7.425 pushrods
Safety Car
Joined: Jan 2001
Posts: 3,879
Likes: 3
From: Hobart, WI
^
Or measure the stock PR with a 8" caliper, measure the no preload installed length from the adjustable PR then add .100.
ie. if you measure a stock PR it does actually measure 7.4" end to end, so the actual and measured are the same. There is about .230-.250 of compression available in the lifter and actual dyno testing has shown ~.100 preload is best.
Or measure the stock PR with a 8" caliper, measure the no preload installed length from the adjustable PR then add .100.
ie. if you measure a stock PR it does actually measure 7.4" end to end, so the actual and measured are the same. There is about .230-.250 of compression available in the lifter and actual dyno testing has shown ~.100 preload is best.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Sleeper, I see you have come a long way from the Z06 cam!
Modding is addictive, isn't it?
Below is a real shadetree way to see if your preload is in the ballpark, It will not take the place of a good measurement tool, but it's a good way to get pretty close. Fun way to play around while you wait for that fancy pre-load checker tool to arrive.
Awhile back I was chasing the lifter noise/preload thing, and came across an interseting old thread in the archives here.
Can't locate it now, but the gist of the topic was how to get in the ballpark on preload by counting the turns on the rocker bolt as you tighten it down. (not like a smallblock, bear with me).
Basically the stock lifters like about .100 preload, as discussed here (don't know about the Caddy lifters). This guy figured out that one turn of the bolt (.050 threads, times the 1.7 ratio) equaled about 0.80 preload on the pushrod. So, about 1 1/4 turns on the bolt gave the desired .100 preload. (2.7/1.7=1.58 times .050 = 0.79).
To do this, get the cam lobe on the lowest point, loosen the bolt until the pushrod is free, and let the lifter cup rise to the top of the lifter as the internal lifter spring pushes it up. Then very gently tighten the bolt while feeling and spinning the pushrod until the slack is out and the pushrod is resting on the lifter cup against the lifter spring with no slop, but not compressing the little spring in the lifter.
Then tighten the bolt all the way to a positive stop (but don't torque it down very hard) and count the turns. You should get 1 1/4 turns for the .100 preload. (later torqueing of the bolt will add a bit of turn, but this is mostly bolt stretch, so don't count this).
I tried it, it worked pretty good, certainly accurate within 0.025, which is a close as you can get with the pushrod assortment available today.
Now, let me tell you about stuffing lawnmower starter cord in the cylinder to change valve springs, and pouring water down the throttle body to break up carbon. And how about dis-assemblying thermostats and poking a small ball bearing under the plunger to create a 180 thermo.
Cheers,
DG
Modding is addictive, isn't it?
Below is a real shadetree way to see if your preload is in the ballpark, It will not take the place of a good measurement tool, but it's a good way to get pretty close. Fun way to play around while you wait for that fancy pre-load checker tool to arrive.
Awhile back I was chasing the lifter noise/preload thing, and came across an interseting old thread in the archives here.
Can't locate it now, but the gist of the topic was how to get in the ballpark on preload by counting the turns on the rocker bolt as you tighten it down. (not like a smallblock, bear with me).
Basically the stock lifters like about .100 preload, as discussed here (don't know about the Caddy lifters). This guy figured out that one turn of the bolt (.050 threads, times the 1.7 ratio) equaled about 0.80 preload on the pushrod. So, about 1 1/4 turns on the bolt gave the desired .100 preload. (2.7/1.7=1.58 times .050 = 0.79).
To do this, get the cam lobe on the lowest point, loosen the bolt until the pushrod is free, and let the lifter cup rise to the top of the lifter as the internal lifter spring pushes it up. Then very gently tighten the bolt while feeling and spinning the pushrod until the slack is out and the pushrod is resting on the lifter cup against the lifter spring with no slop, but not compressing the little spring in the lifter.
Then tighten the bolt all the way to a positive stop (but don't torque it down very hard) and count the turns. You should get 1 1/4 turns for the .100 preload. (later torqueing of the bolt will add a bit of turn, but this is mostly bolt stretch, so don't count this).
