question directed to john mummert


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By 1964fordf100292 - 16 Years Ago
hey john. i see in your profile picture that you have roller rockers on your y-block. where do you get those fancy y-block roller rockers???
By Ted - 16 Years Ago
While I’m not John, I’ll interject what I do know on the subject.  Dove Manufacturing and Rocker Arm Specialist currently make aluminum roller tipped rockers for the Y while PRW and Harlan Sharp are both actively working on their own high performance rocker arm prototypes for the Y.  Although I’ve only used the aluminum 1.6:1 ratios for the Y, it’s my understanding that Rocker Arm Specialist does offer it in the 1.5:1 ratio.  The Harlan Sharp rockers are looking to be 1.6:1 but will be possibly fully rollerized at the shafts also.  As with the last conversation I had with PRW, they are leaning towards a bushed aluminum rocker arm for the stock diameter shafts.
By ejstith - 16 Years Ago
Ted, I assume that if one had 1.6 that would be no problem for a stock, otherwise, motor ??
By Outlaw56 - 16 Years Ago
Ted,



Do any of the high performance rocker prototypes include an improved oiling system?

Darrell Howard
By John Mummert - 16 Years Ago
There's nothing wrong with having oil in the shaft and holes at the bottom of the shaft to oil the rockers. The problems start when the supply of oil to the shaft is decreased or stops.

There are 2 major reasons why the oil flow stops: either sludge in the passage or a worn center cam bearing along with a shallow groove in the cam.

Because there is no pressurized oil to the lifter bores on a Y-Block you can't supply oil through the pushrods. This limits the options on how to oil the rockers and the types of rockers you can use.

I considered various options while working on the aluminum head and many Y-Blockers had asked about individual stud mounted rockers. I couldn't come up with a reasonable way to oil stud mounted rockers without making the head incompatible with stock rockers.

By Vic Correnti - 16 Years Ago
I'll interject my recent ignorant experience adding Dove rockers. Dove rockers were not a bolt in operation on my Y-Block. Rocker geometry and the push rods did not cut it as is. My 5/16 diameter push rods rubbed the bores in the heads. I had to raise the rocker shafts 1/4 inch and use longer push rods (8.312). Then I decided to use solid spacers which need to be shimmed for clearance with each other which is time consuming. Ted's articles on push rod length and rocker geometry are a must. I just finished it today so I hope to have it back in the car by the end of next week. I hope this helps you if you go to the 1.6 rockers and avoid the problems I had.
By Ted - 16 Years Ago
ejstith (9/18/2009)
Ted, I assume that if one had 1.6 that would be no problem for a stock, otherwise, motor ??
The 1.6:1 rockers will work with no mods up to 0.480” lift at the valve or 0.505” gross lift.  The at valve value is figured after you take out for the valve lash.  Any more lift at the valve than this will require checking valve to piston clearances at both the piston and the edge of the cylinder wall on the intake valve side.  Unless the heads are heavily milled, you can likely still run more lift than this without any modifications but check anyhow.  As Vic mentions, if the valve train geometry is out of whack, the 1.6:1 rockers will bring to the forefront any problems related to that and especially if the lobe lift at the camshaft is increased at the same time.  If raising the rockers, the pushrod lengths will also typically be increased an equal amount unless they too are not correct to begin with.

Outlaw56 (9/18/2009)
Do any of the high performance rocker prototypes include an improved oiling system?
Darrell.  You’ll have to expound on ‘improved’.  With a caged bearing in the rocker, the slots in the rocker shaft at the rocker oiling holes can not be used so that’s one change that will take place that I’m aware of.  Oil holes in the bottom of the shafts remain though.  The only other mods that come to mind are at the cam journal to insure an adequate amount of oil gets to the top end but those mods should be done on any Y build and not just those with aluminum roller rockers.

Although I’ve still been using the overflow tubes on many of the Y builds, they are pinched heavily so that they are essentially only bleeding off the air in the shafts and only a small amount of the oil actually leaving by way of the tubes.  I’ve actually done away with the overflow tubes on the EMC engine at this point but I have just enough leakage at the locating dowels I’ve put in the end stands (that are used to maintain rocker shaft orientation) that I’m still running the shafts purged of air.

By 1964fordf100292 - 16 Years Ago
thank you so much for the info.  Got another question for john. Are you gonna be carrying any of these brands of roller rockers?????
By John Mummert - 16 Years Ago
I haven't sold any Dove rockers for some time. The difficulties of pushrod length, rocker spacing and where to put straight, offset left and offset right rockers on the shaft made assembling and retailing them prohibitive. Its one thing to spend a ton of time doing this on an expensive engine build, quite another to do it just to sell a set of rocker assemblies.

I have not had any contact with any of these companies regarding pricing, actual production dates, ect. Impossible to answer the question right now.

I am a little concerned about needle bearings in the rockers. It is quite common for the needles to work their way out of the cage. They will eat right through the ends. When the needles get lose in the engine they find their way to the oil pump. Bad things follow.

Then there is the problem of hardness of the shaft. Since it becomes a bearing race with needle bearings it would need to Rockwell up near 50c. This is not currently available. I think a high quality bushing is the best answer.