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Can you use a mechanical lifter head on a hydraulic motor?
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Author:  Reed [ Tue Apr 14, 2009 4:14 pm ]
Post subject:  Can you use a mechanical lifter head on a hydraulic motor?
I am kicking ideas around here and i like the no-valve-lash-adjustment of the hydraulic motors but I have a big valve head built out of a 1972 198 cylinder head I might want to run.

What do I have to do to a mechanical lifter head to use it on a hydraulic lifter motor? Do I just have to swap to a hydraulic lifter rocker assembly and rear holdown bolt or is there more?

Thanks!
Author:  Ron Parker [ Tue Apr 14, 2009 4:25 pm ]
Post subject: 
Why do you not like the mechanical lifter head? thanks Ron Parker












Bee Good Or Bee Gone :D
Author:  Reed [ Tue Apr 14, 2009 4:37 pm ]
Post subject: 
No, I DO like the mechanical lifter head. I want to use the mechanical lifter head on a hydraulic motor, but I want to keep the hydraulic lifters. I want to make sure that I can do this.

I guess what I am really asking is two questions:

(1) does a hydraulic motor head have different or more oil passages than a mechanical lifter head and

(2) will the rocker assembly, including the rearmost bolt, from a hydraulic head swap onto a mechanical head

Thanks. Sorry if I wasn't clear.
Author:  Joshie225 [ Tue Apr 14, 2009 4:44 pm ]
Post subject: 
Yes, you can put the older head on the hydraulic short block with the hydro valve gear. You may need to drill out the rear-most rocker shaft hold-down hole.
Author:  Reed [ Tue Apr 14, 2009 4:50 pm ]
Post subject: 
Quote:
Yes, you can put the older head on the hydraulic short block with the hydro valve gear. You may need to drill out the rear-most rocker shaft hold-down hole.
What all would be involved in the drilling? How deep? Would it need to be tapped?

Thanks!
Author:  Joshie225 [ Tue Apr 14, 2009 4:54 pm ]
Post subject: 
If memory serves the rear most bolt at the bottom is smaller as the hydro head has a stepped bolt. You just need to drill it through the same size as the other hold-down bolt holes.
Author:  slantzilla [ Tue Apr 14, 2009 7:07 pm ]
Post subject: 
The big question is does the mechanical head have a big enough oil passage to support the hydro valvetrain?

I do not know. :?

Josh, is the stepped bolt that much longer that you can drill deeper into the head or do you just need to run a heli-coil down the hole to give it 5/16" threads? :?:
Author:  Reed [ Tue Apr 14, 2009 7:59 pm ]
Post subject: 
Quote:
The big question is does the mechanical head have a big enough oil passage to support the hydro valvetrain?

I do not know. :?

Josh, is the stepped bolt that much longer that you can drill deeper into the head or do you just need to run a heli-coil down the hole to give it 5/16" threads? :?:

Uh-oh. Can anyone answer this? :?
Author:  Reed [ Tue Apr 14, 2009 8:41 pm ]
Post subject: 
Well, I went out and compared the rearmost rocker arm bolts out of a hydraulic head and a mechanical head. The mechanical bolt was MUCH fatter and longer and was not stepped like the hydraulic bolt. The hydraulic bolt was shorter and narrower. The hydraulic head bolt was not hollow or special in any way besides being narrow and stepped.

This leads me to believe that, so long as Chrysler did not reroute the oil passages in the head, I can cut the mechanical head bolt to a shorter length and oil will still reach the push rods like it would on a hydraulic head.

True? :?:
Author:  Reed [ Tue Apr 14, 2009 10:23 pm ]
Post subject: 
Bummer. I spent some time looking at my 84 Dodge van shop manual and I don't think it is possible to use a mechanical cam head on a hydraulic cam motor and keep the hydraulic cam. The rear bolt on the hydraulic motor it narrower because the oil is supposed to flow by it at full pressure and fill up the rocker arm.

Grrr.

Back to the drawing board.

Thanks for being my sounding board guys!
Author:  Joshie225 [ Tue Apr 14, 2009 10:47 pm ]
Post subject: 
You'll get enough oil. This has been done successfully before. You might do a little oil passage matching if it will help you sleep better.
Author:  66aCUDA [ Wed Apr 15, 2009 5:28 am ]
Post subject: 
Reed
Why cant you do as Zilla suggests? I would think then you use your Hydro back bolt and everything would be the same.
Just thinkin,
Frank
Author:  DusterIdiot [ Wed Apr 15, 2009 6:48 am ]
Post subject:  And then....
Even if he does the above mods, is he going to have problems with the static valve train/push rod length if the mech head isn't matched to the same height as the hydro head? The hydro lifters can only pump up and take up so much lash (or the push rods are too long and ...).

-D.Idiot
Author:  Reed [ Wed Apr 15, 2009 8:52 am ]
Post subject: 
If someone can confirm for me that they have done this swap and it will work fine, then I will relax. It is just that I look at the hydraulic slant oiling diagrams and rocker shaft end bolt and I can't help but think that Chrysler made such a large change in the rear bolt and pocket for the rear bolt for a reason.

Image

I know the lifters only need something like 4-5 pounds of oil pressure to pump up, and the head was not milled, it just has oversize valve in it.

Maybe I am just being paranoid. :shrug: I just don't want to put this on there and then kill the motor due to oil starvation or something.
Author:  rock [ Wed Apr 15, 2009 9:35 am ]
Post subject:  Reed, without taking out my rear bolt, I can tell you I did
Reed,

I hate answers that don't answer the question, but here is what I did that may let you infer.

In a chain of errors I once ended up with and ran very successfully a hyraulic RV cam installed with solid lifters, solid lifter rocker arm set, and head milled .100. I used a peanut plug head whose year I don't know. Oil pump was a bone stock new one, not high performance. I believe it was Doctor Dodge who advised me to set the lash at .012 and .022 with the hydro cam on solid lifters.

Worked great! So....how many peanut plug heads had the bolt you are asking about? IF all, I must think what you want will do fine, from my installation.

rock
'64d100
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