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hydraulic valves in late slant6s
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Author:  bob fisher [ Mon Jan 15, 2007 8:21 am ]
Post subject:  hydraulic valves in late slant6s
hello sl6 sages- most sl6s have solid valve lifters. i understand in 80 and until the end of production in 87 they switched to hydraulic valve lifters. had solids in all my sl6s and the only issue was periodically adjusting the valve lash (.10 and .20). heard hydraulic lifters wear out faster since they are hollow to allow for oil fillup. in any event. what is your opinion on the desirability and durability of the hydraulics? any concerns? wondering if this is an example of if it aint broke dont fix it. perhaps the di or the doctor might weigh in on this. regards paladin.
Author:  Doc [ Mon Jan 15, 2007 9:32 am ]
Post subject: 
The hyd. lifter design for the SL6 was an "after-thought" set-up at best.
The main disadvantage is that the lifters have to get their oil from up top, from the rocker arm assembly and down the special pushrods. In general, the oil has a long way to go before getting to the lifters and that can lead to lifter "clatter" during start-up.

This aside, the main reason I never liked Mopar hydraulic lifter engines is based on the non-adjustable stamped steel rocker arms they used. The hydraulic lifter needs a set amount of plunger preload and setting this on a Mopar can only be done by adjusting the length of each valve stem or pushrod. (when the rocker arms have no means of adjustment)
The factory had a way to set this (so we hope) but once you get a little wear or valve seat recession, you are in for poor preformance , lifter clatter or "pump-up" and no easy way to fix it.

I feel you are better off with the adjustable solid lifter engine, giving you the ability to set the lash where it needs to be. The down side, setting the lash on solid lifter engines in getting to be a "lost art", not a lot of today's mechanics have ever done it. :roll:
DD
Author:  oldgoat83 [ Mon Jan 15, 2007 10:11 am ]
Post subject: 
What would be your suggestion for those of us with hydraulic lifters that clatter, short of replacing the head?
Author:  Doc [ Mon Jan 15, 2007 11:27 am ]
Post subject: 
Do you have clatter with cold start-up or do you also have it when the engine is hot and at idle - low RPMs?
DD
Author:  oldgoat83 [ Mon Jan 15, 2007 12:17 pm ]
Post subject: 
Mostly when turning faster. It's not a problem when at low RPM, hot or cold. But is definitely more prevalent at higher RPMs when cold.
Author:  Doc [ Mon Jan 15, 2007 1:49 pm ]
Post subject: 
Do you know how much oil pressure the engine has at higher RPM, does it have an oil pressure gauge?
Have you had the valve cover off while the engine is running? Is it getting lots of oil up to the rocker shaft and down to the lifters?
DD
Author:  oldgoat83 [ Mon Jan 15, 2007 3:42 pm ]
Post subject: 
Truck doesn't have oil pressure gauge, so I have no idea. I have never taken the valve cover off, but was thinking about repainting it. I assume I should look for clogs and such? Would clearing the passages clear up or reduce the clatter?
Author:  72polara [ Mon Jan 15, 2007 5:09 pm ]
Post subject: 
Doug,

Could one run the adjustable (solid lifter) rockers with custom hollow pushrods so as to get the correct preload on each lifter?

I assume that the solid rockers are missing oil holes or something to prevent this from being easy...
Author:  emsvitil [ Mon Jan 15, 2007 5:13 pm ]
Post subject: 
The hydraulic rockers have an oil passageway so oil gets from the rocker arm shaft to the hollow pushrods (then to the lifter).
Author:  Doc [ Mon Jan 15, 2007 5:57 pm ]
Post subject: 
Quote:
Doug,

Could one run the adjustable (solid lifter) rockers with custom hollow pushrods so as to get the correct preload on each lifter?

I assume that the solid rockers are missing oil holes or something to prevent this from being easy...
I have looked at this before and there is no easy way to get the oil supply into the pushrod when using the adjustable ball stud design the solid rocker arms have.

