push rods
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
push rods
I will be assembling my engine (swapping over stuff to short block) and I am going to be on a tight time frame
My issue is correct push rod length. I am installing a new cam, with my "unmilled" heads. I am presently running 7.4 length with yella terra rockers and don't know what length I will wind up needing.
Question; I know it's logic but I am a mentally burnt out right now
, so, will installing the steel washer increase or decrease the effective "length" of the pushrod.
Another words, If the 7.4 is too long, can I shim the pedestal to avoid buying a "slightly" smaller rod? Not worrying about the cost so much, just don't have the time to delay the build
My issue is correct push rod length. I am installing a new cam, with my "unmilled" heads. I am presently running 7.4 length with yella terra rockers and don't know what length I will wind up needing.
Question; I know it's logic but I am a mentally burnt out right now
, so, will installing the steel washer increase or decrease the effective "length" of the pushrod.Another words, If the 7.4 is too long, can I shim the pedestal to avoid buying a "slightly" smaller rod? Not worrying about the cost so much, just don't have the time to delay the build
Le Mans Master
Joined: Jan 2009
Posts: 6,226
Likes: 33
From: Morton illinois
St. Jude Donor '14-'15
Your time will be even worse if your valve train takes a dump. Do it right. Get a gauge , get the right length and overnight the pr's. Even the slightest miscalculation could mean bound up rockers and a dropped valve. Don't short cut it
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Use the shims to set the wipe, especially important with Dart heads due to the bronze guides. Making to too wide will cause premature guide wear. Once you have the wipe set, measure for pushrods. Larger pushrod OD is better if they will fit, but as I recall my Dart heads not sure they will fit. I went with double taper pushrods on my AFR heads for that reason.
As for cost, if you stay with 5/16" pushrods for now Trend has them reasonably priced and they make them for most other companies including Comp. They stock every size so getting them quick is not an issue.
As for cost, if you stay with 5/16" pushrods for now Trend has them reasonably priced and they make them for most other companies including Comp. They stock every size so getting them quick is not an issue.
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
I'm not going to take any short cuts at the risk of the valve train, but the shims are included in the yella terra's to adjust preload and aligement, just hadn't had time to think it through whether it would increase or shorten clearance. (would appear to increase at first thought.
I'm running hardened pushrods now, but it's been a while since I installed them, so I'm not sure the diameter.
I was hoping the cam
This is the technique I HOPE to use (if I can get my fingers in there)
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
My heads are at the machine shot now swapping the springs and being checked out, so I may see if he will let me borrow his push rod checker...
I'm running hardened pushrods now, but it's been a while since I installed them, so I'm not sure the diameter.
I was hoping the cam
This is the technique I HOPE to use (if I can get my fingers in there)
1. Using the EO/IC method, get the lifter to the base circle of the cam.
2. Using a known length pushrod (7.400" is a good start with stock rockers) run the rocker arm bolt down to zero lash. This is easily done with your fingers "wiggling" the rocker, the point at which the "slack" is just gone is zero lash.
3. Set your torque wrench to 22 lb./ft. Tighten the rocker to full torque and count the number of turns it takes to get there. 1 full turn wtih a stock 8mm X 1.25 bolt is ~.047" preload as measured at the pushrod/rocker interface.
4. I normally shoot for 1 1/4 to 1 3/4 turns with stock type lifters like Comp 850's, LS1, LS7 etc.
For an example, if you use a 7.400" pushrod and come up with 3/4 of a turn, you will need at least .025" longer pushrod to get into range. If you end up with 2 1/4 turns, you will need one .025" shorter...
I might not know everything but I will tell you that this method has worked for me year after year cam swap after cam swap. We average 3 cam swaps a week here so you can do the math.
My heads are at the machine shot now swapping the springs and being checked out, so I may see if he will let me borrow his push rod checker...
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Since the heads are off the car, the wipe is very easy to set up using a set of check springs and either a dial indicator or good rule. Here is how I did my AFR heads on the work bench. Note that for my heads the YT provided shim didn't provide a good pattern and I went to a thicker shim. This may not be the case with Darts but I never ran the YT's on my Dart heads when they were on the car. Here is the link on how to set the wipe pattern: Link
Also worth noting, the pushrod length will have no effect on the wipe pattern. If you are following the original YT instructions they are at worst wrong and at best mis-leading. The shims set the wipe, the pushrods set the preload. Setting up the wipe correctly with bronze guides is required if you want the guide wear to remain in check.
Also worth noting, the pushrod length will have no effect on the wipe pattern. If you are following the original YT instructions they are at worst wrong and at best mis-leading. The shims set the wipe, the pushrods set the preload. Setting up the wipe correctly with bronze guides is required if you want the guide wear to remain in check.
