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Head and valve cover difference question
https://www.slantsix.org/forum/viewtopic.php?t=39611		 Page 1 of 2
Author:  Psevins [ Sun Mar 28, 2010 6:55 pm ]
Post subject:  Head and valve cover difference question
Not a project I'm doing, but my Dad and brother rebuilt a '83 slant 6 out of a Ram 150. They replaced the head with a junkyard find and upon reassembly the valve cover wont fit. (the original '83 one) They haven't had much luck finding anyone local who knows anything about this little problem. I told them I would consult online for some ideas. I've done some research and found that 1959-1988 were the same valve cover (at least from what I've cobbled together)

Any clues ohh wise ones of the slant 6?

-Corey
Author:  SlantSixDan [ Sun Mar 28, 2010 7:42 pm ]
Post subject: 
Welcome on the board.

It means the head swapped on was from a 1980 or earlier slant-6 engine. Any pre-1981 (1960-1980) slant-6 valve cover will fit correctly with the gasket for the '60-'80 engine. On an '83, to keep all the hookups as intended, use a '70-'80 valve cover. Should be easy and inexpensive to find.
Author:  Psevins [ Mon Mar 29, 2010 5:23 am ]
Post subject: 
thank you sir! I will pass this information along.

-Corey
Author:  hantayo13 [ Mon Mar 29, 2010 6:13 am ]
Post subject: 
81 was the year valve cover changed as did lifters from solid to hydo...the 81 up valve cover has a slight dogleg...pre 81 is straight
Author:  hantayo13 [ Mon Mar 29, 2010 6:14 am ]
Post subject: 
81 was the year valve cover changed as did lifters from solid to hydo...the 81 up valve cover has a slight dogleg...pre 81 is straight...rocker went from adjustable to non adjust
Author:  Psevins [ Mon Mar 29, 2010 5:20 pm ]
Post subject: 
So they shouldn't have any issues with the lifters then?
Author:  Psevins [ Tue Mar 30, 2010 5:38 pm ]
Post subject: 
They found a valve cover off a 66 Valiant and all seems to lining up correctly. The next problem they ran into is the stock pushrods (from the 83) aren't long enough for the pre-'80 head. I not being the mechanically inclined family member still questioned their next move. They plan on using the push rods from the '66 Valiant which do give them the length. My question was (and still is) Can you use the older solid pushrods on hydraulic lifters without causing problems down the line? The original pushrods are hollow (I assume to allow oil to flow upward).

Any thoughts? Their response when asked about this was "I dunno, should work I think" Famous last words!
Author:  SlantSixDan [ Tue Mar 30, 2010 6:24 pm ]
Post subject: 
No, you must use the whole hydraulic valvetrain. Camshaft, lifters, pushrods, rocker arms, the whole works. You cannot mix and match, it will not work.
Author:  Psevins [ Tue Mar 30, 2010 6:36 pm ]
Post subject: 
That was my feeling. I talked to them again tonight again asking my questions (more out of curiosity and trying to prevent a disaster) They were telling me that the pushrods from the '83 WERE the same length as the ones from the '66 but that the ends were different. Err, if thats the case (which I believe) then why use the ones from the '66? The ones from '83 should be used.

If memory serves the ones the gathered today have a a flat bottom (or cupped) and the original have a ball.

They aren't planning on working on it again till the weekend and I think I finally got the seed of doubt planted.

Thanks again!
Author:  SlantSixDan [ Tue Mar 30, 2010 7:03 pm ]
Post subject: 
On the hydraulic ('81+) slant-6, the lifters are fed from the top: Oil is pumped to the rocker shaft, thru the rocker arms, down thru the pushrods, and into the lifters. That's why you have to use all the pieces and not mix/match.
Author:  Psevins [ Tue Mar 30, 2010 7:21 pm ]
Post subject: 
Indeed, Im enjoying the learning curve of all this without the grease under my nails! I *think* they are thinking that the oil will be distributed through the however it would work for a non-hydraulic one. That might just be how I'm seeing it.

So there shouldn't be any issues with length (at least not to a degree that will require any major changes). They arent building a performance engine or anything. He and my dad got the truck for trade on a storage/towing bill. I plan on borrowing it to move mulch on occasion so I guess I do have some interest in it.

Thanks!
Author:  SlantSixDan [ Tue Mar 30, 2010 9:16 pm ]
Post subject: 
Quote:
I *think* they are thinking that the oil will be distributed through, the way it would work for a non-hydraulic one.
No. The mechanical parts (rockerarms and pushrods) do not direct oil thru the pushrod so there is no way to feed oil into the hydraulic lifters when using those parts.
Author:  Psevins [ Wed Mar 31, 2010 3:01 pm ]
Post subject: 
well they are pushing forward anyway. They've got a guy who says it will work and thats all they need. Just because you CAN do something doesnt mean you SHOULD do it. They explained it to me that there *should* be enough oil pressure to push the oil down into the lifters. I personally don't like the word should when it comes to engines. My prediction is this, it will start and look like its working (ie they said they can tell if its getting *enough* oil when its running and everything is open...how do they quantify enough?) but put it under any stress (load, speed, heat) I think you will see an epic failure.

I'll keep you posted as to the end results though
Author:  Psevins [ Wed Mar 31, 2010 3:03 pm ]
Post subject: 
I should mention that the only different parts they are using are the pushrods and head. The rollers, lifters, etc.. are all '83 era
Author:  Reed [ Wed Mar 31, 2010 3:19 pm ]
Post subject: 
Quote:
On the hydraulic ('81+) slant-6, the lifters are fed from the top: Oil is pumped to the rocker shaft, thru the rocker arms, down thru the pushrods, and into the lifters. That's why you have to use all the pieces and not mix/match.
Listen to what The Dan says.

If they are trying to use hydraulic lifters with the 66 non-hydraulic slant six pushrods, the lifters WILL NOT pump up. The lifters are fed by the mildly pressurized (like 4-6 PSI) oil that flows from the block, to the rocker arm shaft, to the rocker arms, to the hollow pushrod tube, and then down into the lifters.

If they are really lucky (and I doubt they will be this lucky), they might get away with using a set of mechanical rocker arms and be able to adjust the valve lash to keep the hydraulic lifters permanently compressed, and therefore achieve some semblance of a proper valve lash. However, this probably won't work, and I highly DON'T recommend it.

I strongly encourage your father and brother to keep the valve train either all hydraulic or all mechanical. Anything else is asking for an expensive disaster.
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