I tried it, it worked pretty good, certainly accurate within 0.025, which is a close as you can get with the pushrod assortment available today.
Now, let me tell you about stuffing lawnmower starter cord in the cylinder to change valve springs, and pouring water down the throttle body to break up carbon. And how about dis-assemblying thermostats and poking a small ball bearing under the plunger to create a 180 thermo.
Cheers,
DG
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Sleeper, I see you have come a long way from the Z06 cam!
Modding is addictive, isn't it?
Below is a real shadetree way to see if your preload is in the ballpark, It will not take the place of a good measurement tool, but it's a good way to get pretty close. Fun way to play around while you wait for that fancy pre-load checker tool to arrive.
Awhile back I was chasing the lifter noise/preload thing, and came across an interseting old thread in the archives here.
Can't locate it now, but the gist of the topic was how to get in the ballpark on preload by counting the turns on the rocker bolt as you tighten it down. (not like a smallblock, bear with me).
Basically the stock lifters like about .100 preload, as discussed here (don't know about the Caddy lifters). This guy figured out that one turn of the bolt (.050 threads, times the 1.7 ratio) equaled about 0.80 preload on the pushrod. So, about 1 1/4 turns on the bolt gave the desired .100 preload. (2.7/1.7=1.58 times .050 = 0.79).
To do this, get the cam lobe on the lowest point, loosen the bolt until the pushrod is free, and let the lifter cup rise to the top of the lifter as the internal lifter spring pushes it up. Then very gently tighten the bolt while feeling and spinning the pushrod until the slack is out and the pushrod is resting on the lifter cup against the lifter spring with no slop, but not compressing the little spring in the lifter.
Then tighten the bolt all the way to a positive stop (but don't torque it down very hard) and count the turns. You should get 1 1/4 turns for the .100 preload. (later torqueing of the bolt will add a bit of turn, but this is mostly bolt stretch, so don't count this).
I tried it, it worked pretty good, certainly accurate within 0.025, which is a close as you can get with the pushrod assortment available today.
Now, let me tell you about stuffing lawnmower starter cord in the cylinder to change valve springs, and pouring water down the throttle body to break up carbon. And how about dis-assemblying thermostats and poking a small ball bearing under the plunger to create a 180 thermo.
Cheers,
DG
Modding is addictive, isn't it?
Below is a real shadetree way to see if your preload is in the ballpark, It will not take the place of a good measurement tool, but it's a good way to get pretty close. Fun way to play around while you wait for that fancy pre-load checker tool to arrive.
Awhile back I was chasing the lifter noise/preload thing, and came across an interseting old thread in the archives here.
Can't locate it now, but the gist of the topic was how to get in the ballpark on preload by counting the turns on the rocker bolt as you tighten it down. (not like a smallblock, bear with me).
Basically the stock lifters like about .100 preload, as discussed here (don't know about the Caddy lifters). This guy figured out that one turn of the bolt (.050 threads, times the 1.7 ratio) equaled about 0.80 preload on the pushrod. So, about 1 1/4 turns on the bolt gave the desired .100 preload. (2.7/1.7=1.58 times .050 = 0.79).
To do this, get the cam lobe on the lowest point, loosen the bolt until the pushrod is free, and let the lifter cup rise to the top of the lifter as the internal lifter spring pushes it up. Then very gently tighten the bolt while feeling and spinning the pushrod until the slack is out and the pushrod is resting on the lifter cup against the lifter spring with no slop, but not compressing the little spring in the lifter.
Then tighten the bolt all the way to a positive stop (but don't torque it down very hard) and count the turns. You should get 1 1/4 turns for the .100 preload. (later torqueing of the bolt will add a bit of turn, but this is mostly bolt stretch, so don't count this).
I tried it, it worked pretty good, certainly accurate within 0.025, which is a close as you can get with the pushrod assortment available today.
Now, let me tell you about stuffing lawnmower starter cord in the cylinder to change valve springs, and pouring water down the throttle body to break up carbon. And how about dis-assemblying thermostats and poking a small ball bearing under the plunger to create a 180 thermo.
