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Head questions
https://slantsix.org/forum/viewtopic.php?t=28903
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Author:  6shotvanner [ Mon May 12, 2008 12:40 pm ]
Post subject:  Head questions

Head/engine in question is 83.Can the hyd cammed engine get a 100ths head shave with no ill affects? Also I'm looking at the stock valves and there sure doesn't look like a whole lot of room for bigger valves.I'm running 264h comp cam,bored 60ths,clifford/clifford and eddy 500 cfm. She's coming apart for an oil pressure problem so I'm thinking of a little top end work to wake it up a bit more.Wished I'd found this forum BEFORE the engine rebuild.As always,Thanks.

Author:  Doc [ Mon May 12, 2008 1:19 pm ]
Post subject: 

Quote:
...Can the hyd cammed SL6 engine get a 100ths head shave with no ill affects?
The short answer is "No".

In general, you need to be careful to maintain proper lifter preload with any engine that has hydrualic lifters and non-adjustable rocker arms.

You can do "some" head milling if you adjust-out the added lifter plunger preload, by using rocker arm shaft shims, shorter pushrods or by shortening the amount of valve stem length the rocker arm "sees".
(shorten the stem or pull it down into the guide, by raising the valve seat, up into the combustion chamber)

The machinest doing the head work needs to know that you are working with a non-adjustable r-arm (Mopar) set-up so he gets all the valve stem heigths equal. Check their work by laying a straight edge across all the valve stem tips.
DD

Author:  Fopar [ Mon May 12, 2008 4:15 pm ]
Post subject: 

What are the possibilities of using the rockers from a solid lifter head and adjusting them to run the hydrolic lifters?

Author:  tlrol [ Mon May 12, 2008 4:35 pm ]
Post subject:  Hydraulic cam and head shave

Doc,

Just so I understand correctly--with a 1982 Slant Six (hydraulic cam) a head shave is only possible IF the pushrod lengths are modified--presumably shorter. Is this correct?

Thanks

tlrol

Author:  6shotvanner [ Mon May 12, 2008 4:56 pm ]
Post subject: 

Allrighty then,so is it possible to run solid lifter/pushrod/rocker arm on the hyd cam? Don't have the spec right here but comp cams sells the 264 in a h and s version.Don't both rocker/rod/lifter sets oil the same way on the slant? I'd sure like to get a bit more gettyup without buying another cam,what say you Doctor? Sorry if it's a dumb question but I'm sort of like water,I'm seeking the path of least resistance here :wink:

Author:  Charrlie_S [ Tue May 13, 2008 3:26 pm ]
Post subject: 

It is possible to run solid lifters, adj rockers, and pushrods, on a hydraulic cam, but not recommended. The clearance ramps are totally different. It is not possible to run hydraulic lifters with the adjustable rockers, and pushrods. The lifters will not get any oil, and will collapse.

Author:  Doc [ Tue May 13, 2008 3:37 pm ]
Post subject: 

You need to use all the hydrualic hardware because the lifters get their oil from the special, non-adjustable rocker arms... and the matching hollow pushrods, with oil passage holes at each end. If your engine is already a hydrualic lifter engine, then you have all the correct parts.

The solid lifter, adjustable rocker arms and pushrods do not feed enough oil down to the hydro lifters.

So buy your 'hotter' cam and do a valve job on the cylinder head, along with some basic porting (valve pocket clean-up work) and take a .060 cut on the head surface.

Be sure the machine shop gets all the valve stems at the same height and everything should work fine. ( the shop will have to face down the stem ends to get them all even, that should off-set the head surface "cut")

In the end, if there is to much lifter plunger pre-load, you will have to shim-up the rocker shaft, there are shims available to do this.
DD

Author:  6shotvanner [ Tue May 13, 2008 7:15 pm ]
Post subject: 

Thanks guys :) Looks like I've got a little bit more replanning on this redo.Oh well,we do what we must.Sometimes I feel like old Carlo Rossi"I like making wine but I'd rather drink it".Me I can work on engines,but I'd rather hear them run :wink: Hummm,fix this one,stuff it back in and start a correct ground up hot build on the spare motor.Now where are my catalogs...Honey!!! 8)

Author:  Aggressive Ted [ Tue May 13, 2008 7:26 pm ]
Post subject: 

Doc,

If you take .060 of the head, do you take .060 off the valve stems too? or is it less?

