in my motor, it was 2.5 complete turns to reach 22 ft. lbs. from zero lash. After ordering, and installing, the correct length push rod it was only 3/4-1 turn from zero lash to reach 22 ft. lb.
If you are NOT pre-loading the lifter, and you ARE on the base circle of the cam, just maybe the cam was ground on a smaller profile than factory and needs the extra length.
I just went through this and my cam was ground on a LARGER profile than factory so I had to get shorter pushrods. 7.300" is what I ended up with (and they measured 7.315" in actuality).
Did you try the zero lash and then count the # of bolt turns until you reach 22 ft. lbs? It is far less scientific than using the adjustable push rod but it is another method to compare to what you are doing now. The more turns it takes the shorter the pushrod you need. When I tried the factory push rods in my motor, it was 2.5 complete turns to reach 22 ft. lbs. from zero lash. After ordering, and installing, the correct length push rod it was only 3/4-1 turn from zero lash to reach 22 ft. lb.
01-01-2017, 08:46 PM
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I just went through this and my cam was ground on a LARGER profile than factory so I had to get shorter pushrods. 7.300" is what I ended up with (and they measured 7.315" in actuality).
Did you try the zero lash and then count the # of bolt turns until you reach 22 ft. lbs? It is far less scientific than using the adjustable push rod but it is another method to compare to what you are doing now. The more turns it takes the shorter the pushrod you need. When I tried the factory push rods in my motor, it was 2.5 complete turns to reach 22 ft. lbs. from zero lash. After ordering, and installing, the correct length push rod it was only 3/4-1 turn from zero lash to reach 22 ft. lb.
Did you try the zero lash and then count the # of bolt turns until you reach 22 ft. lbs? It is far less scientific than using the adjustable push rod but it is another method to compare to what you are doing now. The more turns it takes the shorter the pushrod you need. When I tried the factory push rods in my motor, it was 2.5 complete turns to reach 22 ft. lbs. from zero lash. After ordering, and installing, the correct length push rod it was only 3/4-1 turn from zero lash to reach 22 ft. lb.
Thanks for the response, greatly appreciated. It's kind of funny, I've rebuilt the motor from scratch and didn't have as much issue with any of it as I have been with figuring out this.
01-02-2017, 06:58 AM
#4
Noting all the recommendations above, when you go from 11 to 12 turns it may be too much. When at 11, carefully find out what feeler gauge thickness will fit between the valve stem tip and the rocker without depressing the lifter plunger. Let's say you get 0.010" for a feeler gauge thickness. Divide that number by 1.54 (assuming stock rockers) and that is the pushrod length that must be added to get to actual zero lash. So for this case, that is 0.006" or 1/8 turn on the adjustable pushrod. Since you are adding a full turn, you are actually adding 0.050" which may be too much. You can add the 1/8 turn and then try again to see where you are.
Do you have a set of calipers that will measure the adjustable pushrod?
Also, when I did my Morels when they were new, they were very touchy with regards to depressing the lifter plunger and I found the first couple of times I tried the plunger was moving so you need to be very careful. You might want to use a pushrod and push on the plunger with a flashlight and see what it takes to make it move so you are familiar with how sensitive it is if it is in fact moving.
Do you have a set of calipers that will measure the adjustable pushrod?
Also, when I did my Morels when they were new, they were very touchy with regards to depressing the lifter plunger and I found the first couple of times I tried the plunger was moving so you need to be very careful. You might want to use a pushrod and push on the plunger with a flashlight and see what it takes to make it move so you are familiar with how sensitive it is if it is in fact moving.
01-02-2017, 10:04 AM
#5
I just rotate the checker until the point the rocker does not "tap" up and down on the pushrod. The checker is very touchy. The rocker may tap then you move it an 1/8 of a rotation and it will not. I do this while the rocker is torqued down. It takes quite some time since you are going to have to keep loosening the rocker to adjust the checker. Also, I can not stress the importance of using a digital caliper to measure the checker as opposed to using the counting of turns method. Then whatever your checker measures, add your desired preload measurement and you have your pushrod length.
01-02-2017, 11:25 AM
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Noting all the recommendations above, when you go from 11 to 12 turns it may be too much. When at 11, carefully find out what feeler gauge thickness will fit between the valve stem tip and the rocker without depressing the lifter plunger. Let's say you get 0.010" for a feeler gauge thickness. Divide that number by 1.54 (assuming stock rockers) and that is the pushrod length that must be added to get to actual zero lash. So for this case, that is 0.006" or 1/8 turn on the adjustable pushrod. Since you are adding a full turn, you are actually adding 0.050" which may be too much. You can add the 1/8 turn and then try again to see where you are.
Do you have a set of calipers that will measure the adjustable pushrod?
Also, when I did my Morels when they were new, they were very touchy with regards to depressing the lifter plunger and I found the first couple of times I tried the plunger was moving so you need to be very careful. You might want to use a pushrod and push on the plunger with a flashlight and see what it takes to make it move so you are familiar with how sensitive it is if it is in fact moving.
Do you have a set of calipers that will measure the adjustable pushrod?
Also, when I did my Morels when they were new, they were very touchy with regards to depressing the lifter plunger and I found the first couple of times I tried the plunger was moving so you need to be very careful. You might want to use a pushrod and push on the plunger with a flashlight and see what it takes to make it move so you are familiar with how sensitive it is if it is in fact moving.
I don't have a set of calipers large enough, but I'll be grabbing one today.