Cheers,
DG
Look like I'll be busy this coming Saturday with your advice and instructions.Yes I have come a long ways from the ZO6 cam and heads. The car runs great and is nice and strong except for the annoying valve train noise. I realize it won't be as quiet as the stock but on a scale of 1 to 10..I'd be happy with 5.
I'll let you and the others who helped out know how this turns out.
BTW this is the way it sounds now.
Sleeper
Last edited by SLPRC5; Jun 27, 2007 at 02:48 AM.
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Guess I'm use to the stock valve train sound.
I'll see how it goes after this weekend with the 7.425 push rods and the after market rockers. on a scale of 1 to 10 if I can get a 5 or 6 quietness I'll be happy, if not I'll have to live with it.
I'll see how it goes after this weekend with the 7.425 push rods and the after market rockers. on a scale of 1 to 10 if I can get a 5 or 6 quietness I'll be happy, if not I'll have to live with it.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Whooo-Yaah, ain't no Z06 cam in there, for sure.
Actually, my baby 212/218 cam clicks a little.
I love the even sewing-machine sound, but I also have one
distinct tick, like one single lifter clicking a bit more.
Now, that I don't like at all; makes me think something is wrong.
I played around trying to isolate it for awhile, that's when I did the preload checky thing - even though my cam has a stock base-circle.
Couldn't find anything wrong with any of the pushrods, springs, rockers, pre-load, so I try to ignore it.
Its been 2 years now, and still that slight tick-tick-tick about 6 times/second.
Question; is this normal, to hear one or two lifters tap just a bit more than the others? I thought I heard that in your audio, but not sure.
Really has a nice powerful sound, though.
DG
Actually, my baby 212/218 cam clicks a little.
I love the even sewing-machine sound, but I also have one
distinct tick, like one single lifter clicking a bit more.
Now, that I don't like at all; makes me think something is wrong.
I played around trying to isolate it for awhile, that's when I did the preload checky thing - even though my cam has a stock base-circle.
Couldn't find anything wrong with any of the pushrods, springs, rockers, pre-load, so I try to ignore it.
Its been 2 years now, and still that slight tick-tick-tick about 6 times/second.
Question; is this normal, to hear one or two lifters tap just a bit more than the others? I thought I heard that in your audio, but not sure.
Really has a nice powerful sound, though.
DG
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Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Whooo-Yaah, ain't no Z06 cam in there, for sure.
Actually, my baby 212/218 cam clicks a little.
I love the even sewing-machine sound, but I also have one
distinct tick, like one single lifter clicking a bit more.
Now, that I don't like at all; makes me think something is wrong.
I played around trying to isolate it for awhile, that's when I did the preload checky thing - even though my cam has a stock base-circle.
Couldn't find anything wrong with any of the pushrods, springs, rockers, pre-load, so I try to ignore it.
Its been 2 years now, and still that slight tick-tick-tick about 6 times/second.
Question; is this normal, to hear one or two lifters tap just a bit more than the others? I thought I heard that in your audio, but not sure.
Really has a nice powerful sound, though.
DG
Actually, my baby 212/218 cam clicks a little.
I love the even sewing-machine sound, but I also have one
distinct tick, like one single lifter clicking a bit more.
Now, that I don't like at all; makes me think something is wrong.
I played around trying to isolate it for awhile, that's when I did the preload checky thing - even though my cam has a stock base-circle.
Couldn't find anything wrong with any of the pushrods, springs, rockers, pre-load, so I try to ignore it.
Its been 2 years now, and still that slight tick-tick-tick about 6 times/second.
Question; is this normal, to hear one or two lifters tap just a bit more than the others? I thought I heard that in your audio, but not sure.
Really has a nice powerful sound, though.
DG
The headers as you know also make a ticking sound.
Another CF member "mvvette97" used my base circle number (1.493) to figure out what size push rods to use. He figured that with the 7.425 push rods I'm .040 under the pre-load for the lifters.
Do this weekend in goes the push rods and Garland rocker rollers..between the two I hope to have it quieter.
It runs really great...has power starting in the lower mid band all the way up to 6200RPM.
It is a fun car and will surprise alot of folks.
Sleeper...
