Slant Six Forum :: valve cover interchange

Quote:

The heads will interchange too, but you have to make sure to use the right rocker gear for your shortblock. And rocker cover.

I am nit-picking here, and normally wouldn't bother slantzilla about anything he writes since he has much more experience building motors than I do, but the rocker gear has to match the cam, not the short block. You can run a "hydraulic" head on a "mechanical" block using a "mechanical" cam so long as you use the "mechanical" rocker arms and rocker arm shaft. You can run a "mechanical" head on a "hydraulic" block and a "hydraulic" cam so long as you run the "hydraulic" pushrods, rocker arms, and rocker arm shaft. The one thing to watch out for is the rearmost hold-down bolt in the rocker arm shaft It went from a single width to a stepped width around 1977. The rearmost rocker arm shaft hod-down bolt must match the cylinder head you are using. When using a hydraulic rocker arm shaft on a pre-1977 (or so, double check on the head you want to use) you must drill out the rearmost hole in the hydraulic rocker arm shaft to allow the larger pre-77 rearmost bolt to pass through the bottom of the rocker arm shaft.

For example, my brother's 1983 Dodge van is currently running a 1976 225 block, a 1972 198 head, and a 1983 hydraulic cam and valve train. Everything works happily together but we had to drill out the rearmost bolt hole in the rocker arm shaft.

I have also personally installed and seen run a 1983 225 hydraulic bock and valve train with a 1960s era head. No problems as long as the correct rear rocker arm shaft bolt was used.

See more info about the nuances of the differences between the mechanical and hydraulic valve trains here: http://www.slantsix.org/forum/viewtopic.php?t=46756

Finally, the valve cover must match the head, nothing else. 1960-1980 heads need the 1960-1980 "mechanical" valve cover. 1981-1987 heads need the 1981-1987 "hydraulic" valve covers.

Hopefully that will clear things up a bit about mixing and matching hydraulic vs. mechanical era components.

Author:	Reed [ Thu Feb 20, 2014 12:47 pm ]
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60-80 head profile on the left, 81-87 profile on the right. Look at the bottom left corner of the heads in this picture. Compare the profile of the lip near that head bolt hole.

Author:	1930 [ Thu Feb 20, 2014 4:32 pm ]
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Quote: What's this dog-eared notch? Any pictures for clarification? I will assume that Reed is meaning this portion of the slant head all the way to the front lower. This is a 1984 head Did not see the second page. Info already posted

Author:	1930 [ Thu Feb 20, 2014 4:35 pm ]
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Quote: Quote: The heads will interchange too, but you have to make sure to use the right rocker gear for your shortblock. And rocker cover. I am nit-picking here, and normally wouldn't bother slantzilla about anything he writes since he has much more experience building motors than I do, but the rocker gear has to match the cam, not the short block. You can run a "hydraulic" head on a "mechanical" block using a "mechanical" cam so long as you use the "mechanical" rocker arms and rocker arm shaft. You can run a "mechanical" head on a "hydraulic" block and a "hydraulic" cam so long as you run the "hydraulic" pushrods, rocker arms, and rocker arm shaft. The one thing to watch out for is the rearmost hold-down bolt in the rocker arm shaft It went from a single width to a stepped width around 1977. The rearmost rocker arm shaft hod-down bolt must match the cylinder head you are using. When using a hydraulic rocker arm shaft on a pre-1977 (or so, double check on the head you want to use) you must drill out the rearmost hole in the hydraulic rocker arm shaft to allow the larger pre-77 rearmost bolt to pass through the bottom of the rocker arm shaft. For example, my brother's 1983 Dodge van is currently running a 1976 225 block, a 1972 198 head, and a 1983 hydraulic cam and valve train. Everything works happily together but we had to drill out the rearmost bolt hole in the rocker arm shaft. I have also personally installed and seen run a 1983 225 hydraulic bock and valve train with a 1960s era head. No problems as long as the correct rear rocker arm shaft bolt was used. See more info about the nuances of the differences between the mechanical and hydraulic valve trains here: http://www.slantsix.org/forum/viewtopic.php?t=46756 Finally, the valve cover must match the head, nothing else. 1960-1980 heads need the 1960-1980 "mechanical" valve cover. 1981-1987 heads need the 1981-1987 "hydraulic" valve covers. Hopefully that will clear things up a bit about mixing and matching hydraulic vs. mechanical era components. Thanks for the info Reed. I really want that earlier ribbed valve cover and this may be the way I get it. Can you tell me year to year used that ribbed or finned valve cover?

