Checking push rod length with Johnson short travel lifters
05-07-2019, 11:28 AM
#1
Race Director
Thread Starter
Checking push rod length with Johnson short travel lifters
Whats the procedure you guys use when checking push rod lengths with the Johnson short travel lifters. Whenever I get to zero lash on the base circle of the cam with the checkers then add .03 preload to the lengths and put them back in and tighten bolts its opening the valve. From my understanding the valve shouldnt be opening with the .03 preload. First time with these short travel lifters and dont want to screw stuff up.
05-07-2019, 01:09 PM
#3
Race Director
Thread Starter
Its a really long story. Its a buddies car it blew up after about 150 miles so he was reusing the lifters and he did pump them up. He was thinking maybe they were junk from when the motor blew up so he got some new ones and is trying it again. At this point I dont think they are pumped up.
05-07-2019, 01:29 PM
#4
I spoke with Joe Lewis the product manager at Johnson Lifters. He told me that the springs in my 2116LSR reduced travel (not short travel) are very strong and could manage to push the valve down before the first run.
So what I did was just took the zero lash measurement with an adjustable pushrod and added .035 to that number, and had my pushrods made to that length. My car has good compression across all cylinders. I hope this helps.
So what I did was just took the zero lash measurement with an adjustable pushrod and added .035 to that number, and had my pushrods made to that length. My car has good compression across all cylinders. I hope this helps.
Last edited by freddyvette; 05-07-2019 at 01:30 PM.
05-07-2019, 01:44 PM
#5
Le Mans Master
Whats the procedure you guys use when checking push rod lengths with the Johnson short travel lifters. Whenever I get to zero lash on the base circle of the cam with the checkers then add .03 preload to the lengths and put them back in and tighten bolts its opening the valve. From my understanding the valve shouldnt be opening with the .03 preload. First time with these short travel lifters and dont want to screw stuff up.
05-07-2019, 02:04 PM
#6
Race Director
Thread Starter
I spoke with Joe Lewis the product manager at Johnson Lifters. He told me that the springs in my 2116LSR reduced travel (not short travel) are very strong and could manage to push the valve down before the first run.
So what I did was just took the zero lash measurement with an adjustable pushrod and added .035 to that number, and had my pushrods made to that length. My car has good compression across all cylinders. I hope this helps.
So what I did was just took the zero lash measurement with an adjustable pushrod and added .035 to that number, and had my pushrods made to that length. My car has good compression across all cylinders. I hope this helps.
It does. Sounds like the same way I do regular GM lifters.
05-07-2019, 02:07 PM
#7
Race Director
Thread Starter
Basically sticking pushrods in and watching the movements. I think the problem is he pressurized the oiling system and pumped up the lifters. Once he added .03 to the checkers and put them back in and tightened the bolt it was opening up the valve.
05-07-2019, 02:17 PM
#8
Le Mans Master
Maybe your eyes are off man...no disrespect intended. The correct way is when the exhaust valve begins to open, you set the intake valve and when the intake valve begins to close, you set the exhaust. The rocker doesn't tell the whole story unfortunately.
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Eli-Z06 (03-01-2023)
05-07-2019, 02:29 PM
#9
If your valves are "open" on the base circle, the car won't make compression. Test it out.
05-07-2019, 02:35 PM
#10
Race Director
Thread Starter
Thats what I meant about watching the movement of the pushrods. Im sure we are on the base circle, and yes I think I am going blind.
05-07-2019, 08:57 PM
#11
Instructor
I may be wrong but I thought the Johnson short travel lifters want less preload than .030 and I do know that the length has to be pretty well dead on as there is very little range. I use the Johnson slow leak down lifters at .035 and they are plus minus .010 max. So with the short travels you may very well need 16 different length pushrods with a very tight tolerance as well to set them up right. Also a lot of the custom pushrod makers supply in .025 amounts which may well fall outside what length you need which narrows down the number of suppliers to a handfull and they are more expensive.
Last edited by G8Pumpkin; 05-07-2019 at 09:00 PM.
05-08-2019, 07:43 AM
#12
Burning Brakes
Where did you get 0.030 pre load from? I've only ever seen 0.035 with johnson lifters. More than other Johnson lifters, the limited travels command much more of a need for near perfect push rod length.
05-08-2019, 08:30 AM
#13
I have the short travel lifters. .035 sounds right to me since they are .058 travel. Now when your actually tightening down the rockers once to get to the top of the lifter where you feel your bolt get tight it should only be a 1/2 rotation to tight with your wrench... 9 o’clock max.