Last edited by SLPRC5; Jun 27, 2007 at 06:36 PM.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Sleeper, yes that 1.493 base circle is quite a bit smaller than stock.
Stock is 39.4mm, or 1.551".
So, your base Circle is 58 thousands smaller.
The push rod sees the lobe radius, or 1/2 of that base circle change;
So the effective loss in preload is 29 thousands.
Sooo, if you use a 0.025 longer PR, you are back within 4 thousands of the original preload, or maybe 0.096"
However, if you milled the heads (say 0.020) that effectively brings the rocker closer to the cam, and adds 0.020 preload.
So, theoretically you could be at 0.116 preload with the 7.425 PR.
Do you know how much was milled off? And are the Patriot heads the same thickness to begin with as the stockers?
Since you have 3 variables going here (new base circle, new PR, new head thickness?) I think I would do at least two of the following:
1. Find out how much was milled, and do the theory math as above.
2. Verify with the shadetree method above.
3. Get the PR checker and be sure.
We're having fun now!
DG
Stock is 39.4mm, or 1.551".
So, your base Circle is 58 thousands smaller.
The push rod sees the lobe radius, or 1/2 of that base circle change;
So the effective loss in preload is 29 thousands.
Sooo, if you use a 0.025 longer PR, you are back within 4 thousands of the original preload, or maybe 0.096"
However, if you milled the heads (say 0.020) that effectively brings the rocker closer to the cam, and adds 0.020 preload.
So, theoretically you could be at 0.116 preload with the 7.425 PR.
Do you know how much was milled off? And are the Patriot heads the same thickness to begin with as the stockers?
Since you have 3 variables going here (new base circle, new PR, new head thickness?) I think I would do at least two of the following:
1. Find out how much was milled, and do the theory math as above.
2. Verify with the shadetree method above.
3. Get the PR checker and be sure.
We're having fun now!
DG
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Sleeper, yes that 1.493 base circle is quite a bit smaller than stock.
Stock is 39.4mm, or 1.551".
So, your base Circle is 58 thousands smaller.
The push rod sees the lobe radius, or 1/2 of that base circle change;
So the effective loss in preload is 29 thousands.
Sooo, if you use a 0.025 longer PR, you are back within 4 thousands of the original preload, or maybe 0.096"
However, if you milled the heads (say 0.020) that effectively brings the rocker closer to the cam, and adds 0.020 preload.
So, theoretically you could be at 0.116 preload with the 7.425 PR.
Do you know how much was milled off? And are the Patriot heads the same thickness to begin with as the stockers?
Since you have 3 variables going here (new base circle, new PR, new head thickness?) I think I would do at least two of the following:
1. Find out how much was milled, and do the theory math as above.
2. Verify with the shadetree method above.
3. Get the PR checker and be sure.
We're having fun now!
DG
Stock is 39.4mm, or 1.551".
So, your base Circle is 58 thousands smaller.
The push rod sees the lobe radius, or 1/2 of that base circle change;
So the effective loss in preload is 29 thousands.
Sooo, if you use a 0.025 longer PR, you are back within 4 thousands of the original preload, or maybe 0.096"
However, if you milled the heads (say 0.020) that effectively brings the rocker closer to the cam, and adds 0.020 preload.
So, theoretically you could be at 0.116 preload with the 7.425 PR.
Do you know how much was milled off? And are the Patriot heads the same thickness to begin with as the stockers?
Since you have 3 variables going here (new base circle, new PR, new head thickness?) I think I would do at least two of the following:
1. Find out how much was milled, and do the theory math as above.
2. Verify with the shadetree method above.
3. Get the PR checker and be sure.
We're having fun now!
DG
All I know is the Patroit heads had the chambers milled from 64cc to 62cc. The heads themselves were milled down...
At present I have the Harland 1.7 roller rockers installed and i'm waiting for a set of valve cover spacers to come in so i can put the VC back on and fire it up to see if they made a difference as some say they will.