Author:	Reed [ Thu Feb 20, 2014 4:39 pm ]
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Quote: Quote: What's this dog-eared notch? Any pictures for clarification? I will assume that Reed is meaning this portion of the slant head all the way to the front lower. This is a 1984 head Did not see the second page. Info already posted Yep, that's what I am talking about. The ribbed valve covered were from 60-around 67. The only way to use one is to use a pre-1981 head.

Author:	63Valiant [ Thu Feb 20, 2014 4:46 pm ]
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Thaks for those pics guys, that clears that up for me, I'm fairly sure I've never noticed that before, but then most of my stuff has always been from the '60s, a 70's slant is new to me. Any insight as to why they made that change to that corner?

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Author:	Reed [ Thu Feb 20, 2014 5:08 pm ]
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Quote: Any insight as to why they made that change to that corner? None. Absolutely no technical reason for it. My only thought is the fact that the change coincided with the introduction of hydraulic lifters suggests that changing the valve cover was done to give the mechanics used to adjusting valves on the old mechanical lifter slant a easy visual heads up that this slant was different and had the newfangled hydraulic lifters. :shrug: Even changing the rearmost rocker shaft bolt had an obvious technical reason- to prevent the installation of the rocker arm shaft upside-down and cause poor oil flow to the rocker tips. Changing the profile of the valve cover serves no real reason that I can see.

Author:	JR [ Thu Feb 20, 2014 6:13 pm ]
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As for an early cover (like an Offy) on a later head the problem is the passenger (sparkplug) side of the head. All of the bolt holes line up perfectly on the driver (intake) side. I still think an adapter/spacer plate could be made fairly easily if someone had access to a CNC. Early gasket over a later gasket. Offy cover on a later engine. Offy cover on top of a later cover.

Author:	slantzilla [ Thu Feb 20, 2014 6:52 pm ]
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Mopar Performance did chrome stock style covers for the late heads that were very nice. I have never seen any other type of aftermarket late cover.

Author:	Reed [ Thu Feb 20, 2014 7:37 pm ]
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I could swear I saw the cheapo Chinese chrome vcs for the later heads on eBay, but I could easily be wrong. I would rather spend my money on polishing and then clear powder coating a stock stamped steel vc.

Author:	JR [ Thu Feb 20, 2014 7:53 pm ]
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Yeah, me too......oh wait...crap...nevermind.....I got one of the early model ebay chromies. I had to weld baffles in it to keep most of the oil in the engine. After you weld on one it kinda ruins the chrome.... It was cheap.

Author:	slantzilla [ Thu Feb 20, 2014 8:54 pm ]
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I don't even count the cheap crap as real parts.

Author:	1930 [ Fri Feb 21, 2014 1:02 am ]
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The more I think about it and look at the pictures I believe I will just modify an earlier valve cover to fit the later head. I believe this will be a fairly straightforward mod, I can post pict but am lacking the valve cover at this point. If anyone has one for a reasonable price than I would be interested. Thanks

Author:	Rick Covalt [ Fri Feb 21, 2014 4:04 am ]
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The Cox brothers made up some super nice sheet metal aluminum valve covers that were for the later heads. Lou has one on his project V. I think they made 3 or 4 maybe? I have no idea if there are any still around. Rick

Author:	JR [ Fri Feb 21, 2014 12:55 pm ]
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Quote: The more I think about it and look at the pictures I believe I will just modify an earlier valve cover to fit the later head. I believe this will be a fairly straightforward mod, I can post pict but am lacking the valve cover at this point. If anyone has one for a reasonable price than I would be interested. Thanks You will have to split it and widen it about 1/4" and maybe swap the mounting surface from a later cover onto the plug side. A stamped stock cover it could be done pretty easy, a finned cover wouldn't be worth the time or money to cut one up. If you were dead set on an aluminum cover for a late model it would be less work (aluminum welding) and fab time to just make an adapter and then sell them to guys like me who don't have the time to make our own.

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Author:	Reed [ Fri Feb 21, 2014 12:57 pm ]
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Or, if you are dead set on aluminum bling, the easiest solution would be to run a pre-81 head. No fabrication necessary.