Author:  Doctor Dodge [ Tue May 13, 2008 9:34 pm ]
Post subject: 

Quote:
Doc,

If you take .060 off the head, do you take .060 off the valve stems too? or is it less?
Personally, I would mock up the engine, measure the amount of hydrualic lifter preload and cut the stem lenghts to give .040 to .060 of plunger preload.

The key to success, get all the stems the same height, that will allow you to "fine tune" the preload with shims.
DD

Author:  Charrlie_S [ Wed May 14, 2008 5:24 am ]
Post subject: 

Quote:
Quote:
Doc,

If you take .060 off the head, do you take .060 off the valve stems too? or is it less?
Personally, I would mock up the engine, measure the amount of hydrualic lifter preload and cut the stem lenghts to give .040 to .060 of plunger preload.

The key to success, get all the stems the same height, that will allow you to "fine tune" the preload with shims.
DD
Theoretically, if the lifter preload is correct, and then you mill the head .060, it woukd require the valve stems be shortened by .090.
But if you raise the rocker shaft, using shims, it would require less then a .060 shim. Not sure but I think about .030 shim.

Author:  tlrol [ Sat May 17, 2008 6:46 am ]
Post subject:  More Head Questions...

So, can a person just replace the hydraulic cam and associated hardware (rocker arms, pushrods, lifters, etc, etc) with a mechanical lifter setup? Or is it easier to nab the mechanical lifter head? How often does one need to adjust the value lash on a mechanical tappet Slant Six? Or does the idea of going to a mechanical lifter setup just smack of silliness, and should a guy stay with a hydraulic setup? The reason I am asking is that I am slowly going through the "usual" Slant Six upgrade path and I am soon to be looking at a head shave on a 1982 D150 Slant Six. It sounds like you don't quite get the same bang for the buck on a hydraulic lifter head as you do on a mechanical lifter head...

Author:  Doctor Dodge [ Sat May 17, 2008 8:44 am ]
Post subject: 

Quote:
..It sounds like you don't quite get the same bang for the buck on a hydraulic lifter head as you do on a mechanical lifter head...
It's not the cylinder head as much as all the hydro hardware that goes with it.
The only difference with the head is that it is wider and uses a wider valve cover / VC gasket. The wider head allows for bigger (1 inch) holes where the push rods go down to the hyd. lifters. The larger holes allow you to pull the hyd. lifters out, with-out removing the head. (it's not easy, but it can be done)

What does this say about the design? Did the engineers have a feeling that lifter access, for replacement, would be needed? (yes)

So let's review:
-The conversion to hydro lifters was an after-thought, done to an engine that was never designed to use them.
-The switch was done for emissions, not performance or ease of maintainance.
-The hydro set-up is much harder to initially set-up, but once it's correct, it works with-out adjustment.
-A hydro lifter has more moving parts and will wear-out sooner. This set-up is much more sensitive to dirty / poor quality oil.

I have always felt that the time I saved on ease of installation of the solid lifter set-up, far outweighs the time needed to keep them in adjustment. I have spent way more time "fussing" to correct poorly assembled or worn-out hydraulic lifter components.
DD

Author:  tlrol [ Sat May 17, 2008 2:03 pm ]
Post subject:  So, to wrap up...

Doc,

So, in short, it apears that a very direct way to improve the performance of a hydraulic cammed 82 Slant Six would be to simply replace the head (and ALL associated stuff) with an earlier head from say a lae 70ish Dart or so. Is this correct? Are the blocks the same? Is this swap basically plug and play (given new lifters, camshaft, pushrods, cylinder head, rocker arm, etc...). Such a swap would allow for use of the various cams out there as well as the head milling. What is the periodicity of valve adjustment?

Thanks

tlrol

Author:  SlantSixDan [ Sat May 17, 2008 2:49 pm ]
Post subject: 

Somebody please correct me if I'm wrong (I've never actually built an '81+ hydro-lifter engine) but I believe the mechanical-lifter pushrods, rockers, and rocker shaft can be installed in conjunction with a cylinder head originally equipped for hydraulic lifters. Oil volume to the top end would probably want restricting (the oil to the top must be increased in volume when going the other direction and installing hydro lifters in a solid-lifter engine, for the lifters are fed from the top, through the rocker shaft, rocker arms, and pushrods.)

Tappet clearance adjustment periodicity with solid lifters is roughly 20k miles, plus or minus as needed.

Camshaft selection is indeed much wider with the solid lifters.

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