Sleepe
Drifting
Joined: Jan 2005
Posts: 1,271
Likes: 1
From: V town california
You can't measure length with a caliper and determine the pushrod length. This is because the actual pushrod length used by the manufacturers and printed on the pushrod is "gauge" length, which is determined from a fixed diameter on the ball end of the pushrod (typically where the ball is 0.140" diameter). Thus, if you measured 7.400" with a caliper the actual gauge length is about 0.017" shorter (this is an approximation) or the 7.385" quoted above. The adjustable pushrod you buy to measure length has a preset closed length and then every turn of the pushrod open adds 0.050" to the length. However, the length being measured is gauge length which is then what you buy. For example, if you have the Comp adjustable, the closed length is 6.800". Lets say you measure and find that it takes 10.5 turns to adjust the pushrod to get zero lash. You would add this onto the closed length:
6.800 + 10.5 X 0.050 = 7.325"
However, now you must add in your lifter preload to set the plunger in the lifter. If you want the preload to be 0.100", you would add that on and end up with 7.425" pushrods.
Hope this all makes sense.
6.800 + 10.5 X 0.050 = 7.325"
However, now you must add in your lifter preload to set the plunger in the lifter. If you want the preload to be 0.100", you would add that on and end up with 7.425" pushrods.
Hope this all makes sense.
what pushrods i need and what setting preoad on lifters is all about.
i have a 408ci
with 257/266 .643/.622 110 lsa cam on 66cc heads with .040 gasket.
also my pistons are -8cc. first of all can you determine what size rods i need with this set up with out using a pushrod checker? and second i have ls7 lifters, so i cant jus install them i have to set a preload for them? ive never set a preload on my previous 346 heads/cam set ups.
not tryin to hijack.
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
im completely lost man. im tryin to figure out
what pushrods i need and what setting preoad on lifters is all about.
i have a 408ci
with 257/266 .643/.622 110 lsa cam on 66cc heads with .040 gasket.
also my pistons are -8cc. first of all can you determine what size rods i need with this set up with out using a pushrod checker? and second i have ls7 lifters, so i cant jus install them i have to set a preload for them? ive never set a preload on my previous 346 heads/cam set ups.
not tryin to hijack.
what pushrods i need and what setting preoad on lifters is all about.
i have a 408ci
with 257/266 .643/.622 110 lsa cam on 66cc heads with .040 gasket.
also my pistons are -8cc. first of all can you determine what size rods i need with this set up with out using a pushrod checker? and second i have ls7 lifters, so i cant jus install them i have to set a preload for them? ive never set a preload on my previous 346 heads/cam set ups.
not tryin to hijack.
At present I have installed a set of 1.7 roller rockers and I'm waiting for the valve cover spacers to come in so I can put it back together to fire her up and see if this helped the sewing machine sound.
Good luck to you...
Sleeper
Thread Starter
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
There was a guy on the sale section that had a set of 1.7 rockers for sale.
Guess I'll have it together for this coming weekend
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
im completely lost man. im tryin to figure out
what pushrods i need and what setting preoad on lifters is all about.
i have a 408ci
with 257/266 .643/.622 110 lsa cam on 66cc heads with .040 gasket.
also my pistons are -8cc. first of all can you determine what size rods i need with this set up with out using a pushrod checker? and second i have ls7 lifters, so i cant jus install them i have to set a preload for them? ive never set a preload on my previous 346 heads/cam set ups.
not tryin to hijack.
what pushrods i need and what setting preoad on lifters is all about.
i have a 408ci
with 257/266 .643/.622 110 lsa cam on 66cc heads with .040 gasket.
also my pistons are -8cc. first of all can you determine what size rods i need with this set up with out using a pushrod checker? and second i have ls7 lifters, so i cant jus install them i have to set a preload for them? ive never set a preload on my previous 346 heads/cam set ups.
not tryin to hijack.
Drifting
Joined: Jan 2005
Posts: 1,271
Likes: 1
From: V town california
Several things will have an affect on lifter preload. The base circle of your cam, your thinner than stock gaskets, if you milled your heads and what rockers you are using (stock or aftermarket). The best way to figure it out is to buy an adjustable pushrod for about $20 and then once the motor is together take a measurement to ensure you get the correct ones. It is very easy to use once you have it. You will need one that is adjustable in the LS1 range, Comp makes one that goes from 6.800" to around 7.500".