One idea I have not tried but could work is to install tall lifter galley stand-off tubes and submerge all the hyd. lifters in a pool of oil to make sure they stayed supplied. You would want to increase the flow of oil to the rocker arms so the "pool" would fill-up fast.
DD
Image
Author:  AnotherSix [ Mon Jan 15, 2007 5:58 pm ]
Post subject: 
I don't have any experience with the setup other than not liking what I found out about it worked when thinking about going hydraulic. It seems to me to be a marginal system at best, and once there is some wear on the shaft and rockers would lose oil pressure to the lifters. Non adjustable is a pain too. I have posted this idea a couple of times about hydraulics with no reply, maybe the Doc has some input. I have thought about plumbing the lifter bores from the outside of the block, using v-8 lifters, cut to length or order custom pushrods and the adjustable rockers. The big question I have not had time to work out is access to the lifter bores near the distributor and fuel pump. Maybe not an issue or maybe they could be drilled into the next cylinders lifter bores. Otherwise I am sure it would work great and the plumbing could be done a couple of ways. I have yet to have bare block to ponder over, any thoughts?
Author:  Doc [ Mon Jan 15, 2007 6:18 pm ]
Post subject: 
The SL6 lifter bores are above the main oil gallery by a couple of inches so it is not a simple matter of cross-drilling 12 holes to connect each lifter bore to the main oil supply.

If you have access to gun drilling equipment, it may be possible to drill a new front to back passage to connect all the lifter bores, right through their mid-points, then you could run some hard line to connect that new passageway to the main oil supply.

As you noted, once you find a way to supply main pressure right to the lifters, you can run the ones out of the V8 and use the adjustable rocker arms off a solid lifter engine. This would allow you to individually set each lifter's pre-load and compensate for any wear over the life of the engine.
DD
Author:  bob fisher [ Mon Jan 15, 2007 6:51 pm ]
Post subject:  additional comment on the hydraulic valves issue
hello doctor and other sl6 sages- thanks doc for the info onthe hyraulic valves. i didnt realize they were so undesirable. here is my question- i thought the hydraulic valves went in the sl6 in 80(last year for the volares and aspens)but i was just told by a mechanic that the 80 had solids and the hydraulics didnt go in until the mid 80s near the end of production of the sl6. i do know that my 76 has solids. so whats the story did the 80 have solids? regards paladin
Author:  AnotherSix [ Mon Jan 15, 2007 8:04 pm ]
Post subject: 
Thanks for the reply. What I was thinking was to drill into each lifter bore right from the outside of the block. Something like a 1/4" hole and finish the outside of the hole with 1/8" npt. Then add fittings and plumb it all to a manifold or log with steel tubing. I suppose you could drill 12 more holes and loop the tubes right down to the main galley too, but thats seems like allot of holes, especially if it does not work out and they end up needing to get plugged. Another thought was to go up to 1/4" or 3/8" npt between each pair of lifters but not all the way thru the block wall and then drill at an angle to each lifter bore. The latter would only need six external lines. This the approach from the outside is why I suspect the lifter bores around the fuel pump and distributor might be a problem. The manifold or log could be supplied with oil externally from the oil pump. Gun drilling and one external line or one at the front and back would be nice and it would work just like an LA block. Then the cam blank to use would be one with the two holes just like a mechanical blank. It would be nice to use some of the modern hydraulic lobe designs and have adjustable rockers. You can get the v-8 lifters in the "anti-pump up" type with the heavy circlips too.
Author:  72polara [ Mon Jan 15, 2007 10:40 pm ]
Post subject: 
Well, I've pretty much got the short-block of my hydraulic motor together, so it's too late to try anything radical, but the standpipes sound like something that could be tried w/o disassembling the short block - just use some pressed in pipes in the drain holes. Think this would be worthwhile w/o increasing oiling to the top end?

And I guess it still doesn't solve the main annoyance: no way to adjust the preload on the hyd lifters. I'm going to have to order custom pushrods since I've milled over .1", so I was figuring on just setting the preload to the tight side of the spec.
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