Rocker Arms

robertw · Feb 23, 2017

I was wondering if any of you have tried these Murphy's rocker arms either the 1.7 or 1.9 high ratio rockers arms and was wondering if there is any hp gain if so how much ? I pull in the antique class with a 1951 Farmall m in the 6500 LBS. class and on a hard track i could you just a few more hp not much though does good on a soft track spins out with little effort on the motor in top five or better most times hard track need maybe 2 or 3 hp would do it i know that i probably should have posted on the pulling site after i started this but maybe some go back and forth any way i would appreciate any opinions you guys have.

Thanks Robertw

Janicholson · Feb 23, 2017

Added lift works when cylinder filling is the limiting factor. If you are turning 2500 rpm, or are stroked and bored, the valve opening might help cylinder filling. If near stock I would say not much help. Are you using a 450 cam? Jim

robertw · Feb 23, 2017

Jim i don't know what i have for a cam i bought it a couple years ago a the guy said it was suppose to have 55 hp i checked the compression and it has a little over 150 lbs. dry check i can tell looking in the spark plug hole it has dome pistons and that alone i don't think would bring the compression to that number and if the head has been milled and the rocker arms open the vales a little further could be problem there it runs pretty strong so i can't answer your question i would like to know that to.
Thanks Jim for your opinion

Robertw

Janicholson · Feb 23, 2017

Unless it has a radical cam in it, the mild timing and overlap of low speed engines usually do not crash. I would put a piston on TDC compression then compute the difference in total lift with a high ratio rocker, and then push those valves on that cylinder open that amount with a depth gauge to determine the amount to see if it hits. Jim

robertw · Feb 23, 2017

Thanks Jim. I might add that the guy i bought it from had it for 17 years and just push snow with it mainly had blade on it when i got it. He said he got it from a older person and that's who done the work to it or had it done and he didn't know what happen to him if even he's around and he didn't ask what was done to it that's why i know nothing about the motor. He just told him it had 55 hp.

Robertw

jon aller · Feb 23, 2017

My last puller was an H with 3 3/4 bore and half inch stroker. Just 210 cid and very much smaller than all the WCs that I pulled against. I made my own high lift rockers by cutting half way through the short side of the bottom of the arm, near the adjuster. I squeezed the gap together and welded it solid. My H would do 60 hp on the dyno at 540 pto, and I would power out in 4500 in low on a tough track before I did the rockers. After the rockers, I would rarely power out in 4500. One of the welds let go a few weeks later, so I bought the roller set from Murphy's, at that time you could only get the 1.7. It ran as good with the roller set as the home made ones. I sold it before I could dyno it again.

Rocker Arms

robertw

Member

Janicholson

Well-known Member

robertw

Member

Janicholson

Well-known Member

robertw

Member

jon aller

Member

Similar threads