Hello all. New to the forum as this is the first time i'm going to actually work with the existing 225 in my new project, a 66 Valiant Signet. Engine runs but i'm going to pull it and freshen it up. One of the things I would like to do is go from the existing mechanical lifters to hydraulic. After looking on net I get differing opinions. Can I rebuild the existing head using all the hydraulic components and install a hydraulic cam, or do I have to find a hydraulic lifter head at the bone yard?

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1966 Canadian Built Valiant Signet
Purchased 03/13
3 yr resto time line

You can reuse your original head, provided you switch to the hydraulic camshaft valve train. In other words, the hydraulic cam, hydraulic lifter, hollow hydraulic pushrods (only factory available in 225 length), hydraulic rocker arms, and hydraulic rocker arm shaft. Read about the differences in the hydraulic versus mechanical valve train here: http://www.slantsix.org/forum/viewtopic.php?t=46756

If you are still running the original 66 head, you may want to track down a post 67 head for the revised combustion chamber. But if you are building a daily driver the revised combustion chamber isn't really necessary.

The 81-up cylinder head has a larger rearmost rocker arm shaft bolt, the revised combustion chamber, a different valve cover, hardened valve seats for unleaded gas, and the later "peanut" spark plugs as well as passages for air injection. The three main advantages to this head over your 66 original head would be the revised combustion chamber, the hardened valve seat, and the peanut plugs. The peanut plugs don't use the spark plug tubes so the engine won't be a prone to leak oil. However, the peanut plug heads don't have nearly the clearance around the pushrods which some people don't like (it makes pulling lifters harder). Like I said above, the revised combustion chamber is't necessary on a mild street car, and the value of hardened seats is debatable. The passages for air injection can be easily blocked off using a plate over the passage opening at the rear of the head.

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Casually looking for a Clifford hyperpak intake for cheap.

Make sure that for the swap you have these things in mind:

1) If using a junkyard camshaft, that the lifters match the lobes they came from, no mix and match on used lifters.
2) You will also need to check the preload on the lifters and length of the pushrods, because of the wide variation in tolerances in the 225 over the generations, you may find that the stock pushrods may be too short in the early slant six and you'll end up ordering a shorter set (since there is no adjustment like the solid lifters on the rocker arms).

-D.Idiot

Setting tha correct lifter pre-load is the biggest concern when using a hydraulic cam set-up in a Slant Six.

The hydro rocker arms are non adjustable so the correct lifter preload must be engineered into the system from the start.

Block, decking, head milling, head gasket thickness, cam regrinding, lifter resurfacing, valve seat heigth, valve stem length and pushrod length must all "add-up" to the correct lifter pre-load... 12 times.

The most important of all... is setting all the valve stem heigths to be exactly the same so preloads can be adjusted with pushrod length (in sets of 12) or by shimming the rocker arm shaft.
DD

I think threads on the forum will support this here: hydro was more or less an afterthought on the slant. Check the threads on the slant hydro cam oiling path.

I went with a hydro cam on my last build. In retrospect, i would ditch it and go solid lifter. The first cam I ordered was a hydro cam on a solid blank (not good). the replacement I got was a hydro grind on a hydro blank, but was not ground anywhere close to straight up. I had to go a couple teeth on the timing set plus offset bushings to get the valve timing right.

Upon the recent teardown, there was wear on the lifters after a relatively small (~25k) miles.

Hydro is ok, but the selection and knowledge on the solid cams seems to be significantly better!

Interesting. As that thread I linked to shows, back in October of 2011 I swapped the camshaft in the 225 in my brother's 1983 Dodge van from a mechanical cam to a hydraulic cam. The block is from a 1976 Volare, the head is from a 1972 Demon (198 motor to boot), the cam, pushrods, and rocker arm assembly are from a 1983 Dodge van, and the lifters were "new" reground lifters from Delta camshaft in Tacoma, WA. No special measuring or pre-loading or parts matching was done, just pull the old stuff and stick the new stuff in there.

I don't believe the head or block have been shaved, although both have been rebuilt.

The motor was a bit noisy at first, but I believe this was due to the fact that the pushrods had been sitting for a while and were a bit gummed up. Some time running the motor with a bottle of Marvel Mystery Oil added to the crankcase got the lifters pumped up and everything quieted down. The motor has run perfectly fine for the last 1.5 years.

If I remember correctly there is a large amount of plunger travel in the stock lifters. This excess plunger travel gives you some wiggle room as far as having a factory hydraulic cam reground or milling the head or block. I also seriously doubt that from 81-87 Chrysler employed an army of machinists to measure lifter pre-load and valve stem height on every hydraulic slant that rolled off the assembly line.

If you are building a "hot" motor, then I would definitely spend the time to verify things like lifter pre-load and valve stem height. However, if you are doing a stock rebuild or a mild motor, I wouldn't be as concerned with going hydraulic. It certainly has made the maintenance on my brother's van much simpler (you should try adjusting the valves on cylinders 1 and 2 in a van, not fun).

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Casually looking for a Clifford hyperpak intake for cheap.

Wow, that's all kind of info. Reading between the lines I think i'm reading that I could rebuild my stock head using all new hydraulic parts in place of the mechanical as long as I don't let the machine shop go crazy. I am only planning on using brand new parts. Did I see that you can only get the push rods from chrysler for this? I have also heard rear cam bearing is different on hydro units. Is this correct? I'm also planning to at least get the 2-barrell set up from a newer engine, although I see summit has a 4 barrel intake available. Any advantage to this or just stick to a 2 barrel?

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1966 Canadian Built Valiant Signet
Purchased 03/13
3 yr resto time line

On a stock rebuild, go no bigger than a two barrel. Factory hydraulic camshafts had a groove in the rearmost bearing journal to provide continuous full oil flow to the rocker arm assemblies. Mechanical camshafts had just a hole drilled to allow oil flow. There are pictures of this in the article I linked to.


To ensure that the hydraulic lifters have sufficient oil flow to operate properly, you will need to make sure that either the rearmost cam journal has a groove in it or the rearmost cam bearing have a groove and the holes drilled and aligned or the oil passages.

Your stock head should be able to be used, but you will need to drill out the rearmost rocker arm shaft bolt hole to use the rearmost bolt that will match your stock head.

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Casually looking for a Clifford hyperpak intake for cheap.