I just rotate the checker until the point the rocker does not "tap" up and down on the pushrod. The checker is very touchy. The rocker may tap then you move it an 1/8 of a rotation and it will not. I do this while the rocker is torqued down. It takes quite some time since you are going to have to keep loosening the rocker to adjust the checker. Also, I can not stress the importance of using a digital caliper to measure the checker as opposed to using the counting of turns method. Then whatever your checker measures, add your desired preload measurement and you have your pushrod length.
Thanks guys, greatly appreciated
01-02-2017, 11:39 AM
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Do you know the base circles of your old cam and new cam?
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01-02-2017, 05:26 PM
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Went from stock 01 Camaro LS1 cam with stock 7.385" pushrods/LS7 lifters to TSP 228R with 7.400" hardened pushrods/LS7 lifters (as per recommendation from TSP) to TSP228R with ?.???" pushrods (working to figure that one out now)/5315 lifters.
From my understanding, the TSP cams tend to have a smaller base circle, so it would make sense that I would have needed a longer pushrod. My point of confusion is that, from everything I've read, the Morel tends to be taller so should need a shorter pushrod, but my reading comes up larger.
Picked up an 8" digital caliper, so I'll be redoing all the checks and going from there.
From my understanding, the TSP cams tend to have a smaller base circle, so it would make sense that I would have needed a longer pushrod. My point of confusion is that, from everything I've read, the Morel tends to be taller so should need a shorter pushrod, but my reading comes up larger.
Picked up an 8" digital caliper, so I'll be redoing all the checks and going from there.
01-02-2017, 05:58 PM
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Originally Posted by Shigun
Went from stock 01 Camaro LS1 cam with stock 7.385" pushrods/LS7 lifters to TSP 228R with 7.400" hardened pushrods/LS7 lifters (as per recommendation from TSP) to TSP228R with ?.???" pushrods (working to figure that one out now)/5315 lifters.
From my understanding, the TSP cams tend to have a smaller base circle, so it would make sense that I would have needed a longer pushrod. My point of confusion is that, from everything I've read, the Morel tends to be taller so should need a shorter pushrod, but my reading comes up larger.
Picked up an 8" digital caliper, so I'll be redoing all the checks and going from there.
From my understanding, the TSP cams tend to have a smaller base circle, so it would make sense that I would have needed a longer pushrod. My point of confusion is that, from everything I've read, the Morel tends to be taller so should need a shorter pushrod, but my reading comes up larger.
Picked up an 8" digital caliper, so I'll be redoing all the checks and going from there.
I always recommend using a caliper. Just be sure you specify when ordering "as measured with caliper" so the vendor can adjust accordingly or else you end up with about 015" longer than you wanted.
01-02-2017, 06:30 PM
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IIRC the base circle on the 228r is .062" smaller vs the stock cam. Might be even more smaller. You mean what I know...
I always recommend using a caliper. Just be sure you specify when ordering "as measured with caliper" so the vendor can adjust accordingly or else you end up with about 015" longer than you wanted.
I always recommend using a caliper. Just be sure you specify when ordering "as measured with caliper" so the vendor can adjust accordingly or else you end up with about 015" longer than you wanted.
EOIC method, put it to where exhaust was opening to measure the intake. Applied teflon tape to pushrod length checker to prevent undesired movement.
Started off with the pushrod at 10 full turns, installed and held down rocker with fingertip pressure, checked lash. Went up 1 full turn, checked lash again, very minimal. Went up 1/8th, repeated once more till 0 lash. Took rocker bolt and hand tightened till 0 lash, then took torque wrench and torqued down to 22ft/lbs.
Result: 11 1/4 turns, 7.385", 5/8 turn to 22ft/lbs.
Swapped over to exhaust, repeated procedure described above.
Result: 11 1/4 turns, 7.385", 7/8 turn to 22ft/lbs.
So, with the above stated, and going on the fact that Morel states the 5315 needs 0.045"-0.050" preload, I believe I should get 7.435" pushrods. Can somebody confirm?
As well, to note, I am a little confused on the turns of the rocker bolt to torque method, as both of those, from what I have read, would indicate that I need a longer pushrod to get the needed preload (one full turn is ~0.047", so I would need to go up a bit in pushrod length to get the full 1 turn to be in the preload range), which would negate the pushrod checker result.
01-02-2017, 06:44 PM
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The rocker bolt turn method is more a double check. Set your pushrods length checker to 7.435" install it. Find dead soft touch with the rocker bolt. Then mark the bolt and turn it until it bottoms out. Don't torque it. Just until it bottoms out. Should be about 2/3 to 3/4 turn
If you mark it at 12:00, should end up around 8:00-9:00
If you mark it at 12:00, should end up around 8:00-9:00
01-02-2017, 06:57 PM
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The rocker bolt turn method is more a double check. Set your pushrods length checker to 7.435" install it. Find dead soft touch with the rocker bolt. Then mark the bolt and turn it until it bottoms out. Don't torque it. Just until it bottoms out. Should be about 2/3 to 3/4 turn
If you mark it at 12:00, should end up around 8:00-9:00
If you mark it at 12:00, should end up around 8:00-9:00
Seem right?
01-02-2017, 06:59 PM
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That seems just a hair long but it'll run perfectly fine
01-02-2017, 07:09 PM
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My pleasure. And that's how you do it right. You measure exactly how you did it. Then verify with rotation method.
1-full turn with zero torque is .076". .050" preload should be right around 8:00-9:00
Most likely you had about 010" preload in your original measurement and 7.425 is perfect
1-full turn with zero torque is .076". .050" preload should be right around 8:00-9:00
Most likely you had about 010" preload in your original measurement and 7.425 is perfect
01-02-2017, 07:13 PM
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Originally Posted by Shigun
Just noticed, I'm not seeing anywhere that sells a 7.43x pushrod. Should I just use a 7.425", as it seems to be the closest I can find.